Diff Replacement--ON CAR--End Play Check & Ordering Parts--Few Qs

**Mr D** · 07-15-2012

DD--03 GTP 128K mi. RPOs L67 MN7 2WR69

1st, Automatic trans simply terrify me, so all help is greatly appreciated. I have convinced myself that my vibrations and clunks are from my differential and decided to grow a pair & do (Attempt) an on car replacement. I have done a good amount of reading and homework, and feel I understand about as much as I will from reading & pics.

I plan to buy parts from gmpartsgiant.com. They take a week to arrive with normal shipping, and thats what I can afford. & since this is my DD, I would like to be able to have all parts before I start. I use Illustration Key # when refering to parts so I don't get confused, because the key #s seem to be consistant even when name of parts & manufacturers part #s are not.

I am getting Diff Carrier Assembly (700)-$210.

I have NOT found a how-to specifically for on-car procedeure. My 1st concern is "Differential Carrier End Play". Is there a test, and what tools are required, for it on-car? Which leads into, there are 9 different sizes of Diff Carrier Thr Washers (714)??? Is this something to skip or is there something I should/can do about the Test and selecting the proper Selective Thrust Washer (714)?

Also, in general, are there other parts I should order, which would be accessable from on-car procedure, that should also be replaced? Such as:
Front Diff Carrier Sun Gear Shaft (689)-$70
Internal Gear Thrust Bearing (695)-$12
Front Diff Carrier Sun Gear (697)-$50
Front Diff Carrier Thrust Bearing (715)-$10

Thanks in advance.

**Rico** · 07-15-2012

View topic - Illustrated 4T65E Rebuild : PontiacBonnevilleClub.com

**Mr D** · 07-15-2012

Thanks again Rico. Awesome write up. RE: Diff End Play Test, interesting--but not sure what is being measured--ie, he starts by zeroing out on pinion, then prys up on diff thru full travel with screwdriver--maybe this makes more sense to me when I have parts in my hand. Also, this & manual both have diff carrier upright for test, which is not possible on car, ? Correct? Does it matter, horizontal or vertical?

Regardless, seems like its time for me to get a decent micrometer.

**Rico** · 07-15-2012

Push the diff towards the driver's side and do the measurement. For measuring the depth you'll need some digital/analog calipers that measure 0.001".

**Mr D** · 07-15-2012

Thanks. Measuring End-play=depth. Thats why carrier is vertical.

**BillBoost37** · 07-16-2012

Technically I don't believe you can check the end play with the full trans assembled and in it's normal position (horizontal).

**Rico** · 07-16-2012

I believe you can with both half axles removed. The output shafts may skew the measurement?

**BillBoost37** · 07-16-2012

Thinking about it. IIRC the book has you put the diff pieces in with only the pinion loaded in the casing. Then measure. That way there's no possible anything pushing on the diff. You could likely do it like you are saying Chuck.. since nothing else holds the output shaft except the diff and axles..I suppose it would work.

Anyone have a case of selective washers?

**Rico** · 07-16-2012

I doubt he'll end up needing the washers. I'll bet it's dead nuts.

**BillBoost37** · 07-16-2012

There is always a washer in there with the bearing. The reason for measuring is to select the proper spacer/washer.

**Rico** · 07-16-2012

You mean thrust washer.

**Mr D** · 07-16-2012

Thanks for the dialogue. When I replaced axles, I noted instructions say to do only 1 at a time, if both CV axles are out at same time, internal components may be misaligned--thats a problem thats over my head, and I'm not ready to deal with.

Originally from instructions on diff end play test, I thought diff play was a measurement of eccentricity on rotation, and that the selective thrust washers varied in diameter. Now, with your help, I understrand play measurement is of depth, & selective washers vary in their thickness.

Now I think I'm on right track, and now I can try to figure out how to rig a tool to get best measurement I can.

I plan to order parts at lunch, hopefully they arrive by Fri. Now I'm thinking I should order: Diff carrier assem (700), Int Gr Thr Brg (695), sun gear (697), Fr diff carrier thr brg (715), & all 9 diff carrier thr washers (714).

Please share if you have more thoughts on diff end play testing/other.

**BillBoost37** · 07-16-2012

Typically I don't run into end play issues because I'm working in the same casing with the same parts. Therefore they were usually correct from the factory. However I've seen enough people put the washer that came with a diff into the casing and have it work well enough that you don't hear issues from it.

On your mention of not replacing both axles at the same time, this is not an issue. Would you share the source of that info, I'd like to read more on it. I've had both axles out of a transmission too many times to count and rebuilt a few as well. There isn't anything that can fall out if you pull both CV's at once. Only piece that could possibly come out would be the output shaft. If that happened, you'd reseat it into the diff.

**Rico** · 07-16-2012

Ah, that makes perfect sense. The differential may flop on one side or the other without at least one axle in place. The axle will hold the output shaft which holds the differential square to the case.

You learn something every day.

**BillBoost37** · 07-16-2012

Originally Posted by Rico

Ah, that makes perfect sense. The differential may flop on one side or the other without at least one axle in place. The axle will hold the output shaft which holds the differential square to the case.

You learn something every day.

Uh..What?

The diff cover holds the diff up. The output shaft is supported by the guts of the trans that it passes through. There isn't any worry of misalignment etc when you have both axles out. otherwise guys R&R'ing transmissions would have some other magical J tool in their stash to hold the guts in properly.

**Mr D** · 07-16-2012

I bought NAPA axles, 1 new & 1 reman. They came w/ same instruct sht. pg 5, top.
"NOTE: To avoid having any parts of the differential gears become mislocated, do not remove both drive axles at the same time. Complete the removal and reinstallation of one axle before removing the second."

I'm sure I read similar somewhere else as well, but can't recall where now. But it seems like it is consistant w/ your explanation/fix.

**Rico** · 07-16-2012

I think the issue here is that the measurement is usually done with the transmission on end which naturally aligns the diff against the thrust washers. Am I way off here?

**Mr D** · 07-16-2012

Rico, I am on same page as you. Test is specified to be done vertically, with gravity at work. My issue is for an on-car solution, ie test performed horizontally, taking measurment while keeping everything aligned properly while rotating gear despite the effects of gravity.

The parts are accessable while on car, but this test seems important enough and not sure yet what to do about it?

**Rico** · 07-16-2012

We're back to square one.

Bill

Any more ideas? I may be doing this soon also...why I'm interested.

**BillBoost37** · 07-16-2012

Ok.. if your diff came with a washer or you had a washer for the old diff... You should be able to measure the two diffs instead of the clearance to the case. (assuming you didn't swap non-hd to hd). If you are going to HD and the bearing and washer are there, use them and smile when nothing bad happens. (Seen a ton of people do it this way).

On the diff being able to flop.. it can't. This extension we see on the top of the diff. It rides in the bearing in the diff cover. This diff has the bearing and selected washer on it in the picture.

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