The Fugitive

iTrader: (6)

okay so how would you measure to make sure that it is within the 1 degree? (like where to measure from and etc.)

dlandsvZ28

As I recall from the article (which I can't find) you measure the angle at the face of the u-joint joint bearing cap and compare the differences between front and rear.

Edit: This might be the link I think. If not this doc explains driveshaft angle also.

http://www.iedls.com/IEDL_PTS_LGL_091008_Secure.pdf

5.3LJimmy

iTrader: (10)

There is no bearing cap on the front shaft yoke. Some people will measure the angle by placing a straight edge on the harmonic balancer, but the accurate way would require a jig made from a transmission yoke. This would still require trial and error with shims to match the angle of the front and rear ujoints.

I just went measure my stock m6 tranny mount with a dial caliper and it is 1.815" tall. The easiest thing would be to measure your poly mount and add shims to match the height of the stocker. Don't worry about the angle because GM has already figured that out. Just set the height of the mount to 1.815 and you'll be good.

dlandsvZ28

My description is not correct for what I referred to as bearing cap but review the pdf doc from Inland.

GM figured out the angle and if everything is still stock then the wrong thickness poly joint can cause vibration. But there can be other factors too that change the angles if non-stock parts have been installed such as:

K-member
Is the k-member still stock? Is it exact compared to the stock k-member to not less than an 1/8 of an inch?

Transmission mount
Has the stock transmission mount been replaced with an aftermarket? If so is it exactly the same specs as the stock one?

If vibration is caused by just an 1/8 of an inch then if the non-stock transmission mount is off by that much that could/would affect the u-joint angle as well.

I'm not disagreeing with you - but other parts not to spec can alter GM's calculations.

The Fugitive

iTrader: (6)

hmm good info with that link dland. I will see about the mount height and if the pinion is the same as the engine angle. Seems as though I have my work cut out for me

71novaguy

iTrader: (2)

I will try the 1/8th in shim. I dont know where people are getting stock mounts are cheap. I believe the one from the parts store was like 60 bucks. A poly was around 30. If all it is a simple off angle problem, that would be amazing.

The drive shaft still has the weights on it, I remember look at them when I had it off to replace the u-joints.

The Fugitive

iTrader: (6)

man try autozone kragen o'reilly's or whatever parts store like that I got mine for $15 at autozone. Also did you mark your driveshaft before you took it out? I don't know if that will make a difference but I did that with mine.

dlandsvZ28

Autozone - I recall mine was less than $15.

71novaguy

iTrader: (2)

anyone know the overall height of the factory trans mount?

dlandsvZ28

Read post #23

71novaguy

iTrader: (2)

not sure how I missed that

dlandsvZ28

The next questions, however, are:

Is the tranmission crossmember PN the same for the M6 and A4?

Is the stock transmission mount the same PN for the M6 and A4?

The transmission crossmember mount height posted in post #23 is for an M6. Is the that correct height for the transmission crossmember mount for an A4?

There are several part numbers posted in different threads for the transmission crossmember mounts if you buy at Autozone, Advance Auto. Are any of those PN's the correct replacement PN?

For example, the height was not the same as my stock mount when comparing the Auto Zone mount and the stock mount and the Autozone design was somewhat different. I have an A4.

So when all said and done.

It might not be the poly mount at all that causes vibration but instead the height and correct PN of the replacement mount if not a genuine stock GM mount.

f-bodyguy

iTrader: (9)

i vote drive shaft

71novaguy

iTrader: (2)

I measured the poly mount I got. It measures over 2". Is 100% 1.815 correct? I just cant figure out why there would be so much of a difference

71novaguy

iTrader: (2)

well, I removed that spacer that came with the mount. That placed it at just about 1.850, nearest I could tell. The damn caliper decided it didnt want to come on today. It seems like when I bought the thing, the paper work said the spacer was required. I took it on a quick test run and it feels better. There was usually a little shimmy when I first take off. That is now gone. There is still some vibration at 65-70, which I understand is normal for these cars. Above 70 feels much better. When I get a chance to really try it out on flat roads, I will report back. We are in a tornado watch and I dont want to get stuck 30 miles from home just to find a flat road.

5.3LJimmy

iTrader: (10)

It sounds like you are working in the right direction and I hope that fixes it for you completely. Let us know when you get to do a little more driving.

71novaguy

iTrader: (2)

From the seat time I got this week, its not solved.
0-60, the vibration is almost un-noticable. about 65 I can start feeling it. I expecially notice the vibration if I'm loading the engine. Say cruising 65 in
6th, and goosing it a little to get up to 70.

Does anyone have a diagram of the power flow thru the transmission for each gear? I'm beginning to think it is internal. The vibration I feel is more pulsing when I find a steady cruise. I will trying going through different gear/rpm/speed senerios to see if I can isolate a certain gear thats causing an issues. If I can get that diagram I can see what shafts it is going through.