Rear End Options
|UPDATED: August 23, 2021 CONTACT|
M A I N S
|G80 in a 240
||Other Misc Rear End Stuff
G80 Locking Differential
(from a 700/900)
into your 240
|The G80 Automatic Locking
Differential is a special differential that Volvo
began putting in 740/940/960 models as standard equipment (NORTH AMERICAN market only) beginning in
late 1991. It was also made available as a factory option
for the 240 in 1993. Volvo referred to it as the Automatic Locking
Not all 1991 700/900 models got a G80, but it should be found in all 1992 and later 700/900 Volvos (North American market).
|Here are some videos from Eaton explaining how this
If you intend to install a used G80 differential in a 240, it is a direct (or nearly a direct) bolt-in to the 240 Dana 30 (1031 and 1041) rear end.
In most cases, these differentials will bolt in and run just fine with no adjustments, even without replacement of any bearings or shims.
You MUST remove and reuse your own ring gear, which matches your existing pinion gear, unless you plan to change both of those.
If you're concerned about installing a used G80 diff "as is," you can take an extra step by also checking the ring gear backlash after installing. This is done 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 over time.
CORRECTING EXCESSIVE BACKLASH:
There are shims under the carrier bearings, which can be added or removed. This will adjust the ring gear closer to the pinion gear (which will reduce backlash) or farther from the pinion gear (to increase backlash). Removing bearing and changing shims will of course increase the difficulty of this installation, because these bearings are pressed on. It can be difficult to remove these bearings without damaging them and some will tell you the quickest removal is cutting them off.
|REMOVING A CARRIER BEARING (AKA: Differential Side Bearing) WITH A BEARING PULLER
So far I have avoided having to deal with removing or replacing any carrier bearings on two different G80 installations in my 240s. In my cases I simply installed the G80s with the bearings and races that came with the differentials from the donor cars. I did not remove the bearings.
If you find yourself needing to change, pull or adjust bearings, here's a little info below that may help.
If you have the correct Volvo bearing puller tool (shown here), then pulling these bearings can allegedly be done without damaging them.
Without this tool, it is reportedly more difficult to remove these bearings without damage. Damaging them means new bearings. If anyone can offer better info than what I have here, please email.
More information: https://forums.tbforums.com/showthread.php?t=317970&page=2
<<< I have not personally experienced this puller 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:
|G80 DIY BOLT-IN INSTALLATION NOTES
There are some people who will tell you that the only "correct" way is to fit the differential just as you would a brand new differential replacement, using new bearings, shims and a professional technician. But that can be expensive.
The choice is yours, however many "junkyard" DIY mechanics (myself included) have already done this successfully as (*nearly) a simple bolt-in.
*Regarding the "nearly" a bolt-in thing: The one exception is for 1991 and older 240s. See the info below on trimming the right side axle.
See that round silver metal disc below?
I'm not certain of it's function, but I've seen it referred as an "oil slinger" or a "crown wheel screw lock plate" (to prevent ring bolts from loosening on limited slip differentials). You'll almost never see this plate in a photo of a removed G80 or a retrofitted one, because they're almost never re-used. That cover is found on all Volvo G80 differentials. It covers the ring gear bolts. It will prevent you from removing the ring gear bolts if the bearing of that side is still in place. The only way to remove this cover intact is to first remove the bearing on the ring gear side. These bearings are pressed on, so removing them can damage them if you don't have experience or tools.
If you don't plan to remove this bearing, you can simply cut that plate 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:
If you remove a G80 from a salvage yard yourself, make sure you save 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.
TRIMMING THE RIGHT SIDE AXLE:
This is the part that makes this installation nearly a bolt-in instead of a 100% bolt-in. If your rear end is from a 1991 or older 240, you will need to trim a small amount off of the inner end of the RIGHT side axle. This is because the right axle is a bit too long to fit all the way back in with the G80 in place.
The amount that needs to be trimmed is about 1/8 to 1/4 inch.
Sometime in 1992 the 240 was 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 installation will be a 100% bolt-in.
|SENSORS, TONE RINGS and MODIFICATIONS
All related to 240s with Electronic Speedometers (1986-93).
and later 240s came with electronic speedometers that were triggered by
a speed sensor (VSS) in the rear differential cover. There were two types.
1986-1992 240 without ABS (below left).
1991-92 240 with optional ABS (below right).
1993 240, ABS was standard (below right).
If your G80 came with a 48 tooth tone ring (standard for all ABS Volvos) and your electronic speedo 240 uses a 12 tooth tone ring (standard for NON-ABS 240s), your speedometer will not work correctly.
Some DIY installers have successfully modified the 48 tooth tone ring using a Dremel cut-off wheel. Keep in mind that you should probably use the sensor that works for the 12 tooth ring. And if you installed a newer aluminum differential cover from a later car, the earlier sensor might have fitment issues. For such a custom installation, some sensors may be adjustable for depth and some may need shims added or subtracted to adjust depth.
Check your clearance with a feeler gauge through the filler hole. Turn the pinion as you do so to check clearance. Start with a thin gauge and go thicker until you can feel the rotating tone ring.
G80 INTERNAL MODIFICATIONS:
Modifying the G80 is optional. It has been a fairly popular fad 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).
I agree 100% with this statement and it's what I have found with my unmodified G80.
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:
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 below 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 email@example.com 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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