lsd's, final drives and some advice!
Turbo Mini Forums

hey up all, ive decided to swap from my x pin diff to an lsd for when the turbo lump makes its way into my trackday/race mini.
anyway im just after a bit of advice as to what final drive i should go for realy, im sort of undecided as to weather i should try and keep it as long as possible and make the torque do the work, although i think the longest ive seen is 3.44 for the lsd? or go to a 3.9 + and possibly up the cam to a phase 3 and use the top end a bit more :S
its an out and out track car made from iains old shell so road manners arn't a problem. im just purely after something that will be fun to drive on the track.

im sure i saw a link on here somewhere to an artical about making your own crownwheel for an lsd out of a standard one, but i'l be damned if i can find it. would be greatfull if anyone can point me in the right direction!

the next incarnation of my engine will sort of depend on this too, if i keep the long diff i keep it 1380 and just make it a little more bullit proof. if i go shorter im gonna go for a short stroke crank and make it a bit more rev happy.... any thoughts would be most apreciated!

steve

doh! why did i start messing with it!

The outer diameter of an LSD is much larger than the outer diameter of a standard or cross pin diff, this is why a different crownwheel is needed. The crownwheel sizes vary with ratio, meaning that basically anything much under a 3.444 is too small to be able to machine it out to suit an LSD.

It is possible to modify a standard crownwheel to an LSD type, you need to machine the centre out and then re-drill holes to bolt it up to the diff. However this is much more difficult than is sounds as the material the crownwheel is made from is tough as old boots. Fastcarl I believe does offer this service, may be worth you contacting him.

Hey steve ill buy your old diff off you if you decide to sell it im going to buy one anyway, no rush or anything if you want to sell it :)

Previous Engine: 1040cc Morespeed engine, 1275 turbo head T2 Turbo Mirage Manifolds Megajolt
Previous engine: STD metro turbo, megajolt
Drives: 399bananahp (flywheel) Honda Civic Vtec b18c4 T28 Turbo 1968 Mini

Megajolt maps to download: http://www.jamesfawcett.co.uk/cms/index.ph...&gid=3&Itemid=3

forget the phase 3 for sure!

stick with the phase 2
stick with the 3.4 F/D ratio

stick with the standard crank stroke!

it seems to me you are over complicating things for your self

usually when this happens people get pissed with the time and money they have spent seeing no light at the end of the tunnel and abandon the project.

stick with what you know and design your engine on some of the best motors on here

you will have your motor on the road sooner and will be more than happy with the performance

just a few examples are….. turbo daves, T3 tone, miniWilliams, giallofly, just to name a few ....... sorry if i have left anyone out theres too many to name!

these are my thoughts

Edited by BENROSS on 24th Jun, 2006.

cheers everyone well i went to minispares today because they managed to get my lsd in in time for this weekend, anyway talking to rich about it we decided on a 3.9 in the end, partly because eventualy the racer will end up doing some miles on hillclimbs etc and i think the 3.9 will be a little quicker off the mark, and partly becasue the 3.9 was the only one he would sell me due to the 3.44 diffs having some machining mistakes on the teath which are causing big problems.

thanks for the advice, i'll leave it as is for the time being and see how she go's.
ive got no complaints on it as a road engine at the moment, it pulls like a train through all the gears and its only at the 10ish psi mark (my guage aint that great!) but should handle 15psi without too much fuss once its set up. i was just considering changes that could be made to improve it for when it goes to track only dutys in the racer that was all.

oh and feebs yeah if you want the x pin its coming out next week mate, its one of minispares own jobbies.

steve

doh! why did i start messing with it!

Did you buy a 3.9 then ? If not i have a 3.9 semi helical CW&P for an LSD, if you're interested.

Phil.

WWW.TURBO-MINI.COM

bollocks!!

yeah i just bought a new set! i was going to get them from ebay or put a wanted add up but then i thought it might just hold up the swap for too long and risk not making avon so i bit the bullit and bought a new one :(
sods law eh!

steve

doh! why did i start messing with it!

grrr that jinxed it good and propper.

the cw&p from minispares is no good, its jamming up and locking the box solid once the diff casing is nipped up. ive removed plenty of material from the casing too and double checked it so its definately not binding there.
looking at the crown wheel and the pinnion they just simply dont mesh properly :( rich at minispares did say they had some trouble with a bad batch so i guess this is one of em


i might be needing that cw&p after all turbophil!
pm sent!

steve

doh! why did i start messing with it!

why sell it if he knew there where some bad ones there....?

it was because i was supposed to have a weeks holiday this week coming, in which i was planning to do some work on my mini in preperation for avon. i wanted to put the lsd in before avon if possible and since the engine is out this week anyway its the right time to do it. i didnt know about the problems with the crown wheels untill i'd already ordered the diff and gone to collect it. so it left me with the dilema of do we risk it and try and find a good set out of minispares stocks, or do i go elsewhere but get stopped up waiting for the parts to come.
we went for the first option but obviously we picked a dud! :S
theres no blame going to anyone, it was a caculated risk and its backfired pure and simple!

steve

doh! why did i start messing with it!

But you should be able to return the parts to MS and get another set to try??

www.shag.no

i had a chat with minispares today and the company who make the diffs are saying every one is tested before its shipped so there should be no problems with them. rich at minispares is saying no there are some problems, and i can vouch for it too.
anyway im taking it back to minispares at the weekend and rich was saying he's gonna test a couple of sets in the donkey engine there.
its just not worth risking the time going all the way to minispares, getting back trying it and finding its no good again!
steve

doh! why did i start messing with it!