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What lsd to go, Helical or disc
fregis - 21/11/20 at 08:32 AM

Hi
Short Helical or disc type LSD? or other? prons / cons - for light casr.

Considering buying new LSD for ford 7" diff (visco dont work right), but i not decide what type go....
How handling differentiate between these type LSD?

Also Quaife atb have different angles (sierra one angle, caterham other), how choose?. I hear some don't like Quaife atb how work, maybe angle to aggressive?...
Disc type, what preload not to big? ramp angle? 1.5way (because i am noob)?
Which manufacturer to avoid?

Locost AWD (little heavier +150kg than rwd)
Driving hill climb, slalom type race for fun.



[Edited on 21/11/20 by fregis]

big_wasa - 21/11/20 at 10:13 AM

I've read you can get the ford lsd adjusted, pumped up with a heavier oil ? That makes it act like a disc lsd. One firm being Bara motorsport.

scootz - 21/11/20 at 11:59 AM

The Quaife ATB was designed for front wheel drive gearboxes to eliminate torque-steer (and it's apparently very good at it).

It's usefulness in a lightweight RWD car triggers a lot of debate.

rdodger - 21/11/20 at 04:01 PM

I have always believed that a plate type was best but need regular maintenance and proper set up for the weight of car etc. Fine for competition but less good in a high mile road car.

ATB's are torque biasing so if you lift a wheel off the ground you do loose drive to the wheel still in contact with the road. They are pretty much fit and forget though

As already said you can get the sierra lsd tightened up so may be an option?

Oddified - 21/11/20 at 07:54 PM

I've had various plates diff's over the years in various cars, and i think for ultimate performance when setup correctly, correct ramp angles, plates, pre-load for the car, power and grip they're the best. I've just fitted a Quafe ATB in the back of the Metro and more than happy with it, smooth/quiet and more progressive than the previous plate diff but will lock/drift if i feel like it

Plate diffs need maintenance and can be noisy, harsh, judder, none of which matters if it's used mainly for racing of course!

snapper - 22/11/20 at 02:34 AM

quote:
Originally posted by big_wasa
I've read you can get the ford lsd adjusted, pumped up with a heavier oil ? That makes it act like a disc lsd. One firm being Bara motorsport.


It’s not oil in a viscous diff it’s silicon fluid, their is a defined air volume and some pump air in to adjust the locking but it’s a bit of a bodge.

Plate diffs are really only for race or serious track use as they need maintainable and setting up.
Quiafe diffs are not just for front wheel drive but are used to good effect due to good on street manners.
I have one in my 7 replica Sierra diff and it works great except that there is an almost imperceptible delay as I push hard, then you feel the grip.

All LSD’s will add some under steer, I haven’t felt it even on a North Weald handling day but if you did you can dial it out with shock settings and tyre pressure