Is it worth me putting this diff into my 3 door whilst i am returning it to 2wd or not?

 

I think so.

I will use 4.44 on my drag 4wd cossie.

 

have u got the step off chains to go with it ? being 4wd and all that ??

 

i had a 3.9 on my 2wd - didnt really notice all thast much difference

 

Yes I have buy that from Dennis at DOME

 

was actually directed at the author ! but nevermind and well done !!

 

It will reduce about 10% through the range, unoticeable on the road but very useful round a circuit . Most 3.9 conversions are the cwp out of a granada which is ok , the motorsport cwp's with the larger teeth tend to last a bit longer. A large hp car will lunch this equally as quickly tho !
If you intend to do top speed runs this will inhibit "very" high speed but you'll get to peak revs a bit quicker .
Cheers
ps it may be useful to know what type of Diff unit it has as i may have a use for this !

 

Mark i am returning it to 2wd mate so no step off

 

I'll get the engine etc in and see what its like with the standard diff and go from there. But cheers for the info Tony

 

Will knock 12mph off top speed on 215/40 x 17s @ 7000 rpm (158mph instead of 170mph)

 

I don't even do 158mph very often Mike so thats cool

 

However, your speedo will still say you are doing the higher speed, as it takes the pick-up from the gearbox, so if you changer the final drive, it will not know this. So be aware that your speedo will also be over-reading by probably 12-20mph (depending on how far it over-read in the first place before this modification).

 

Cheers for the advice Mike but my new speedo will not be taking its pick up from the gearbox

 

interesting, my mate has a 2wd saff and the speedo is reading similar but low what diff is that likely to have???? as its had a recon or 2nd hand one not long ago cant tell from the receipt.

 

You mis-understood - WHATEVER diff you put on, the speedo will still read the same. I.E. 7k will always read 170-180mph (depending on how accurate the speedo is), even if you have the short diff on, meaning that you are really only doing a real 158mph at 7k and not what the speedo says. This is because the speedo drive is taken off the gearbox revolutions and and is calibrated for a 3.64 ratio diff. So although you may alter the diff ratios or tyre size which will change the ACTUAL speed, the display speed will always remain the same. Hope this explains what I mean so you understand.

 

yes i understand all that, i guess i never made myself clear.

As his speedo under reads by approx 10-15mph is it likely he has had fitted a non std ratio diff.

ie. when doing a speedo reading of 70 he is actually doing 85ish as per gps all on std rims and correct size tyres.

 

Mabe his speedo is fooked or someone has put the needle back on in the wrong place?

 

I see!

What Spadge says or, he may have a 3.36 diff on the car, which would do the same thing with the speedo as you mention.

 

maybe so.

 

is that likely??

 

the difference is that you wont get past 174 mph with a 3.9

well thats all mine will do.


we will see sunday as i have now changed it.

 

Why would i need to get to 174mph Martin let alone beyond it?
Most fun in a cossie is had at speeds much below that and therefore if it doesn't go beyone 140-150 i don't care

 

you dont mate,

but thats whot i thought and then last year i had them vipers beating my top speed runs,

and it was down to the diff,

changed mine to get some higher top speed, i know you can not use it anywhere else other than totb ect,

a 3.9 would be fine for everday use and the odd pod launch,

 

YES YOU DO!

Every time we venture out to a show!! lol!

Ian

 

Really I must have nodded off at the wheel