I have a 87 GTA with the 700R4 and I replaced my broken stock mount with the energy suspension one. Now as I accelerate it vibrates around 30-50 ESPECIALLY IN THIRD GEAR, seems like 3rd amplifies it or something. Would new U-Joints solve this problem or has the pinion angle changed. I have also read that if I use 1/8 inch washers between the frame and trans crossmember it would also fix it. Any ideas??

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89 Iroc 350 TPI,
Forged pistions
Comp roller Cam .510 lift 230dur
Flowmaster exhaust
Dart Iron Eagle heads 200cc runners 64cc chambers
MINI RAM SOON!!!!!
stock TPI for now 24# inj
87 Trans Am GTA 350 TPI
had engine fire
SHE NOW RUNS!!!! GREAT!!
Flowmaster exhaust
LT1 Injectors

Sounds like the pinion angle. Or it could simply be that the stiffer mount transmits vibrations through the car more.

Check the pinion angle, if you have the equipment. Or have a shop do it. Better safe than sorry.

AJ

[This message has been edited by AJ_92RS (edited October 23, 2001).]

I noticed a bit of a vibration from my driveline after I swapped to an ES poly mount but it all went away when I installed my Inland Empire aluminum driveshaft.....

The factory steel shafts are well known as a shotty piece....

Also, before you condemn any parts, check and see if the movement upward caused by the thicker ES mount hasn't caused any of the exhaust to ground out on the frame......er-body...... I had a couple sources of vibration after the ES poly trans mount install on my GTA. My intermediate pipe was rubbing slightly on the floorpan after I swapped in my mount (due to the slightly thicker dimensions of the mount I am guessing) but I adjusted the pipe a bit farther away and it was fine. The vibration from the driveshaft remained so I swapped that out next..... She is pretty smooth now, aside from a tire vibration or two..... oh well, time for some new rubber on a set of 4th gen 17x9s I guess!!!

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1987 GTA L98 MD8
355, TFS Heads, LT4 Hot Cam
My GTA

The Minnesota F-body Club

Also you may want to take the 'shim' off the poly mount even though it says not to on the instructions. It gave a bit more clearance and helped massively with the vibrations- ie stopped them!

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'86 IROC ZZ4
Holley 750 dp, Shorty Headers, BW POSI 3.27 rear, Southside sfc's, Probuilt 700r4, Hurst Dual Gate Shifter.
Best Run 13.8 @ 100mph- far more to come!
London-England (Brothers In Arms)
British Firebird/Camaro Site

Utilizing a poly-urethane trans-mount will always cause more vibrations/noise than stock rubber kind. I have one installed in my '89 Camaro and after a year it will subside and wont be as harsh. It's normal!!!!!!

At times it almost feels like it is going to shake my car apart!! Im going to try u-joints, it has 71000 miles on it wouldn't hurt to change them any way. After that I might consider a alum. drive shaft???

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89 Iroc 350 TPI,
Forged pistions
Comp roller Cam .510 lift 230dur
Flowmaster exhaust
Dart Iron Eagle heads 200cc runners 64cc chambers
MINI RAM SOON!!!!!
stock TPI for now 24# inj
87 Trans Am GTA 350 TPI
had engine fire
SHE NOW RUNS!!!! GREAT!!
Flowmaster exhaust
LT1 Injectors

Before you replace your U-joints, take that shim out of the mount. I don't know why they tell you to install it, but it kills your driveline angle. That shim shouldn't be there!

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If you live in Southeastern US, check us out!
South East Thirdgen

1987 Trans Am 305
14.88 @ 92.81

I left my shim out two. I had both the ES mount and a stock replacement one when I did the install. Without the shim made them the same height.

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1992 Pontiac Firebird 350/Six Speed
1987 Toyota Pickup 383/500+ HP

Ok I will try that. Yeah it did not vibrate THIS bad till I messed with it and changed the mount. Funny my 89 IROC does not vibrate even with the metal shim in. HMMMM.

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89 Iroc 350 TPI,
Forged pistions
Comp roller Cam .510 lift 230dur
Flowmaster exhaust
Dart Iron Eagle heads 200cc runners 64cc chambers
LT1 intake soon...If I can find one!!!!
stock TPI for now 24# inj
87 Trans Am GTA 350 TPI
had engine fire
SHE NOW RUNS!!!!
Flowmaster exhaust
LT1 Injectors
LT1 intake also if I can find one!!!

[This message has been edited by AaronIROCZ (edited October 25, 2001).]

yes if the mount was up high or lower before altering the pinion angle can make a vibration, also a shot u joint will do the same, you can mess around with shimming it, i dont think its a u joint if it was fine before, also if your engine shakes at those speeds dont forget a poly bushing is VERY tough and doesnt give and absorb shock like the rubber does.

I had the same problem. I emailed Steve Spohn for his opinion, he said "take out that damn shim plate they give you". I was like ok, anything is worth a try....sure enough he knew what he was talking about, all the vibrations instantly disappeared

I had the same problem. Have been running for two years w/o the shim plate and it's fine. I need to have my trans removed soon, so I will shim the crossmember to to fit the plate back in. Unless you are running huge HP and TQ, you don't need it.

Well I took out the shim and the vibration instantly disappeared. Thanks guy's!!

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89 Iroc 350 TPI,
Forged pistions
Comp roller Cam .510 lift 230dur
Flowmaster exhaust
Dart Iron Eagle heads 200cc runners 64cc chambers
LT1 intake soon...if I can find one!!!
stock TPI for now 24# inj
87 Trans Am GTA 350 TPI
had engine fire
SHE NOW RUNS!!!!
Flowmaster exhaust
LT1 Injectors
LT1 intake also if I can find one!!

Ok I thought it disappeared. Last night I drove up my street to 40 mph and it seemed fine. Today on my way to work on the interstate it still vibrated at around 65 mph, +- 5mph. It doesn't vibrate as bad though. Any other ideas yes I know that it is a harder mount and it will transmit more vibrations than the stock one did but to have the dash pad shaking up and down, I think that there is more to it than that. Im still thinking u-joints.

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89 Iroc 350 TPI,
Forged pistions
Comp roller Cam .510 lift 230dur
Flowmaster exhaust
Dart Iron Eagle heads 200cc runners 64cc chambers
LT1 intake soon...if I can find one!!!
stock TPI for now 24# inj
87 Trans Am GTA 350 TPI
had engine fire
SHE NOW RUNS!!!!
Flowmaster exhaust
LT1 Injectors
LT1 intake also if I can find one!!

I left the shim in but shimmed between the frame and x member

I have the energy suspension mount, and i have the plate installed, and there is noticeable vibration but not enough for me to go thru the trouble to take it out,but down the road i think i will.

also hey MKOS1980 the coil is workin great and i polished the plenum to match the ASM throttle plate! thanks again

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87 IROC-z 305 TPI
Borg Warner T-5 fresh rebuild
10-bolt 3.73 Richmond gears rebuilt GM posi,
formerly BW 9-bolt w/3.45 gears(broke it)
Ported Plenum and Runners Homemade AFPR
ACCEL 8.8 wires, High output coil,and cap & rotor
Bosch platinum + 4 plugs
Ram Air w/ K&N filters,
MAF sensor screens removed, TB coolant bypass
Polyurethane tranny and torque arm mounts
Dynomax catback w/custom tips
K&N oil filter,Mobil 1 synth, Futura GLS Super Sport tires 265/50/15 rear and 235/60/15 front mounted on 86 monte carlo SS rims ,

400 sbc and a 6 spd in the works

I'm glad I'm not alone....just installed one in my 87 t-5 Z28, and it hits me in third and forth...I'll pull teh shim, and
see if it goes away...