I installed poly motor mounts on my 97 and I started getting a weird vibration ( almost sounds like a rub) somewhere in the driveline under hard acceleration. I figured that it might be cuz I left the stock tranny mount so I replaced the stocker with a poly and now it is worse than ever. The vibration is terrible and I can't really pin point where it is coming from because my headers are now banging on the floorboard. WTF is this normal for the prothanes?? Has anyone else had this problem with poly mounts?? What did you do to fix it??

 

heh Didn't research this much huh? Poly's are stiffer, so you're going to get more vibration. Apparently replacing the torque arm mounts with poly really helps solve a bit of the vibration. Yea, not quite the answer you wanted I'm sure :\

 

I don't quite understand how a poly torque arm bushing is going to keep my headers from bouncing off of my floor pan, I should have checked the tranny mount height opposed to stock. I talked to a guy at UMI and he said that he was having some problems with his so he went with a stock on the DS but a poly on the PS to combat engine torqueing on the mounts but I don't really like that idea either...

 

Well, the poly torque arm mount solution is for those who upgraded the trans mount and noticed vibrations. Seeing as you did it, and got MORE, I figured you could cut down on it if you added that small and quick bushing. As for your headers bouncing off stuff, then I'd say that they're somehow loose. How it bounces off more now vs when you had rubber, kinda baffles me. I'd think that with the more 'wobbly' stockers, the exhaust would have more room to move. I don't really have a solution

 

Got some extra vibrations with mine as well. Chalk it up and ride brother

 

I think that makes for a good point: If you're going for performance, there's obviously going to be a reduction in ride quality.

Now! I do understand the annoyance of now having headers clack the floor, that's understandable and should be remedied. But vibration to some degree, will be something you'll have to deal with :\

 

Yup our cars weren't made to be comfortable rides for the most part. My SFC's added a few new rattles to the dash after I put them on so keep that in mind too if you have plans to put a set on in the future.

 

Another thing you can do, I know you wouldn't like but take a ball peen hammer to where the header is hitting.

 

I am wondering if somehow the height of the poly was wrong. I got some extra vibration from the motor mounts and I can live with a little bit but after the trans mount it not only got worse but the headers hitting is unacceptable to me. I realized that i am going to lose a little bit of ride quality for performance I am just trying to find a happy medium because this is by no means a drag car. I already have SFC installed and to be honest when Iput those in they quieted down the rattles and squeaks almost completely. I am thinking about just going back to stock mounts all around the drivetrain and save the poly for the suspension, I really don't know what else to do at this point, everytime I try to get something done on this thing something else goes wrong.

 

Try to remove the load plate (the thing that looks like a spacer) under the trans mount. How are your u-joints? Maybe they're worse then you thought, and this was just picking up on how bad they really are. :\

Yes, I agree with the headers being unacceptable, but depending on HOW much it's hitting, a little BFH action wouldn't be bad.

 

The BFH method almost never lets me down, I've actually nicknamed my sledge "the manipulator" but I don't want to beat the hell out of my car! Is there a fool proof way to check U-joints?? I usually just rock the driveshaft back and forth and feel for play, and what spacer exactly are you talking about, BTW I really appreciate your help!

 

what about replacing the stock Driveshaft with a Balanced Aluminum Drive shaft i have heard this causes vibration in the LT1's and the stock driveshaft is heavy anyway!

 

Not sure if the brand you got came with it. It's INTENDED to be installed, and should be as well, but I thought I read that before Energy Suspension revised their Trans mount that the Camaros had a bad vibration issue and removing the plate (what I thought was called the "load plate") helped due to changing the drive train geometry. Now, yes, F-Body is an F-Body, but it's a documented issue with Camaros. How, why, I don't know lol

#1 is what I"m talking about
http://www.turbofirebird.com/Suspens...5/Default.aspx

You could always cover the BFH with some rubber to kind of keep it from scratching up the body. But I feel ya with not wanting to "manipulate" the car any I probably should've whacked my inner fenders a bit for better tire clearance, but the 1/8" was enough lol

 

yeah I have been thinking of the whole driveshaft bit, but it seems like it is more than that, I also though about putting some washers on top of the tranny crossmember to space it down a little bit or just go back to stock on the tranny, i don't want to spend too much time thinking about the torque arm either because I am def going to get a tunnel brace mounted one sometime

 

I installed the headers and 4L60E at the same time and decided at the
last minute to replace the mounts since the engine would have to be
lifted. I bought the Prothane 3-point kit (poly engine and tranny mounts),
but only installed the motor mounts, since the [stock] tranny mount was
in good shape.

Even with only the poly engine mounts, I noticed an increase in driveline
vibration. Eventually, the tranny mount broke (like the 3rd time in as
many years), so I decided to install the poly tranny mount. I instantly
noticed an extreme increase in vibrations. I expected this, but not to
the extent that the vibrations are at now.

This is to be expected however - rubber mounts are used just for this
very reason - to absorb as much of the harmonic vibrations from the
engine / drivetrain.

For me, as with you, I still question the *source* of the vibration. I have
a couple of potential sources: one would be the [rebuilt] 4L0E or the
torque converter. Obviously, the only way to rule those out is to put the
stock TC and another 4L60E, which isn't happening

My car has 164k miles on it, and I question the driveshaft - obviously
the u-joints. Although they appear to be "tight" by hand-inspection, it
might be worth it to just change them out, just to be sure. I've also read
where rotating the driveshaft 180* can help. I've tried this and didn't
seem to help much.

I'm sure of one thing - the LT1 FBody cars are notorious for the tranny
mount breaking (3 in as many years for me) - they tranny mount breaks
because it is an inferior design and because of the excessive vibrations,
it fails much sooner than it should. IIRC, numerous folks opt for the
Caprice tranny mount, because of it's superior design. (I think it's the
Caprice tranny mount - maybe someone will chime in to confirm or
correct me on this).

So, in closing, I want to reiterate that it's *no doubt* you will experience
more vibrations using a poly tranny mount - it's the nature of the beast.
I suggest changing out the u-joints if your car has high-mileage - that
will at least eliminate that possibility. Rotate the driveshaft 180* and see
if that helps any and check to ensure the counterweight(s) haven't slung
off - this begs the question - is the driveshaft out of balance? Good luck
and let us know the outcome.

 

I am going to go back to the stock tranny mount and see about getting a balanced aluminum driveshaft with new u-joints and see if that changes anything, BTW does a tunnel mount torque arm add any extra vibration or cause any drivability issues??

 

The tunnel mount should, I think, cut down a lot on the vibration. I'd look into getting new ujoints now, since they'll be the same ones for the alu shaft. You're using an A4 so that helps, but how muc HP you think you're pushing, or do you not goto the track alot? Thats the one thing people say about the Alu shafts, is not handling lots of strip time. Yet some have had their for a long time *shrug*

 

I put the ES motor and tranny mounts in my '96, and while there was a slight increse in vibration, it wasn't objectionable. However, I did remove the "pre-load" plate from the tranny mount, as well as sand down the "nubs", as has been suggested in a couple of other threads here. I don't know if the Prothane part has these "nubs".

I chased a vibration for a long time, until I found out it was an incorrect pinion angle. I installed an adjustable torque arm at one point, and incorrectly thought I knew how to set the pinion angle. Once I got it straightened out, the vibration went away.

However, you have a somewhat different problem, as your headers are bangin' the floor. Did they do that before you changed the motor mounts? If not, either you got incorrect replacement mounts, or the originals were well worn and sagging, giving you extra clearance. You could try loosening the bolts on the heads, and reset the pipes. And yes, a "tunnel mount" torque arm will transmit MORE noise into the car.

 

i haven't had this setup to the track and am still chasing down gremlins before I can take it to have it dyno tuned. I am guessing I am putting down somewhere around 330 rwhp. I didn't have a problem with the headers until I installed the tranny mount, clearance wasn't an issue with the motor mounts that is why I was thinking that maybe the tranny mount is the wrong height. I was also thinking pinion angle might be giving the slight vibration but I would like the car to be as comfortable as it can yet still perform at the track. Next question...is a new trans crossmember with the torque arm relocation as opposed to the tunnel mount going to give less vibration or are you damned either way due to the necessity for a poly mount with either set up??

 

OK I guess I can follow the TA relocation adding more vibration, due to the mount being connected directly to the car as apposed to the back of the trans which is separated from the car by the trans mount (and indirectly the motor mounts too). So either way you go, cross member or tunnel, you'll get more vibration. A guess, I'd think you'd have less on the cross member since it's a more solid piece of metal.

Try removing that plate I mentioned, and that leadfoot took out. See how that helps, assuming yours has it too.