Rippers

Can someone explain in detail what this conversion is all about please, whats involved, pro's, con's and costs.. From what I've heard so far it seems right up my street

Si B

iTrader: (59)

Doug Stirling may be able to comment on here - I'm sure he had this done recently on his Escos.

Makes acceleration better at a loss of topend - but who REALLY needs 180mph plus performance on the road?

I may look into this conversion myself as and when Marco releases the MULLET DIFFS!!!

Not sure on the technical ins and outs, will leave that the the pros!

Si

Rippers

Anyone who knows me I love acceleration over top speed

It sounds like I need a new diff and different transfer chain, but I really need to know a bit more detail

dave cos4x4

iTrader: (5)

what ratio is the diff you have bought Paul, they will have to be the same ratio.

Rippers

Dave from what I understand you can change the rear diff and by changing the transfer chain steps down the front. I'm assuming the front diff I bought was standard ratio

dave cos4x4

iTrader: (5)

thought you have to match the front diff ratio with the ratios in the gearbox bit.

Rippers

tis why I'm asking the questions mate.. I just don't know

Need input

T4T

You can either use step off gears on the transfer chain or run with a matched front diff

BTW the 2.0 XR4x4 uses 3.92 front and rear diffs

Cheers Matt

dave cos4x4

iTrader: (5)

i always though that if you wanted different ratios then you changed the front diff and the ratios in the gearbox so they both match.

i may be wrong though Paul.

but if i'm right....you have to have the same ratio in the box as the diff you have got.

xr4x4rs

iTrader: (5)

the 2.0l gearbox is the same as a cossy

so if you want 3.9 you can either use a rear diff out of a 2.0l and change the chain or sumthign not to sure

or easier is use matching 3.9 diffs front and rear and leave the box alone

kelv has 3,9 rear and step off in teh box on his

so he will know a bit more about it

Rippers

Was hoping to catch Kelv on MSN but he's not been on yet

marco polo

iTrader: (1)

Hi Paul

basically you can use any rear diff providing you get the right step of gear ratio for the 3.6 front diff

i can get any of these ratios for the 7" diff rear CWP 3.1,3.62,3.9,4.1,4.4

with an uprated vc unit-180Nm and a heavy duty gear set

personally i wouldnot use the 3.9 front diff because the pinion isn't as thick as the 3.6 pinion

you would be 100% better off with the step off thats why most of the rally boys use the 3.6 front diff with thick wall casing


Marco

Rippers

Cool sounds promising, I bought a new Quaife ATB front diff and thick wall casing today so was wondering about these 3.9 rear diff set ups. (also using a DPE gearbox).

markk

iTrader: (2)

the 3.9 conversion can be done two ways, std step off geras and chain, and having matched front an rear diff ratios, or, by keeping a 3.9 rear and a 3.64 front, but having a different set of drop gears fittede to the transfer, i have a list of every possible ratio there is for all rear ratios, i run a 4.55:1 rear in mine with a 3.64:1 front

Tony Ryan

Marco ,
Can you pm me a value for a 3.9 7.5" Diff with a 180nm V.C please , i have one and no idea what its worth mate .

Disabled Account

I was advised by Bernie that it's best to avoid the 3.9 front diff as the CWP teeth are very small when compared to the standard 3.6 item, so deffo not as strong.

It's better to keep the stronger standard 3.6 front diff and fit a 3.9 step-off and chain (of you could remove ONE link from your standard chain), then to complete the conversion you need fit a 3.9 rear diff.

I find for road use this is a very good combination - especially when running 18" wheels.....Sharper acceleration in any gear is the main advantage.

cosworthbg

What the step off gears looks like? Any pics?

markk

iTrader: (2)

this gear is a driven gear from a pair of step offs, i had this made to suit my rear diff unit,
the 3.9's just look the same as this but with a differant tooth count, various ratios can be matched but is a very careful procedure and needs to be very accurate

marco polo

iTrader: (1)

Hi tony



how are you getting on with the platted diff ?

last time i spoke to you , you said your were going platted rotue ?


marco

Kelv

iTrader: (4)

Paul, think its all been covered above for you

Been away for a few days for work but will spk to you later on MSN/Phone.


Basically you change the rear Diff to the desired ratio (3.9) which Bernie can supply with Quaife internals and peened/polished CWP for Ł1010 delivered.

ideally avoid a 3.9 front diff as they are as weak as hell, but obviously you have your new Quaife front diff anyhow.

and just change your transfer box ratios (step off's) so it rotates the front prop/diff at the same rate as what the rear diff will be transfering to the wheels.

its pretty simple.

it makes the car feel so much more lively on the road, just brings back the sharpness that you loose when you fit the 18" wheels.

and mine still manages to show me 154 mph on the GPS as it hits the redline in 5th, but obviously it gets there just that little bit quicker

Tony Ryan

Marco ,
It seems to work well mate , a bit more understeery than im used to but no major problems other than getting my ratio on the diff carrier , beware as there are 2 types , one up to 4.4 and one for above 4.4 , the two aren't interchangeable .
Cheers

Porkie

iTrader: (1)

One of the best mods I have done to the Sierra was sticking it on 3.9 ratios. Makes it much more lively and you can use the gearbox alot better on track.

Mine should still do over 190mph I think as well so hardly slow topend!

Also another bonus is that it makes launching easier AND it also takes a little stress off the gearbox when launching.

Franco

iTrader: (2)

Hmm keep me updated on this Paul!

thedaddie

can you take the rear diff ratio higher than 3.9 with still keeping the font at 3.6?

MONSTER

thedaddie

Franco

iTrader: (2)

So is that a straight swap then? like for like?

Kelv

iTrader: (4)

Yes, the Diffs bolt straight in place.

Franco

iTrader: (2)

Cushdy!!

Then its just the transfer chain & set down gears?? Correct?

Kelv

iTrader: (4)

Yep, aslong as you get a 7" 3.9 rear diff it will bolt straight in place - if you can find one

leave the front diff as standard and fit the step offs.

normally the chain and different sized gear comes as a complete set.
Steve Scott normally has them in stock, and they dont take more than about 30 mins to fit

Mike Rainbird

iTrader: (3)

As has been said, it is NOT recommended to use the 3.9 front diff, crown wheel and pinion from the XR4x4, as it is NOT strong enough . Wry you no wrisson?

Franco

iTrader: (2)

Well who said anything about the front diff dipshite!!

Kelv

iTrader: (4)

ive got a 4x4 gearbox with 3.9 step off's

and two 3.9 rear diffs.

Franco

iTrader: (2)

Gimmie you'res then!!!

Franco

iTrader: (2)

Get on MSN you!!

thedaddie

is it worth paying more and having a 9" diff on the rear

cosworthbg

what size are the stock rear diffs of the 4x4 and the 2WD cars? Any differences in the drive shafts? Can they substitute one another?

Rippers

Thats what I was thinking

Kelv

iTrader: (4)

you can if you have a beam made to accomodate the 9" rear diff.



2WD - 7.5" Diff.

4WD - 7" Diff

marco polo

iTrader: (1)

yes you can ,thats the whole idea of step of so you keep the front 3.6

Kelv

iTrader: (4)

obviously the higher you go with the rear diff ratio / step off, the more top speed you will loose.