How much float in driveshaft flange is OK?

[Eric_Oz_S2]

I am in the process of dropping the transaxle to replace the flywheel pilot and throwout bearings. When I disconnected the CVs from the trans I noticed quite a bit of float in the driveshaft flanges - maybe 2-3mm in-out and 1-2mm up down. What is normal?

Has anyone replaced the driveshaft carrier bearings? Looking at the shop manual replacing the bearings it doesn't appear too difficult - and presumably if I use the same R&P, I can use the same shims - yeah?

[944 Ecology]

Danger, Will Robinson...

if you screw up the carrier bearings (which also make the backlash adjustment for the ring and pinion, you will ruin your transaxle in short order. Unless you are an expert on setting up backlash, I would take it to someone who has the right measurement tools and techniques.

[175mph951]

The in and out is normal, not sure on up and down never checked

[bazar01]

In and OUt is normal. The drive flange journal is a slide fit on the carrier, and no bearings. There is no up and down on the drive flange. If there is up and down, either the diff carrier bearing is worn or the drive flange journal is worn.

Easy to change the diff carrier bearing, it's setting the shim thickness behind the new bearing that is very challenging. Requires lots of assembly and dis assembly to get the right backlash. And where to get the shims is another challenge. Maybe you can reuse the old shim setting and check the backlash.

[Slam]

I've been wondering about this, too. I've got a spare tranny that needs diff carrier bearings and I'd like to try swapping them. If the bearings are the same size and the spacers are undisturbed, then shouldn't the thing go back together within tolerance?

[many944s]

The newer bearings you would be installing are from a different manufacturer. Even if you tracked down original manufacturer bearings, they would be from a different production lot, thus the machine that turned the races down would not have been at the exact same settings... Long story short, there are a lot of size differences that come into play with bearings, race dimensions, roller bearing thickness, inner race spacing.... and so on.

Leaving the existing shims and not measuring lash would be like buying a used 944 with no records, replacing the belts, and leaving the pump and rollers. Just not a good idea if you want to keep it for any amount of time!

-Nick

[Eric_Oz_S2]

So if I can figure out what the original bearing thickness was and compare it to the new bearing size I can make up the difference in the shims?

I suppose I could always invest in some dial gauges - but where do you get the shims from?

[Slam]

Thanks, Nick - and as Eric_Oz_S2 says - where do I get shims?

[many944s]

They can be ordered here on Pelican (113 517 202 a) for example.

There are also some rebuild supply houses that sell them in bulk for a tiny discount. Pelicans are around $3.25 each, I bought like 20 of each thickness from my distributor and the price only came down a few pennies! if you let me know what thickness shims you need, I'll see if I have any in stock. Since I rebuild around 1-3 of these trannys a month, I go through them like candy! oh, and a word of caution: if you are not VERY careful when removing the old bearing races, you will destroy the current shims, guaranteeing that you will need to replace them all!

Hope it helps,
-Nick

[Eric_Oz_S2]

Originally Posted by bazar01

In and OUt is normal.
Easy to change the diff carrier bearing, it's setting the shim thickness behind the new bearing that is very challenging. Requires lots of assembly and dis assembly to get the right backlash. And where to get the shims is another challenge. Maybe you can reuse the old shim setting and check the backlash.

What did you use to remove the outer diff carrier bearing races from the case/side cover? It looks like you need a split collet type extractor ($$$). Can you use a normal internal puller?

[bazar01]

Yes, it's some type of a split type expanding collet for internal races. I'll see if I can find a pic of the tool.

[bazar01]

Carrier taper roller bearing removal:



Outer race removal using the SKF bearing tool:



Good luck and have fun

[Eric_Oz_S2]

Thanks Baz.

That internal puller looks expensive....

[Jeff N.]

Reviving an old thread....

Bazar, is there a way to determine which of the following applies while the diffy is in the car? I have ~1 to 2 mm of radial play in my LHS output shaft and would like to try to better assess the source.

If there is up and down, either the diff carrier bearing is worn or the drive flange journal is worn.

If it helps, when my unit is street driven, it's quiet. When I come off the track and the unit is hot, I have a ring and pinion type noise on accel and deccel (not at neutral throttle). Unit cools, all is good. Unit had a new pinion bearing installed not too long ago but the carrier bearings checked out OK at that time. Thoughts?

[Eric_Oz_S2]

I've got myself an LSD and now (finally) looking at the install.

Question - Is it possible to test fit the bearing race and remove it again without damaging the race if i use a split collet extractor?

[bazar01]

Originally Posted by Jeff N.

Reviving an old thread....

Bazar, is there a way to determine which of the following applies while the diffy is in the car? I have ~1 to 2 mm of radial play in my LHS output shaft and would like to try to better assess the source.



If it helps, when my unit is street driven, it's quiet. When I come off the track and the unit is hot, I have a ring and pinion type noise on accel and deccel (not at neutral throttle). Unit cools, all is good. Unit had a new pinion bearing installed not too long ago but the carrier bearings checked out OK at that time. Thoughts?

I did not even see this thread until now.

If there is a 1-2 mm radial play on the LHS while holding the RHS drive flange, there is a considerable wear on the open diff spider gear bore or shaft. I am not an expert on 944 transaxles and somebody more knowledgeable may chime in.

The ring and pinion clearance is getting affected by heat. It may be that the pinion bearing housing bore is expanding with heat during track use allowing the bearing clearance to go beyond spec and allowing it to spin in the housing. Do you have a transaxle cooling loop?

[bazar01]

Originally Posted by Eric_Oz_S2

I've got myself an LSD and now (finally) looking at the install.

Question - Is it possible to test fit the bearing race and remove it again without damaging the race if i use a split collet extractor?

Test fitting a new bearing race will be fine but it is a very tight fit which makes it very challenging to mount and dismount a few times. Be careful with the shims.


944 transaxle shops have an extra bearing race from the same brand bearing ground to undersized outside diameter so they can easily slip it in and out of the housing for test fitting purposes and setting backlash and proper mesh. And they also measure the starting torque on the output shaft.

Let us know how it turned out.

[Jeff N.]

Thanks Bazar. Yes, the unit has a cooling loop. I'll pass these notes on to my builder and see what he reports. I'm going to pull the unit and get it inspected.

Details to come...appreciate any other ideas. Good thread!

[wild man]

Just wondering, would it be advantageous to to have the pinion depth and backlash checked and re-set after a transmission has, say, over 140K miles of wear on it? Or will the settings be maintained, no matter how much wear the gears have on them? It doesn't seem to me that they would be.