Lockers/limited slips for racing
The three main LSD's are:
Gear type (Quaiffe), clutch type (Gripper / Salisbury), detroit locker, I guess also viscous coupling but I'm going to ignore that one. This would be like a Nissan or Subaru LSD probably.
The gear type diffs reward smooth driving. If you lift an inside rear wheel, it WILL spin and you will lose some but not all of your drive (open diff you lose all). In Jack's car, I suffered from that but Jack didn't after learning to be smooth in the FV. Forced me to pat attention to smoothness. Gear type diffs are pretty bullet proof, they rely on some creative use of worm drive gears as I understand it. If both wheels are on the ground, it will transfer torque to both properly and not spin the inside tire. Overheating doesn't appear an issue. There are very smooth in engagement - can't feel it.
Clutch type have many adjustment options if you choose to use them. They require some care in what lubrication you use since they are using clutches in an oil bath. The clutches can wear over time so there is some maintenance needed. They can also produce heat when being actively used, that can be an issue in longer events. They can keep an inside wheel from spinning when off the ground. They are progressive in takeup.
Detroit Locker is not generally available in the TR diffs, they are rare in the big TR's, not sure if they are even available in GT-6 / spit. They act like an open diff on corner entry so no push but act like a welded diff on power on exit of turns. They are mechanical, reliable and not sensitive to which lube you're using. This is the one that fits MY driving style. You can feel them engage at times - I don't notice while racing but do notice it in the rain or when pussy footing around. Would be horrible on the street I'd think.
Cheers, Tony Drews
Very well summarised, thank you Tony I do run a Gripper in my TR3, which is indeed a plate type LSD, but with the advantage over the other Salisbury plate LSDs that the clutch discs do not have a friction material coating. Therefore they (almost) do not wear vs the usual coated discs, which can wear very quickly under hard use. Advantage over a Quaife : again, as the other plate LSDs the Gripper is fully adjustable and does not need traction on both wheels to work, meaning it works on snow (very useful here for Winter rallies in the Alps), slippery surfaces, and in case of wheel lift, where the Quaife is lost, as it needs an amount of grip both sides. I run the car mostly in hillclimbing (and road as well, it is street legal) and the gripper does its job very well.
I have a couple of comments on the rear locker situation. First
off, the competition department paid for the tooling to make the
lockers for all the Triumph cars. I know cause I had to find the
money to pay for them.
Now on to handling of the various lockers etc. The locker is
strong, dependable but will give some under steer. The clutch
type diff will have a lot less under steer but is not as strong
driving out of the corner cause it does slip and it also produces
a lot of heat because of this slippage. On our Sebring cars in
1966 it was necessary to run a diff cooler cause in an hours practice
they all (four) burned out the pinion seals and leaked like sieves.
I have run TR-3' s with a welded diff and if you want under steer
baby this will give it to you. But boy you talk about drive off
the corner, when you have it set it beats anything. The welded
diff stops you from pointing the front in early without being
on the gas. If you are good this is okay but if not you are still
on the gas when you are gone. By choice I used the Detroit locker
because it was always there and did the job. Work out the little
under steer with suspension settings.
Except for about eighteen months in
the mid-1970s, my TR3 has been a RACE CAR
all its life. I have logged about one hundred and seventy-five
The car came with a Detroit Locker and a 4:1 ring and pinion.
It is an incredible piece of equipment. I understand it was developed
for a light truck, so it is VERY stout. A couple times each year it will
make a noise like the rear end fell out, that is because it is mechanical,
and has no clutches. But when we take it apart and examine it, it still
looks like brand new. I can't believe it. I love it.
Last year we won the E-Production
part of SVRA's BADGER 200 at ROAD AMERICA. Don't be impressed...two hundred miles is a long way, and
we just broke later than everyone else. While we were still running at the end,
we had a broken ring and pinion. Again, when we rebuilt, we found the Locker
was just fine.
Bob Wismer and I are running a Quaiffe
in the Thunder Bolt. It is similar, and smoother. It is more modern, and has clutches. I am sure
it is easier on the drive line. We like it, but have not run it long enough
to judge its long term dependability, and based on my TR3's experience, how
important can that be?
Last summer we set up two more axles...a
4:55 and a 3:73. The 4:55 has a locker in it, and the 3:73 is welded. I know the vast majority
of old TR racers will tell you a welded rear end is 'the way to go'
(and that is based on economies), but I can't subscribe to that. All you have
to do is push a car with a welded rear end around a parking lot to decide
a 'Locker or Quaiffe' is money well spent.
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