Rear End Options
|UPDATED: July 3, 2019 CONTACT|
M A I N S
G80 Locking Differential
(from a 700/900)
into your 240
|The G80 Locking
Differential is a special differential that Volvo
began putting in 740/940
rear ends (standard in North
American market only) beginning in
1991. It was also made available as a factory option
for 240s in 1993. Volvo referred to it as the Automatic Locking
Not all 1991 740/940 models got them, but nearly all RWD cars got this differential from 1992-on (North American market).
|Here are some videos from Eaton explaining how this
| This differential is a direct (or
nearly a direct) bolt-in to the 240 Dana 30 (1031 and
1041) rear ends. In most cases, these
differentials will bolt in and run fine with no
adjustments, usually even without replacement of any
bearings or shims. You must remove the ring gear and bolt your own ring gear on. If you're
concerned about installing a G80 "as is", you can check
the ring gear
backlash after installing by using a dial
caliper. Backlash is the amount of rotational movement
(back and forth) of the ring gear when the pinion gear
is stationary. The
Volvo specification calls for around .005 to .007
inch (5 to 7 thousands of an inch) of backlash.
There are how-to videos on YouTube for checking ring
gear backlash on a rear end. If the backlash is
out of spec, the rear end may whine at some speeds or
there may be unusual wear.
CORRECTING EXCESSIVE BACKLASH: There are shims under the carrier bearings that can be added or removed to adjust the ring gear closer to the pinion gear (to reduce backlash) or farther from the pinion gear (to increase backlash). Changing shims will of course increase the difficulty of this installation, because the bearings must be removed and these bearings are pressed on. It's difficult to remove these bearings without damaging them or cutting them off.
|PULLING CARRIER BEARINGS (AKA: Differential Side Bearings)
So far I have avoided having to deal with replacing any carrier bearings on two different G80 installations in 240s. I installed them with the bearings and races that came with the G80.
If you find yourself needing to change, pull, adjust bearings, here's a little info.
<<< If you have the correct Volvo bearing puller tool, then allegedly pulling these bearings can be done without damaging them.
Without this tool, it is supposed to be more difficult to remove these bearings without damage (requiring new bearings), but if anyone can offer better info that what I have here, please email.
More information: https://forums.tbforums.com/showthread.php?t=317970&page=2
|<<< I have not personally experienced this tool, but it looks pretty good in the below videos:
Here's a video of an interesting carrier bearing puller made by Matco (Part Number MST4520) that appears to be doing very well on a carrier bearing:
And here's the OTC version (PN 4520), which looks identical to the Matco: https://www.youtube.com/watch?v=-eh8WF_ON6g
|There are some that will tell you that the only
"correct" way is to fit the differential just as you
would any other new differential replacement, using a
professional technician. This can be expensive. The
choice is yours, however many "junkyard" DIY mechanics (myself included) have already done this successfully as a
(*nearly) simple bolt in.
*Regarding nearly a bolt in: Exception for pre-1992 240. See Axle Trimming info below.
See that round silver
metal disc? That's a cover (AKA: oil
slinger) that you'll almost never see in a G80 photo
(because they're almost never re-used or
re-installed). That cover is found on most (maybe
all) Volvo G80 differentials on the ring gear side. It
will actually prevent you from removing the ring gear
bolts, which must be done to install your own ring gear.
The only way to remove this cover intact is to do what
the person in this photo did; to remove the bearing on
the ring gear side. These bearings are pressed on, so
removing them usually damages them.
<<< There's another way to deal with this. You can simply cut that disc off with tin snips and toss it. That way you can swap your ring gear without having to mess with pulling/installing new bearings. (Photo borrowed from G80 modification article: https://www.turbobricks.com/mods.php?content=art0027)
Here's a YouTube video of someone pulling a G80 from a Volvo at a salvage yard and you can see this disc on that differential: https://www.youtube.com/watch?v=wwQh9mMtmvE
If you remove a G80 yourself, make sure you keep the bearing races and mark them RIGHT and LEFT with a marker so they end up on the same side as they were originally.
|If you're shopping for a
used G80, keep in mind that this differential was used
in a lot of different cars and trucks. Some have
different axle spline counts.
<<< The ones used in Volvo cars are made for a Dana 30 with 27 spline axles (identified as a 1041 axle). All such differentials from a Volvo it will have "VOLVO" and a Volvo part number stamped into it as shown here. The part numbers seem to be pretty various and seem to have changed a number of times over the years.
BEWARE: I have seen that some on-line sellers REMOVE the carrier bearings before selling a G80. If you want the bearings INTACT, be sure to check that before buying.
| TRIMMING THE RIGHT SIDE AXLE:
This is the part that makes this installation nearly a bolt-in instead of a 100% bolt-in. In most cases when fitting this differential to a 240 rear end, you will need to trim a small amount off of the inner end of the RIGHT side axle. This is because the right axle will not fit all the way in with the G80 in place. The trim amount is about 1/8 to 1/4 inch. In 1992 the 240 changed so that the right side axle was slightly shorter. This means that some 1992 and all 1993 models will not need any axle trimming and this will be a 100% bolt-in.
If your G80 came with a 48 tooth tone ring and your later 240 uses a
12 tooth tone ring, many DIYers have successfully modified the 48 tooth tone
ring using a Dremel cut-off wheel. Keep in mind that the sensor mounted in the differential cover may need the depth adjusted, especially if you installed a new
aluminum differential cover from the later G80 car. Some sensors are adjustable
and some will need shims added or subtracted to adjust.
740/940 Notes Worth Mentioning:
The stock axles from a 1041 G80 rear end in a G80 equipped 740 or 940 are a bit shorter (and fatter) than the stock 1031 axles in a pre-G80 car. Some knowledgeable DIY 700/900 owners are swapping in both axles from a G80 car when fitting the G80 in their earlier 740s and they fit just fine. Cutting a right side axle is only for a 240 installation.
Modifying the G80 is not required, however it has been a fairly popular thing among hot-rodders. A modification is done to the G80 before installing to alter the internal locking mechanism. Altering the internal mechanism can be done to make it stay locked through higher speeds or to even stay locked at all speeds. But at least one person says, "Even an unmodified G80 will stay locked at much higher speeds than 25 as long as the power is increased. I've had stock units stay locked up until at least 60 mph in turbo cars." (Source: https://forums.tbforums.com/showthread.php?t=240436&page=2 Post #78).
If you decide you want to modify your G80, this can be done by a couple different methods and these are outlined in the article links below. Not all of the methods are the same, so if this part interests you, read it all.
<<< You can begin by reading this modification tutorial in Turbobricks: https://www.turbobricks.com/mods.php?content=art0027
More resources below.
Disassembling and Modifying a G80
AND DISCUSSION LINKS:
|Limited Slip Info for Volvo Rear Ends
This info BELOW was compiled years ago.
So some of it may be a bit out of date.
I have left it up at the request of users for the sake of the info it contains.
I hope it helps.
Cutting through all the myths about just what 240's and 740's came with what type of rear end and what Limited Slip or Locker differentials will actually fit these cars has been a long struggle. The following information has been submitted and compiled by various experienced Volvonuts over the years and will hopefully help you in making the right decisions.
If you have any additions or corrections, or if you can provide any photos that will help with these discussions, please email me.
Thanks, Dave Barton.
between a Volvo 1030 and 1031 Differential Case
Above photos are from Anthony Hyde's Volvo Differential Page
Stealthfti from the Turbobricks Forum wrote:
There are measurable differences between a 1030 and 1031 rear end housing. A 1030 is about 10.125 inches from the rear cover mounting surface to the front of the pinion neck. A 1031 is almost exactly 0.5 inches longer.
Also it does seem all
1031s have the "ears" on the right side of the pumpkin
(they are not machined on 240s). These ears
attach to the torque arm on the 740 suspension.
Justin's source for the info on the "ears" and the
1031 axle is Mike Knell, who authored the Volvo V8
swap information in JagsThatRun.
From reading posts on 4x4 chat groups, the Trutrac sounds like a great LSD, especially for street performance. The Dana Powr-Loc (which appears to be the LSD Volvo offered for standard towing packages) is also supposed to be a good, long-lasting differential (although quite expensive when new).
UPDATE NOTE 07/16/06:
UPDATE NOTE: (JUNE 2007)
-from Mike Perry (mikep at Turbobricks)
Trutrac Installation notes for differentials using Speedo Tone Rings:
For the first tone ring car I installed a Trutrac diff into, I welded a speedo tone ring onto the diff. It was a big pain. I had to cut the ring apart and weld it to the carrier, then grind down the welds, which were brittle from conduction hardening, so I had to braze the cracks.
Then I did a Trutrac install for Michael Towery. I cut grooves with a die grinder and cutoff wheel. It was so easy and worked so well that I only do it that way now. The grooves need not be wide. The count just has to be the same. I think it's 12 grooves for the speedo. I'm not sure of the count for ABS. You can adjust the clearance by sliding the cover up or down, or by using a press in extreme cases. I have done probably 8 of the Trutracs in total, and the ones for 3.73 gears also work for 3.31 in most cases. The PN 912A411 in the first pic is in a 3.73 geared 1031 axle (my son's car) and the PN 912A588 is in a 3.31 geared 1031 axle. I also set up a few plate diffs and some locked (welded) for Rob's drift car. Maybe 12 Volvo axles total, not counting repair jobs.
Regarding differential part numbers... the Jeep front diff ("low preload", actually with a different hypoid angle) is a PN 912A314. I have done plenty of these, but they slip in turns with a big rear sway.
The old number for a Volvo rear with "high preload" is PN 912A411. I have done two of these. The new number is PN 912A588... better case material, high preload. I have done one. It is the number for high gear ratio numbers, but I think it went in a low number car.
One more bit of info: The diff manufacturers list a split in ratios at 3.51 or something, however I have never found a difference. I have measured diffs from Jeeps and Volvos with 3.31, 3.55, 3.90, and 4.11 ratios, and ALL were interchangeable. I recently put the new Trutrac PN 912A588 diff in a car with 3.73 gears, and have already put one in a car with 3.31 gears.
UPDATE NOTE APRIL 2008:
Jonas Borgegård of Sweden firstname.lastname@example.org wrote:
I have my own company in Sweden www.bakaxel.se and I sell mostly parts for Volvo. I sell rear axels and rebuilt BMW/ZF gearboxes to fit in Volvos and other parts.
If you wants ABS you can take the ring from the old differential and "move" it over to the Trutrac (PN912A588). You need to put it in an machine to take away some steel to be able to get it "on" and move out the pickup for the speedometer 2-3 mm. I have also made a CAD file and made a water cut metal "plate" that I wrapped around the Trutrac and then welded it together.
|Here's a discussion thread on
installing a Truetrac in a Volvo 1031 rear end:
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