z28 justin

I've been chasing down a vibration issue going over 80MPH ever since I had my S60 installed a couple years ago. I've had the driveshaft rebalanced and I finally decided to measure the driveshaft. it's about 39-1/2" from center of front caps to center of rear caps. I've also measured the overall length according to Denny's diagram B to be 42-13/16". Is this overall length how long the shaft should be?

If it's too short, how can I tell how much longer it needs to be?

Injuneer

You determine the required length based on providing the proper clearance at the front for the slider. Support car on all 4 wheels (or jackstands under year axle to provide normal ride height). Take the bolts off the rear u-joint caps, and slide the DS forward until the front slider bottoms out. That is your clearance. Stock seems to be 1/2". As HP goes up you want more clearance. In your case look for at least 3/4" clear.

If you have the 3/4" clearance (up to 1" would be OK), your current DS is the right length. If not, add or subtract the amount required to get the clearance to 3/4".

Have you adjusted the pinion angle?

z28 justin

Thanks for the quick reply.

I had the pinion angle set at -1.5, measuring the angle from the balancer on the front of the engine and setting that as 0, then turning the yoke on the axle horizontal and measuring from there as I adjusted.

I can push the driveshaft in till it squishes the transmission seal, is this bottomed out? It moves a little more than 1-1/4". I've read that 1-1/4" is ok for a racing application, but this thing is mostly street, maybe track once a year. Should I remove the transmission seal and see if it can move further? Is there an easy way to remove the transmission seal without damaging it?

Injuneer

From my experience, 1" is all you want. I've had 3 different setups and all of them have been measured with 1" clearance for an 800HP/800lb-ft application. I actually got into a huge argument with ACPT when the first DS with that setup failed (front steel yoke tore loose from carbon fiber tube), and they claimed it was because the DS was too long and bottomed out on the trans output shaft. I was able to prove through a 3rd party that is did have exactly the 1" clearance that ACPT wanted - got my $780 back.

By trans seal do you mean the rubber dirt seal just inside the end of the housing (10 years since I got rid of the T56 so my memory might be rusty)? You wouldn't want to chance the slider assembly being forced into that and tearing it up.

While the requirement of the two u-joints is that the engine and pinion shaft have to be level making the front and rear u-joint angles equal, the generally accepted and successful method of measuring the pinion angle is to try and get the difference between the pinion shaft and the drive shaft to equal the desired pinion angle (-1 to -2*). That presupposes that the engine is level, and it is worth checking as you did. Steve Spohn set my pinion angle at 1.8*, based on the difference between the pinion shaft and the drive shaft.

Tough call. 1/4" shouldn't be producing vibrations. Pinion angle should be OK, but worth checking .

z28 justin

After doing some digging, I've seen some guys say the shafts that Strange ships for the S60 conversion is 39-3/8" (which is what mine is). I've seen other guys say it was 40" (rounding up maybe?) and one guy said his DS for his S60 setup (not a Strange) was 41-3/4". I have e-mailed Strange to see if they can shed some light on the matter.

I've reset the pinion angle to 0, just to try it out. My tires are pretty old (bought them in '06 and only have about 20K on them), I might take them in to get them balanced and see if that helps.

z28 justin

So I swapped out the Strange yoke for a Spicer piece from Dennys and had the shaft rebalanced. It's now smooth as butter compared to what it was. Not sure what was wrong with the Strange Yoke. It's a U1667 piece with the date 09/07 stamped on it.

matLT1

The strange yoke could have been out of balance as well. Some come with counter weights welded and/or weight removed via drilling.

AyoNice

Are all drive shafts the same length from 83-02 w/ and without center support bearings?