bitsilly
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| posted on 4/5/09 at 06:24 PM |
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Options for an LSD BEC diff?
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
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Johneturbo
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| posted on 4/5/09 at 06:32 PM |
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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
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slimtater
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| posted on 4/5/09 at 06:40 PM |
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Someone like Phil Jones will build an LSD into a normal Sierra diff for about £600
http://www.picturetrail.com/sfx/album/view/19919222
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blakep82
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| posted on 4/5/09 at 06:46 PM |
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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?
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bitsilly
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| posted on 4/5/09 at 07:34 PM |
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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!!
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blakep82
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| posted on 4/5/09 at 08:13 PM |
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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
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ss1turbo
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| posted on 4/5/09 at 08:35 PM |
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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?
Long live RWD...
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bitsilly
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| posted on 5/5/09 at 12:03 PM |
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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
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blakep82
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| posted on 5/5/09 at 12:45 PM |
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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
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bitsilly
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| posted on 5/5/09 at 01:53 PM |
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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!
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blakep82
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| posted on 5/5/09 at 02:30 PM |
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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
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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bitsilly
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| posted on 7/5/09 at 07:21 PM |
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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
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bitsilly
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| posted on 7/5/09 at 07:26 PM |
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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!
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blakep82
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| posted on 8/5/09 at 12:29 AM |
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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
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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bitsilly
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| posted on 8/5/09 at 10:00 AM |
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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?
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