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Author: Subject: LSD Options?
BangedupTiger

posted on 6/2/14 at 11:08 PM Reply With Quote
LSD Options?

I'm looking at upgrading my current sierra 7" open diff with push in shafts to an LSD.

I want to keep my rear brake drums, am I right in thinking that all sierra LSD are bolt on? and does that mean they won't work with rear drums?


What options do I have?

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hkp57

posted on 7/2/14 at 07:02 AM Reply With Quote
Rebuild your current Diff with a Quaife ATB unit inside or a 3J Drivline ATB

That way you keep your entire drive shft and brakes as is.

http://quaife.co.uk/shop/products/qdf15z-0

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daniel mason

posted on 7/2/14 at 07:13 AM Reply With Quote
check blatchat. loads of the caterhams run a sierra 7" LSD with push in shafts






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Paul Turner

posted on 7/2/14 at 09:00 AM Reply With Quote
Had 2 LSD's in my Caterham, first was the factory supplied ZF unit which was eventually replaced with a Quaiffe unit. Both have used the same kit supplied push in shafts.
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mcerd1

posted on 7/2/14 at 09:04 AM Reply With Quote
you have 3 options:

1 - aftermarket diff that will accept you current shafts - like Quaife, Gripper, Tran-X or the old ZF..

2 - hybrid shafts with ford LSD - push-in one end and bolt-on the other - these are fairly straight forward and do work, but tend to wear out faster due the mismatched CV joint designs

3 - bolt-on shafts and modify your drum brakes to fit - you'll need the LSD, bolt-on shafts and the bolt-on/ disc brake hubs (bolt-on hubs use different bearing sizes to the push-in so you can't mix and match here) - then offer up your drums and 'adjust' till they fit - this should be technically possible, but I've not seen anyone try it as they normally just upgrade to rear discs....



the best LSD's are the aftermarket ones - you pick the type that suits your style and get it setup to fine tune it for your car (ramp angles etc) - but these aren't cheap

I think its quaife that most caterhams use, and here's flak monkey's old thread about fitting a tranX one:
http://www.locostbuilders.co.uk/viewthread.php?tid=138216


[Edited on 7/2/2014 by mcerd1]





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Matt21

posted on 7/2/14 at 11:35 AM Reply With Quote
why not just upgrade you're rear brakes to discs?

is there a benefit of keeping drums brakes or do you want to keep them becuase theyre one and work fine?

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BangedupTiger

posted on 7/2/14 at 12:20 PM Reply With Quote
Cheers guys.

how much better is an aftermarket LSD compared to a standard ford one? I think i'm going down the standard bolt on and modify the shafts / hubs.

I'm not likely to be taking it out every other weekend to adjust ramp and preload etc. I really justy want a basic fit and forget option.


Not wanting rear calipers as I dont see them as an upgrade, if anything they will just upset the balance of the braking and over brake the rear.

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Matt21

posted on 7/2/14 at 01:06 PM Reply With Quote
I've not had any issues with mine being over braked on the rear, if anything it could do with a bit more as the fronts lock up well before the rears (standard sierra brakes all round)
if you find too much braking on the rear you can fit a bias adjuster in easy enough.

but then if you're not wanting maximum braking, which i assume means you wont be hammering it on roads or track? why bother with the lsd in the first place?

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Paul Turner

posted on 7/2/14 at 01:20 PM Reply With Quote
quote:
Originally posted by BangedupTiger

I'm not likely to be taking it out every other weekend to adjust ramp and preload etc. I really justy want a basic fit and forget option.


Not wanting rear calipers as I dont see them as an upgrade, if anything they will just upset the balance of the braking and over brake the rear.


When I had teh ZF plate diff in and was using the car on the hills and sprints the diff needed checking and shimming before the season started and 1/2 way through to ensure the car was 1005 perfect (well as near as you could get it.) I was lucky to have a mate who had the kit and shims and did it for beer tokens.

When I stopped using the car on the tracks the wear to the plates etc was minimal, you would rerely need to get it adjusted.

But if you fit a Quaiffe you will never need to touch it. The one in mine was fitted in 1999. The car did about a dozen sprints just after I fitted it and has also done probably 6 trackdays. They are really a fit and forget solution.

Think the XR4x4 viscous ones are fit and forget as well.

With regards to rear discs brakes on the road you never get them hot enough to be an issue but on track after a few laps the car becomes very tail happy under braking. A simple pressure reducing valve solved it for me at minimal cost but some Caterham racers (in series where valves are not permitted) simply reduce the area of friction material on the pads with a hacksaw or similar tool.

But standard Caterhams like mine use the old style Girling calipers as used on Spitfires etc. If you have a Sierra based car or Escort/Cortina M16 calipers which are much bigger there should not be a problem.

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BangedupTiger

posted on 7/2/14 at 02:36 PM Reply With Quote
I use wilwood powerlite 4 pots with solid discs up front. Brakes are fine.

Diff is needed due to additional power soon going in, z16ler with k04 hybrid.

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old_timbo

posted on 8/2/14 at 12:27 AM Reply With Quote
I went the hybrid shaft route and the Sierra LSD. Works well and has been fit and forget. If you go this route you will need the larger 27mm dia push-in drive shafts as a starting point, then remove the inner CV joint and fit the bolt on type instead. I think these shafts are not the most common as they were fitted to the later diesel and DOHC Sierras only.
The drum set-up gives a lighter unsprung weight than the standard Sierra disc set up due to the heavier CV joints, bigger hubs and bearings , weight of calipers etc.. So in my view the only reason to go disc at the rear is for cosmetic purposes. Even with drums I had to fit a balance valve to prevent an over braked rear when using cheapo motor factor pads at the front.

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BangedupTiger

posted on 8/2/14 at 10:45 PM Reply With Quote
quote:
Originally posted by old_timbo
I went the hybrid shaft route and the Sierra LSD. Works well and has been fit and forget. If you go this route you will need the larger 27mm dia push-in drive shafts as a starting point, then remove the inner CV joint and fit the bolt on type instead. I think these shafts are not the most common as they were fitted to the later diesel and DOHC Sierras only.
The drum set-up gives a lighter unsprung weight than the standard Sierra disc set up due to the heavier CV joints, bigger hubs and bearings , weight of calipers etc.. So in my view the only reason to go disc at the rear is for cosmetic purposes. Even with drums I had to fit a balance valve to prevent an over braked rear when using cheapo motor factor pads at the front.


Thankyou.

I'm going to keep my eye out for a sierra LSD with shafts. Once sourced i might send you a u2u regarding the necessary modification if thats ok?

if nothing turns up, i'll go down the quaife route.

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old_timbo

posted on 9/2/14 at 12:21 AM Reply With Quote
No probs. LSDs come up quite often on Ebay, so getting hold of the larger shafts will probably be the main issue. What diameter are the ones you have already? The smaller ones are approx 24mm and don't have the right splines on the end for use with the bolt on (Lobro) CV joints.
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BangedupTiger

posted on 9/2/14 at 12:26 AM Reply With Quote
honestly dont know, I assume 24mm. donor car was a 2.0 sohc sierra.

will the 27mm shafts be compatible with the outer cv's? would using a 7.5 diff and shafts be a problem as i'm currently using 7".

[Edited on 9/2/14 by BangedupTiger]

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old_timbo

posted on 9/2/14 at 10:47 PM Reply With Quote
The outer stub shafts that go through the bearing and drum are the same (the diff. end is as well) for both diameters of drive shaft. Don't know about the 7.5" diffs, I've only used the 7" type.
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