75 Series LSD rear

Post by **Buggerific** » Tue Apr 07, 2009 6:27 pm

Hi all...

Had my rig on the hoist today... Not 100% sure about the state of my rear diff. It's supposed to be LSD.

Basically when I rotate one wheel the other does rotate the same direction. But if i stop rotating and start again the other wheel will stay still.

Should both wheels always rotate or is this pretty normal?

Post by **Shadow** » Tue Apr 07, 2009 6:44 pm

should both turn the same until theres a significant resistance at the other wheel.

Post by **Buggerific** » Tue Apr 07, 2009 6:53 pm

I thought the point of an LSD was similar to a locker but obviosly not to that extent... I thought they helped if a wheel was off the ground?

But regardless... sometimes i can spin one wheel and with no resistance on the other wheel it will be still.

Does that sound like its dying?

Post by **Shadow** » Tue Apr 07, 2009 6:59 pm

Buggerific wrote:I thought the point of an LSD was similar to a locker but obviosly not to that extent... I thought they helped if a wheel was off the ground?

But regardless... sometimes i can spin one wheel and with no resistance on the other wheel it will be still.

Does that sound like its dying?

an LSD is a "Limited Slip Diff".

It will slip, like an open centre, but it limits the slip to when there is significant difference in traction, or, the main reason, so that when your turning a corner on high traction surface, your outside while can spin faster than your inside wheel.

If your car is on a hoist, it should be impossible for you to stop a tyre spinning while your mate spins the opposite.

That said, you have a Toyota LSD. Not a very robust LSD, and rarely lasts more than a few 4wd trips.

How many k's has it done? Have you always used LSD oil? using normal; gear oil can let the friction plates wear much faster than normal.

Its very strange that you can spin one wheel, and the other wheel doesnt turn without anyone, or anything holding it.

Post by **Buggerific** » Tue Apr 07, 2009 7:11 pm

Yeah it's the toyota sucker!

I have always used LSD oil BUT i've only had it long enough to change the oil once... So who knows.

its done 175000kms

it's weird... Sometimes they will both spin and i cant stop it while the other wheel is being spun. But other times one will stay still while nothing is holding it!

Guess she's buggered then...

Post by **Shadow** » Tue Apr 07, 2009 7:15 pm

Buggerific wrote:Yeah it's the toyota sucker!

I have always used LSD oil BUT i've only had it long enough to change the oil once... So who knows.

its done 175000kms

it's weird... Sometimes they will both spin and i cant stop it while the other wheel is being spun. But other times one will stay still while nothing is holding it!

Guess she's buggered then...

sounds random.

The way it works is with a whole set of friction plates. Apply enough resistance to one wheel to break the friction plate mesh and it will turn independant of the other wheel.

Its like yours is getting stuck open, which would mean there is a problem in the centre.

If i was you, I would probably drop the oil and look for some metal fragments to make sure something hasnt gone bang, but other than that, i wouldnt worry about it.

Post by **Buggerific** » Tue Apr 07, 2009 7:36 pm

well it drives fine with not a great deal of noise... changed the fluid a few months ago and it was fine but maybe worth doing again...

Post by **Shadow** » Tue Apr 07, 2009 8:16 pm

Buggerific wrote:well it drives fine with not a great deal of noise... changed the fluid a few months ago and it was fine but maybe worth doing again...

use a real clean container and reuse the oil if its only a few months old.

just look for metal fragments.

Post by **mule75** » Tue Apr 07, 2009 8:30 pm

there's nothing wrong with it..... it's just worn.

you can pull them out and shim the clutch pack to get it tighter but if you're happy with the way it drives just leave it.

Post by **Shadow** » Tue Apr 07, 2009 8:39 pm

mule75 wrote:there's nothing wrong with it..... it's just worn.

you can pull them out and shim the clutch pack to get it tighter but if you're happy with the way it drives just leave it.

my 60series LSD (same centre) would always spin the other wheel and it had 420thousand on it before i had it rebuilt.

Even after 420thousand it was still hard to stop one wheel from spinning while someone spun the other.

Post by **Buggerific** » Tue Apr 07, 2009 8:43 pm

thanks mule...

So do you think the diff is ok just the lsd clutch is worn?

If I were to fit a locker at some point would this diff be ok or does it sound like I should look into replacing it before getting a locker in there?

Post by **mule75** » Tue Apr 07, 2009 8:46 pm

mine wasn't.. when i got it at about 250k. even when i shimmed it, it only lasted 12 months or so. i could jack up one wheel and spin it easy.

it just sounds like the clutches are very worn but that doesn't really matter. if you wan'tit to drive better off road get a locker.

Post by **mule75** » Tue Apr 07, 2009 8:48 pm

Buggerific wrote:thanks mule...

So do you think the diff is ok just the lsd clutch is worn?

If I were to fit a locker at some point would this diff be ok or does it sound like I should look into replacing it before getting a locker in there?

if it's not noisy the pinion c/wheel is probably fine. just check for wear when you pull it out for locker install.

Post by **Barno111** » Tue Apr 07, 2009 10:59 pm

Mate my 75 is the same! toyota dont have good LSD's and they tend to let go early on in life! You can have them redone! but i have a mate whom had his 75 done twice and after a couple of trips it was back to norm! My way of fixing it is LOCKERS. Although if you are happy leave it! But i regularly spin one of my back wheels climbing hills! so looks like im doing some saving to put some air in those diffs and lock them up!

Post by **Buggerific** » Wed Apr 08, 2009 6:56 pm

Yeah I won't bother spending money repairing something that wont last... I'll just save for the locker instead. Or most likely will just spend it on something else!

Post by **Barno111** » Wed Apr 08, 2009 7:40 pm

Yer mate its the only way to go! i looked into re doing my whole LSD at one stage but it was going to cost almost a grand so i might as well put that money into a locker! Air lockers or electric lockers are they way! dont bother with auto lockers! They are good in a open diff. But in LSD's they click and bang when just driving on the hard top!

Post by **Buggerific** » Thu Apr 09, 2009 10:59 am

Ha ha, really... By auto lockers you mean the ones that go for around $599?

How do the electrical ones compare to the air lockers... In function and price?

I would probably go the air ones and do a setup where I can use the air tank for tyre inflation and the like. Don't know if that's actually doable but I would assume so!?

Post by **Barno111** » Fri Apr 10, 2009 1:38 pm

Yer mate by auto lockers i mean them! Air lockers and electric lockers are much and much! electric lockers work on magnets pull the diff together to lock the diff up! price wise they are much and much as well! the only advantage i can see with the electic lockers is if you brake your wires running to the locker all you have to do is hook up a positive feed from one of your battery's and you have a lock diff again!

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75 Series LSD rear

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