would there be much improvement changing a 4.10 diff to 4.27

[Alex]

would fitting a 4.27 diff in place of a 4.10 make much noticable difference do you recon

[sati]

i think higher the ratio the better the car is for get up a go and lower ratio for better speed , but you dont want to go to high as you might just make frist gear pointless. (this is just my veiw, not fact)

[Alex]

well my is will have a 4.10 diff (i presume) and its getting a little whiney so ive thought about getting a refurbed 4.27 from germany

http://cgi.ebay.de/BMW-E30-Differential ... 240%3A1318

40 euro to ship over too which aint too bad

[aj_mckay]

You'd be better off going for a LSD 3.91 IMO, Alex. Yeah it might technically be a LITTLE slower acceleration wise but not noticable and the benefits you'll gain in cornering etc will be worth it... Plus it'd be more fun

[town325i]

a 3.91 would make the an i s dog slow

[aj_mckay]

Surely wouldn't be THAT bad!!!

[johnl320]

It depends on what you use the car for, lots of motorway cruising and I'd be tempted to go the 3.91 route. Lots of town/McDonalds car park stuff and I would stick to the 4.10. I don't think going the 4.27 route would make that much difference, but would annoy you on long journeys with those higher revs at motorway speeds. Myself and Stubedoo ( and a lot of other people) have experimented on here with different ratios and come up with the conclusion that it really depends on what you want out of the car. BMW didn't just stick any old diff on.

HTH
john

[monkey]

i asked the same question a week or so ago and 3.91 was recomened for an iS i also asked fritzs bits and they say the same but i am looking for an lsd and 4.1 lsd's are hard to find so i here . a 4.27 is going to make it a bit lower geared

[aj_mckay]

Or if you're not bothered about getting an LSD you could just stick an open 3.91 in like this one Dips has for sale...

http://cgi.ebay.co.uk/BMW-E30-316-318I- ... 240%3A1318

Cheap and cheerful. I personally think the iS would benefit from slightly longer legs for motorway driving etc and this would help that a bit.

[Alex]

nah a 3.91 would be awful in a 318is

johnl320: i would be maily using it around town and country roads, but i do occasionally do motorway trips once or twice a month

[johnl320]

I'd keep on the look out for another 4.10 and keep running the whiney one. Mine last for 17 000 miles before it got really loud

john

[GrindCulture]

I love my 4.27 diff. Acceleration is a fair bit snappier, but you need to change gear more often. Motorway cruising isn't that bad, the higher revs of the engine are a shit load quieter than my old winey 4.10 and fuel consumption isn't any worse at all. If I like it in a touring it'll be better in a 2door I'd imagine.

[Alex]

so what cars came with the 4.27 diff, was it 316i tourings ????

[GrindCulture]

All manual 4 pot tourings.

[Alex]

cheers

[Bob_S]

3.91 ISNT bad it's hardly noticeable but a 4.27 on an is does go really well.. although you will hit the limiter in 5th at about an indicated 137mph
If it was me I'd be putting a 4.27 on one, mine has one atm and it's brilliant fun, infact all is' are especially cheap ones

[Alex]

3.91 ISNT bad it's hardly noticeable but a 4.27 on an is does go really well.. although you will hit the limiter in 5th at about an indicated 137mph
If it was me I'd be putting a 4.27 on one, mine has one atm and it's brilliant fun, infact all is' are especially cheap ones

i dont think the max speed of 137mph is a problem

[town325i]

my 320 touring had a 4.27 in it

[e30bmlover]

i must admit i dont miss my 4.1... the 3.64 slipper is great for me as it dosent put too much strain on the engine, and the constant gear changes with the 4.1 were a fucking nightmare!

[Alex]

is the 3.64 in an IS

[town325i]

is the 3.64 in an IS

no its in a 325i

[Alex]

is the 3.64 in an IS

no its in a 325i

was gunna say

[junkman]

i have a 327i and the open 4.45 diff an its quick on 1st 2nd 3rd and 4th, but you lose out on top end and can piss you off quite easy changing gears every second lol. 5th gear 60mph 3000 rpm imagine the rest...i think the more logical would be 3.64 lsd.

[Alex]

is there any mathematical way of calculating what rpm you will be doing at different speeds etc

[DHFiS]

is there any mathematical way of calculating what rpm you will be doing at different speeds etc

How good is your maths? If you know the RPM, the gear ratio, the diff ratio and the circumference of the wheel then its fairly straight forward.

[anisotropy]

I've a 4.27 lsd in my IS, it does make it a little noisier on the motorway but I think its worth it for the b-roads and quick starts. I'd do it at that price.

[Alex]

is there any mathematical way of calculating what rpm you will be doing at different speeds etc

How good is your maths? If you know the RPM, the gear ratio, the diff ratio and the circumference of the wheel then its fairly straight forward.

i will give that one a miss then lol

[junkman]

is there any mathematical way of calculating what rpm you will be doing at different speeds etc

http://www.metricmechanic.com/

has information on differentials and gear and speed calculations, a bit to complex for me to understand,maybe someone whose maths is good would find this usefull.

[johnl320]

Put up your tyre and alloy size and I'll do it for you

john

[Alex]

yer been on there site before will have to check out the speed calculator thingy

[Alex]

Put up your tyre and alloy size and I'll do it for you

john

at the moment normal 14" bbs lol thats all i know, car is in storage at the moment

[johnl320]

So your tyres will be 195/65 -14

4. 27 diff will give you

70 mph at 3374rpm

124mph at 6000rpm


4.10 diff will give you

70mph at 3240rpm

130mph at 6000rpm


3.91 diff will give you

70mph at 3090rpm

136mph at 6000rpm


3.64 diff will give you

70mph at 2876rpm

146mph at 6000rpm

HTH
john

[HairyScreech]

get 15s then fit 205/50/15s that will lower your ratio by ~ 0.15, by fitting a 3.95 diff you will end up with the same ratios as standard.

[Alex]

yer ive got some 15s in the garden

[GrindCulture]

get 15s then fit 205/50/15s that will lower your ratio by ~ 0.15, by fitting a 3.95 diff you will end up with the same ratios as standard.

But your speedo will overread a fair bit more than in probably does already.