MalteseFalcon

hi, after breaking the original Ford diff about 3 times, I decided it was time for something more stronger and as a bloke I know already fitted one and was seeing how good it was I decided to go that way as well. This is a BMW E36 M3 diff which is a 8.5 inch a much stronger than the ford one. Incredibly so, it's similar to the ford diff and even the shafts match just need a spacer on the left shaft and you have two choices for the prop shaft (1) or cut the BMW prop flange and weld the Ford flange so it will match the ford propshaft or (2) get hold of a BMW M3 E36 prop shaft, dismantle from the cross than dismantle the Ford Prop shaft from the cross, than use the BMW part to fit the diff and the Ford part to go into the gear box. To make it fit into the Ford beam a jig was made and some pieces were welded to the diff to fit into the original ford beam.... here are some pics http://s799.photobucket.com/albums/yy272/marko3star/

MK MOTORSPORT

iTrader: (1)

hi are the diff cases alloy or iron

thanks mark

MalteseFalcon

cast iron

-beefy-

iTrader: (6)

seems like a good conversion , and clear pics of the machined rings fitted to the drive shafts >?


it looks like the bmw diff is thinner than a cosworth item .


what power rating is it good for ?

b

botters

iTrader: (2)

ive personally made 2 of these diffs shit themselves with standard m3 power allthough i was giving them a bit of abuse not sure how they would hold up against turbo power allthough they seem to be allright on turbo beemers? maybe im just a bit heavy footed lol

lee2cossies

iTrader: (2)

Very interesting.I was going to have a go at doing this to my cosworth at one point. How does it affect the gearing though? Is it a taller ratio or lower?

MalteseFalcon

where they M3 E36???? if you see the diff from inside you will notice that the pop shafts and crown wheel and pinion are much stronger, I forgot to take measurements but sure you can find on the web....A lad from Malta which runs a 600bhp+ on an RS500 has one of these and he didn't break it and he broke about 9 ford diffs and two Ford 9inch as well. here is a link to see him on the drag strip... he manage 10.5 with 1.5 first 60 feet
http://youtu.be/gkrWH4bs56s

MalteseFalcon

beef....it's a 8.5 inch unit and can handle up to 800bhp, if you compare to the ford unit it's about 1.5cm wider but then the BMW is more bulky, the one I have has a 40% lock lsd and cwp is heat treated as well,

R5FORD

iTrader: (1)

how the hell did he break a 9" diff and not break a 8.5" diff

MalteseFalcon

couse the ford 9inch diff has the same cwp as a 7.5.....

R5FORD

iTrader: (1)

Ahhh ok

BRAMMER

iTrader: (23)

Nice conversion if it works - good opportunity for someone with the know how to make a conversion kit

MK MOTORSPORT

iTrader: (1)

hi it dosent have the same one

thanks mark

MalteseFalcon

for some one who is handy with a welding set and know how to fabricate steel ecc is not a big deal....Ours was made by a local engineer for 700 euros

MalteseFalcon

I think a saw a thread a while ago saying that the thikness of the pinion of the 9" is the same as the 7.5" thats were I got it that they are the same... any way they break as the guy who made it here in Malta broke two ( using it on the strip) and now he have the bmw with no prob...I think even in the touring car they used to break and than switched to jag diff...This I read from a Ford magazine when they made a story about Zoo motorsport...always if my memory serves me right ( it doesn't a lot )

turnover

Chris,s car kalanc runs a 9inch live mustang axle chap and has ran 8.9,no bmw diff in that

botters

iTrader: (2)

yeah both e36 m3's mate both times i was doing donuts with sticky tyres on dry tarmac lol

ive also torn the floor around the diff on an e46 m3 lol though i believe this was quite common on e36 and e46!

Rob_DOHC

iTrader: (4)

3.2 evo diffs are much beefier than the 3.0 diffs if that makes any difference?

Rob,

Rob_DOHC

iTrader: (4)

Im not sure the Jag diff is the way to go, he's eaten 3 now in his xjr.

Rob,

botters

iTrader: (2)

no doubt it would i bet i could still break one tho lol!

ive never broke a cossie diff allthough the cossie belongs to me and the m3s didnt so i had much less mechanical sympathy for the bm's lol

Rob_DOHC

iTrader: (4)

Lol, (~note to self, don't lend botters any cars~)

MalteseFalcon

I think you will even break a 9"

MalteseFalcon

You are right but in his left hand drive 1/4 mile 9sec sierra, His father's RS500 has the BMW infact I used his jig for making mine.... They look almost identical but one is lhd anf the other is rhd which has escort cossie wheels.....

R5FORD

iTrader: (1)

Im sure I read that the 9" diff is a hell of alot stonger? Iv been told I could launch etc on that diff and I wouldnt have any issues

_SpeedX_

iTrader: (1)

its been talked about on passionford before...

Rod-Tarry

850bhp/666ft-lb done 25 Topspeed runs & 50k road miles fitted in 1999 yep!!! your right not the solution . The Jag diff is used in drag cars with well over 1000bhp.

Rob_DOHC

iTrader: (4)

Im sorry Rod, i forget you are all knowing.

550ft-lb's and 1710Kg.... and he actually drives it. Maybe a different model diff?

Rob.

EDIT xjr's are 1790Kg, so i guess the extra half a ton hurts diffs more than an extra 100 ft/lbs...

turnover

yes your correct as i know chris well,but his dads rs500 isnt nowhere near the power of the lhd one with the old escort engine in,but nano,s rs500 is alot stronger rear end than standard

MalteseFalcon

you never know which engine is in which car as they got plenty..... but the rs500 is always near 600bhp where the lhd is about 800bhp....so...they run almost identical engines but with the lhd having a much bigger turbo....
http://youtu.be/33tZGBfptdo

RickyLee53

Traction and torque are probably the main thing to break diff's.

Rod probably doesn't make anywhere like 666 in first gear. It'd simply spin the wheels or not put the engine under enough load. The gearbox is a torque multiplier so obviously the diff probably see's a couple of thousand lb/ft in first gear. When you in 4th etc its more like what the flywheel torque is so much less relevant.

Sta1n1

this is a 2wd rear beam ? would it be possible to do it on a 4x4 rear beam ? and is it any difference on the e36 m3 diffs, what year is the one you used ?

MalteseFalcon

my friend is using it on an Escort Cosworth 4x4, the diff is modified to fit into the Cosworth beam so It can be used on a 4x4 beam... it is an e36 M3 diff...http://cgi.ebay.co.uk/ws/eBayISAPI.d...#ht_1179wt_825

Phil2002

iTrader: (3)

4x4 beam is different to the 2wd by 1/2inch.

Sta1n1

okey, thank you im thinking of putting an zf gearbox from m3 and a diff like this on my cosworth. It should be able to cope with the power im thinking of, do you have any tips for me on how to modify the diff to fit ? pm me if you prefer that

MalteseFalcon

you need to make a jig to fit the BMW diff on the Cosworth beam, unfurtantely I didn't take any pics of the jig as I borrowed it from a friend but it's not really a big deal...If you know to weld and handy with fabricating steel than it wouldn't be a problem for you...If you look carefully at the pics ypu will see the weld on the diff...

MalteseFalcon

indeed you need to mofify to fit the 4x4 than....

Sta1n1

thank you, are you sure you cannot get a hold of some pics of the jigg ? would be alot of help