LSD Ratio Alteration

[Eddie25]

Hi All

Been a while since i've posted on here;

A while back now I purchased an LSD from the zone in immaculate condition, the case is spotless.

However it's a 3.91 which for a 325 is a bit much. 75mph will see around 3500rpm so long motorway drives arent ideal.

Therefore how much of a job is it to lower the ratio? Perhaps to a 3.64 or 3.73? Is it just a case of swapping the crown wheel? Is there a zoner that undertakes this type of work?

Apologies for all the questions, its a job that's annoying me.

[Eddie25]

bump

[Barx325i]

hmm, well.. a crown wheel and pinion swap isn't throw away cash, but if you're sure the LS unit, clutch packs etc are good, maybe this is the way forward.

Gareth on here may be able to help a) sourcing relavent CWP's and b) he will do the swap.

Having said this, if you lay trust in a third party, swapping the entire diff for the desired ratio is another option

F0xy has a 3.73 for sale in Warrington, but there's not enough between them. Ideally you're after a 3.64 if the RPM is ever in the corner of your eye.

www.unixnerd.demon.co.uk/revs.html

gear ratios are in the wiki - apologies for lacking the enthusiasm to list them individually

[Eddie25]

That's fantastic thank you very much Barx.

Will have a word with Gareth and see what he thinks.

I must admit country lanes etc are great, with the cam and BTB it sounds and goes savage but the motorway rpm does concern me if i'm going any distance.

Thanks again.

Eddie.

[Barx325i]

cam and BTB it sounds and goes savage.

hth

[Eddie25]

The link says 16 inch wheels would drop the engine speed by around 100 rpm at 80mph using the values already set, hmmmmm

[Barx325i]

choices choices.. What wheels/profiles are you currently using?

[Eddie25]

Currently 15inch Ronal LS on 205/55/R15

They do look a little lost with the cow plough on the front.

[Barx325i]

hmm, ronal LS are a damn good wheel, but 16's will make the difference

Hartge 1 piece are desirable, not very easily picked up at present seemingly, failing that some alpina 7j's all over will tide you over.. A staggered set are not only rare but very dear.

225.40.16
205.45.16

are what you're heading for ideally as per hartge (using a 7.5j all over)

[Eddie25]

Hmmm love Hartge wheels but not sure they'd sit right with the Alpina cow plough.

Would really love some BBS splits as per your sig but the few i've seen come on ebay I'd have needed a mortgage for

[Barx325i]

tough decision re the hartge/alpina setup.. staggered pina's are 7 & 8.. I found the 7.5 hartge in each corner were great with the tire choice as above. Ideal in fact, IMO.. Sadly the ones in my sig are 15's, they run blissfully, almost to the point where the extra half inch isn't a concern..

I guess it's OEM over aftermarket at this point..

[gareth]

as above. Swapping a CW&P is not cheap but if done properly (new bearings, seals etc) will get a decent life out of the diff. Most are getting very leggy nowadays and well overdue an overhaul