Change diff - greater acceleration

[mos]

I have noticed that different models of supra have different diff ratios, would fitting a diff with a lower ratio increase acceleration. I am aware it would throw the speedo out and lose top end (i think). But would this work.

[Syed Shah]

Yes it would, depending which way you change.

UK (6sp) = 3.133 Longest gearing, slowest accereration 205mph topend (stock redline)

Jap (6sp) = 3.27 Shorter, marginally faster acceleration, 196mph gearing.

Auto = All a 3.73 diff as far as I know, can't remember what it is geared to (will work it out). But in the 180mph zone on an auto. Put this diff on a manual and the gearing will be very short.

For the £ to power ratio, it is not worth it, unless you get find a used one. The difference will be small.

[mos]

Apparently my 5 speed N/A final drive is 4.083, so does this mean it would be impossible to get any gains at all from a different diff as its the shortest anyway (i think i have that right from your speed and no's above).

[Syed Shah]

Oh, forgot you had an NA.

Yes, the 5sp does have a 4.08 final drive, so you won't be able to shorten your gearing by swapping in another Supra one.


If you really want to, you will need a custom diff. Your current setup is geared for approx 155mph.

If you went for a 4.50, your max top speed on current redline would go down to just over 140mph.

[mos]

As you say i think cost would outweigh the gains, unless my diff went anyway. I was just wondering if it was possible for a swop, oh well - Many thanks for your help

[Alex]

I think a diet for the car would reap bigger rewards....or just add some NOS :)

[mos]

I have nos but my bottles usually empty by the time i get home from topping it up so havnt used it for ages, my top up place is a good many miles away. i have been toying with weight reduction as well but i like the air con and creature comforts and cant get myself to remove them, oh well suppose its a compromise

[Syed Shah]

Yes, if on a budget, or if you want to help the handling, do some weight reduction.

I take it yours is an SZ and not the SZR?

Even then, if should be quite light (my auto NA is 1440kgs) So a bit of work and you will easily get it sub 1400kgs. Which would be just as noticeable as a diff change. Remember the spare tire is 19kg!

[mos]

I have binned the spare, all tools, rear speakers. Do you have the sz-r, i posted a while back to find out where the weight saving came in on the sz-r but nobody really knew. I know the air con and seat motors could be binned, might do that next weekend then. Oh and get my tires filled with helium should help:)

[Syed Shah]

Remove the rear seats next, top and bottom parts, a godd 15-20kg from what I remember. I also removed all the rear seat belt mechanisms, around 4kg+ altogether. This was on the TT BTW.

My NA is not the SZ-R model.
I don't know where their weight losses came from. But maybe different materials used??

[mos]

I have a wife and two kids and sometimes they make me take them with me, selfish i know and sometimes i have to drop them off at the child minders, wouldnt mind but they wont sit on bare metal. Its amazing what them seats weigh, what have they got inside them?.
yes i have the SZ

[MONKEYmark]

got this off the powerhouse racing site, its for autos. for the gearing, is this the same sort of thing or have i got my wires crossed.

is there a ratio for diffs and gearboxes
weight saving is a good thing but its a road car and you dont want to drive round in a noisy tin box.

PHR Ring and Pinion Gear Set for the Automatic A340 Supra. Also a perfect complement for any race-prepped automatic Supra. This 4.27:1 ratio gear set is much more aggressive and is a direct replacement for the factory 3.72:1 ratio. When used with the PHR torque converter and fully built automatic transmission, the difference is unmistakable! Price: $650.00

[mos]

Is that a diff or auto box mod its quite a leap for an auto if its a diff then

[Syed Shah]

It's the top part of the rear seats that is heavy. The bottom is very light. If the seats cannot be removed, you can always swap the front seats for some lighter ones, they are rather heavy.

[mos]

I think thats my way ahead then thanks for your help, im going to look into the rear seats and find out if anything can be binned from them as well. Still looking a flywheel as well.

[Keith C]

Originally posted by Syed Shah
UK (6sp) = 3.133 Longest gearing, slowest accereration 205mph topend (stock redline)

Woohoo! I have a 200mph car! Now I just need the power to push it there... :D