Couple g80 swap questions

So I?ve been doing a fair amount of research on swapping a g80 into my 90 760 turbo wagon. The I?d sticker is ineligible on my car, but research and a one wheeled burnout tells me that I?ve got a 1031 axle. On my latest junkyard trip, I grabbed a g80 diff out of a 93 940 na. Now most of my findings have been mainly about swapping the g80?s into either 240?s, or older 700 series cars. All sources tell me that one axle has to be shortened on the 240?s, but all my research on the 700 cars are mainly getting swapped into the older 1031?s without abs, and the less toothed tone ring, or swapping the whole rear end. Since my 760 is my only drivable car at the time, I?d rather know for sure what to expect going into this. Is one of the axles shorter, and if so which one. It seems that most say the passenger side, but I?ve read a couple posts where people claim the drivers side. When I pulled the g80, I took the axles all the way out, and set them inside the car at the junkyard on the correct side. I?d rather go get the shorter axle from there than start hacking away at mine.

I do plan on chopping the counterweight off before installing. I went snow drifting today, and there was one time I could?ve used two wheels spinning haha. I?d also like to keep the 4.11 gears, but I?ve no way to remove the pinion from the junkyard unit, and I?ve read that swapping pinions is more than just remove the old, install the new.

The stock 1041 G80 740 or 940 axles are a bit shorter then the stock 1031 axles, when I swap to a G80 I also swap the g80 axles into my older 1031 740, but the little bit longer axles might work, I never tried that. Both are shorter. Thicker also..

Hello wesdunns, a G80 is a locker and not a LSD!!! It is a realky stupid thing. Did you ever drove a car with a welded dif? The G80 is doing nothing else: lock the differential. Ok, if you go slow it will be like a open differential.
And don't cut the weight, don't weld it. Other solutions are better.
Best solution: buy a proper LSD
Regards, Kay

Ahhh so both axles are shorter! I saw a few places mention that the g80 axles were different. Looks like I’ll be grabbing them.

Mocambique, when I said there was times I could’ve used both wheels spinning, it was mainly because I’d gotten stuck once, and could barely climb a hill. I’ve never driven a car with any locker, lsd, or welded diff before, but there has been times I wish I did have them. You say not to cut the counterweight, I’m assuming you say this because it helps “soften” the lock. Less likely to break anything at 25mph or under than at 50mph. I’d love to buy a better option like the trutrac, but for the price of 50$, I figured why not run the g80 and get my own personal opinion on it as it seems some people love it, others hate it. If it ever goes boom, hopefully it’ll get an upgrade.

Thank you both for your help

I took out a G80 from a 1991 940 GLE and only the passenger side axle was shorter than the ones on my 1990 740 NA car but I swapped the 2 axles from the 940 in the 740 just to be sure. If you keep the gear that came on the G80 you also need to get the pinion gear from that 940 and install a new crush ring on it before you put it in. Be sure to keep the bearing caps from your 740 and and mark them so you put them back in exactly where they were.

I welded the counterweight on mine and never had problem apart from a little tire chirping on very tight corners. In snow you will have to be cautious at high speed when cornering. That 940 NA should also have a 4.11 final drive.

It does have the 4.11, but I can’t figure a good way to get the pinion off. I saw One post where someone had made a counterhold tool that bolts to two of the driveshaft bolts to hold the flange while loosening the pinion nut, but they didn’t have any measurements on where to drill the holes.

Is it as easy as pulling out the old pinion, and reinstalling the 4.11 pinion with the new crush washer? I heard somewhere that swapping pinions was a very involved process needing special tools for clearances and whatnot?

One final question, I’ve watched one video that says to mark the ring gear in relation to the diff unit itself so you can install in the correct orientation. How would I go about making sure the the ring that’s currently in my car goes onto the g80 the right way? If I decide to go with 4.11’s it won’t matter so much, but if I keep my current gearing I’m not really sure how to do this

The idea behind welding the weight is so the locker will work at speeds over ~25mph, the weight works as a governor so the locker will not work over a certain speed. If you want a cheap locker, great! This will work. They are abrupt and unpredictable as they age. Some people have had good luck with shimming the clutch plates to "ease" the engagement of the g80.
If you want to do high speed drifting, tack weld the weight to the case. If you want a locker that will work at low speeds to help you get some traction, leave it alone. The g80 is not very durable if you drive aggressively with them modified.

When swapping pinions you have to set the "depth" of the pinion. This requires a bit of luck, measuring tools, and gear marking compound (or white lithium grease/prussian blue/etc). It's a pretty involved process, but it can be done by a newb if you are careful and pay attention. Plan on it taking at least all day your first time. Keep all of the bearings pressed on and the bearing "cups" with each "cone".

No need to mark the ring gear. If it's that out of tolerance, you don't want to be using it.

I looked up the axles in the Hollander's interchange book. It showed that the axles from a 1988 760 wagon and a 1991 740 sedan with G80 were interchangeable. I've had it in the plans to do the swap for years, but it probably won't ever get done.

I’m gonna be cutting the weight instead of welding it. My car doesn’t make much power over stock, but has plenty of suspension upgrades. I won’t be doing much beating on it, just the occasional burnout and maybe a little sideways action, I doubt I have enough power to break the tires loose at anything over 25mph at this point, but I will be making her faster over time.

Luck is not in my vocabulary, so I’ll just keep the same ring and pinion that’s with tne car, just swapping the ring gear from the 1031 to the g80 unit.

About the axles, above I’m being told that the pass. Is shorter but the drivers is the same, and now lummert says they’re the same. I’m beginning to wonder if the difference is between 9xx and 7xx cars, not so much early/late versions of the same series. I’ll probably end up buying both axles, measuring and installing if there’s a difference and returning the other axle. There’s a couple inches of snow on the ground, so it’ll be at least a week before I crawl around my driveway

I'll say it again, the 1041 G80 axles are shorter and thicker then the stock 1031 axles. Now you saying one needs to be cut is a thing you do if you are putting a G80 in a 240 rear end.

The stock 1031 740 axles might work fine with a g80, I never tried it. They are not much longer then g80 ones, I'll post a pic here in a bit. They are thicker and stronger, that is why I swap them out. Ever broke an axle? I broke a bunch, they break right where they go into the carrier.

As a reminder, not ALL 240 axles need to be cut. Seems like the ABS rear ends (at least the one that I swapped into my old 242 turbo) don't need to have the axles shortened.

culberro said:

As a reminder, not ALL 240 axles need to be cut. Seems like the ABS rear ends (at least the one that I swapped into my old 242 turbo) don't need to have the axles shortened.

Click to expand...

Yes, the 91-93 ABS 240 axles were set up with a different axle set that allows the G80 to swap right in.

If you look at the Volvo parts book, the part number for axles changes some time in '92 or '93, I think there's a chassis number split. If you don't have one of these cars WITH ABS, you're gonna need to cut the pass side axle. I'm doing the same swap in my '91 with ABS, and research showed I would need to trim it. I may, however, open it up and find it not to be the case. Your results may vary.

I’ve never broken an axle, but since I’ve already got them pulled out of the g80 car and inside of it, I guess I oughta just shell out the money, just since they are thicker...I’ve never broken an axle, don’t want to either. Since I’ll be keeping my current gear ratio, it seems the main thing I’ll have to keep an eye on is the orientation of the bearing caps

shoestring said:

If you look at the Volvo parts book, the part number for axles changes some time in '92 or '93, I think there's a chassis number split. If you don't have one of these cars WITH ABS, you're gonna need to cut the pass side axle. I'm doing the same swap in my '91 with ABS, and research showed I would need to trim it. I may, however, open it up and find it not to be the case. Your results may vary.

Click to expand...

Let us know what you find.

Wesdunns70t5m said:

It does have the 4.11, but I can?t figure a good way to get the pinion off. I saw One post where someone had made a counterhold tool that bolts to two of the driveshaft bolts to hold the flange while loosening the pinion nut, but they didn?t have any measurements on where to drill the holes.

Is it as easy as pulling out the old pinion, and reinstalling the 4.11 pinion with the new crush washer? I heard somewhere that swapping pinions was a very involved process needing special tools for clearances and whatnot?

One final question, I?ve watched one video that says to mark the ring gear in relation to the diff unit itself so you can install in the correct orientation. How would I go about making sure the the ring that?s currently in my car goes onto the g80 the right way? If I decide to go with 4.11?s it won?t matter so much, but if I keep my current gearing I?m not really sure how to do this

Click to expand...

You need special tools and skills to s setup a pinion. I used a 24" pipe wrench wedged against the floor pan to hold the flange to loosen the pinion nut but I was only changing the seal. My rear end is an older 1030 with a solid spacer instead of the crush washer so I dosed it with red locktite and torqued it back to spec with a 300 ftlb torque wrench.

OE number for the axle shafts from a 1031, non-G80 rear diff is 1232100 (6814100), same number for both sides. Can't find an OE number for axles from a 1041 rear. Found mention of running the Volvo G80 in a Jeep Dana 30 axle. This Volvo to Jeep swap required trimming 10 mm from one axle shaft.

Here is the info you're seeking:

http://www.turbobricks.com/forums/showthread.php?t=191987

Yeah I’m definitely gonna keep my ratio the same. And thanks for the link, that was all very helpful!

Ha, posted at 1041

Just leave the pinion gear alone, swap the carrier bearings AND races over from the donor car, swap your ring gear over from YOUR car and you should have great luck. Measure backlash, or just skip if too cheap to buy a dial indicator. I bet you didn't grab the aluminum cover or donor car bearing races and marked for each side, huh!? I didn't! I used my carrier bearing races on the donor g80 carrier bearing rollers; not recommended.

My hack (below) of the tone ring failed. Lost the speedo. Still working on getting it back....I even tried swapping the aluminum diff cover from a g80 car and still no dice. Hopefully getting the correct sensor will fix this, but yet to test.

But I like dumping the clutch on onramp lights and in the rain