Shavarsh
Shavarsh Reader
8/23/21 4:30 p.m.

Anything wrong with driveshaft spacers? My brand new driveshaft seems to be a bit short, with well over an inch of exposed transmission yoke. The differential is fixed so I don't need much room for yoke movement. The yoke also has a bit of play coming out of the transmission tailshaft and I figure having the yoke extended any farther than it needs to be will amplify that play and cause vibrations.

 

So... anything wrong with driveshaft spacers? This is an 8.8 so its just a matter of adding a spacer to the pinion flange.

Keith Tanner
Keith Tanner MegaDork
8/23/21 4:35 p.m.

Even with a fixed diff, there's usually some unused plunge depth to ensure there's no chance of the driveshaft bottoming out. Memory says it's usually about an inch.

What's the difference between your old and new driveshaft lengths?

Tom Suddard
Tom Suddard Director of Marketing & Digital Assets
8/23/21 5:40 p.m.

Two thoughts:

  1. No, a properly machined driveshaft spacer won't cause any problems. 
     
  2. An inch isn't necessarily bad. Not sure there's enough information to make a better recommendation. 
Shavarsh
Shavarsh Reader
8/23/21 6:35 p.m.

I'll give some more information when I get home and can measure everything again. I wouldn't think twice about using the new driveshaft as is normally, but with the play in the yoke at the transmission I'm worried about extra leverage. Hopefully I don't find out that the yoke OD or tailshaft bushing is out of tolerance...

ShawnG
ShawnG UltimaDork
8/23/21 6:37 p.m.

Used one in a Chevy Tracker 4x4 lift for a customer three years ago. No issues so far.

Keith Tanner
Keith Tanner MegaDork
8/23/21 6:40 p.m.

I have an adapter at the end of my driveshaft that is effectively a spacer. You don't want loose bolts there, but it's been trouble-free. I just want to make sure we're not "fixing" something that isn't broken :)

Shavarsh
Shavarsh Reader
8/23/21 6:45 p.m.

In reply to Keith Tanner :

I have a knack for doing that, it's part of the reason I posted here.

Patientzero
Patientzero Dork
8/23/21 10:55 p.m.

I'd think 1" is perfectly acceptable.  That still leaves 3-4" in the trans?  What transmission and spline count do you have?  

Shavarsh
Shavarsh Reader
8/24/21 1:36 p.m.

Alright, some pertinent information. First off, the yoke sticks out 2" when bolted to the rear end. When pushed up against the dust boot the yoke isn't bottomed out yet and it measures at 3/8". Next the yoke OD measures 1.490 (+/- for harbor freight calipers). The transmission is a T5Z from a 93 mustang, the driveshaft is from a 1990 lincoln towncar with an auto (should be the same yoke).

 

 

Given all this, it seems I should order a spacer to bring that 2" down to 1" of yoke exposed. Thoughts?

Patientzero
Patientzero Dork
8/24/21 4:26 p.m.

Is this at ride height or with the rear end hanging?

Shavarsh
Shavarsh Reader
8/24/21 4:48 p.m.

In reply to Patientzero :

The diff is fixed (IRS)

Patientzero
Patientzero Dork
8/24/21 4:53 p.m.

A spacer wouldn't hurt.

APEowner
APEowner SuperDork
8/24/21 4:55 p.m.
Shavarsh said:

In reply to Patientzero :

The diff is fixed (IRS)

With that in mind I'd use a space to slide that in more and an inch looks about perfect.

Toyman01 + Sized and
Toyman01 + Sized and MegaDork
8/24/21 6:49 p.m.

I have run spacers without any issues. I've even made a few successfully. 

Shavarsh
Shavarsh Reader
8/25/21 12:23 a.m.

Thanks all, lets see how this goes.

Toyman01 + Sized and
Toyman01 + Sized and MegaDork
8/25/21 7:04 a.m.

The last one I built was to adapt a CV joint to a flanged rear end. It survived longer than the transmission did. 

20200904_073242.jpg

wspohn
wspohn SuperDork
8/25/21 11:24 a.m.

I made one years ago as I switched to an overdrive (shorter) gearbox in one of my race cars.  Just turned up a 1 1/8" alloy spacer, contoured on the ends to mate with the diff and rear driveshaft yoke.  No issues, used it for decades.

Shavarsh
Shavarsh Reader
8/30/21 4:22 p.m.

I whipped up a spacer about 1 1/8". The driveshaft now fits much better. However I've still got more play than I want at the transmission yoke. Must be time to replace the tail shaft bushing (hoping to avoid buying a new yoke). Do any of the parts stores rent the tool to pull the old one without removing the tail shaft housing? Or does someone in Socal have one to lend?

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