The Volvo Limited Slip

A couple weeks ago my friend and I released our first video on our new channel. This was the start of a 3 part video series covering the Volvo Limited Slip Differential that can be found in 240/740/765 Turbo models and non turbo models with a tow package.

Since then we have made our part two segment explain how to find it and some additional info.

By all means we are the know-it-alls. We have tried to make that known. Some things we say may not 100% exact and we are encouraging people to pitch in their .02 cents. This is a learning experience for all of us!

We will be doing a lot more than just this volvo thing. So subscribe and enjoy what we will be doing down the line.

Part 1:

https://www.youtube.com/watch?v=xevx06aay7E


Part 2:

https://www.youtube.com/watch?v=VtEQaWj0LSc

I'd never heard of this. Looks like my local yard has a plethora of 740's.

More info on the Volvos themselves:

http://www.turbobricks.com/mods.php?content=art0014

Basically it sounds like I need to find an 89+ automatic 740 turbo to be on the high side of the carrier split. Manuals had the 3.55-down diff.

anthrax323 said:

I'd never heard of this. Looks like my local yard has a plethora of 740's.

More info on the Volvos themselves:

http://www.turbobricks.com/mods.php?content=art0014

Basically it sounds like I need to find an 89+ automatic 740 turbo to be on the high side of the carrier split. Manuals had the 3.55-down diff.

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Yes I'd say thats correct.

The website is thrown around a lot, its one of the only real sources of info. But to be honest I'm sure the limited slip is talked about frequently on Volvo forums. I just haven't made it a mission yet to find one and search.

Limited slip in the front can be useful for Part-Time 4WD on the dirt but its not a great match for Full-Time with the NP242--go around a corner and the outside front spins fastest so the transfercase sends the torque up there, then the differential pulls up and yeargh both front tires are pulling forward all of a sudden. Works good on the dirt with a 231 for locking up the front when one of them is slipping though.

interesting. nice job guys

so this is for the dana 30?

jeeptorino68 said:

so this is for the dana 30?

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Yes. The mentioned volvo models have the D30 as their rear axle, thats why it works.

ehall said:

Limited slip in the front can be useful for Part-Time 4WD on the dirt but its not a great match for Full-Time with the NP242--go around a corner and the outside front spins fastest so the transfercase sends the torque up there, then the differential pulls up and yeargh both front tires are pulling forward all of a sudden. Works good on the dirt with a 231 for locking up the front when one of them is slipping though.

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Good point. Never thought of that.

ehall said:

Limited slip in the front can be useful for Part-Time 4WD on the dirt but its not a great match for Full-Time with the NP242--go around a corner and the outside front spins fastest so the transfercase sends the torque up there, then the differential pulls up and yeargh both front tires are pulling forward all of a sudden. Works good on the dirt with a 231 for locking up the front when one of them is slipping though.

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I don't see a problem with power going to the tire with most traction. Would be great for Fulltime 4wd (technically AWD) when the power only gets delivered on acceleration and is free spinning on decel. Not ideal for rock crawling but is beneficial on slippery surfaces like snow and dirt.

LSD changes the power delivery from going to the path of least resistance to the path of greatest resistance. If anything, once you get use to it, LSD should enhance steering and handling response.

this is awesome info. Good job guys.

highspeed said:

I don't see a problem with power going to the tire with most traction. Would be great for Fulltime 4wd (technically AWD) when the power only gets delivered on acceleration and is free spinning on decel. Not ideal for rock crawling but is beneficial on slippery surfaces like snow and dirt.

LSD changes the power delivery from going to the path of least resistance to the path of greatest resistance. If anything, once you get use to it, LSD should enhance steering and handling response.

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We've used it in a racing application and so have friend's of ours. Never had an issue using it in full time. It was mainly dirt/mud with some rocky terrain but nothing serious rock wise.

We've used it specifically in a rock environment before and it appeared to do quite well.

The point of the third video will be to show you this.

highspeed said:

I don't see a problem with power going to the tire with most traction. Would be great for Fulltime 4wd (technically AWD) when the power only gets delivered on acceleration and is free spinning on decel. Not ideal for rock crawling but is beneficial on slippery surfaces like snow and dirt.

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When you make a turn, the outside wheel spins faster than the inside wheel. The whole point of limited slip is to get both axles spinning at the same rate. These are mutually incompatible and something has to give. Its fine in the dirt, but its not fine on pavement in any kind of weather. You have to coast through corners or just take it out of full-time at which point there's no reason to have it.

ehall said:

When you make a turn, the outside wheel spins faster than the inside wheel. The whole point of limited slip is to get both axles spinning at the same rate. These are mutually incompatible and something has to give. Its fine in the dirt, but its not fine on pavement in any kind of weather. You have to coast through corners or just take it out of full-time at which point there's no reason to have it.

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you know, it has slip in the name for a reason. It's designed to accommodate going around a turn. That's why it has clutches that slip and not side gears like a mechanical locker.

It's absolutely no different in principal than the georotor diffs used in the quadradrive setups that came from the factory. It will work fine.

It responds to torque. Same thing when I goose my dad's F150 around a corner, the LSD makes the rear end chirp and waggle. Its undesirable with the front axle when you are trying to stay on the pavement. Well, good for drag racing on pavement, not good for cornering in the rain.

ehall said:

It responds to torque

Same thing when I goose my dad's F150 around a corner, the LSD makes the rear end chirp and waggle

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no, it doesn't. A gerotor style one does because it's got a hydraulic pump that gets spun by the side gear, when that happens it increases pressure and locks the diff.
A torsen gear driven style will also respond to torque, but only when it senses severe wheel slip past it's torque bias.

a plain old LSD with clutches and steels is simply a friction device that links the two shafts with spring pressure. It does not adapt to torque or wheel speed. When one tire needs to go faster than the other it overcomes the friction and does so.

This is awesome. Do you have a general idea of what the JY charges for that carrier? And it seems from the video it is indeed the full carrier and not just a spider gear replacement?

Jeepedo129 said:

This is awesome. Do you have a general idea of what the JY charges for that carrier? And it seems from the video it is indeed the full carrier and not just a spider gear replacement?

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LSD carriers are different than open carriers, so yes you do the whole thing.

which means you need to set the gears back up again, and probably do the carrier bearings too.

what a yard charges depends on the yard, your area and the like. Call one and ask.

So the only difference for the Volvo trutrac is you have to cut off 3/8" off of the driver shaft to make it fit, compaired to a regular trutrac?:wave:

ehall said:

When you make a turn, the outside wheel spins faster than the inside wheel. The whole point of limited slip is to get both axles spinning at the same rate. These are mutually incompatible and something has to give. Its fine in the dirt, but its not fine on pavement in any kind of weather. You have to coast through corners or just take it out of full-time at which point there's no reason to have it.

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Not correct. Sorry, I have to wholeheartedly disagree with you. I have had LSDs in multiple AWD and FWD applications and never have my axles "locked" together at the same rate of speed. That is not the purpose of an LSD.

You don't have to coast thru corners with LSD, but definitely have to with a lockers. I have had 3 DSMs (eagle talons, eclipses, etc.) that were AWD. I would weld the center diff(making is real 4wd) and have a viscous rear LSD and install a clutch type front or use an insert up front. Never had any issues and once drove 12 hours through a snow storm using this setup on my last eagle talon AWD, I was the only one on the road and never had an issue.

I know AWD talons are way different than a XJ, but the principal is the same.

Okay I see there is a big debate on the whole LSD combined with AWD thing going on. In regards to the volvo diff, Its a mechanical torsion locking limited slip diff (No friction packs, first vid explained this.) Both sides dont lock, it gives power to the traction side when there is a difference in 100 rpms between the two wheels and thats it. (Yes, I know we didn't mention that bit the first time around, our bad).

There was a video out there explaining this a friend told me about but I can't find it at the moment sadly.

Jeepedo129 said:

This is awesome. Do you have a general idea of what the JY charges for that carrier? And it seems from the video it is indeed the full carrier and not just a spider gear replacement?

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Yes its a full carrier. You take the entire diff, bolt on a ring, and gear it like you would anything else. It is a tight fit but it works. The Volvo ring gear may appear to be a lot thicker than a regular D30 ring. Don't be scared.

I paid 100 for mine which may seem like a lot to some, but thats because of the rarity in my area I didn't care. You could get away with 50ish depending on the yard. Sometimes they might not be able to tell the difference between and open diff and something more "special" if you will.

Thehowler said:

So the only difference for the Volvo trutrac is you have to cut off 3/8" off of the driver shaft to make it fit, compaired to a regular trutrac?:wave:

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Yes, thats just the way it is or else your shorter shaft will be too long and stick out a tad. Remember we are taking a diff out of a centered dana 30 rear axle from a volvo with its own certain length shafts.