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Differential Rebuild - first of many questions
Posted by: jamesolefjensen ()
Date: March 14, 2020 04:30PM

I'm almost done tearing down a 66-69 differential. The last thing is the front pinion bearing race. The manual instructs one to use a press. I don't have one. I've read on the interweb that a wood block and a hammer will work. I have those. Are these my only choices?

I do realize that the clutch bearing support shaft thing will have to come out with this race.

James
65 Corsa

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Re: Differential Rebuild - first of many questions
Posted by: nirvairna ()
Date: March 14, 2020 04:40PM

A block of wood and a hammer will work just fine, try to keep it square and bang away.

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Re: Differential Rebuild - first of many questions
Posted by: vairmech ()
Date: March 15, 2020 05:03AM

I use a short section of pipe that just fits inside the diff case opening. I have broken the snout by hitting it on the end.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Differential Rebuild - first of many questions
Posted by: TheRealHip ()
Date: March 15, 2020 08:44AM

Make sure you are 'tapping' on the outter ring of the bearing. You can damage the bearing if you are hitting on the inner ring.

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Re: Differential Rebuild - first of many questions
Posted by: corvairdoug ()
Date: March 15, 2020 08:58AM

Be REALLY sure your adjustments and measurements, lash, etc are spot on. I had one done years ago, something was a hair off. It howled like an air raid siren at about 20 mph.

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Re: Differential Rebuild - first of many questions
Posted by: joelsplace ()
Date: March 15, 2020 09:20AM

TheRealHip Wrote:
-------------------------------------------------------
> Make sure you are 'tapping' on the outter ring of the bearing. You can damage the bearing if you are hitting on the inner ring.

? Doesn't apply here.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...

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Re: Differential Rebuild - first of many questions
Posted by: Bru ()
Date: March 15, 2020 09:55AM

A large puller and creative use of steel plate scraps might do it. Heat could help. When you get to shimming the rear bearing, I highly recommend buying an extra pinion bearing (same brand) and opening the bore to a slip fit. It’ll save a lot of time pressing during the setup. If the new bearings don’t go on with light hammering on the right size pipe, redi-rod through the pinion shaft could work.

Good luck!

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Re: Differential Rebuild - first of many questions
Posted by: jamesolefjensen ()
Date: March 15, 2020 02:19PM

I'm planning on replacing all four bearings and to reuse the pinion shim. I'm thinking since the gears are also being reused, I can get away with it. This worked out on a axle I rebuilt for my Chevelle. Am I fooling myself?

James
65 Corsa.

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Re: Differential Rebuild - first of many questions
Posted by: Wagon Master ()
Date: March 15, 2020 02:37PM

jamesolefjensen Wrote:
-------------------------------------------------------
> I'm planning on replacing all four bearings and to reuse the pinion shim. I'm thinking since the gears are also being reused, I can get away with it. This worked out on a axle I rebuilt for my Chevelle. Am I fooling myself?
>
> James
> 65 Corsa.


No, that should work. Just use care setting your preloads and check tooth contact pattern.

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Re: Differential Rebuild - first of many questions
Posted by: jamesolefjensen ()
Date: April 08, 2020 09:30AM

Hey Kids!

I hope you all are staying safe and sane (the latter is becoming challenging)

I am making progress on my differential rebuild. All four new bearings are installed and I think I am ready to start putting it all back together. Thanks for all the good advice so far.

I noticed the spider gear cross shaft has some wear from the side gear "nuts". That is to say, the shaft has some new flat spots right where it touches the nuts.I know this will increase the yoke axial play.

Is this a big deal?

Is there a yoke axial play number that should make me worry?

I have not measured the wear so i'm guessing its in the ~.02" range, maybe less. The rest of the shaft seems just fine (spider gears fit on the shaft OK, etc.).

James
65 Corsa

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Re: Differential Rebuild - first of many questions
Posted by: vairmech ()
Date: April 08, 2020 03:50PM

Thst is nothing to worry about in a street car.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Differential Rebuild - first of many questions
Posted by: Vairismo ()
Date: April 08, 2020 05:47PM

Once again, a threaded rod or long bolt used creatively will pull the snout and bearing race into the interior of the case.

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Re: Differential Rebuild - first of many questions
Posted by: v8vair ()
Date: April 08, 2020 07:28PM

With new bearings I would go on the tight side of bearing preload, especially on the pinion bearing.

1965 Crown V8 Racer
1964 Bill Thomas Monza Replica Racer
1964 Spyder Street Car
1979 Mazda RX7

Mike Levine

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Re: Differential Rebuild - first of many questions
Posted by: vairmech ()
Date: April 12, 2020 05:54AM

v8vair Wrote:
-------------------------------------------------------
> With new bearings I would go on the tight side of bearing preload, especially on the pinion bearing.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

That is a yes!

When I build a diff and have everything done and setting the final turning torque I use my drill motor and actually spin the diff at the speed of the drill motor. After doing that guess what? the turning torque is less! I go back in and adjust back to the high side, this is one time to err on the high side rather the low. After adjusting the second time I spin the diff and check the turning torque again and adjust until it doesn't change.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Differential Rebuild - first of many questions
Posted by: joelsplace ()
Date: April 12, 2020 06:13AM

I use a rubber mallet on it. I usually have to tighten it several times.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...

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Re: Differential Rebuild - first of many questions
Posted by: 1STLM ()
Date: April 12, 2020 12:02PM

Ken, are you spinning the whole assembly with a drill to adjust preload, or the pinion and side bearings separately? Should the side bearing preload be in the same range as the pinion bearings (9-11 in lbs)?

Brice

66 Corsa Turbo Convertible

Bozeman, Montana

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Re: Differential Rebuild - first of many questions
Posted by: vairmech ()
Date: April 12, 2020 07:04PM

1STLM Wrote:
-------------------------------------------------------
> Ken, are you spinning the whole assembly with a drill to adjust preload, or the pinion and side bearings separately? Should the side bearing preload be in the same range as the pinion bearings (9-11 in lbs)?
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

If you read the shop manual the side bearings are adjusted 2-3 notches tight when you are at your backlash setting. You then just hand snug the pinion bearing and get the assy turning torque. Even just turning the pinion by hand you will be able to turn the adjuster tighter by hand. So, your baseline torque is the carrier adjusted properly and the pinion bearing just snug at zero lash. You will have anywhere from next to nothing turning torque to almost 10 lbs.in. turning torque. Save that number then adjust the pinion bearing to add 10-11 lbs. in. turning torque.

So your initial turning torque was 5 lbs.in. add 10 lbs.in. to that and you adjust to 15lbs.in. turning torque. I then spin everything in the case for a minute or so and check and reset the turning torque. I repeat again.

Keep in mind that this is INITIAL turning torque not the rotating torque. When I check the initial turning torque I spin the assy by hand for a couple of revolutions, stop and then immediately see what the torque is to start the diff turning. This is done after you do the drill motor spinning.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Differential Rebuild - first of many questions
Posted by: 1STLM ()
Date: April 12, 2020 09:44PM

Ken, thanks for the response. I have read the manual, several times. If the bearing preload is decreasing after turning the assembly with a drill, it seems likely that the side bearing and pinion bearing preloads are both decreasing. I thought that if there was a side bearing preload target range, it might make sense to readjust the left side adjuster to within that range rather than just going 2 or 3 notches. Could an initial side bearing preload end up too low after rotating with a drill? If only the pinion adjustment is used to bring the total preload back into range could the result be too much preload on the pinion bearings and not enough on the side bearings?

Brice

66 Corsa Turbo Convertible

Bozeman, Montana

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Re: Differential Rebuild - first of many questions
Posted by: vairmech ()
Date: April 13, 2020 05:08AM

The carrier bearings do not change as drastically as the pinion bearing. I have went back in and tightened the carrier bearings if the initial turning torque changes appreciably. Even after spinning you can loosen the pinion bearing adjuster and recheck the initial turning torque if you feel the need. After you get to your target backlash you don't want to be turning just one side adjuster, if you do anything you want to tighten the side adjusters equally. Or you need to recheck the backlash after you adjust. Keep in mind that the backlash is also part of the contact pattern, just because the backlash is within the range doesn't mean the contact pattern is correct. I have had to have the backlash out of specs in order to get the pattern correct. Out of spec was not .002" or .015" but rather just .001-.002 over spec. Let me see it would look something like this, -.001, +.002 The out of spec limits for me is minus .001 on the low side and +.002 on the high side. And then it also makes a difference what the diff will be used for. A V-8 car will get a little tighter backlash as will a dune buggy with high shock loads.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Differential Rebuild - first of many questions
Posted by: joelsplace ()
Date: April 13, 2020 08:29AM

I've found the same thing Ken is talking about. It seems like all of them I've done are on the high side of backlash when the pattern is right. The contract pattern is much more important than backlash.

Joel
Northlake, TX
5 Ultravans, 113 Corvairs and counting...

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