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Official differential information.

simmy_binker

simmy_binker

winning!
Joined
Dec 19, 2007
Location
Hamilton, Ontario
after doing numerous searches on here for differential info; I found a LOT of info, but not a lot of straight facts. hopefully we can nail down some straight facts in here on differentials on all RWD Volvos, and when someone does a search for "differentials" next time, they should stumble upon this thread, with the giant lettering...

[edit: it HAD giant capitals in the title, but there's a built-in feature on the site to make them all small letters automatically ftl]

straight up, what years and models came with what differentials?

I'm going to start hacking through the interweb jungle for info; but if one of you has the info already, then please post it.

all this spawned from me wanting a good rear end on my '86 745ti, and I wasn't able to find the info quickly on here. if the info comes up quicker than it takes me to go jack up the rear of my car, and spin some wheels, then I salute TBs.

for those who come after me: a quick way of telling for sure, is jacking up the back of your car (on level ground, and/or blocks on the front wheels) and spinning one rear wheel with your hands (parking brake off). if the other rear wheel spins in the SAME direction, you've got a limited slip differential. if it spins the other way, or does not rotate, you have an open diff.

an additional resource, would be the location of the stamp on the diff, telling the owner which diff they own. I'm going to check right now in the interweb where it is found, but again - see if you can beat me to it.

to start this off, I'll toss in the link to the obvious and awesome post of how to mod your G80 locker at home:

http://www.turbobricks.com/mods.php?content=art0027

thanks all for building this info, and if there's already one of these threads, please direct me to it.
Sim
 
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simey_binker said:
for those who come after me: a quick way of telling for sure, is jacking up the back of your car (on level ground, and/or blocks on the front wheels) and spinning one rear wheel with your hands (parking brake off). if the other rear wheel spins in the SAME direction, you've got a limited slip differential. if it spins the other way, or does not rotate, you have an open diff.
Click to expand...
I don't think that is a good way to tell. For one, our cars didn't come with limited slips, and I believe that a locker acts as an open differential until it locks, and you will not be able to do this by spinning the wheel by hand.

Do a burnout, then you'll know.
 
Poik said:
I don't think that is a good way to tell. For one, our cars didn't come with limited slips, and I believe that a locker acts as an open differential until it locks, and you will not be able to do this by spinning the wheel by hand.

Do a burnout, then you'll know.
Click to expand...

good to know. gooood to know. I'll make an adjustment to the original post in a bit when I find more info. I know it was repeated a bunch of times on TBs that this was "valid" - but maybe my wording is clumsy; I haven't done it myself yet.

as for the burnout diagnosis; I do often, but I rarely check my asphalt tracks. in snow/gravel my back end swings around awesomely; not like Brett's 200-series "doughnuts" in his "na na na na" thread (which I can't effing find right now...)


Sim
 
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Poik said:
I don't think that is a good way to tell. For one, our cars didn't come with limited slips, and I believe that a locker acts as an open differential until it locks, and you will not be able to do this by spinning the wheel by hand.

Do a burnout, then you'll know.
Click to expand...
Poik,
Just making sure you are referring to 7 series with that comment...cause my 81 gle 245 came with a limited slip...
 
miller.jpg


= Locker :)
 
Poik said:
I don't think that is a good way to tell. For one, our cars didn't come with limited slips, and I believe that a locker acts as an open differential until it locks, and you will not be able to do this by spinning the wheel by hand.
Do a burnout, then you'll know.
Click to expand...

A limited slip differential locks the axles together until a predetermined load makes one side slip.
If you have a limited slip, jack up one side and try to turn by hand, it shouldn't move. If you apply enough load (with a bar or something) the wheel will start to move. You can measure this with a torque wrench, the torque required to make the one wheel move is known as the breakaway of that diff. If it moves by hand, you have an open diff, or a stuffed LSD ;-)
 
svengali said:
A limited slip differential locks the axles together until a predetermined load makes one side slip.
If you have a limited slip, jack up one side and try to turn by hand, it shouldn't move. If you apply enough load (with a bar or something) the wheel will start to move. You can measure this with a torque wrench, the torque required to make the one wheel move is known as the breakaway of that diff. If it moves by hand, you have an open diff, or a stuffed LSD ;-)
Click to expand...

very good. but as said they don't come with LSD's (apart from a few optional ones on early 700's). they come with G80 lockers which require a spinning wheel to have speed to engage the locker mechanism. until that happens it acts like an open diff
 
ravennexus said:
very good. but as said they don't come with LSD's (apart from a few optional ones on early 700's). they come with G80 lockers which require a spinning wheel to have speed to engage the locker mechanism. until that happens it acts like an open diff
Click to expand...

And here I though Volvos "locker" thing was a LSD up to a certain speed, then unlocked.

What do I know, anyways?
 
The "locker" can be engaged by hand, you give one tire a very brisk spin(wheel differentiation > 100RPM), and it should spin the tires opposite directions, then engage (lock or very nearly lock)with a crappy clunking noise and stay locked until traction is regained..
once driveshaft speed is over 25MPH, the locking feature is locked out.

Another quick check would be to pop off the rear cover, and see if there are an abnormal number of busted pieces.
 
yeah - I've read up on all the locker info. heard the lockers are disengaged above 25 mph. and at anything lower than 25 mph; it's only locked when you've got a wheel differentiation of over 100rpm. makes sense.

now... I've got a few problems:
A: we're still unsure of which cars came with what diffs from the factory
B: the WELDING mod makes it a full-time locker, right? at all speeds, and all wheel differentiations - full time lockup? (is that poor on the rear tires if it's a DD?)
C: the G80 locker "mod*" allows "drifting" at higher speeds, and dual wheel traction at higher speed if you're dragging, I take it - right? simply allows the wheels to be potentially locked at any speed (even above 25 mph).
D: why on earth, if I've got a locker diff, do I still get stuck in effing snow? I've gotta do more experiments (or rip my diff apart), because the car seems to drift out fine on gravel and whatnot; it just gets bloody stuck in the snow with the one tire spinning madly. at least; that's what I remember of last winter...

thanks,
Sim

*
http://www.turbobricks.com/mods.php?content=art0027
 
my '92 240 sedan has a limited slip differential that requires a friction modifier. The locking differential in my '93 240 wagon does not require gear oil without a friction modifier.
 
Yes, welding it makes it a solid link between both wheels at all times. Full traction to both wheels no matter what. Tirewear is only bad if you drift alot, and with a welded diff you just can't help it. :) There are some minor downsides, but that's what you get for doing a free mod.

The modded G80 locker seems to be the best factory solution, since it acts like a welded diff except in very slow speed turns when it's basically an open diff. That's where a welded diff chatters the tires alot, and underground parking garages are just hilarious.

If one tire is spinning, then you have an open diff. One can drift just fine with an open diff, but going to a welded/locked/slipped diff makes it soooooo much easier and more controlled.
 
volvorsport said:
it uses a clutch pack to enagage the lock !

check your axle tag - it should tell you what it is .
Click to expand...

No, there is no clutch pack in a G80. It is a ratchet type device. Total mechanical interlock. Rock solid when locked. Greg Irvin removed the weight altogether on his G80. Once he gets back from the Larrison Rock Hill Climb event this weekend, possibly, he will post what he thinks of the way it works when modified that way.
 
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