i think my rear trans mount is bad but not certain. is there anyway i can tell for sure?

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2006 Crown Vic, white P71 interceptor. Push bar, 35% tint.

TRADED IN! 2008 G8 Ignition Orange Metallic LY7, 47k miles, Flowmasters, all options but sunroof.

SOLD! 2000 SSEI Black, 180 t-stat, autolite 104's, 3.4" MPS, custom M&D CAI, 1/8" phenolic S/C spacer, throttle body heat sheild, solid front mount, MSD wires, shift kit, 3rd brake light overlay, cleared headlights, tinted and cleared tails, 20% tint, Syntec, ARP license plate bolts Goodyear Eagle GT's,disabled DRL's, 8000k H.I.D's, pilot angel eye fogs

TRADED IN2004 GXP Black. 53,000mi.... drop in K&N filter, 5000k H.I.D. lows, 8000k H.I.D fogs, switchback 5000K turn signals. cleared headlights. 20% Tint.

Well you already have a solid front mount. What makes you think the rear is bad? Does the engine move?

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

i have a slight shudder on light acceleration. kinda feels like the engine is rocking back and forth. isn't it kinda a common problem for the rear mounts to go bad?

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2006 Crown Vic, white P71 interceptor. Push bar, 35% tint.

TRADED IN! 2008 G8 Ignition Orange Metallic LY7, 47k miles, Flowmasters, all options but sunroof.

SOLD! 2000 SSEI Black, 180 t-stat, autolite 104's, 3.4" MPS, custom M&D CAI, 1/8" phenolic S/C spacer, throttle body heat sheild, solid front mount, MSD wires, shift kit, 3rd brake light overlay, cleared headlights, tinted and cleared tails, 20% tint, Syntec, ARP license plate bolts Goodyear Eagle GT's,disabled DRL's, 8000k H.I.D's, pilot angel eye fogs

TRADED IN2004 GXP Black. 53,000mi.... drop in K&N filter, 5000k H.I.D. lows, 8000k H.I.D fogs, switchback 5000K turn signals. cleared headlights. 20% Tint.

Common for the fronts, not the rear.

During acceleration, the engine wouldn't be rocking back and forth, it would be pulling back as hard as it could.

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

well its under very very light acceleration. i guess idk i just want this *dang* thing fixed its about the only thing that makes scene in my head anyways. any other ideas? the mount is only $30 new so i might just do it to eliminate that possibility.

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2006 Crown Vic, white P71 interceptor. Push bar, 35% tint.

TRADED IN! 2008 G8 Ignition Orange Metallic LY7, 47k miles, Flowmasters, all options but sunroof.

SOLD! 2000 SSEI Black, 180 t-stat, autolite 104's, 3.4" MPS, custom M&D CAI, 1/8" phenolic S/C spacer, throttle body heat sheild, solid front mount, MSD wires, shift kit, 3rd brake light overlay, cleared headlights, tinted and cleared tails, 20% tint, Syntec, ARP license plate bolts Goodyear Eagle GT's,disabled DRL's, 8000k H.I.D's, pilot angel eye fogs

TRADED IN2004 GXP Black. 53,000mi.... drop in K&N filter, 5000k H.I.D. lows, 8000k H.I.D fogs, switchback 5000K turn signals. cleared headlights. 20% Tint.

Have you ruled out all the other possible causes? Plugs, wires, transmission fluid, etc.? The mount may be inexpensive, but it is a real PITA to change.

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*Gone, but not forgotten* - Black 2000 SSEi, HIR Headlights, Angel Eyes fogs, 3rd brake light overlay, hi-flo cat, 180 degree thermostat, HS 1.9 rockers, LSx yellow springs, Intense FWI, PCM, shift kit, push rods, and 3.4 Pulley. ZZP Power Log.

yeah all that has been changed... twice actually. but now i have a bigger problem to deal with. the output shaft came out with my axle......

_________________
2006 Crown Vic, white P71 interceptor. Push bar, 35% tint.

TRADED IN! 2008 G8 Ignition Orange Metallic LY7, 47k miles, Flowmasters, all options but sunroof.

SOLD! 2000 SSEI Black, 180 t-stat, autolite 104's, 3.4" MPS, custom M&D CAI, 1/8" phenolic S/C spacer, throttle body heat sheild, solid front mount, MSD wires, shift kit, 3rd brake light overlay, cleared headlights, tinted and cleared tails, 20% tint, Syntec, ARP license plate bolts Goodyear Eagle GT's,disabled DRL's, 8000k H.I.D's, pilot angel eye fogs

TRADED IN2004 GXP Black. 53,000mi.... drop in K&N filter, 5000k H.I.D. lows, 8000k H.I.D fogs, switchback 5000K turn signals. cleared headlights. 20% Tint.

I have the exact same problem under either very light acceleration or when I decrease acceleration back to a cruising speed. I think others have described this as either surging or bucking. If I then completely let off the the gas and resume it goes away, until I try light acceleration again. Under moderate to heavy acceleration - nothing. I suspected igintion for a while but have since suspected "engine rocking" as a result of spongy old mounts which I know I have. If I let off abruptly from a hard accelaration... BANG the engine smashes back down.

I haven't replaced my front mount yet but have the whole hockey puck assembly ready to install. I'll hurry and elimate that possibility and will report back.

_________________
Mark
The Familyman's Trans-Am
Intense 3.4 MPS, Intense FWI, Intense PCM, copper NGKs TR55's, MSD wires, MSD coils, BWD ICM, MagnaFlow High Flow Cat, drilled 180 'stat, solid front mount, Monroe Max Air rear shocks, Moog rear mounts, Moog suspension bushings, cleared front corners, 190,000 miles

i also experience a subtle surging under light acceleration. i just assumed it was because i removed my MAF screen. The little bit of air comin through the throttle body is tumbling pretty bad at at that throttle angle.

My theory on "Hesitation/Bucking at light accelation because of worn front mount" has been debunked!

I installed my "3-hockey-puck-and-a half-dozen-washers on a 7/12 plus inch bolt-with an end link bushing-under the frame" mount tonight and...she still bucks the same way at lite exceleration, mostly noticeable on upper gears.

Do get a different vibe for sure from the engine. Even heard the dash starting to rattle a bit for a while, so still keeping "going back to oem" option open. But I love that the engine doesn't slam down on 'accelation let-offs' anymore. I will post pics of "torn" original mount, torn underneath and not visible...so you can't judge from just exterior looks for ruptures.

So the puck mount has certanly stabilized the engine but "she feels a little different", and at my age that's not necessarily a bad thing..

_________________
Mark
The Familyman's Trans-Am
Intense 3.4 MPS, Intense FWI, Intense PCM, copper NGKs TR55's, MSD wires, MSD coils, BWD ICM, MagnaFlow High Flow Cat, drilled 180 'stat, solid front mount, Monroe Max Air rear shocks, Moog rear mounts, Moog suspension bushings, cleared front corners, 190,000 miles

If you put a swaybar bushing on the bolt between the frame, you can eliminate that vibration.

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

Your surging or bucking is more than likely a trans problem, Pressure Control Solenoid or the Torque Converter Clutch isnt unlocking properly.

Yeah the solid mount gives you a more positive feel of the car as a whole as far as Im concerned, more "racecarish" i spose. But yes throw some sort of rubber bushing under the subframe between it and the bolt nut, as mentioned an old swaybar bushing works good.

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Surging and bucking is usually an ignition related problem 100x before it is a trans problem.

_________________
Andrew - owner/operator of Bonnevilles Unlimited

2004 Bonneville GXP | 60k | White Gold Tricoat | custom built supercharged 3800 hot rod | garage queen
1997 Corvette | 55k | Silver Metallic | Z06 wheels | Date-night Hauler/Parts runner
2014 Town & Country Limited | Cashmere Pearl | 95k | Family Hauler
2002 Ram 1500 Quad Cab Sport | Black| 260k | Official Bonneville Hauler

But if it goes away under heavy accel, wouldnt a ignition problem still be present? Im thoroughly convinced mine is a trans problem.

EDIT-- Cause the trans has to downshift, unlocking the torque convertor.

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Not neccesarily. I've had more than one mechanic say that especially with GMs the hesitation/surge at low accelaration is ignition related. I have been narowing down this problem for a while and replaced the cat, worn plugs, and ignition wires with progressive improvements with each (especially the new plugs). I have to replace the coils now if I want to eliminate the ingnition theory.

From another current thread it appears that the issue may centre around the tranny, TCC and possibly the presurre control selanoid.

_________________
Mark
The Familyman's Trans-Am
Intense 3.4 MPS, Intense FWI, Intense PCM, copper NGKs TR55's, MSD wires, MSD coils, BWD ICM, MagnaFlow High Flow Cat, drilled 180 'stat, solid front mount, Monroe Max Air rear shocks, Moog rear mounts, Moog suspension bushings, cleared front corners, 190,000 miles

as far as ignition problem. i've replaced plugs, wires, coil packs, and ignition modual all in the past year.........

_________________
2006 Crown Vic, white P71 interceptor. Push bar, 35% tint.

TRADED IN! 2008 G8 Ignition Orange Metallic LY7, 47k miles, Flowmasters, all options but sunroof.

SOLD! 2000 SSEI Black, 180 t-stat, autolite 104's, 3.4" MPS, custom M&D CAI, 1/8" phenolic S/C spacer, throttle body heat sheild, solid front mount, MSD wires, shift kit, 3rd brake light overlay, cleared headlights, tinted and cleared tails, 20% tint, Syntec, ARP license plate bolts Goodyear Eagle GT's,disabled DRL's, 8000k H.I.D's, pilot angel eye fogs

TRADED IN2004 GXP Black. 53,000mi.... drop in K&N filter, 5000k H.I.D. lows, 8000k H.I.D fogs, switchback 5000K turn signals. cleared headlights. 20% Tint.

Another area to check is a vacuum leak. Under light acceleration, you have nearly full manifold vacuum so if there's a leak, everything is off. Under full acceleration, manifold vacuum goes to atmosphere( 0psig) so you don't notice a problem.
Look under the supercharger snout to be sure there isn't a crack or leak at the tee.

Update! I yesterday decided to check on the new solid mount and tightened down the nut a few more turns, with relative ease I might add. I guess the mount may not have been fully secured originally or perhaps the bolt head later seated differently. Well for over a day's travelling now my engine surging and bucking on very light acceleration in 3rd/4th gear is now 99% gone!

EDIT: 100% gone for a couple of days now! So for me, the "bucking on very light acceleration" was in fact caused by a torn original mount and then an insufficiently tightened new mount.

So, Dan-o maybe try tightening up some more your front solid mount and who knows? Maybe that's all it is...

Here's a pic of the torn mount (torn underneath out of sight): http://i415.photobucket.com/albums/pp23 ... 0_5321.jpg

_________________
Mark
The Familyman's Trans-Am
Intense 3.4 MPS, Intense FWI, Intense PCM, copper NGKs TR55's, MSD wires, MSD coils, BWD ICM, MagnaFlow High Flow Cat, drilled 180 'stat, solid front mount, Monroe Max Air rear shocks, Moog rear mounts, Moog suspension bushings, cleared front corners, 190,000 miles

its worth a try! i'll try it some time this weekend when i get a chance.

_________________
2006 Crown Vic, white P71 interceptor. Push bar, 35% tint.

TRADED IN! 2008 G8 Ignition Orange Metallic LY7, 47k miles, Flowmasters, all options but sunroof.

SOLD! 2000 SSEI Black, 180 t-stat, autolite 104's, 3.4" MPS, custom M&D CAI, 1/8" phenolic S/C spacer, throttle body heat sheild, solid front mount, MSD wires, shift kit, 3rd brake light overlay, cleared headlights, tinted and cleared tails, 20% tint, Syntec, ARP license plate bolts Goodyear Eagle GT's,disabled DRL's, 8000k H.I.D's, pilot angel eye fogs

TRADED IN2004 GXP Black. 53,000mi.... drop in K&N filter, 5000k H.I.D. lows, 8000k H.I.D fogs, switchback 5000K turn signals. cleared headlights. 20% Tint.