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Pinion shims

alpinelover

alpinelover

Donation Time
Hello everyone i just wanted to say how amazing the SAOCC forum is .
So many knowledgeable and helpful people out there and I can't believe how much time i have spent just surfing through the info in here.

I know this subject has probably been beaten to death on the forum but i was just looking for a little info that after many searches i couldn't find.
A little while back i had a problem and broke an axle shaft on my series IV alpine while diving and luckily i wasn't going fast.
Thanks to the fantastic help on here i was able to locate a replacement axle shaft with a bearing already on it and in good shape , makes that part of the install easier.
After getting the car home and dismantling the rear end i found the usual broken and loose bolts on the crown wheel , So i thought to myself this would be the perfect time to finally swap the 4:22 for a 3:89.
First off i know i know what your thinking it's going to be a challenging job figuring out backlash , pinion preload etc....but i'm willing to give it a shot i'm not in any hurry .
So after ordering a new crown and pinion set and inner bearing from SS i know i need sims for the bearing preload and SS doesn't stock them anymore. I do have two crown and pinion sets that are 4:22 's
There are sims on the both the old pinions under the inner bearing which may or may not survive if i try to remove the bearing off the pinon. I have about 7 shims total for the inner bearing so hopefully that will be enough for that one.
I know it's going to be a lot of removing and installing the inner bearing to get the clearances right and if anyone has any advise i'd be more then grateful of any easy ways of doing it, experiences ,etc.
My question really is has anyone been able to find pinion shims( pinion depth) and diff bearing shims ( backlash) that they managed to use from another vehicle and made fit.
I did read the article from Jan about the rebuild in the Alpine Marque so i think i know what to expect... maybe... probably not.
Short of trying to fabricate them myself i'm a bit stuck for ideas.
Thanks
Alan
 
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Shannon Boal

Shannon Boal

Platinum Level Sponsor
OK, pinion depth...(If you can measure the pinion depth after removing the differential but before removing the pinion, that will give you a good place to start with the new gears. I use a depth mic on a machinist's straightedge across the housing face measuring down to the end of the pinion gear...) Shims:Measure the original shim using a micrometer. To make a thicker shim, you stack additional shim(s), cut from shim stock with scissors. Shim stock can be 0.001, 0.003", etcetera. To cut the inside of the circle, fold it in half and cut it as a half-circle. Beverage cans make good shim stock, IIR, about 0.0016". Shim to produce the same pinion depth as the previous gearset had, then test for gear pattern to determing if different depth is needed. Complete set up with appropriate preload (pinion bearings and differential carrier bearings) and backlash, the pattern testing.....getting the gear pattern "smear" with prussian blue. To get an accurate imprint, the pinion must be turned with 50+ foot-pounds while the crown gear is restrained to resist turning with.... a wooden wedge between the housing and the crown gear. Not rocket science, but time consuming. Make your work space comfortable and well lit.
 
alpinelover

alpinelover

Donation Time
Thanks Shannon for the info.
What i thought about doing was something i had found online. When the guy was doing his pinion depth ,he had a spare bearing identical to the new one he was going to install. What he did was slightly hone out the inside of the bearing to allow for easier install and removal. I figured it might be easier to play with pinion depth that way instead of having to press the bearing on all the time.
I like the way you cut your shim i never would have thought of that.
I’ll have to put the pinion wheel assy back in carrier unit and do the measurement like you suggested for the pinion depth. I’m assuming i will need to install the coupling for the driveshaft and torque it to get a correct reading on the pinion depth
At least that way I’ll have a ball park figure to work with.
Thanks again
 
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