Howdy folks,

I bought a kit to replace my 489 case's crush sleeve with a solid spacer and shims. I pulled the chuck apart and measured the (crushed) crush sleeve length. I put this amount of spacer/shims in to replace it and torqued it together. The bearing preload was essentially nonexistent.

I keep pulling out shims by 0.002" increments and reassembling it, and after about 0.008" less I am seeing a little, but not much, preload. Would the required shim pack have to be 0.010" (or so) less than the measured crush sleeve length? I figure the crush sleeve may have extended a bit (0.010"??) after untorqueing it.

If no one has advice, then I will continue removing shims until I see preload.

Thanks much,

Lou

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Home of Slant6-powered fun machines since 1988

You are on the right track Lou, you do see some "rebound" from the crush sleeve.
If these are used bearings, keep the preload light, I use about 1/2 of the new bearing load and that seems to work OK.
DD

I agree with, Doc. Just keep at it, trial and error. When you're done, take note of the final thickness of spacer and shims, and post it. That'll give some kind of ballpark for the rest of us, and it'll speed up the next guy who's wanting to do it.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

Hey Guys,

Thanks much for the replies - that's what I thought. Unfortunately, with all this trial and error, I have partially messed up the threads on the end (last 1/4") of the pinion, and gone through two nuts. I'm hoping I'll have enough thread luck to finish it withouth completely trashing the pinion.

I'll post the spacer thickness when I'm done.

Cheers,

Lou

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Home of Slant6-powered fun machines since 1988

Hey, Lou;
If you don't already have one, a good tool to have in your tool box is a thread file. The ones I have are about 8-10" long. They are about 5/8" square in cross-section, and they have teeth on each face on each end that correspond to different thread counts(tpi). So one tool has 8 different thread faces. They work great for dressing-up external threads. Alot cheaper than 8 different dies.

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'70 Cuda AAR
'74 Duster 360
'79 MagnumGT
'79 Chrysler 300

Thanks for the file tip. I'll look into those.

Lou

_________________
Home of Slant6-powered fun machines since 1988

OK folks, I'm out of the woods on this thing, I think. Finally got the right pinion bearing preload on my 489 case with solid spacer/shims. When I pulled out the crush sleeve, it was 2.939" long, but I ended up with 2.929" spacer (2.907") + shims (0.014" + 0.008") to get about 15 in-lb preload. I should have listened to my initial instincts, which told me that the crush sleeve would "grow" about 0.010" when untorqued, but I started with 2.939" total and went down in 0.002" increments (6 different settings!) to 2.929". I got the spacer/shim kit from Randy's (www.ring-pinion.com) for $23.

I borrowed a 3/4-16 die and chased the mucked threads on the pinion, and they are OK. Word of advice - do NOT reuse a marginal pinion nut (use a nut 3 times fully torqued at most) or it will tear itself up on the way off and damage the endmost threads. Also, make sure to use a grade 5 or LOWER nut so it will rip up before the threads on the pinion.

I reassembled the diff, and just need to whip up a spanner tool to adjust the side clearance (backlash) and diff bearing preload. The holes in the adjusters are centered 2.55" apart and are about 0.280" diam. I am going to make a straight steel bar with 1/4" studs sticking out of it on one side 2.55" apart and a bolt head centered between them on the other side to drive with a wrench/socket.

The whole reason for this job was to replace the 7260 yoke with a 7290 yoke (billet steel, coarse spline, from Randy's for $110 - nice piece) to fit my new HD driveshaft (www.dennysdriveshaft.com) and pinion-mounted parking brake (www.tsmmfg.com).

In the end, I think that setting up a new ring/pinion would not be that bad. The only thing I didn't do for that job is the pinion spacer depth. I would probably buy/borrow a tool to get that spacer thickness if I were to do the whole job.

Torquin',

Lou

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Home of Slant6-powered fun machines since 1988

I'm looking forward to seeing some pics of that pinion brake deal. I was thinking of doing the same deal on mine. Let me know what you think of that kit..

matt-

I bought some spanners 4 or 5 years ago, from an industrial tool place. I think they were only about $25 for the pair. They work great and don't hurt the adjuster or slip out. If I think of it next time out in the garage, I'll see if they have a brand name and/or PN.

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'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

I made-up a spanner wrench 20 some-odd years back out of a piece of flatstock and a pair of bolts combined with some welding.
The thing works like a champ but it's not pretty looking.

Great job on getting that pinion set.
As you found-out, the big "hassel" with rebuilding a rear gear is that you have to get everything "set" before you can check the preloads & mesh. (gear contact pattern)
If anything is off you have to disassemble it all to change the shims, then assemble it all over again. Not real hard, just takes time and some special tools.
DD

The name and numbers are: Martin #430

_________________
'70 Cuda AAR
'74 Duster 360
'79 MagnumGT
'79 Chrysler 300