Smallest/lightest live axle LSD diff you can get?

[Shifty]

Firstly, please don't say Hilux or R31 and please don't suggest a spool.

I am after prettymuch the lightest live axle diff, that I can get a decent LSD for.

At this stage I'm thinking perhaps an AE86 diffs? I don't know a lot about them, but from what I understand:

* they're the right stud pattern (4x114.3)
* they are disc brake (import only?)
* strong aftermarket so LSDs should be available (expensive though)
* available in other cars, should be able to swap gears/ratios with those?
* they're reasonably strong
* there are two versions, I assume one is lighter?

Thoughts on this? Is there a lighter option that you can get something aftermarket for? If there's an extra 5-10kg of diff weight that I can ditch, I'd rather go that way even if it means I break a diff/axle at some stage.

I'm looking at a finished product with a maximum of 150rwhp and a maximum weight of 750kg including driver & fluids... so it doesn't need to be strong but it does need to be a decent LSD.

[oldcorollas]

jap AE86 came with T series. heaps of LSD's

aus AE86 came with S series. lighter, I know of at least 1 LSD bonus is that people throw them away, so heaps fo spare axles/gear sets

lighter still is U and b series etc (KE30, starlets), but the 6" TRD LSD's are hard to come by
the 5.6" LSD is relatively easy tho, but need early starlet axles.. probably too small

[Shifty]

Any idea how much lighter is the S-series over the T-series? I'd assume being drum rather than disc that would even the weight back up a little? What about the 5.6" LSDs, what do they go into?

If I need to, I'll get billet axles made.

[big_zop]

You might also want to mention what vehicle you are trying to put this in as the total width could become a factor as you wouldnt want the added expense of shortening a diff, or looking at something too narrow and wont fit.


Although, by the sounds of things you probably are looking for a Clubman or similar.

[Shifty]

Hi mate, thanks for your interest... though I'm resigned to the fact that the diff will need shortening regardless of which one I choose. Hence my not minding getting a set of billets made up as I'm already up for shortening axles, which is a big chunk of the cost just to get new ones made.

Similar intent to a clubman with modest power & brakes but minimal weight to make it all work. In my case what differs is that I'm just trying to build a front-engined, rear-drive monocoque car as light as I can, being ridiculous about cost or saving every last half a kg.... just selecting major components wisely but without overkill. There is always someone with more ability/care/money, but I want to see what a genuine backyarder can do without going completely crazy.

Similarly the engine setup will be very simple. 100rwhp is achievable from most small motors and is quite lot if your car has an on-road weight of 750kg!

To put in perspective how light 750kg "as driven" really is... my CA18DET 120Y is 1060kg with fluids, driver, etc.

[thechuckster]

note: you can fairly easily convert T-series diffs from RA23/28/40 to disks. So it might be cheaper to build a frankenstien diff rather than try to locate an intact and complete import AE86 diff.

Also,. Bog Zop's point about target vehicle width would factor into possible donor diffs.


edit: why solid rear axle? If it's a bespoke race car then IRS diff and fabricated arms/suspension would equate to better handling. Or look at Bill Sherwood's racecar with the IRS diff and DeDeon axle. Also, Race magazine's 'Social Climber' project car has a developed a fairly cheap universal upright (hub) for folks fabricating their own suspension arms.

[oldcorollas]

5.6" is for early KP6x starlets.
5.7" is KE1x corolla
6" is KE30

the 6" LSD goes with the 5.7 gears and housing too, and both have 1mm larger axles than the 5.6"
I have an S series LSD atm. you can convert them to disc.

but as Charles said..de-dion might be a better simple way for a light vehicle. gives you huge choice for centres

[Shifty]

IRS is starting to get a little bit outside my budget/ability.

Just seeking something with a beam axle that I can get an LSD for. I think the Sprinter jobs might be the 'safe' option but fark they're not cheap!

[thechuckster]

fair enough - I'd still recommend a diff from an open-centre unit (e.g. RA23), rear disks from early 80's Corona (ST14x) will bolt on with shim plate between bearings and bearing retainer. As will rear disks from Nissan Pintara (wagon or sedan - not sure). Then find T-series LSD diff centre.

[Sam_Q]

imported ae86 diffs are stupidly overpriced, have tiny disks and are almost gaurenteed to have flogged out LSD's. I suggest getting yourself the diff out of any RWD celica as all bar one has the T series LSD and then fit an ae86 LSD which can be surprisingly affordable second hand. They do come up for sale cheap sometimes on the ae86dc forums. Cutting and resplining the stock should be quite affordable as well, but watch out that if your going to shorten that it's not less than the minimum possible, it's safer to buy a longer diff on purpose and shorten that. As a bonus you could add a little negative camber and toe. You know what width you would like though? The TA22 housing is only 1370mm face to face. 3.9:1 and 4.1:1 ratios are very common, getting anything out of this range up to 5.3:1 is fairly straight-forward but expensive. Check the trans plate for what ratio the vehicle has.

Forget about the S series LSD, as far as I know they are stupidly rare and the stock spider gears are absolutely tiny.

[oldcorollas]

$600ish for a new or reconditioned to new spec T series LSD is not that expensive?
not compared to $1000+ for a 6"

if you measure the spider gears of a T series, i'll measure the spider gears of the S series

[Norbie]

Just seeking something with a beam axle that I can get an LSD for. I think the Sprinter jobs might be the 'safe' option but fark they're not cheap!

Agree with the above, Celica T-series with a disc brake conversion will give you the same thing at a much lower cost. The only way you could justify the expense of an AE86 LSD rear end is if you already own an AE86 and you're lazy.

Just quietly, you can have the T series diff out of my RA23 if you help me replace it with the F series I stole from your old MkII.

[cooter]

t18 diff is aquirable too. same as the celicas, T series

just a question

"As a bonus you could add a little negative camber and toe"

how does one alter camber and toe on a live axle diff??

[thechuckster]

how does one alter camber and toe on a live axle diff??

a big press and subtle application of heat?

[oldcorollas]

as long as the side gears have enough play not to bind/bend on the axles..
too much and you will break axles at the spline