Powertrain and independent suspension mounting arrangement for front-wheel-drive vehicle

In a front-wheel-drive vehicle having a powertrain with a transversely positioned engine and transmission and independent front-wheel suspensions each with a control arm, there is provided a cradle to which the drive-wheel suspension control arms are swingably mounted. A plurality of cushion mounts support the cradle at high impedance points on the vehicle body and provide a soft substantially linear spring rate at small vibratory amplitudes of the cradle in both a fore and aft direction and a vertical direction relative to the vehicle and a stiff substantially linear spring rate at all vibratory amplitudes of the cradle in a lateral direction relative to the vehicle. The powertrain is directly supported on the cradle by a plurality of cushion mounts which have soft substantially linear spring rates in the same directions as the cradle mounts. In addition, both the fore and aft rate and vertical rate of the cradle mounts and also the pitch rate of the powertrain mounts are controlled so as to be non-linear at large amplitudes of the cradle and powertrain in the respective directions. Furthermore, a rigid strut is cushion mounted between the powertrain and a mounting point on the vehicle so as to be in either tension or compression depending on whether the transmission is in forward or reverse drive. The strut mounts provide a soft substantially linear rate at small-amplitude powertrain pitch motions occurring at low powertrain torque and provide a non-linear rate at large-amplitude pitching motions occurring at high torque and cooperate with both the cradle mounts and the powertrain mounts to control and isolate pitching motions of the powertrain.

This invention relates to mounting arrangements for mounting an 
engine-transmission-differential assembly and independent front-wheel 
suspensions in a front-wheel drive vehicle and more particularly to such 
mounting arrangements wherein the engine and transmission are mounted 
transversely in the vehicle. 
In front-wheel-drive vehicles, it is common practice to have the engine and 
transmission mounts cushion the torque reaction of the differential as 
well as that of the engine and transmission. In the case where the engine 
and transmission are mounted longitudinally in the vehicle, the torque 
reaction of the differential is in the pitch direction relative to the 
vehicle while the torque reaction of both the engine and transmission is 
in the roll direction. As a result, the torque reaction of the 
differential is not difficult to deal with at the cushion mounts for the 
engine and transmission since the pitch forces on the powertrain may be 
simply resisted by their vertical spring rates while adequate roll 
resistance is retained for the engine and transmission. However, in the 
case where the engine and transmission are mounted transversely in the 
vehicle, their torque reaction is then in the pitch direction and the 
torque reaction of the differential which is also in the pitch direction 
is then directly coupled therewith. This imposes a much greater duty on 
the cushion mounts supporting the engine and transmission since the 
pitching forces in addition to the normal engine and transmission torque 
reaction are then influenced by the product of the axle ratio at the 
differential and the acting transmission ratio. According to conventional 
practice and irrespective of the relative position of the engine and 
transmission in the vehicle, it is desired that the cushion mounts 
therefor be located adjacent the points of minimum vibratory force in the 
system, i.e. the node points, to derive maximum benefit in isolating the 
vibration of the sprung mass including the differential. However, where 
the vehicle is of compact size and where the engine is of the type with 
relatively high degrees of vibration, e.g. an in-line four-cylinder and a 
V-6 versus a V-8 engine, there is typically little space for a 
conventional cushion mounting arrangement capable of effectively 
controlling and isolating pronounced powertrain vibrations and 
particularly the vertical motion or shake and pitching motion thereof 
where both the engine and transmission are positioned transversely in the 
vehicle. 
Moreover, such front-wheel-drive vehicles typically have independent front 
suspensions separate supporting the front-drive wheels. These suspensions 
include control arms which also vibrate but as a result of contact of the 
drive wheels with an irregular road surface. To control and isolate these 
vibrations, there is normally provided a cushion mounting arrangement 
therefor whose characteristics are typically substantially different in 
certain respects from those desired of the cushion mounting arrangement 
for the powertrain. Prior cushion mounting arrangements, including those 
with a cushion mounted subframe having the suspension arms mounted thereon 
and the powertrain at least partially cushion mounted thereon have 
exhibited limited ability, so far as known, in effectively controlling and 
isolating the vibrations of the independent front suspension control arms 
and the powertrain from each other and from the vehicle body and/or 
chassis wherein both the engine and transmission are positioned 
transversely in the vehicle and the engine has pronounced vibration. 
The present invention is directed to providing improved vibration control 
and isolation in a front-wheel-drive vehicle of compact size having both a 
powertrain with a transversely positioned engine and transmission and 
independent front-wheel suspensions each with a control arm. In the 
preferred embodiment, there is provided a rigid cradle or subframe to 
which the drive-wheel suspension control arms are swingably connected. A 
plurality of cushion mounts support the cradle at high impedance points on 
a unitized vehicle body remote from the powertrain with each of these 
cushion mounts providing a soft substantially linear spring rate at small 
vibratory amplitudes of the cradle in both a fore and aft direction and a 
vertical direction relative to the vehicle and a stiff substantially 
linear spring rate at all vibratory amplitudes of the cradle in a lateral 
direction relative to the vehicle. Moreover, the cradle mounts are 
provided with rate control so that they become non-linear at large 
vibratory amplitudes in the fore and aft direction and also the vertical 
direction wherein their rate in these directions then increases with 
increasing large vibratory amplitude. The cradle mounts with their soft 
linear rates in the fore and aft direction and vertical direction are 
particularly effective in isolating small-amplitude high-frequency 
vibrations of the front-suspension control arms caused by front wheel 
impacts with an irregular road surface while their stiff linear rate in 
the lateral direction is effective in providing good lateral stability 
while controlling and isolating lateral vibrations of the front-suspension 
control arms at all amplitudes and throughout the frequency range for good 
road handling. On the other hand, the non-linear rates of the cradle 
mounts in the fore and aft direction and the vertical direction are 
particularly effective in controlling and isolating large-amplitude 
vibrations of the front-suspension control arms caused by severe 
front-drive wheel impacts with an irregular road surface as well as high 
forces due to braking and acceleration. Moreover, this combination of 
linear and non-linear rates in the cradle mounts is used to help control 
and isolate vibrations of the powertrain. 
In the present invention, none of the weight of the powertrain is directly 
supported on the vehicle body and instead, a plurality of cushion mounts 
directly support the powertrain at mounting points on the cradle and with 
soft substantially linear spring rates in the same directions as the 
cradle mounts. Moreover, the powertrain mounts are provided with pitch 
rate control so that they become non-linear at large vibratory amplitudes 
in the pitching direction of the powertrain and with a rate which 
increases with increasing large vibratory pitching amplitude. With such 
series arrangement of the powertrain mounts and the cradle mounts, they 
provide very soft effective spring rates between the vehicle body and the 
vehicle body for controlling and isolating small-amplitude high-frequency 
vibrations of the powertrain in the fore and aft, vertical, lateral, roll 
and yaw directions as well as providing some control and isolation of the 
pitching motions of the powertrain at low torque. Then at high-amplitude 
vibrations, the non-linear rates of both the cradle mounts and the 
powertrain mounts are particularly effective in controlling and isolating 
low-frequency vibrations of the powertrain as well as providing some 
control and isolation of the powertrain pitching motions at high torque. 
To provide for effective control and isolation of powertrain pitching 
motion throughout the torque range, there is added a rigid torque reaction 
strut which is connected with cushion mounts between the powertrain and a 
cross-member on the vehicle body so as to be in either tension or 
compression depending on whether the transmission is in forward or reverse 
drive. The strut mounts provide a soft substantially linear spring rate at 
small vibratory pitching amplitudes occurring with low torque and together 
with the soft linear rates of the powertrain mounts and both the soft fore 
and aft linear rate and soft vertical rate of the cradle mounts 
effectively control and isolate small-amplitude pitching vibrations of the 
powertrain at such low torque. Then for large pitching powertrain 
amplitudes occurring at high torque, the strut mounts are additionally 
provided with non-linear rates that then become effective and increase 
with increasing large pitching amplitudes and together with the non-linear 
rates of both the cradle mounts and the powertrain mounts effectively 
control and isolate large-amplitude pitching vibrations of the powertrain 
at such high torque.

Referring to the drawings and particularly to FIGS. 1-4, there is shown a 
front-wheel-drive vehicle of compact size having a unitized body and frame 
10 which will hereinafter be referred to as the vehicle body and on which 
independent front-wheel suspensions 12 and a powertrain 14 are cushion 
mounted according to the presently preferred embodiment of the invention. 
To provide clear viewing of the details of the invention, certain vehicle 
components or parts not necessary to understanding the invention are shown 
only partially or have been omitted entirely. 
Turning first to the independent front-wheel suspensions 12, each of the 
front wheels 16 is suspended with a MacPherson type strut arrangement 17 
which is mounted between a high impedance point on the vehicle body 10 and 
the steering knuckle 18 of a wheel mount and brake assembly 19. The front 
suspensions further include a telescoping coil spring 20 and hydraulic 
shock absorber 21 integrated with the suspension strut and a 
wishbone-shaped lower control arm 22 which is pivotally connected at its 
outboard end to the respective steering knuckle 18 and is swingably 
mounted at its inboard end indirectly on the vehicle body 10 as described 
in detail later. All this front suspension structure is shown in FIGS. 1 
and 2 for the left front wheel and it will be understood that the 
suspension for the right front wheel has corresponding components. 
Furthermore, it will be understood that a stabilizer bar (not shown) is 
connected to the cradle 30 and lower control arms 22 and that a steering 
system (not shown) is connected to the steering knuckles 18 to 
respectively effect stabilization and steering of the front wheels. Each 
of the front wheels 16 is thus supported sprung, damped and steered in a 
well-known manner and therefore further detailed description, apart from 
the mounting of the lower control arms 22 is unnecessary. 
The powertrain 14 comprises a V-6 engine 24, manual transmission 26 and 
differential 28 which are rigidly joined together in a conventional manner 
with the combination of the transmission and differential commonly 
referred to as a transaxle. As shown in FIG. 4, the engine 24 is located 
ahead of the differential 28 and positioned transversely or crosswise of 
the vehicle body 10. The transmission 26 is also positioned transversely 
of the vehicle body and is joined to the rear end of the engine at the 
left side of the vehicle and selectively drivingly connects the engine to 
the differential with different forward drive gear ratios and a reverse 
drive gear ratio. The differential 28 with its reduction and differential 
gearing is located directly between the front wheels 16 and is connected 
to drive these wheels through half-shafts 29. The powertrain is of a 
conventional type and therefore further description thereof, apart from 
its cushion mounting and vibratory motion under certain conditions, is 
unnecessary. 
The powertrain 14 and the lower control arm 22 of both the independent 
front-wheel suspensions 12 are supported on the vehicle body 10 through a 
rigid cradle or subframe 30 separate from the vehicle body and mounted on 
the underside thereof. The cradle 30 comprises two side-rails 32, 34 and 
two cross-rails 36, 38 which respectively extend laterally and 
transversely of the vehicle body with the cross-rails joined at their ends 
to the side-rails at points inward of the ends of the latter as seen in 
FIGS. 1-4, 7 and 14. The control arms 22 are swingably mounted at their 
inboard end to the respective side-rails 32 and 34 of the cradle by a pair 
of brackets 39 which are welded in the outboard side of the respective 
side-rails and each receive the end of one of the two legs of the control 
arms on this side. As seen in FIG. 7, an elastomeric bushing 40 is mounted 
in each end of the control arm legs and has a sleeve 41 extending 
centrally therethrough. The sleeve 41 is bonded to the bushing 40 and a 
bolt 42 extends through each bracket 39 and the associated bushing sleeve 
41 and is secured with a nut 43. All the above front-suspension control 
arm mounting structure is shown for the left control arm and it will be 
understood that the right control arm is similarly mounted. 
The cradle 30 is mounted at four high impedance points on the vehicle body 
10 on opposite sides of the front wheel wells and remote from the 
powertrain 14. The cradle cushion mounting arrangement comprises two front 
cushion mounts 44 and two rear cushion mounts 45. Each of the front cradle 
cushion mounts 44 is located adjacent the front end of one of the cradle 
side-rails 32 and 34 ahead of the transversely positioned engine 24 and 
transmission 26. Each of the rear cushion mounts 45 is located adjacent 
the rear end of one of the cradle side-rails 32 and 34 rearward of the 
differential 28. With the relative arrangement of the powertrain 14 and 
the cradle 30 shown, a greater portion of the weight of the powertrain is 
supported by the two rear cradle mounts 45 as well as the roll stabilizer 
bar loads. In the cradle cushion mounting arrangement shown, the two front 
mounts 44 are identical to each other and the rear cradle mounts 45 are 
also identical to each other and similar in construction and assembly to 
the front cradle mounts 44. In the description of the left front cradle 
mount 44 that follows, it will thus be understood that such description 
applies to the right front mount and that the corresponding parts of the 
rear cradle mounts 45, as shown in FIG. 7, will be identified by the same 
numerals but primed. Furthermore, it will be understood that the 
appropriate parts of the rear cradle mounts are made proportionately 
larger in load bearing capacity is than the front cradle mounts to handle 
the higher loading thereon as will be seen by the higher spring rates they 
are provided with as described later. 
Describing now the left front cradle mount 44 which is best seen in FIGS. 
5, 6 and 7, there is provided a pair of ring-shaped elastomeric cushions 
47 and 48, a spacer 50, a retainer 51, a bolt 52 and a cage nut 53. The 
spacer 50 engages at its upper end with the lower side of a rigid front 
underbody portion 54 of the vehicle body 10 about a cradle mounting bolt 
hole 55 therethrough over which the cage nut 53 is located. The spacer 50 
has an annular downwardly extending and radially outwardly flared rate 
control collar 56 formed integral therewith and the upper cushion 47 
engages at its upper end with the lower side of the spacer 50 inward of 
its rate control collar. The rate control collar 56 provides for 
non-linear rate control in the cradle mount in the vertical direction as 
will be described in detail later. The upper cushion 47 has a washer 57 
bonded to its lower end which engages the upper side of the cradle 
side-rail 32 about a mounting hole 58 therethrough which aligns with the 
overhead bolt hole 55 in the rigid underbody portion 54. A sleeve 60 
having a radially outwardly extending shoulder 62 at its lower end is 
bonded to the lower cushion 48. The sleeve 60 extends vertically upward 
through the mounting hole 58 in the cradle side-rail while the shoulder 62 
on the sleeve engages the lower side of the cradle side-rail about the 
hole. The spacer 50 also has a centrally located elongated hollow neck 64 
of generally rectangular cross-section which extends vertically downward 
through a correspondingly-shaped central opening 66 in the lower cushion 
48 and engages at its lower end with the upper side of the retainer 51 
about a central bolt hole 68 therethrough. 
The retainer 51 engages the lower end of the lower cushion 48 and the 
spacer 50 and retainer 51 are clamped together through the spacer neck 64 
and against the lower side of the rigid underbody portion 54 by the bolt 
52 which extends vertically upward through the retainer bolt hole 68, 
spacer neck 64 and underbody portion bolt hole 55 and is threaded to the 
cage nut 53. The lower cushion 48 has an integral upwardly extending 
annular neck 70 which is bonded at its periphery to the interior of sleeve 
60 along its length except as described later and has a central opening 
therethrough co-extensive with cushion opening 66 through which the spacer 
neck 64 extends with an interference fit. Thus, the elastomeric annular 
neck 70 is tightly captured between sleeve 60 and spacer neck 64. In 
addition, a pair of perforated rate plates 72 are molded in place in the 
elastomeric neck 70 of the lower cushion 48 on opposite sides thereof with 
these plates extending longitudinally or fore and aft of the cradle 
side-rail and thus the vehicle body. Furthermore, a pair of voids 73 are 
formed at diametrically opposite locations between the interior of the 
sleeve 60 and the periphery of the elastomeric neck 62 in the two areas 
intermediate the rate plates 72. The voids 73 extend vertically the length 
of the sleeve 60 and are bisected by a plane extending longitudinally or 
fore and aft of the cradle side-rail and thus the vehicle body. The voids 
73 leave the elastomeric neck 70 with diametrically opposite relatively 
thick radial sections 74 each containing one of the rate plates 72 and 
joining the spacer neck 64 and the sleeve 60 at opposite sides thereof in 
the lateral direction relative to the cradle side-rail as seen in FIG. 6. 
In addition, the voids 73 leave the elastomeric neck 70 with diametrically 
opposite thin radial sections 75 trapped between the spacer neck 64 and 
the sleeve 60 in the fore and aft direction relative to the cradle 
side-rail as seen in FIG. 5. The thin radial sections 75 of the 
elastomeric neck 70 are spaced radially inward of the interior of the 
sleeve 60 and provide non-linear rate control in the cradle mount in the 
fore and aft direction as described in more detail later. To fix the above 
described orientation of the cradle mount assembly relative to the cradle 
and thus also to the powertrain mounted thereon, the mounting hole 58 in 
the cradle side-rail is provided with parallel flats 76 which extend 
longitudinally or fore and aft of the cradle side-rail and engage 
corresponding parallel flats 78 formed on the periphery of the sleeve 60 
which is bonded to the lower cushion 48. 
With the cradle mounting arrangement thus provided and as shown 
schematically in FIG. 16, the cradle mounts 44 and 45 operate to provide a 
low or soft substantially linear spring rate cushioning cradle motion at 
small vibratory amplitudes in the vertical direction (shake) relative to 
the vehicle body (e.g. less than 5 mm). This is accomplished by their 
upper cushions 47, 47' providing through their height soft linear spring 
rates in compression at relatively low and high values to resist upward 
vertical movement of the cradle 30 relative to the vehicle body at these 
mounting points until further compression thereof is resisted by the rate 
control collars 56, 56' while the lower cushions 48, 48' through their 
height provide correspondingly soft substantially linear spring rates in 
compression at relatively low and high values but to resist relative 
downward movement of the cradle. At large vibratory amplitudes in the 
vertical direction (e.g. greater than 5 mm), the deformation of the upper 
cushions 47, 47' is then resisted by gradual engagement with the rate 
control collar 56, 56' resulting in these cushions then providing 
non-linear rates in the vertical direction which then increase with 
increasing large vibratory amplitude of the cradle in this direction at 
these mounting points to thereby provide increasing stiffness to control 
and isolate such vibrations. 
The cradle mounts 44 and 45 also operate to provide a low or soft 
substantially linear spring rate cushioning cradle motion at small 
vibratory amplitudes in the fore and aft direction (e.g. less than 5 mm). 
This is accomplished by the transverse shear resistance along the thick 
radial sections 74, 74' of the elastomeric necks 70, 70' parallel to the 
rate plates 72, 72' which effectively provides soft substantially linear 
spring rates at relatively low and high values resisting such motion at 
small vibratory amplitudes at these mounting points until the thin radial 
sections 75, 75' of the elastomeric necks bottom out in the voids 73, 73' 
at large vibratory amplitudes in the fore and aft direction (e.g. greater 
than 5 mm). With such bottoming out, there is resultantly provided 
non-linear spring rates in the fore and aft direction in the front and 
rear cradle mounts of relatively low and high value which increase with 
increasing large vibratory amplitude of the cradle in the fore and aft 
direction at these mounting points to control and isolate such vibrations. 
On the other hand, the cradle mounts 44 and 45 operate to provide a high or 
stiff substantially linear spring rate cushioning cradle motion at all 
vibratory amplitudes in the lateral direction relative to the vehicle body 
(e.g. 0-5 mm). This is accomplished by the thick radial sections 74, 74' 
of the elastomeric necks 70, 70' each with their separate rate plate 72, 
72' acting in compression and tension transverse to the rate plates at all 
vibratory amplitudes of the cradle at these mounting points in the lateral 
direction relative to the vehicle body. 
The above arrangement of cradle mounts 44 and 45 with their soft linear 
rate in the fore and aft direction and in the vertical direction has been 
found to be very effective in isolating small-amplitude high-frequency 
vibrations of the front-suspension control arms (e.g. greater than 25 Hz) 
caused by front-drive wheel impacts with an irregular road surface while 
their stiff linear rate in the lateral direction has been found to be very 
effective in controlling and isolating lateral vibrations of the 
front-suspension control arms at all amplitudes and throughout the 
frequency range for good road handling. On the other hand, the non-linear 
rates of the cradle mounts in the fore and aft direction and vertical 
direction have been found to be very effective in controlling and 
isolating large-amplitude low-frequency vibration of the front-suspension 
control arms (e.g. less than 25 Hz) caused by severe front-drive wheel 
impacts with an irregular road surface and/or braking or acceleration 
loads. Moreover, this combination of linear and non-linear rates in the 
cradle mounting has been found to be very effective in helping to control 
and isolate vibrations of the powertrain when mounted on the cradle as 
will now be described. 
In the vibratory system of the powertrain 14 that is shown, there are two 
points A and B of minimum vibratory force, i.e. node points, in the first 
bending mode with the point A located on the transverse 
engine-transmission axis TA near the front end of the engine 24 and the 
other point located on this axis near the rear end of the transmission 26 
as shown in FIGS. 3 and 16. The powertrain 14 is mounted so that all of 
its weight is directly supported by the cradle 30 adjacent these node 
points and this is accomplished with a three-point cushion mounting 
arrangement comprising a single engine mount 82 located adjacent and below 
the elevation of node point A and two transmission (transaxle) mounts 84 
and 86 located on the respective front and rear side of the transmission 
26 adjacent the opposite sides of and below the elevation of node point B. 
With such orientation of the transmission mount 84 and 86, they will be 
referred to as the front and rear transmission mount respectively. 
As shown in FIGS. 1, 2, 3, 4 and 12-14, the engine mount 82 comprises an 
elastomeric block or cushion 88 which has an M-shape in side elevation 
(FIG. 12) and is bonded at its lower and upper side to a cradle mounting 
bracket 90 and a cushion mounting bracket 92 respectively. The cradle 
mounting bracket 90 is bolted to a bracket 95 which is welded to the inner 
side of the cradle side-rail 34 at the front end of the engine and the 
cushion mounting bracket 92 is bolted to an engine mounting bracket 97 
which in turn is bolted directly to the front end of the engine block 100. 
In addition, a cross-pin 101 is fixed to opposite upstanding sides 102 
integral with the cradle mounting bracket 90 and extends across and above 
a channel 104 formed in the cushion mounting bracket 92 to maintain 
connection between the two brackets 90 and 92 and thus between the engine 
and cradle should separation occur in the elastomeric block 88. As 
oriented, the elastomeric block 88 provides a low or soft substantially 
linear spring rate in the fore and aft, vertical and lateral directions as 
shown in FIG. 16 for cushioning all motions of the powertrain except large 
pitching motions thereof. For large pitching motions of the powertrain, 
the elastomeric block 88 is provided with a pair of voids 106 and 107 in 
the legs thereof which extend longitudinally of the engine and thus 
transversely of the vehicle body and are located adjacent upwardly and 
outwardly extending rate control arms 108 and 109, respectively, formed 
integral with the ends of the cushion mounting bracket 90 as shown in FIG. 
12. As a result, when the powertrain attempts to pitch to a large degree 
(e.g. greater than 3.degree.) in either the clockwise or counterclockwise 
direction as viewed in FIGS. 4 and 16 depending on whether the 
transmission is in forward or reverse drive respectively, the voids 106 
and 107 will respectively close against the resistance of the respective 
rate control arms 108 and 109 and the elastomeric block 88 because of the 
resistance to further deformation thereof will then provide a non-linear 
pitch rate which increases with increasing large pitching amplitude to 
help control and isolate such large pitching powertrain motions. 
The front transmission mount 84, as shown in FIGS. 1-4, 8, 9 and 14, 
comprises a solid elastomeric block or cushion 110 which is bonded at 
opposite sides to a cushion mounting plate 112 and a cradle mounting 
bracket 114, respectively. The cushion mounting plate 112 is bolted to a 
transmission mounting bracket 116 which in turn is bolted to the front 
side of the transmission (transaxle) case 117 adjacent and below the 
elevation of node point B while the cradle mounting bracket 114 is bolted 
to the front cradle cross-rail 36 near the cradle side-rail 32. In 
addition, the mounting plate 112 is provided with an integral hook 120 
which is received through an opening 122 in the cradle mounting bracket 
114 to maintain connection between the plate 112 and the bracket 114 and 
thus between the transmission and cradle should separation occur in the 
elastomeric block 110. The elastomeric block 110 is oriented at 45.degree. 
looking in elevation longitudinally of the engine and transversely of the 
vehicle body as seen in FIG. 8 and provides a low or soft substantially 
linear spring rate in the fore and aft, vertical and lateral directions as 
shown in FIG. 16 for cushioning all motions of the powertrain except large 
pitching motions thereof. For large pitching motions of the powertrain, 
the bracket 114 is formed with an integral rate control arm 124 which is 
engaged by the elastomeric block 110 on pronounced pitching motion (e.g. 
greater than 3.degree.) of the powertrain in a clockwise direction as 
viewed in FIGS. 4 and 16 when the transmission is in forward drive. On 
such contact with the rate control arm 124, further deformation of the 
elastomeric block 110 is then gradually resisted with further increasing 
large pitching amplitude resulting in a non-linear pitch rate which 
increases with pronounced and increasing pitch of the powertrain to help 
control and isolate such pitching motions. 
The rear transmission mount 86, as shown in FIGS. 1, 2, 4, 10, 11 and 14, 
comprises a solid elastomeric block or cushion 130 which is bonded on 
opposite sides to a mounting plate 131 and a cradle mounting bracket 132. 
The mounting plate 131 is bolted to a transmission mounting bracket 135 
which in turn is bolted to the rear side of the transmission case 117 
adjacent and below the elevation of node point B. The cradle mounting 
bracket 132 is directly bolted to the rear cradle cross-rail 38. In 
addition, a hook 139 is integrally formed with the mounting plate 131 and 
is received in an opening 140 in the cradle mounting bracket 132 to 
maintain connection between the plate 131 and bracket 132 and thus between 
the transmission and cradle should separation occur in the elastomeric 
block 130. The elastomeric block 130 is oriented at 45.degree. like the 
front transmission mount but in the opposite direction and provides a low 
or soft substantially linear spring rate in the fore and aft, vertical and 
lateral directions as shown in FIG. 16 for cushioning all motions of the 
powertrain except large pitching motions thereof. For large pitching 
motions of the powertrain, a rate conrol arm 142 is formed integral with 
the transmission mounting bracket 135 so as to be engaged by the 
elastomeric block 130 on pronounced pitching motions of the powertrain in 
the clockwise direction as viewed in FIGS. 4 and 16 when the transmission 
is in forward drive. With such resistance and deformation, the elastomeric 
block 130 then provides a non-linear pitch rate which increases with 
pronounced and increasing large pitching amplitudes of the powertrain to 
help control and isolate such large pitching motions. 
Thus, the powertrain 14 has all its weight elastomerically supported at 
three points on the cradle 30 which in turn is elastomerically supported 
at four high impedance points on the vehicle body 10 as shown 
schematically in FIG. 16. With the powertrain mounts 82, 84 and 86 and the 
cradle mounts 44 and 45 in series, they thus provide an effective very low 
spring rate between the powertrain and the vehicle body which is lower or 
softer than their separate spring rates while the cradle mounts remain 
effective to control and isolate the vibrations of the front-suspension 
control arms 22. The very soft cushioning of the powertrain provided by 
the linear rates of both the cradle mounts 44 and 45 and the powertrain 
mounts 82, 84 and 86 has been found to provide very effective control and 
isolation of small-amplitude high-frequency vibrations in the fore and 
aft, vertical, lateral, roll and yaw directions as well as providing some 
control and isolation of the pitching motions of the powertrain at low 
torque. On the other hand, the non-linear rates of both the cradle mounts 
44 and 45 and the powertrain mounts 82, 84 and 86 have been found to be 
very effective in controlling and isolating large-amplitude low-frequency 
powertrain vibrations as well as providing some control and isolation of 
the pitching motions of the powertrain at high torque. 
To maintain the very effective vibration control and isolation provided by 
the cradle and powertrain mounts in all but the pitch direction as above 
described and to avail of the substantial powertrain pitch control and 
isolation that they do provide as also described above, there is 
additionally combined therewith a torque reaction strut assembly 150 which 
is cushion mounted with both linear and non-linear spring rates between 
the front side of the powertrain 14 and a rigid forward portion 152 of the 
vehicle body 10 which extends transversely thereof ahead of the 
powertrain. As shown in FIGS. 1-4, 14 and 15, the torque reaction strut 
assembly 150 comprises a rigid strut or link 154 which has an elastomeric 
bushing or cushion 155 press-fitted in a circular opening 156 in each end 
thereof with a sleeve 157 extending through the center of and bonded to 
each of the elastomeric bushings. The strut 154 extends longitudinally 
(fore and aft) and generally horizontally with respect to the vehicle body 
and is connected to the powertrain 14 at an elevation above and relative 
to the center of gravity (c.g.) thereof so as to directly resist the 
pitching forces. For such connection, there is provided an engine mounting 
bracket 158 which is bolted to the front side of the engine block 100 at 
this balance point and has parallel arms 160 between which one end of the 
strut 154 is received. A bolt 162 extends through one bracket arm and 
bushing sleeve at this end and then the other bracket arm and is secured 
in place with a nut 164. The ends of the bushing sleeve 157 are serrated 
so as to prevent relative turning of the sleeve on tightening of the nut. 
The other end of the strut 154 is connected to the transverse body frame 
member 152 by a bracket 166, bolt 168 and nut 169 in a similar manner. The 
axes of the strut bolts 160 and 168 are parallel and extend longitudinally 
of the engine and transmission so that with pitch of the powertrain, the 
strut is placed in tension when the transmission is in forward drive and 
is placed in compression when the transmission is in reverse drive. 
The strut elastomeric bushings 155 have a low or soft substantially linear 
spring rate to cushion small-amplitude powertrain pitching motions 
occurring with low torque and have a non-linear spring rate to cushion 
large-amplitude pitching motions occuring with high torque. On the other 
hand, the strut 154 and bushings 155 have no substantial effect in 
controlling purely vertical and lateral vibrations of the powertrain which 
are instead controlled and isolated by the powertrain mounts and the 
cradle mounts as previously described. As shown in FIG. 15, the strut 
bushings 155 have a central annular body 170 which extends about their 
sleeve 157 and is spaced radially inward of the strut in the opening 156 
in the fore and aft direction with predetermined large and small 
clearances 172 and 174, respectively. In addition, the strut bushings 155 
are formed with integral and oppositely extending radial ribs 178 in the 
vertical direction which engage the strut at diametrically opposite areas. 
As a result, the strut bushings 155 cooperatively provide a low or soft 
substantially linear spring rate in shear across their ribs 178 in the 
fore and aft direction to cushion powertrain pitching motions at low 
amplitudes occurring with low torque (e.g. less than 3.degree.) as allowed 
by the large clearances 172 when the transmission is in forward drive and 
at lower amplitudes (e.g. less than 1.degree. ) as allowed by the small 
clearances 174 when the transmission is in reverse drive. Then when the 
powertrain pitching amplitudes become large at high torque in forward and 
reverse drive (e.g. greater than 3.degree. and 1.degree. respectively), 
the large and small clearances 172 and 174 close respectively so that the 
body 170 of each of the bushings 155 then engages the strut and 
cooperatively provide an increasing spring rate in compression with 
increasing large pitching amplitudes to cushion the pitching motions at 
such high torque. 
The torque reaction strut assembly 150 with its soft linear spring rate 
together with the soft linear pitch rates of the powertrain mounts 82, 84 
and 86 and both the soft fore and aft rates and vertical rates of the 
cradle mounts 44 and 45 has been found to be very effective in controlling 
and isolating small-amplitude high-frequency pitching vibrations of the 
powertrain occurring at low torque. On the other hand, the torque reaction 
strut assembly 150 with its non-linear rate together with the non-linear 
rates of both the powertrain mounts 82, 84 and 86 and the cradle mounts 44 
and 45 has been found to be very effective in controlling and isolating 
large-amplitude low-frequency pitching vibrations of the powertrain 
occurring at high torque. 
For example, assuming torque reaction in the powertrain 14 in the clockwise 
direction as viewed in FIGS. 4 and 16 which occurs when the transmission 
is in forward drive, the torque reaction strut assembly 150 will be placed 
in tension to cushion such pitching motions with its soft linear rate at 
low torque and alternatively with its non-linear rate at high torque 
provided by the elastomeric bushings 155. At the same time, the powertrain 
mounts 82, 84 and 86 will cushion such pitching motions of the powertrain 
with their soft linear pitch rate at the low torque and alternatively with 
their non-linear pitch rate at the high torque. Meantime, the cradle will 
be caused to move both fore and aft and vertically with the pitching 
powertrain and thus the cradle mounts 44 and 45 by acting on the cradle 
will also cushion such pitching powertrain motions with their soft linear 
fore and aft rates and soft linear vertical rates at low torque and 
alternatively with their non-linear rates in these directions at high 
torque. On the other hand, when the pitching motion of the powertrain 14 
is in the counterclockwise direction as viewed in FIGS. 4 and 16, which 
occurs when the transmission is in reverse drive and thus typically with 
less engine throttle opening and therefor at lower torque, the torque 
reaction strut assembly 150 is placed in compression to cushion such 
smaller pitching motions with both its linear and non-linear rates in 
cooperation with the linear pitch rate of the powertrain mounts 82, 84 and 
86, the non-linear pitch rate of the engine mount 82 if need be, the 
linear fore and aft and vertical rates of the cradle mounts 44 and 45 and 
also the non-linear rates of the latter if need be. 
In the front-drive vehicle shown, the powertrain 14 weighs approximately 
500 pounds and the cradle 30 weights approximately 35 pounds and effective 
vibration control and isolation of the powertrain 14 and the suspension 
lower control arms 22 was obtained with cushion mount linear spring rates 
about as follows: 
______________________________________ 
Linear Spring Rate (N/mm) 
K.sub.f K.sub.1 K.sub.v 
Cushion Mount 
(fore and aft) 
(lateral) (vertical) 
______________________________________ 
44 360 1860 320 
45 880 2750 860 
82 250 70 360 
84 180 50 1180 
86 220 60 220 
150 350 
______________________________________ 
Furthermore, in the vehicle shown, the cradle 30 is also adapted to 
accommodate the powertrain when provided with an automatic transmission 
and in that case, the rate of the torque reaction strut assembly 150 and 
also the fore and aft rate of the engine mount 82 are reduced as compared 
with their respective rates for the manual transmission because of the 
reduced torque reaction. With an automatic transmission, effective 
vibration isolation was obtained with the torque reaction strut assembly 
having a linear rate of about 180 N/mm and with the engine mount 82 having 
a linear fore and aft rate of about the same value. Furthermore, it will 
be understood that the mounting arrangement is also adapted to accommodate 
an in-line four-cylinder engine in lieu of the V-6 engine shown without 
change in the cradle cushion mounts and without changing the powertrain 
mounting points. However, there will typically be some adjustment of their 
powertrain mounts rates but not necessarily that of the torque reaction 
strut assembly according to the particular vibration characteristics of 
the four-cylinder engine selected. 
Thus, the above described preferred embodiment is intended to be 
illustrative of the invention which may be modified within the scope of 
the appended claims.