Volvo Differential Shenanigans - planning and results
Page 1 of 1

Author:  Fred [ Sun Jun 26, 2016 7:17 am ]
Post subject:  Volvo Differential Shenanigans - planning and results

So, I have too many Volvo differentials, and thus need a solid plan before I do anything. Here's my first cut:


  • 1031 open in 240 wagon, quiet, has good heavy synth in it
  • 10?1 open in 740 sedan, slight whine has developed after many many burnouts on probably very old oil
  • 1041 Eaton G80 locker in caravan, low mileage (140kkm?), quiet worked fine, did skids
  • 1041 Eaton G80 locker on bench, looks OK, clean oil, have not driven, do not know, damaged brake backing plates, relatively new overall
  • 1031 probably-open in parts 240 sedan, no idea of condition, or ratio, but probably useful for whole-axle-swap style work.

What I want:

  • G80 in the 240 for wet traction and more controllable slides in the wet - skids not an option, insufficient power, excess weight
  • G80 in the 740 for skids and traction and controllable slides in the dry or wet - skids an option, sufficient power, acceptable weight
  • Light, compact, diff-less axle with full brakes in the caravan
  • Spare 740 housing, diff, etc ready to swap in when I break the 740 diff :-D This will happen, it's just a matter of time. If I end up with this being another G80 later, great, but anything would do to keep it on the road.
  • Spare 240 housing, diff, etc ready to swap in if I end up breaking the 240 diff. Just in case, as it'll eventually get a double or triple power increase with DOHC turbo.

So, where to start?

Well, I think the best thing to do is to prepare the diff-less axle for the caravan using the
G80 that's on the bench as a base. Remove the G80 core, and the ring and pinion, etc.
Figure out how to support the spline ends of the axle to make the load bearing capability
of it safe. Then swap that in to reduce towing and unsprung weight, and shift the balance
slightly further back (diff head mostly sticks forward of axle).

Out of the caravan will come a complete and happy working G80 axle with good brakes
to go into the 740 sedan. Swap this into the 740 sedan as a unit, while removing the
existing noisy open diff as a unit to keep as a spare. Take the brakes from this and apply
them to the caravan again so it's handbrakeable again.

Which leaves me with a G80 core, an open diffed 240, and a spare entire 240 diff to play
around with. So, get the spare 240 diff on the bench and carefully swap in the G80 core.
Then swap the whole axle into the 240 wagon one sunny day.

Anyway, I made a little progress on this tonight, so here's a few pics for the new thread:

References first:

G80 on bench: ... 3278617600
On stands looking for drain: ... 1903631360
Found unconventional slow drain: ... 3203429376
Eaton G80 guts on display: ... 9014516736
Cleaned back cover with filter built in: ... 0470626305

And in colour:






Comments most welcome, especially from the venerable and knowledgeable sim! :-)


Author:  ToxicGumbo [ Mon Jun 27, 2016 10:20 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

Any chance you can pick up a spool for the caravan axle? Something along the lines of this:


This might be an easy "set it and forget it" kind of thing to keep the half-shafts solidly in place and connected.

Author:  Fred [ Tue Jun 28, 2016 2:55 am ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

Spool is no good, though. I don't want them joined together or it would literally be impossible to turn around in a driveway by hand. I think the open centre from a random other axle is the answer. Maybe that'll come out of the spare 240 axle as a priority?

Author:  Fred [ Thu Jul 07, 2016 1:32 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

So tonight I needed something to make me feel better, so through a bit of chopped logic, I went down and pulled apart the 1041 as pictured above.

First job, out with the axles: ... 8392450048


Then out with everything: ... 2869273600


Pinion looks like new, more or less: ... 0563369985


Axle spacing, as I'm told 240 diffs have longer axles on one side: ... 4141775872


Finally I tried to pull the bearing, but just ruined it instead, fail: ... 6527490049


After that, I tin snipped the disk in half, and because the bearing pulling had moved it a fraction of a mm, the two halves came away. Then I could undo the ring gear bolts and finally the three retaining torx screws, and out came the guts of the G80. The clutch disks are nice and stout/solid. The actuator weights are easy to fling out, no mods to do there. The spring on the disable fly weight was in a weird/wrong place, but maybe I did that without noticing?

Anyway, it's all out on the bench, so I can clean, measure, modify, reassemble, etc. I think to get the other clutches out you'd need to drift out the spider gear pin, and I'm not going to do that. No need, anyway.

What's next? Not sure. But you'll hear about it here.

Author:  ToxicGumbo [ Thu Jul 07, 2016 3:44 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

A couple comments about saving old bearings (most likely for other projects):

  • Even if one's damaged, the core works great for driving replacement bearings. Matched sizing and surface contact.
  • With differentials, especially when you're replacing bearings and races using identical parts, you can grind out some of the bearing inner ring to easily prep for shim use and initial backlash checks.

Author:  Fred [ Thu Jul 07, 2016 10:57 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

Re point 1, yes, I have a collection of old gears and bearings and similar chunks for similar reasons :-)

Re point 2, I don't understand. Care to explain the last half of it?

Author:  ToxicGumbo [ Fri Jul 08, 2016 2:38 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

Building up a differential's pretty easy for the most part, but the biggest pain is testing for proper backlash. You usually have to pre-assemble the differential with both pinion bearings installed and often the front bearing (on the driveshaft end) has to be pressed on (and later, off) as you set the shims between the pinion gear end and rear bearing (most central to the differential). If you ever rebuild a differential with the same gear ratio, using the stock shim is likely safe enough and might not involve any further effort, but the process of fitting, checking, disassembling, etc. is a pain when using a press-fit front bearing that can be damaged without OEM bearing-handling tools. So a trick is to grind out the inside of the bearing so it can be slipped over the pinion by hand. Of course, if you change your gear ratio, the bearings and races change, so this wouldn't work with stock parts.

In my Toyota's case, that front bearing was a total pain in the bum in that it was time consuming and potentially could have been damaged via press fitting and removing. It's one thing to have a decently stacked set shims and ballpark backlash setting, it's another to get it exact and that can take quite a few false tries and spotty readings (as you have to read both sides of the ring gear for drive and coast). I could have saved a lot of effort by simply buying another front bearing to match my new gear ratio, ground out the center for test fit, checked backlash, then assembled the entire unit for a final check and installation. I learned the hard way and found others took this shortcut.

This NAPA article covers it as well: ... ferential/


The main pinion bearing (as well as the carrier bearings) have to be pressed off, we took them to the local NAPA machine shop for that. You don’t want to toss the old pinion bearing, you need it for the set up. Using a fine carbide burr, grind out the inside of the bearing until is slips onto the new pinion shaft easily. This is so you can check the fitment of the gears without destroying bearings.

Author:  ToxicGumbo [ Fri Jul 08, 2016 2:48 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

I got locked out of editing the above while adding the following:

Edit: I don't know how easily you can find the goop for checking backlash there in NZ, but I had a hell of a time here in the States. Some people simply use white lithium grease with food coloring, but I found two solutions after a lot of searching:

  • NAPA has a tube of Prussian Blue marking compound (BK 80038) that's decent and cheap, but splotchy.
  • Any GM/Holden parts dealer can get you yellow GM marking compound (1052351), which works better, but runs around $15.

I ended up using each and occasionally got a sickly green mess (from mild stain) that worked even better.

Author:  Fred [ Fri Jul 08, 2016 3:21 pm ]
Post subject:  Re: Volvo Differential Shenanigans - planning and results

I see what you mean, but that's not relevant to the Volvo diff style at all, as far as I can tell. :-) I won't be touching the pinion gear whatsoever. Only changing centres and adjusting side to side position, if anything.

Appreciate the advice, regardless! Especially the GM marking compound which I should be able to score cheaply/easily through a relly.

Re backlash, dial gauge is another way. I'm miles away from that, though, anyway.

Page 1 of 1 All times are UTC [ DST ]
Powered by phpBB® Forum Software © phpBB Group