Differential overhaul

Discuss mechanical problems here.
philthehill
Minor Maniac
Posts: 8258
Joined: Thu Jul 19, 2012 12:05 pm
MMOC Member: Yes

Re: Differential overhaul

Postby philthehill » Tue Sep 24, 2019 10:41 pm

Whilst the dust cap is a separate piece to the pinion flange it should be a tight fit on the pinion flange and should once fitted not rotate or move.


Declan_Burns
Minor Legend
Posts: 1891
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Differential overhaul

Postby Declan_Burns » Wed Sep 25, 2019 1:41 pm

Measure the shims when you remove the carrier and take note of which side they were on. I can only upload five photos at a time so here are the photos of the carrier disassembly.
Regards
Declan
Attachments
2_0_Removing_carrier_bearing_1.jpg
2_0_Removing_carrier_bearing_1.jpg (610.04 KiB) Viewed 1011 times
2_1_Carrier_shims.jpg
2_1_Carrier_shims.jpg (679.27 KiB) Viewed 1011 times
2_2_Removing_carrier_bearing_2.jpg
2_2_Removing_carrier_bearing_2.jpg (885.97 KiB) Viewed 1011 times
2_3_Carrier_removed.jpg
2_3_Carrier_removed.jpg (317.23 KiB) Viewed 1011 times
2_4_Pin_location.jpg
2_4_Pin_location.jpg (871.68 KiB) Viewed 1011 times


Regards
Declan

Declan_Burns
Minor Legend
Posts: 1891
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Differential overhaul

Postby Declan_Burns » Wed Sep 25, 2019 1:45 pm

...and the pinion. Make sure you have a decent puller as it is usually very tight interference fit. I did post all these photos before but they seem to have vanished.
Regards
Declan
Attachments
1_0_Removing_pinion_bearing.jpg
1_0_Removing_pinion_bearing.jpg (333.21 KiB) Viewed 1010 times
1_1_Pinion_bearing_removed.jpg
1_1_Pinion_bearing_removed.jpg (649.54 KiB) Viewed 1010 times
1_2_Pinion_washer.jpg
1_2_Pinion_washer.jpg (219.08 KiB) Viewed 1010 times


Regards
Declan

ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Wed Sep 25, 2019 2:43 pm

Thanks Declan. Does your bearing puller grip the outer bearing race, or the inner? Does it leave the bearing re-useable?

Having got the diff cage out of the case, I can see the pinion spins freely and smoothly in its bearing, with little noise, so I'm going to leave the pinion alone, just replace the oil seal. Any idea how I can remove the oil seal, which seems to be firmly rusted in there!

I'm also going to leave the diff bearings alone, for the same reason-they spin freely and smoothly, with no noise.

One of the planet gears in the cage has a fair bit of free play along its shaft-should this be the case, or should I renew the thrust washers? Apart from that, all seems ok, no sign of unusual wear on crown wheel, pinion or sun & planet wheels themselves.
cheers N
'69 Traveller, 1275, discs.

Declan_Burns
Minor Legend
Posts: 1891
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Differential overhaul

Postby Declan_Burns » Thu Sep 26, 2019 8:00 am

N,
When you try to remove the carrier bearings you will probably find that the bearing separates and the balls go flying all over the workshop. It is an angular contact bearing so if you do try pulling it, do so in a plastic bag. The inner race can then be pulled off separately. Only then have you access to the shims. That is what makes life difficult on re-assembly. To set-up the differential, if for example you are changing the CWP, you need to remove these bearings several times to find the correct shim size. For this reason I made up a set of set-up bearings by grinding down a set of old bearings with a flap wheel so they can slide on and off without the need for a puller. Another alternative is to possibly put the shims on the outside of the bearings. Using the set-up bearings and a dial gauge you can slide the carrier back and forth with a screw driver to measure the shimming required.
If your bearings are OK then leave everything alone. If the trust washers are worn you can replace them.
To remove the oil seal with the pinion in place, you may have to puncture it to get a screw driver in to carefully lever it out. Maybe somebody else has a better suggestion on that.
Regards
Declan


Regards
Declan

philthehill
Minor Maniac
Posts: 8258
Joined: Thu Jul 19, 2012 12:05 pm
MMOC Member: Yes

Re: Differential overhaul

Postby philthehill » Thu Sep 26, 2019 8:45 am

Clean off all the muck around the seal. Soak with penetrating oil. Put a suitable self tapping screw into the metal part of the seal through a length of flat bar. Use the end of the pinion as a fulcrum point and pull up on the flat bar the seal should rise in the case and eventually come out.


Declan_Burns
Minor Legend
Posts: 1891
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Differential overhaul

Postby Declan_Burns » Thu Sep 26, 2019 12:28 pm

Excellent idea Phil!
Regards
Declan


Regards
Declan

ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Thu Sep 26, 2019 1:18 pm

Thanks for the advice chaps.

In fact, after a bit of gentle persuasion with a knife and two screwdrivers, I managed to prise the oil seal out last night. I did think of drilling a hole in it, then using a punch to try to turn it, but I didn't want to risk getting metal swarf in the bearing.

Here it is, does this look ok?
IMG_20190925_200941~2.jpg
IMG_20190925_200941~2.jpg (789.24 KiB) Viewed 950 times
Is that gap in the side an oilway, for keeping the bearing lubricated?

If stripping the diff cage doesn't involve removing the bearings, I will look at the planet wheels & shims, and renew if necessary.

Cheers N
cheers N
'69 Traveller, 1275, discs.

Declan_Burns
Minor Legend
Posts: 1891
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Differential overhaul

Postby Declan_Burns » Thu Sep 26, 2019 2:13 pm

N,
You don't have to pull the bearings to strip the diff cage. Start by driving out the pin. If my memory serves me correctly it is approx. 4mm. Location as in my fifth photo above.
Regards
Declan


Regards
Declan

Banned User
Minor Fan
Posts: 333
Joined: Tue Jan 29, 2019 9:37 am
MMOC Member: Yes

Re: Differential overhaul

Postby Banned User » Thu Sep 26, 2019 7:16 pm

Silly question. :oops: Why is the crushable spacer apprx 21mm long and the solid spacer is 40.5mm?

ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Thu Sep 26, 2019 10:21 pm

PoolGuy wrote:
Thu Sep 26, 2019 7:16 pm
Silly question. :oops: Why is the crushable spacer apprx 21mm long and the solid spacer is 40.5mm?
Good question, can't answer that. My spare crush washer is 21mm as well.

Ok, here is my dissembled diff cage.
IMG_20190926_213441~2.jpg
IMG_20190926_213441~2.jpg (1.55 MiB) Viewed 924 times
Yeah, the oil seal got a bit mangled!
IMG_20190926_213555~2.jpg
IMG_20190926_213555~2.jpg (1.33 MiB) Viewed 924 times
If you look closely, you can see that the pinion on this side of the cage has worn the cage itself
IMG_20190926_213620~2.jpg
IMG_20190926_213620~2.jpg (758.98 KiB) Viewed 924 times
And here's why. The thrust washer under one of the planet wheels was almost non-existent, just a thin ring of metal (bronze?).

The planet wheels themselves look ok, as do the sun wheels, there is a little wear, but I don't think it justifies replacing them. There is wear on the pinion shaft, I will replace this.
Oversize thrust washers are available from ESM, so I'm going to get two normal and one oversize, and see what combination fits best.

Question-the BMC manual talks about peening over the entry hole that the pinion shaft peg goes in. How do I do this? Will some thread lock or bearing lock retain the pin just as well?

Cheers N
cheers N
'69 Traveller, 1275, discs.

ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Thu Oct 03, 2019 12:32 am

While I've got the back axle off the car and in bits, I've taken the opportunity to do a bit of freshening up. Here are the rear brake backplates cleaned, painted & reassembled, ready for fitting to the also cleaned & painted back axle.
IMG_20191003_000802~2.jpg
IMG_20191003_000802~2.jpg (891.54 KiB) Viewed 875 times
Last edited by ndevans on Thu Oct 03, 2019 1:31 pm, edited 1 time in total.
cheers N
'69 Traveller, 1275, discs.

don58van
Minor Addict
Posts: 615
Joined: Sun Feb 01, 2009 6:24 am
MMOC Member: No

Re: Differential overhaul

Postby don58van » Thu Oct 03, 2019 7:11 am

Hi nevans

Nice work there.

I want to thank you for taking the time to give us a pictorial coverage of your diff rebuild. Good quality pictures too.

I admit that a lot of the detail is going over my head, but I intend to attempt a diff rebuild soon. I hope that once I am hands-on it will all gel.

Don

ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Thu Oct 03, 2019 7:24 am

Thanks. I've never done a diff before either, so it's a steep learning curve for me. I'll be doing some more on the diff itself next week.
Last edited by ndevans on Thu Oct 03, 2019 7:31 am, edited 1 time in total.
cheers N
'69 Traveller, 1275, discs.

Banned User
Minor Fan
Posts: 333
Joined: Tue Jan 29, 2019 9:37 am
MMOC Member: Yes

Re: Differential overhaul

Postby Banned User » Thu Oct 03, 2019 7:30 am

don58van wrote:
Thu Oct 03, 2019 7:11 am
Hi nevans

Nice work there.

I want to thank you for taking the time to give us a pictorial coverage of your diff rebuild. Good quality pictures too.

I admit that a lot of the detail is going over my head, but I intend to attempt a diff rebuild soon. I hope that once I am hands-on it will all gel.

Don
Ditto, I’m just at the ripping it apart stage. Thanks for sharing.

ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Thu Oct 03, 2019 10:57 pm

A few photos this evening of the innards of the diff cage.
IMG_20191003_213329~2.jpg
Diff cage at the top, planet wheels and shaft below, sun wheels either side. The shaft in the bottom left corner is the new planet wheel shaft.
IMG_20191003_213329~2.jpg (2.11 MiB) Viewed 833 times
IMG_20191003_213507~2.jpg
Close up of the planet wheels and the shaft. The planet wheel thrust washers are below the shaft, the one on the left has worn away to a ring. The new thrust washers are at the top, these are 0.035" washers. I have also bought a single 0.054" thrust washer.
IMG_20191003_213507~2.jpg (1.33 MiB) Viewed 833 times
IMG_20191003_213629~2.jpg
These are the sun wheels. The washers are actually fibre washers. They look ok, but I think I will replace them.
IMG_20191003_213629~2.jpg (860.71 KiB) Viewed 833 times
IMG_20191003_213715~2.jpg
Looking inside the cage, the shaft on which the planet wheels sit runs from left to right, through the hole in the cage. The thrust washer sits between the planet wheel and the cage.
IMG_20191003_213715~2.jpg (547.04 KiB) Viewed 833 times
IMG_20191003_213737~2.jpg
The other side of the diff cage. The sun wheels, which are what the inner ends of the half shafts locate in, sit above and below.
IMG_20191003_213737~2.jpg (648.55 KiB) Viewed 833 times
The wear in the diff cage where the thrust washer has worn away to a ring is clearly visible. Can I have this machined out, and fit an oversize thrust washer? I have an 0.054" one available, as well as 2 x 0.035" thrust washers.
cheers N
'69 Traveller, 1275, discs.

philthehill
Minor Maniac
Posts: 8258
Joined: Thu Jul 19, 2012 12:05 pm
MMOC Member: Yes

Re: Differential overhaul

Postby philthehill » Fri Oct 04, 2019 7:48 am

You could get it machined out but finding someone with the correct tooling will be the problem.


Declan_Burns
Minor Legend
Posts: 1891
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: Differential overhaul

Postby Declan_Burns » Fri Oct 04, 2019 9:07 am

I agree with Phil, personally I would look into replacing it rather than attempting to repair it.
Regards
Declan


Regards
Declan

philthehill
Minor Maniac
Posts: 8258
Joined: Thu Jul 19, 2012 12:05 pm
MMOC Member: Yes

Re: Differential overhaul

Postby philthehill » Fri Oct 04, 2019 9:39 am

It should be noted that the ATA and BTA diff carriers are not interchangeable. The damaged diff carrier in the photo above is a BTA diff carrier.

So basically if you cannot find a machinist to do the job you are unfortunately back to square one. :cry:


ndevans
Minor Addict
Posts: 934
Joined: Fri Mar 03, 2006 11:56 am
MMOC Member: Yes

Re: Differential overhaul

Postby ndevans » Fri Oct 04, 2019 9:59 am

Ok thanks gents.

So, if I just fit new 0.035" thrust washers, will it be ok?
What if I was to try to turn down a thrust washer so that it fits in the recess that's been worn? Could that work?
cheers N
'69 Traveller, 1275, discs.


Who is online

Users browsing this forum: geoberni and 7 guests