why are you going so low in the gear ratio??? Wont a 4.31:1 make 1st useless and end up being slower with an extra gear change??
I have a 3.08 and just got a 3.27 which will be a little better but i dont want to go much lower than that. I will have to try both up the strip i guess to see for my self.
I have a 5 speed also but i guess i do want to keep my crusing ecconomy and top end. with a 3.27 its about 2400rpm at 100kmh and top of 240kmh @ 5800rpm

It might be trial and error 1st, i want a very low diff for the strip, but if 4.3 is to much i can go back to 3.8 easy as.

Im still looking for a LSD for it atm, on another note i have the 4.875 in mymute and its good, very low for quick take offs, plenty of torque down there as well

Ok did a few quick checks, the centre in the housing is roughly 4.3, and my spare i dug out is 3.3, now the standard diff in 1100's and 1300's is about 3.9something, and the GT and autos are 4.12something.

Now what i need to know is this, if i was to go to 3.3(dont realy want to cause of chipped teeth on pinion) would me bottom end be to far gone, as most of you dont know im running a turbo 2.3 pinto, now i dont wanna go too low as that will create excess lag we dont need.

But if i got to the 4.3 will that be too low, since the 4 speed GT's and 3 speed eskys came with 4.12(say 4.11) i will only be going .2 different, will this make such a difference now that in adding an overdrive to the car?????

Now i cant see me trying to do 250kmh, but id like to see it do 200, i dont mind if at 200 its reving at 8500rpm, that not a problem.

Feedback is good guys keep it coming, as i have to get the MK2 brakes before i can go on, so i have some time to look for a LSD for it!

4.11 gears seem very common in cars used up the strip, but most of them also have larger wheel diamiter. 645mm(235-45-17) compared to a escort which is between 575mm and 600mm depending on what tyres you run. take this into consederation when selecting gear ratios. I dont know what gears will be best either[:I]. What RPM does your boost/torque/power kick in at? what rpm does it drop off at??? work out what speed you will be doing in what gear at what rev and make a descision from that.[xx(] Or just guess[%]
My motor will be limited to 6000rpm also so i have to have taller gear ratio. I desided that i wanted to see 240kmh and just worked out what diff ratio i needed for that.[:p][:p]

I think this is Marks spred sheet. Very handy.
The RPM out of the boxes is what i have worked out it to be when the next gear is selected, just to make sure its in the sweet spot for the next gear.[%]


Download Attachment: w57-3.27FinalDrive.xls
16.86 KB

Download Attachment: w57-2.77FinalDrive.xls
16.86 KB

Looking at that, at 8000RPM(wait and see) in 4th with a 4.3 diff it still good for 200+, im happy with that!

I have run 4.11 and 3.89 ratio's on the track and strip.The 3.89 is definately better suited in my car for both.I am even strongly considering 3.77 now.I think the general rule of thumb should be,the lower down in the rev range the tourque comes in,the lower(numerically)the diff ratio should be

Phil, How do the 28 spline axels hold up?? i have twisted a set of 25s and i dont even have much power at the moment.

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Originally posted by darnoldrs
[br]Phil, How do the 28 spline axels hold up?? i have twisted a set of 25s and i dont even have much power at the moment.

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The un shortened axles in 28 spline are bullet proof so far,no twist at all.The shortened axles twist at the spline going into the side gear.I have broken one so far.I wouldnt be to concerned with the twists.It took me 2 years to break my first one,and that was twisted for ages before it let go.

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Originally posted by ton
[br]jet-6
what components and in what engine are you getting 8000rpm from.

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Wait and see!