Driveline vibration at higher speeds...

[mustanggt94]

I did a search but couldn't find the exact problem I am having. I recently did an Engine/Tranny swap from a wrecked 95 GT to my 94 GT, and the tranny is a T-5 WC with the 2.95 gear and practically brand new. I was using the driveshaft that came with the car which was a stock AODE driveshaft (since that car underwent a swap) which has that stinkin' rubber balance thing on it. I noticed considerable vibration on the interstate which would fluctuate on and off at speed. I ended up breaking an axle at the track shortly after that (unrelated) and I just put new axles and a diff in there this weekend. I also put back my original 5 speed stock driveshaft with a new U-joint on the front. The vibration is not as bad now, but at above 50 or so whenever I let off the gas I feel it. As long as I keep a load on the car it doesn't vibrate. Any ideas? I think the rearend is fine as everything sounds great.

 

[nmcgrawj]

Well speed tells u its after the engine. So its somewhere between your tranny and wheels. If the u-joints check out, then i'd point at possible the wheels being out of balance, rear end install(but u said thats fine), and i'd even check into getting the driveshaft re-balanced. I got my aluminum rebalanced after i installed my TKO600 and it was off by a bit.

 

[juiced_94gt]

FRPP driveshaft is the answer, it solved all my problems

 

[HISSIN50]

Have you indexed the any of the Driveshafts? I agree that it's likely a DS imbalance issue since it changes with load (on the gas vs off).

I might play with DS indexing or balancing like Nate mentioned.

Good luck.

 

[final5-0]

I saw some info about a crude but effective
method to check the balance on a ds

You make a mark on the ds at 12, 3, 6, & 9 O'clock

Put a hose clamp on at 12 and test

Move it to 3 and test and so forth

Don't have to take the ds off the car
so
The little test is pretty easy to do

Grady

 

[nmcgrawj]

That sure is a slick idea Grady

 

[HISSIN50]

A very smart fellow by the name of Don (Grady, ya might remember him - he was one of the old timer Fox RT guys. GTstang90 or something like that [those items but in a different order perhaps] was his username). Anyhow, he's an engineer as I recall and did some tinkering just like wise ol' Mr Grady noted. He had some pretty good results using the hose clamp as I recall. He even posted up some files with some of the stuff he'd done.

That was a good while back.

FWIW, the stock stuff is loosely balanced at the factory. There is usually a mark on the companion flange and the DS that match up.

 

[88GT17MA]

I saw some info about a crude but effective
method to check the balance on a ds

You make a mark on the ds at 12, 3, 6, & 9 O'clock

Put a hose clamp on at 12 and test

Move it to 3 and test and so forth

Don't have to take the ds off the car
so
The little test is pretty easy to do

Grady

Am I missing something? How does this work? do you keep the clamp tight at 12 and then drive? and see if it moves?

 

[HISSIN50]

Am I missing something? How does this work? do you keep the clamp tight at 12 and then drive? and see if it moves?

The screw-part of the clamp acts like a little weight (as if you used a stick-on lead weight, but instead of stick-um, you use the band on a clamp to hold the weight). Then since it's not a sticky weight, you can loosen and rotate the clamp till you start to counteract the imbalance.

 

[nmcgrawj]

Am I missing something? How does this work? do you keep the clamp tight at 12 and then drive? and see if it moves?

The clamp is just that...a clamp. U would use one of those big worm ones(i think thats their title lol...just a big version of a hose clamp that u can get for a radiator hose) and the part where the bolt is your extra weight...similar to the weight on a wheel when u balance them. So u tighten it down and take it for a drive and see if the vibe gets better or worse. Then u know its a balance issue. You can keep adjusting it to see if u can get it to go away, or you can just go get the DS rebalanced. And they'll weld on a new peice to balance it out like they did mine.

 

[nmcgrawj]

ahhhhhhhhhhhh Hissin you're sneaky.....u beat me to it

 

[HISSIN50]

ahhhhhhhhhhhh Hissin you're sneaky.....u beat me to it

Yeah, but your reply was of better quality.

 

[nmcgrawj]

Yeah, but your reply was of better quality.

Ha i'll take that from one of the wiser fellas on this site

And i'll also mention that when guys have a stock DS with vibes after installing gears and they get the aluminum Ford racing piece and it goes away, its just a balance issue and u could save a few bucks by getting your stock piece rebalanced. But u wouldnt gain the lighter weight of the aluminum. I think i remember reading that gears tend to make an imbalance in the DS much more obvious.

 

[mustanggt94]

Good idea with the hose clamp! I will try that if re-indexing doesn't work. I think I will try to put the spacer on it too just to check (since I am using a FOX size T-5). I have had these gears in before with a stock D/S and didn't have any vibrations, but now that I have this new tranny and that is when it all started. I've tried both stock driveshafts that I have but still get the vibs.

 

[mustanggt94]

Oh, I have one question about the clamp trick....where on the driveshaft should I put the clamp? In the middle?

Also, what should a driveshaft balance cost? I dunno if it is really worth it or to just get an aluminum one.

Thanks!

 

[reddy351]

DS balance should be about $30-$50. Depending on where you go. If it happens to be bent/twisted, they should tell you.

 

[HISSIN50]

Oh, I have one question about the clamp trick....where on the driveshaft should I put the clamp? In the middle?



Thanks!

I'd put the clamp on the rear portion of the DS.

 

[nmcgrawj]

I'd put the clamp on the rear portion of the DS.

x2 thats where they'll put the weight if u were to get it rebalanced.

 

[mustanggt94]

Well I tried reindexing the driveshaft and putting on the D/S spacer and it didn't seem to make a difference. (I'm not sure why re-indexing would work since the D/S should be at zero balance anyway, right?)

I then used the clamp trick and it got rid of the off-accel vibrations but added some new vibrations at cruising speed! Well, at least I know it is the D/S! I found a place that will balance it for $35 so I'll give that a shot! Thanks guys!

Oh yeah, I was also noticing a lot of shifter noise while driving (without the clamp) even while cruising, but only at high speeds. Do you think it is just the driveshaft or maybe my poly tranny mount is causing that problem? I've read other threads about people not liking to use the poly tranny mount with the poly engine mounts. ????

 

[nmcgrawj]

Shifter noise? As in the shifter handle or what? A poly mount is stiffer so it will send up more vibes. Some people do complain of vibes with the poly mount and stick with a rubber one. I dont have that problem though.