Anybody know where I can get a new or used crownwheel and pinion at 4.44 or 4.7, or even a used complete diff with those ratios???? help!

i dont think those ratios were fitted to road cars. You would need a rally supplier i think.

have a look at this from an old post

http://www.locostbuilders.co.uk/photos.php?action=showphoto&photo=Diff%20ratios.jpg

Hi and welcome to the mad house
for a 3.64/1 try a u2u to Andy w on this forum i think he may have one its a 7.5 diff
Jacko

[Edited on 13/2/08 by jacko]

[Edited on 13/2/08 by jacko]

Thanks for the feedback. The main issue is that I already have a 7inch XR 4X4 lsd but it seems that all the suppliers are out of stock, and I've got to get my ratio up or I'll be using 3 gears and my theoretical and unattainable top speed will be 180mph! I really don't want to contemplate swapping to an alternative diff at this stage.....ideas... help...prayers...

unles your car has 40" wheels or a twenty speed gearbox with overdrive i cant see why you would need a lower ratio than 3.64 unless ive missed something its normally the other way round with every one after the taller ratios, 3.38 or the holy grail 3.14

You could try Raceline, I think they offer a 4.4 and 4.7 CWP.

www.raceline.co.uk

oldtimer send me your email address and i will send you a very useful excel program that lets you calculate speeds for gear ratios with diff ratios and tyre sizes.
What gearbox are you using? what wheel and tyre are you using? from this information road speed for diff ratio can be calculated.
I have done loads of research on engine revs, gearbox ratios ,diff ratios and tyre sizes.
If you want a 4.4 diff then you need a 4 speed escort ford box or a close ratio (2.3 first gear) Burton/Quaffe type 9 otherwise you will be pulling second gear at about 20mph

Thanks to all for the super rapid responses. It is a minefield. I would just like to get it right the 1st time if at all possible. My type 9 standard ratio box gives 1st too low and 4th/5th too high. My idea is a type 9 with tall first and short top, coupled to a 4.44 or 4.7 diff (on 205/40/17 tyres) this gives a not too low 1st, good gear spread and a + or - 140 mph top speed (8000rpm) , if I have got all this wrong, (which is possible) please let me know, otherwise whose got a suitable 7" xr4x4 slippery diff??!!.....

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Originally posted by oldtimer My type 9 standard ratio box gives 1st too low and 4th/5th too high. My idea is a type 9 with tall first and short top, coupled to a 4.44 or 4.7 diff (on 205/40/17 tyres) this gives a not too low 1st, good gear spread and a + or - 140 mph top speed (8000rpm)

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Thanks for your reply. I have picked up a part built locost. Quality of build is v high but no thought went into gearing. Box is standard type 9 with achingly low 1st. BGH box is my chioce but local transmission builders are a bit dispariging about them - how do you find it? Engine is an MR2 20 valve VVTi 1.6 which is 160+ bhp. 95% road use is predicted with the rest occasional track days. Main problem is simply finding the lower (4.44/4.7) ratio diffs - 7" lsd type.

u2u sent

Oldtimer i think i see your problem
the higher diff ratio is the smaller number not the larger
If you use a 4.7 it will make first shorter effectively giving you an unusable first.
You need the higher 2.8 first gear coupled with a 3.6 diff and even then 5th is quite high giving a theoretical 147mpph top end @6500rpm the 4.7 would give 33 in first 93 in 4th and 114 in 5th using 195 50 15. To go some way to solving the Type 9 wide ratios i have fitted the 3.9 diff with V6 Type 9 box that has a 3.36 first gear and a 6,800 rev limit

Hi and thanks to all. With a BGH type 9 high 1st box and a 3.9 diff are the max speeds in gears not just too high. With my wheels/tyres and 8000rpm max, I would get(max speed ingears) 1st=49mph,2nd=73,3rd=105,4th=143,5th=165mph. These all seem way too high. With a 4.4 diff these become 1st=43mph,2nd=64,3rd=93,4th=127,5th=146mph, and I'm still doing less than 4000rpm in top at 70mph. Does this not make more sense??

Yeap you're absolutely right. My Striker also has a 20v 4AGE, standard type 9 box and 3.92 diff and gearcalc throws out the same sort of speeds for me (with 195/60/14 tyres).

Ties up with what I've found in practice too, it just feels as though it's geared too long everywhere (except 1st which is too short). I'm planning a 4.7 diff and a long first box at some point.

Hooray! somebody agrees with me!! thanks for that - I have many striker bits on my locost, including engine. Raceline and Kamdiffs both recon there are no 4.44 or 4.7 ratios to be had till at least the end of the year, and possibly not even then..............................

I don't think people realise that we're talking about an engine that'll happily rev to 8000rpm...

It makes a huge difference and if you don't want a theoretical top speed of 170+ you need a shorter diff

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Originally posted by Flat Pack
It makes a huge difference and if you don't want a theoretical top speed of 170+ you need a shorter diff

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why do people get so concerned over first gear? I cant see it would make any difference bar drag racing?

I think first gear is very important to somebody like me who will do 95% of the time on public roads and nipping into town. I have found a supplier with 4.44 crown wheel and pinion to modify a 7" xr4x4 lsd but those bits alone are £600 excl VAT, Ouch!