8.8 Pinion Removal

Rick Simons

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I couldn't leave it alone; I had to find a way to use a solid spacer. My wife refers to this as 'Bulldogging".
Found this at Jeg's: https://www.jegs.com/i/JEGS/555/61216/10002/-1
Received it yesterday and it looks perfect. In addition, a machinist friend is making a collar that will slide over the pinion shaft in place of the companion flange. I am also enlarging the ID of the old inner bearing so it slips onto the pinion shaft easily for checking depth & preload. Got that idea from YouTube.
I've also cut the self-locking section off of the old pinion nut so it threads onto the pinion easily. With these pieces it should take mere minutes to setup & check the pinion.
Anyone know of a spec for carrier bearing preload?
 

Norm Peterson

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I like what you found at Jeg's and the notion of using a free-sliding collar, and I may well upgrade to the solid spacer myself. Have to see if I've got anything I can use or something I can adapt for the spacer.

I already have ground off enough of the OE pinion nut, and yes that does make life easier during the setup if you find you need to re-shim the pinion.

Carrier bearing preload is obtained by adding 0.006" shims to both bearing shim packs after arriving at the proper amount of backlash. That's the factory shop manual procedure.


Norm
 

Rick Simons

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I like what you found at Jeg's and the notion of using a free-sliding collar, and I may well upgrade to the solid spacer myself. Have to see if I've got anything I can use or something I can adapt for the spacer.

I already have ground off enough of the OE pinion nut, and yes that does make life easier during the setup if you find you need to re-shim the pinion.

Carrier bearing preload is obtained by adding 0.006" shims to both bearing shim packs after arriving at the proper amount of backlash. That's the factory shop manual procedure.


Norm
Thanks Norm! Shortly after posting I was looking through the install instructions that I downloaded and found the .006" addition procedure. My setup sleeve (I'll call it that for now) is sitting on my desk, so now I have everything I need to assemble/check/adjust everything. The sleeve is 1 1/4" sch 80 seamless pipe, cut at 45mm lengthsleeve.JPG .
 

Norm Peterson

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Looks easy enough to make if you've already got a lathe or a milling machine. Or at least have access.

I'm thinking more in terms of using an old pinion front bearing (ruining it if necessary wouldn't be a problem, as it's not worth trying to re-use one of those things) or opening up the square drive end of an old socket by enough to slide over the pinion threads.


Norm
 

Rick Simons

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Norm, great minds think alike; I was thinking about the (3/4" drive) socket idea as well, but I didn't have one with a small enough OD to fit the bearing. I found that the collar needs to be 40-45mm in length.
Last night I fitted up the pinion and checked the tooth pattern. The only thing I didn't think completely through was how to hold the pinion while tightening the nut. A hammer handle wedged between the pinion and the case did the trick. Not pretty, but effective. I'll have the companion flange on when I put it together for good, so I can use my holding tool at that point. Looks like I'll need to go a little bit deeper with the pinion, then I'll have it nailed.

drive.jpg
 

Juice

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I don't like that contact pattern. Too low on the power side, too high on the coast side.
 

Rick Simons

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Agreed. I've adjusted the pinion depth since this post and it's much better, but I might go .005" more. I thought I posted the newer pics but I don't see them. Hmmm.
 

Rick Simons

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Well I got the beast back together this afternoon. Pinion turning torque was 23 in. lbs. I used a solid preload spacer & shims, with the pinion nut torqued to 130 ft. lbs. Backlash was .010", and the drive pattern looked great. Coast pattern still looked a little high up on the toe though. The stock pinion shim was .025", and I went up to a .035" shim to get the depth better; .040" was too much. It whines on coast, so I'll be going back into it. Any of you diff experts out there want to share some intel on possible causes for the whine on coast? The only place I varied from the FRPP instructions was I added only .006" to the carrier preload instead of the .012" called for. I simply could not get the diff back into the case with .012" added.
I can tell I'm really gonna like these gears though!
 

Juice

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I cannot think of a single install of gears where I had to mess with pinion shimming. I would take the old shim from the pinion being removed and move it to the new one. Install carrier and set backlash. This has always worked for me.

The shim under the large pinion bearing is originally determined by measuring the housing. If you looked closely at your pinion, on the face of it you find a +/- 1,2,3 etc. You would add/subtract this amount to the pinion shim you removed as this is the difference of the new pinion from tbe ideal zero (perfectly machined). I have not seen a pinion with a number of more than 2. (.002").
 

GriffX

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Well I got the beast back together this afternoon. Pinion turning torque was 23 in. lbs. I used a solid preload spacer & shims, with the pinion nut torqued to 130 ft. lbs. Backlash was .010", and the drive pattern looked great. Coast pattern still looked a little high up on the toe though. The stock pinion shim was .025", and I went up to a .035" shim to get the depth better; .040" was too much. It whines on coast, so I'll be going back into it. Any of you diff experts out there want to share some intel on possible causes for the whine on coast? The only place I varied from the FRPP instructions was I added only .006" to the carrier preload instead of the .012" called for. I simply could not get the diff back into the case with .012" added.
I can tell I'm really gonna like these gears though!
I did this 8.8 rebuild only two times, so not much experience, but used Ratech solid spacer, had 22 in lb preload and got rattling/whining on coast around 40 mph too. I think the preload should have been higher, but when I removed one shim more, I got far over 28 in lb. Next time I buy a different brand as spacer, the Ratech shims were all the same thickness. The carrier shims in the Ford rebuild kit were from Ratech also, same problems, not enough shims with different thickness, had to grind some down.
I hope next time will never come. ;)

Would have been impossible for me to lay on my back and crush a sleeve, the solid spacer is the solution for this.
 

Norm Peterson

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I cannot think of a single install of gears where I had to mess with pinion shimming. I would take the old shim from the pinion being removed and move it to the new one. Install carrier and set backlash. This has always worked for me.
That approach has worked for me twice before, but this time pinion depth with a comparable shim pack thickness ended up being 0.040" shallower with the new pinion. The wear pattern for the OE gearing looks like the pinion may have been a little too deep, but I don't think by that much, and the little aftermarket gauge tool agrees closer with me needing to shim the new pinion by about 0.040" more. I did take gauge tool measurements of the OE setup for comparison.


The shim under the large pinion bearing is originally determined by measuring the housing. If you looked closely at your pinion, on the face of it you find a +/- 1,2,3 etc. You would add/subtract this amount to the pinion shim you removed as this is the difference of the new pinion from tbe ideal zero (perfectly machined). I have not seen a pinion with a number of more than 2. (.002").
I'll have to look into this. Don't recall seeing any numbers, but nothing in the factory shop manual even mentions them (Ford calls for a pretty specialized tool) and nothing about this was mentioned with the installation kit.


Norm
 

Juice

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Look for hand scribed writing on there. No guarantee all gears will have it, but it was there on most of the ones I did.

When the factory was building the rears for the first time, they measure each housing. Then take that measurment, add/subtract pinion marking, and that equals pinion shim needed.
 
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GriffX

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Look for hand scribed writing on there. No guarantee all gears will have it, but it was there on most of the ones I did.

When the factory was building the rears for the first time, they measure each housing. Then take that measurment, add/subtract pinion marking, and that equals pinion shim needed.
I have a question regarding this. It was +4 on my new and nothing on the old, so that means +0.004 for the new shim?
 

Juice

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I have a question regarding this. It was +4 on my new and nothing on the old, so that means +0.004 for the new shim?
Well, sort of. Since you didnt have any marks on the old one, we can only guess that is same as "zero". So yes, you need a shim that is .004 different from what was on the old pinion.
But Im not sure if you are supposed to add or subtract .004. But that is a very small difference IMO. Just using the old shim and setting backlash with the carrier shims should be close enough for a good contact pattern.
 

Rick Simons

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Well it took awhile to find time to finish this, but it's done. I elected to remove the entire axle and set one end on the bench, and support the other end with a ratchet strap from a ceiling joist. This made it SOOO much easier to set up. I could rotate the pinion up to work on it, or down to work on the diff. Removal time was less than 30 minutes; time well spent in my opinion. Re-install time was a little more. I ended up using the original .0245" pinion shim after much experimenting. I borrowed an idea from YouTube and bought another rear pinion bearing to use just for setup. I honed out the bore with a flap wheel on a die grinder to make it a slip fit over the pinion, then when the final setup was complete, took it off and pressed on the permanent bearing. I have 16-18 In. lbs. pinion preload with the solid shim kit and .011" backlash. The patterns were as close to perfect as you could want (sorry, no pics). No noise of vibration any kind.
 

86GT351

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Well it took awhile to find time to finish this, but it's done. I elected to remove the entire axle and set one end on the bench, and support the other end with a ratchet strap from a ceiling joist. This made it SOOO much easier to set up. I could rotate the pinion up to work on it, or down to work on the diff. Removal time was less than 30 minutes; time well spent in my opinion. Re-install time was a little more. I ended up using the original .0245" pinion shim after much experimenting. I borrowed an idea from YouTube and bought another rear pinion bearing to use just for setup. I honed out the bore with a flap wheel on a die grinder to make it a slip fit over the pinion, then when the final setup was complete, took it off and pressed on the permanent bearing. I have 16-18 In. lbs. pinion preload with the solid shim kit and .011" backlash. The patterns were as close to perfect as you could want (sorry, no pics). No noise of vibration any kind.
Good job!
 

Norm Peterson

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I borrowed an idea from YouTube and bought another rear pinion bearing to use just for setup. I honed out the bore with a flap wheel on a die grinder to make it a slip fit over the pinion, then when the final setup was complete, took it off and pressed on the permanent bearing.
I like this idea. May end up eventually using it, so thanks in advance.


Norm
 

RED09GT

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Agreed, the setup bearing saves a lot of time. I also agree that pulling the rear end out of the car is the best way to do it, especially for a rookie. I am also using a solid spacer and shims and that takes a lot of guesswork out of it as well.
 

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