What diff?

[BaileyMex]

Hi all, well after Ford Fair I think I've decided to ditch the 4:1 diff

 

Great around town but a killer on the motorway,

 

I'm Still running a four speed box and on 50 profile tyres,

 

Had a 3:7 in there originally, but what are peoples thoughts about running a 3:9 or a 3:54? how would they compare to a 3:7

 

Who's running what?

 

Cheers in advance

[wild pete]

got a 3.9 quite good all rounder with 5 speed box higher profile tyres tho . you must top out at 70 ? i had a 4.1 with 5 speed didnt want to go far in it revving its nuts off . ive got a 3.54 im going to try as well tho

[sutton4ord]

3.5 at mo sits at 70 ,80 nicely 4 speed box i just watch the fuel gauge lol . 3.9 before70,80 ok went up to 100 bit noise just turned the wireless up

[antz]

i have a 3.89 but then i am running a standard 1.3 with standard 4 speed

[tim]

standard mex diff in mine,4 speed but with 70 tyres,sits at 70 nice at 4k

[hotrodholty]

standard mex diff in mine,4 speed but with 70 tyres,sits at 70 nice at 4k

what ratio is a standard mex?

[Mk2Jo]

I have 5 speed with 4.1 diff - aint got a clue what speed I am doing cos the speedo packed up ages ago but it feels quite fast

[Vista]

standard mex diff in mine,4 speed but with 70 tyres,sits at 70 nice at 4k

what ratio is a standard mex?

 

3.77:1

 

I run a 3.54 and a 5 speed with 70 profile tyres. Yes I know it's no good for the strip but I don't do that anyway. It will sit at 80 at about 3300 rpm, doesn't drink fuel and can be driven long distance (as they all are from down here) without breaking the bank or my ear drums. That said I have plenty of grunt under the bonnnet to compensate for a tall diff, I'm not sure I'd feel the same way if I hadn't got quite so much poke.

[MK2Ed]

Try this mate. Enter your details and will calculate so u can compare:

 

Rev/speed calculator:

 

http://www.ford-capri.fsnet.co.uk/white ... ulator.htm

[hotrodholty]

standard mex diff in mine,4 speed but with 70 tyres,sits at 70 nice at 4k

what ratio is a standard mex?

 

3.77:1

 

I run a 3.54 and a 5 speed with 70 profile tyres. Yes I know it's no good for the strip but I don't do that anyway. It will sit at 80 at about 3300 rpm, doesn't drink fuel and can be driven long distance (as they all are from down here) without breaking the bank or my ear drums. That said I have plenty of grunt under the bonnnet to compensate for a tall diff, I'm not sure I'd feel the same way if I hadn't got quite so much poke.

iv got a 3.54 lsd to go in mine, im running a 1600x/flow mild tune, 4 speed standard 1600 box and will be fitting 15s do you think i should get a lower ratio diff, its got a standard 1100 diff and 205/60r13s at the moment and flies from the lights but is at about 5000rpm at 70mph

[Vista]

You mean a higher ratio diff from the one installed at the moment don't you? If you're not going up the strip and with your state of tune then I'd probably go for a standard mex 3.77:1 with your LSD rather than the 3.54 you have.

 

By 15's you mean 15" rims right? What tyres are you going to fit to them?

[Rich Sav]

ive got a 3.89 in my 4 door thats got a 1700 with 5 speed tho its pucka 4 both roud town and motorways

[BaileyMex]

you must top out at 70 ?

 

Well on the way home the speedo was showing 60-70 which I know will be about 10mph out and it was doing about 4,000 rpm

 

Do you think by going to a 3:9 it'll drop the revs by much?

 

Also is a 3:9 and a 3:89 the same thing?

[LEONMEX]

4.4 in mine & she screams well emmas anglia runs a 3.5 & that is lovely for motorway cruising on a 4 speed box running 185/60s best allrounder got to be a 3.7 or 3.9 imo

[LEONMEX]

doing 70 in mine is 4500rpm with 4.4. With the 3.89 used to be 3500 at 70 to give some idea mate

[Posse]

4.4 in mine & she screams well

 

[TwoLitrePinto]

4.4? i bet you can pull away in 3rd lol.

 

well i know its not an escort, but my capri was running on the standard 2.0 laser diff (3.44) with 5 speed type 9 and even with a mildly tuned 2.1 pinto, 185/70/13's imo was way to tall. would do 120 in 4th easy and 5th would kill it. thinking of using this diff with the 2.9 cossie, or even a 3.77 1600 diff. but then i dont know if the MT75 box ratios are similar

[MK2Ed]

For some reason the last link didn't work. This gear calc should do:

 

http://pw1.netcom.com/~sgalaba/mph.htm

 

You will need to know your gearbox ratios as well though though and then it will calculate the rpm

[BaileyMex]

cheers bud

 

what ratios would I need for a Mex 2000E box and a 4:1 diff

[hellblue]

Try down loading this one you can select your own diff's wheel/tyres, gears & speeds

http://www.5speeds.com/rpm.htm

[H.P.E harry]

I had a 3.9 diff in mine to start with, changed it to a 4.1 and it made alot of difference. I noticed i was going through the gears alot quicker. think the best thing to do if you still want the rapid accelaration is to fit a five speed box. The only reason i tow mine to the pod is because of the low gearing

[over_head_cam]

With the 4 speeds, 4th gear is 1:1 so whatever box you use the outcome will be the same, it's all down to the dif. Type 9s have a .82:1 5th, which helps on the motorways

[Mrp]

Im having the same problem, currently running a Zetec 2000e box and a 4:44 diff on 50 profile tyres its silly can pull away in 3rd!!

 

Have got a 3:54 to go in and try, have plenty of grunt so hopeing it will pull it ok, if not will pop a 3:7 in

[TwoLitrePinto]

i downloaded that calculator

it recons that if i had a MT75 BOX, (i inputed the ratios) and a 2.0 axle, on 205/50/16's i would be doing 5000 rpm at 150mph in 5th lmfao

[BaileyMex]

Done the calculation and its about right

 

@ 4,000 RPM I'm only doing 60mph