suprathepeg

I'm lookin for either a writeup or someone who has done it? I can't seem to find any good info on this.

tc

Talk to node - he's the Mr2 guru on here!

suprathepeg

I'm looking for MK2 supra not the MR2. These are 2 totally different cars.

Toyofast

I thought the Supra rearends were the normal Toyota 8", but setup with a IRS suspension.

suprathepeg

82-86 supra and cresida were 7.5" also the celica GTS of that era had the 7.5 with LSD.

ThomasJ

I cant help you on the 7.5 diff. But here are some write ups on installing the supra LSD in the 8 inch v6 truck diff.

http://www.gearinstalls.com/supralsd.htm

http://www.gearinstalls.com/supralsd2.htm

Just a suggestion, I would just install a locker in the front and the Supra LSD in the rear. You can unlock your hubs on the street and you wont even know the locker is there. Also, the IFS is not very good about keeping both wheels on the ground when wheeling. If you get one wheel of the ground a LSD is useless. The locker would still put full power to the wheel with traction and have no negative effects on street driving as long as you get some manual hubs.

tc

College degree and I still can't read!

node is still the guy for Supras too.

suprathepeg

I live in central Canada where we get lots of snow and ice on the streets for 3 -4 months of the year. My rig is a DD. If I had a locker in the front while using my 4wheel drive I would be dancing with the devil . The supra type LSD is way more appropriate for my use since we see minimal rocks in these parts.

ThomasJ

Ok, I see. That would be pretty scary I did not know you were going to use 4wd on icey streets. Most people on the board are from out west so I assumed you would only use it for off roading.

Flamedx4

Don't do it!
I had a LSD in the front for years, and I will never do that again. The LSD is just as bad as a full locker in the front on ice and snow - scary handling. I was used to it but no one else could drive my Runner in winter, and when it was really slippery out I hated it, really no fun... Save up for an ARB if you want something up front.

suprathepeg

Hmm, I've heard quite the opposite from others with the LSD in front. I wonder, did you have ADD or auto hubs? The LSD would only be in use when the hubs are locked and that would only be on the street when there is heavy snow.

suprathepeg

What I need is the 7.5" that was used from 82-85. I don't need the LSD (got a line on at least one here) What I need is specific details for the install seems like such an obvious swap but I guess there just hasn't been a lot of people who have done it.

Flamedx4

No, it was an '85 with manual hubs.

Heavy snow isn't the problem. Traction is plentiful in heavy snow.

Try smooth shiny packed snow, or ice. The front wants to go straight. The rear doesn't want you turn either. There isn't enough traction to force the lsds to slip, so it's just like having lockers fully engaged - initially it fights your turn, then the front tires - BOTH of them - break loose. Since the rear has an lsd too, you continue going straight.

Having something in the front but not in the rear doesn't work either, because when you turn the wheels the track radius difference still causes the front tires to break loose.

I learned 2 things - drive VERY gently, and to "pitch" it into corners, sort of letting the rear end drift around, then getting on the gas (gently) and getting it to carve the turn like a rally car does.

Even going in a straight line you could lose traction on icy roads, all 4 wheels just loose their grip together and you slowly slide off towards the shoulder.

Best thing you can have when it's really slippery is open diffs front and rear. Excellent control. You need that more than traction.

node

Not a bad idea, consider this though.

In my dealings with trucks, cars etc. LSD's are awsome for strait line traction/mudding etc however in a corner the LSD can actually make a vehicle MORE prone to loose control, heres why. With a normal open type differential when cornering on a slippery surface the outside tire loads up with the weght of the truck adding slightly more grip to that tire. At the same time torque is only applied to the inside tire with less weght, so it quickly overcomes the friction of the surface and begins to spin. The outside tire with no torque on it is handleing all the lateral acceleration around the corner (basically its not helping to pull the truck allong but since no power is appied to it the outside wheel is more likely to maintain grip.

With the LSD when the inside tire begins to slip torque is quickly transfered to the outside wheel causing it to loose traction rather than grip. Folks in the MR2 community are familiar with this. Since the cars are rear wheel drive this event is reffered to as "snap oversteer". Its basically the moment where the LSD transfers power to the outside wheel and the back end goes from having HUGE ammounts of grip and hence lateral G's to an instantanous slide or even spin if the driver isnt paying attention. Lots of fun if you know what your doing BTW

IMO you dont want to drive around with an LSD on the front wheels because it will tend to cause sudden instantanous loss of traction and hence steering. What you should look into for your rig is an electronic locking front diff. that way you can have a bit more predictabillity on icey roads but when you go 4wheeling you can flip a switch and lock the front diff. Best of both worlds for a truck. I would not even consider the supra LSD but yea if you want a cheap alternative that will give improved offroad grip without the issues assosiated with a locked diff, then go for it. I have 2 MKIII supras here at the shop if you want pics. Send me an email if you want more detailed information about how to swap the differential/rig gear etc.. BTW the LSD in the MR2 tranny should work aswell. They are both viscous type couplings and my have issues when used in extreme offroad applications. You may want to look into a gear or clutch type LSD.

GenXr

I'm going to resurrect this old thread because I think node's comments are worthy of discussion.

Currently I've got a line on a 7.5" lsd carrier, but node's comments have given me second thoughts. Is a limited slip or locked front end on slippery streets really that squirrelly or dangerous? I've thinking about installing supra lsd carriers in both of my truck's diffs for added winter traction since it is my DD.

Matt16

After thinking about it, keeping in mind the mechanism of an LSD, I am pretty certain it would be a bad idea to put on in the front as it would be dangerous on ice and useless offroad.

It would be dangerous on ice because it wouldn't take much locking force to cause both tires with similar amounts of traction (ie: road ice) to have both tires slip. This would cause both tires to loose lateral stability and the front tires would lose ALL their ability to steer.

Offroad, there wouldn't be enough bias to cause both tires to lock and it would hardly make a difference compared to an open diff.

Selectable seems really ot be the only option if you drive on ice/ snow in 4wd. Rear is pretty tolerant of anything you put in it.

thook

I can attest to that. My old Plymouth had open front diff, rear LSD, and locking transfer case differential option. It was full time 4wd, but you had to shift the t-case in low or high lock to lock the front and rear drivetrains together. Since the front was open I could steer well enough, but the tail end wanted to slide around in icy conditions. In mud, it was fantastic, though. You had to keep the vehicle straight, of course, but still very doable. On ice, forget it.

Also, my Peugeot 505 has an LSC rear end. But, it's 2wd. So, it doesn't matter if it's ice, snow, or mud. The rear end wants to come around everytime.

Don't think I'd like that behavior in the front end too well.

thook

LSC*.....meant LSD. Sorry...

Computer editing functions are sucky tonight.

annoyingrob

Just to clear up some mis-information,

79-81 (MKI) supras had a 7.5" solid axle, optional LSD
82-86 (MKII) supras have a 7.5" IRS, lsd
82-86 celicas have a 6.7" open diff. ST, GT are straight axle, and GT-S is IRS, but both are 6.7".
86.5-92 (MKIII) supras have an 8" rear end. Turbos had an lsd, n/a had it a an option. The twin turbo R model had a torsen, the rest were clutch type.
93-02 (MKIV) had an 8.5" torsen lsd.

GenXr

I think I'm going to bow out from buying the mkII lsd for the front, and just wait to save for an ARB. MY hesitation with buying the ARB was justifying the cost. Right now, I don't wheel the truck often enough to justify the ARB but I want the added ability of some kind of traction aid.

I've seen enough of you guys' snowy road pictures to appreciate your experiences! Thanks!