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Old 02-24-2016, 12:21 AM   #1
vishmutzy
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Default How To: TrueTrac LSD diff in IRS axle housing

After living with the Volvo “Automatic Locking Differential” (aka: ALD, Eaton GovLock, G80) for a couple years in my LS1 transplanted '97 V90, I started researching options to upgrade to a true limited slip differential. I could easily lay down two stripes when accelerating from a stop, but traction at speed (especially coming out of corners) was difficult to predict with the ALD.

First attempt was to go to a local junk yard and acquire the entire rear subframe (cradle, carrier, axles, suspension links, leafspring) from another V90. Then I purchased a Ford 8.8” IRS with LSD from a '93 Tbird. As a winter project, I was going to try to somehow mount the 8.8 into the Volvo MkII IRS subframe. I know that turbobricks forum member “the poi” has done this, but he also has much better fabrication skills and patience than me. After a few nights of mocking up and sketching some ideas, I put this ambitious project on hold.

More research put me in contact with Jonas at BakaxelDelar, basically the Randy's Ring & Pinion of Sweden. Jonas is very knowledgable on all things Volvo and his company makes some unique parts to facilitate custom rear end builds. One of Bakaxel's adapters opens up the possibility of converting my 1065 MkII to an LSD differential.

So new plan was to install an Eaton TrueTrac torsen-type LSD carrier (high pre-load version for Dana 30 rear, P/N 912A588) into my 1065 housing with no modifications to the mounting points or cradle. But it's not a direct drop in, as the TrueTrac endgears are for 27 spline axles (1031 solid axles) but the axle shafts for the 1065 (MkII IRS) and 1045 (MkI IRS) are 26 spline axles. This is where Bakaxel comes in... they sell an IRS axle flange adapter to fit 27 spline endgears. The only caveat is that you have to use MkI style axle shafts (bolted flange on inboard end) instead of the MkII style (splined at both ends).

The Bakaxel adapters aren't cheap and neither is shipping, but unless you're really good with CAD and have access to a CNC mill/lathe I don't see many other options. Bakaxel also sells a waterjet-cut 48 tooth speedometer tone ring that can be wrapped around the larger TrueTrac carrier and tack welded or brazed. I chose to turn down the diameter of the TrueTrac carrier case by 2mm on a lathe and fit the tone ring from the Volvo carrier so I didn't have to space back the speed sensor on the diff cover to compensate that 1mm offset. I you do turn the TrueTrac on a lathe, use a sharp carbide or coated carbide insert (diff carrier is case hardened steel) and put a small chamber on the leading edge to facilitate install of ring.

I purchased the TrueTrac from Summit, bearings from RockAuto, and other miscellaneous Volvo-specific parts from Tasca. The MkI axle shafts were sourced from a '93 960 (found on car-part.com), and while I was at it I also bought the 1045 rear carrier from the same car for the 3:31 ratio ring & pinion.

Yes, 3:31 gears will work on the TrueTrac even though Eaton lists the carrier break at 3:73 or above. Volvo designs their higher ratio (3:54, 3:31, 3:15, etc) rings gears to have a thinner profile to allow the same diff carrier to be used regardless of ratio. Most other manufactures have carriers for high ratio and low ratio gearsets.

Here is list of parts that I used for this swap. Your requirements may vary.
Tasca or Volvo dealer:
8653928 Axle seal 2
81383 Pinion shim, 0.10mm 2
81384 Pinion shim, 0.15mm 1
3549685 Pinion flange nut 1
11998 Oil plug crush washer 1
6843094 Diff housing bushing 2
1377058 Axle seal **No longer available, substituted 8653928** 2
1340791 Pinion crush sleeve **No longer available** 1

Summit:
DTL-912A588 Differential, Eaton Detroit Truetrac, 27-Spline, Dana 30
OMX-1650201 Gasket, Differential Cover, Dana 30

RockAuto:
LM501314 Carrier bearing cup 2
LM501349 Carrier bearing 2
M86610 Pinion bearing cup, outer 1
M86647 Pinion bearing, outer 1
HM89410 Pinion bearing cup, inner 1
HM89449 Pinion bearing, inner 1
5778 Pinion seal 1

BakAxel:
hub27splines Hubb/gavel 27 splines Volvo multilink 2

Junk yard:
MkI axle shafts with bolts
MkI rear carrier (if you want to swap to 3:31 ring & pinion)

Notes: Axle seals (1377058) and pinion crush sleeve (1340791) no longer available for V90. For the axle seals I compared the parts I removed from 1065 and 1045 housing and they were identical diameters and even part number. So I cross referenced the 1045 and found a different part number 8653928. Gave it a shot and dimensions and fitting were identical to 1377058. Talked to guy at transmission shop and he said the crush sleeve should be a common Dana 30 part. Also, I couldn't find any aftermarket carrier shim kits but the transmission shop had plenty of Dana 30 shims that fit.

I did have the differential installed at a transmission shop by an experienced technician. With the ring & pinion swap, I wanted this done right and didn't feel like investing in tools for hopefully a one-time use.

The only other thing I had to modify was the axle retention c-clips. The 26 spline clips were too thick for the groove on the Bakaxel 27 spline adapters. A little sanding removed enough material (probably 0.2mm) for the clips to fit. The 27 spline adapters were a very tight fit into the TrueTrac but a little persuasion with a brass hammer seated them.

Below are some photos from the project. Hope this helps!

Last edited by vishmutzy; 02-24-2016 at 01:51 AM..
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Old 02-24-2016, 12:35 AM   #2
vishmutzy
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1045 MkI IRS diff from '93 960, only the 3.31 ring & pinion were used:


MkI axle shafts (bolted flange):


1045 26-spline axle shaft on left, Bakaxel 27-spline axle adapter on right:



1065 MkII IRS diff from '97 V90, stock 3.73 gears. Housing sandblasted and painted with RustBullet:



Stock ALD diff with 3.73 gears on left, Eaton Truetrac LSD with 3.31 gears on right:


1065 housing with TrueTrac, 3.31 gears and stock Volvo speedo tone ring tack welded in place...


... and with axle adapters installed.

Last edited by vishmutzy; 02-24-2016 at 09:27 PM..
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Old 02-24-2016, 10:16 AM   #3
lookforjoe
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Pics aren't loaded? Bad links?

The same crush collar and the pinion bearings are also used in 97-99 V70 AWD bevel gear - Volvo likes to repurpose when possible ;)
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Old 02-24-2016, 10:33 AM   #4
vishmutzy
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Originally Posted by lookforjoe View Post
Pics aren't loaded? Bad links?
My technical support team is working on this
*** Image links fixed. Sorry, new to this forum thing. ***

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Originally Posted by lookforjoe View Post
The same crush collar and the pinion bearings are also used in 97-99 V70 AWD bevel gear - Volvo likes to repurpose when possible ;)
Good to know about crush collar. It's surprising that there are consumable parts like this that are "no longer available", even from aftermarket. Volvo doesn't do a very good job providing alternative or superseding part numbers, BMW is much better from my experience.

Last edited by vishmutzy; 02-24-2016 at 09:30 PM..
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Old 02-24-2016, 10:50 AM   #5
lookforjoe
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Originally Posted by vishmutzy View Post
My technical support team is working on this


Good to know about crush collar. It's surprising that there are consumable parts like this that are "no longer available", even from aftermarket. Volvo doesn't do a very good job providing alternative or superseding part numbers, BMW is much better from my experience.
Volvo used to be pretty good about supercessions and keeping old stock - mind you, these are all now over 20years old, so not really surprising. I think under Ford they reduced overall support for older parts supplies.

AWD angle gear pinion - same bearings as 1031, etc. and collar & pinion seal




You can see the bearing #'s are the same as 1031- 183841 & 183839

EDIT: 9183891 for the pinion seal - hmmmm. I had thought the forever in use 942905 pinion seal had directly superseded to the 9183891, but now I'm not so sure. I know the (new) collar is the same - I have one here.

8689678 is the new number for the pre tensioner



I can remove this if it's cluttering your thread, just let me know.

Last edited by lookforjoe; 02-24-2016 at 02:12 PM..
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Old 02-24-2016, 11:26 AM   #6
Homer
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Originally Posted by vishmutzy View Post
My technical support team is working on this


Good to know about crush collar. It's surprising that there are consumable parts like this that are "no longer available", even from aftermarket. Volvo doesn't do a very good job providing alternative or superseding part numbers, BMW is much better from my experience.
He's correct. I used the later crush sleeve on my 1031 axle. Worth noting that it crushes at a much lower torque than the original. I was unable to get the 130 ft lbs of torque on the pinion nut, 115 ft lbs max with that crush sleeve. I just used some red loctite as a backup.
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Old 02-24-2016, 02:38 PM   #7
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Your pictures on the dropbox are on private I tried going to the link to view them.
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no one saw me with my little umbrella and sandpaper though.
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