Originally I was told a Freelander diff with a quaife ATB would be great for a BEC, but having bought a busa turbo it seems I am now better off with a 7 inch Sierra diff to handle the power.
I am also told a plate type LSD is the way to go rather than ATB.
Can anyone tell me if it is feasible to get a 7 inch sierra diff to start with, and then fit a unit to make it LSD (titan/ZF??) or would the car handle too badly?
Or is there another option? eg, Subaru diff? etc? That would work without any upgrading?
I am out of my depth here - please help!!
Cheers

the only usuable sierra ratio with lsd is a 3.62 but that would be way to short for your busa turbo.
but you can swap the crownwheel from say a 3.38 or 3.14 to make it a lsd better ratio

Someone like Phil Jones will build an LSD into a normal Sierra diff for about £600

nothing wrong with swapping an open diff for a new LSD.

plate type diffs can be a bit harsh sometimes, especially on a light car, they have been known to suddenly lock up. the LSD in my bmw is a bit funny like that
setting them up to suit your car is a bit of a black art too lol. rebuilds can be expensive too when the plates wear out.

i've not driven a car with one yet, but i think the quaife atb would be my lsd of choice no setting up needed, no plates to wear out, and apparently they never just lock up, so are a bit more forgiving.

www.gearboxman.co.uk seems to have the best prices. he does all different types of LSD too. maybe worth a chat with him?

Cheers gents,
I have a new ATB unit and Freelander diff, but was told they are "wrong" by a bloke with a Caterham Busa turbo.
I would say that if a freelander takes off and then hits the dirt, the shock to the diff and half shafts would be similar to a busa turbo pushing a lightweight car!

If I got a Sierra LSD and swopped the crownwheel to 3.14, would it be better/comparable to a non LSD 3.14 diff with a ZF/titan unit? Or How would Phil Jones make it LSD?

Thanks, I know this isn't simple!!

i think this caterham dude was maybe just meaning its not his preferred set up.

i think, no matter how you look at it, the freelander diff is going to have a much easier life in you car than in a freelander

On the flip side...has anyone ever heard of a 7" Sierra diff going bang? I've heard of sheared drivehafts (that was a slide-on diff with a Quaiffe unit it), but never a diff going.
I know of a few cars throwing the wrong (good?) side of 300bhp (turbos) through them in the sprint/hillclimb world and nobodys blown one up yet. Wearing out the viscous pack in an XR4x4 one, yes.... These guys do warmup wheelspins on slicks/List 1Bs 2 or 3 times a run - so sheer abuse!

Is a Caterham solution not ideal if there's a more expensive option in the catalogue?

So many options, so few braincells.
At the mo my diff is Sierra so keeping that would mean less chassis mods to fit. I will ring Ashcroft, good call!
Cheers

if you already have a sierra diff, i'd just get a quaife atb for that. that way no chassis mods, new prop shaft, driveshafts etc are needed as they would be for the freelander diff

The options as I see them are to
1) do just that,
2) or do that and change the ratio with a new crownwheel,
3) or find another Sierra LSD and change that ratio (hence save the price of the quaife)
4) Send my diff to whoever and get them to change the ratio, and make it LSD, by whatever means.
5) Find a 3.14 diff and make that LSD

I think thats it!
I would still like to know why plate LSDs are considered better mind!

well, theres this one..
link

2 days left, sitting at £150, with a 3.1 diff and LSD. could be worth it?

someone will know better than me if theres any issues with a 4x4 diff, but looks like its been fully rebuilt, so effectively new, and might be worth the max bid of half a quaife unit (500-600 from quaife?) there is one for £175 buy it now on there too actually but with a 3.62 ratio

i think your option 4 is a non runner. an open diff (as in the actual diff inside the casing) cannot be turned into a LSD, the only way it can be done is by taking out your open diff and putting in a LSD instead. essentially option number 1.

i'm still unsure that a plate diff is better. i'd still prefer the atb

Well I just won that viscous diff 3.1:1 ratio that you put me onto Blake, it was rebuilt a couple of years ago but not used since and according to most people who would get off the fence, it should be fine, although it could become more and more open if I'm tough on it. Then gearboxman.com can do their magic for £175.
A good day!

ps. for the record, plate type diffs like the one Vanman recommended should cause push on understeer on corners so are best for drag strip.
ATB or Viscous are better for the track, but an ATB costs a min of £450 plus price of 3.14 diff or sierra diff plus new custom CWP cost.
Either way I'm happy, recon, LSD, viscous, 3.14:1 and £480 plus petrol to collect!
Result!
Cheers Gents

Which means I have a Freelander brand new diff and brand new ATB to fit it for sale!
Looking for just what I paid for it, £850. U2U me!

coolness mate! hope that one off ebay meets your needs!

seeing as its a viscous diff, altering how it behaves is done by changing the viscousity if the fluid, so in the future, shouldn't need expensive rebuilds if you want to change how it behaves

Part of what gearboxman.com do is fit a tap/drain to allow easier viscosity changes and replacement to suit your car.
The thing is I have not got the experience to be able to say whether it should be made tighter or looser or whatever yet! If it is a complete disaster and I must go ATB, the price of a new CWP to change to 3.14 ratio is more than I paid for the Ebay diff. So I could use its new CWP to change the ratio of the diff I have on the car now, and fit an ATB to that!

Or does anyone know if ATBs can be fitted to Sierra LSDs?

Does this make any sense at all??

Is it too early for a beer?