Differential

[Cypriotgeeza]

Ok so my speedo stopped working, got underneath and low and behold one of the wires had corroded so much it was only being held by one strand of wire lol
Problem sorted..
But while under there i noticed my 318iS has a
3.73 ratio diff I thought iS's had 4.10 ratio diffs fitted?
Im wondering if iS' came with these? and if not what engine size came with these?

Thanx in advance for replies

[AndyE30]

My 325i 89 has this.

[bullwinkle]

I thought all 'is' diffs were 4.1 too - open and LSD.
Had a diff swap? Is it still a small case?

[Cypriotgeeza]

I thought all 'is' diffs were 4.1 too - open and LSD.
Had a diff swap? Is it still a small case?

im thinking maybe it has..how would you know what case it is?

Also would this diff slow down or speed up acceleration?

[bullwinkle]

The 3.7 will ultimately blunt the cars acceleration but will give you better high speed cruising although personally I don't mind being at 4k + on the motorway - at least it revs out in top!

Don't know the specifics of 168 vs 188 diff casings but I'm sure someone will be along shortly to help you identify what you've got!

[charlE30]

Small case diff has 6 bolts holding the back plate on, the medium has 8 bolts

Every possibility that the diff has been changed at some piont in it's life now, especially if any previous owners were zoners

HTH

Charlie

[corkie]

mine had a3.73 before i changed it for the 391

[Cypriotgeeza]

The 3.7 will ultimately blunt the cars acceleration but will give you better high speed cruising although personally I don't mind being at 4k + on the motorway - at least it revs out in top!

Don't know the specifics of 168 vs 188 diff casings but I'm sure someone will be along shortly to help you identify what you've got!

hmmm i might be on the look out for a 4:10 diff now Ive read this! the way i see it acceleration is what i need driving around town etc..hardly ever do motorway driving..

Ok then for a 318iS which is the best for acceleration?

[Rav335uk]

Nothing will help that 4 pot

[Cypriotgeeza]

mine had a3.73 before i changed it for the 391

How was the 3:91 diff in an iS?

[Cypriotgeeza]

Nothing will help that 4 pot

haha now now Rav! dont want to start a debate..

[Rav335uk]

Stick a small case 4.27 if you want acceleration
You'll find that on a 320 cab or 4 pot saloon

[leeparkes]

Id be tempted to go a little higher to say a 4.27 on an is for better acceleration, it will feel quicker anyway if you swaped back to a 4.1

I sure you can get a 4.47 or something around there. Ive got a pic somewhere of a chart with all E30 diff ratio's and what E30's they come off from the factory.
If i can find it ill post it up

Edit: must type faster....

[Cypriotgeeza]

cheers lee! Def going to look into this as my diff is finished anyway! been whining like a good'un for a while now..

EDIT Also cheers to Rav! i knew you wasnt here to tease me lol

[leeparkes]

[Cypriotgeeza]

Saved thanx for that lee!

[fender182]

Just wondering is it possible to conver an open differential to a LSD? not sure if I remember reading it somewhere or if I made it up!

[leeparkes]

Yes (ish)

[Dezzy]

You can convert a open diff to LSD. Easier and alot cheaper to buy the LSD complete. Finding a good one is the tricky bit.

[fender182]

Cheers dezzy, back to the waiting game. lee, I think ill stay away from the welded diff, i like my tyres to last longer than a few hundred miles!

[Cypriotgeeza]

does anyone know if you can get a 4.27 or a 4.45 ratio LSD diff?

[Brianmoooore]

You can get a LSD with any ratio of diff, if the original purchaser ticked the (not very expensive) box. Sadly, very few did.

[Cypriotgeeza]

thanx for the replies guys!

[Cypriotgeeza]

Id be tempted to go a little higher to say a 4.27 on an is for better acceleration, it will feel quicker anyway if you swaped back to a 4.1

I sure you can get a 4.47 or something around there. Ive got a pic somewhere of a chart with all E30 diff ratio's and what E30's they come off from the factory.
If i can find it ill post it up

Edit: must type faster....

Im getting tempted to go all out and put the 4.47 ratio in there..would compromise top end though wouldn't I?

[BMC227]

my e30 alpina c2 2.7 had a 3.91 and i honestly think it's a crap ratio for a car that has plenty of torque. I fitted a 3.46 and the car is beautiful to drive with great power.

[polsta]

i have a 4.10 in mine, a 4.10 (i presume) on the breaker, but have a little leak/whine in the one on the car, so plan is- to put the 4.27 on , and see how i go, i hear it gives better acceleration, so wel see , i dont want to loose the mid/top end power tho or cruising ability, so wel see , il post up once its in there

[Brianmoooore]

my e30 alpina c2 2.7 had a 3.91 and i honestly think it's a crap ratio for a car that has plenty of torque.

Exactly! This thread is about an iS though.

[Cypriotgeeza]

is there anyone here who has fitted a 4.27 or a 4.45 to their iS?

[Cypriotgeeza]

my e30 alpina c2 2.7 had a 3.91 and i honestly think it's a crap ratio for a car that has plenty of torque.

Exactly! This thread is about an iS though.

Thank you brian!

[Game]

Is there a way by checking on the casing if it's got lsd fitted? Or is it a case of lighting up the rears and seeing if you've layed some 11's?

[Cypriotgeeza]

Is there a way by checking on the casing if it's got lsd fitted? Or is it a case of lighting up the rears and seeing if you've layed some 11's?

the plate that has your ratio number on it should have an "S" on it..