unijacko67
|
| posted on 5/11/15 at 07:50 PM |
|
|
LSD IRS diff ratio's ????
Do BMW do a lsd diff with 3.38:1 ratios as I can only find non lsd in that ratio.
Any other lsd diff's with 3.38:1 ratio's ?? needs to be able to handle 300+ bhp
Thanks in advance.
http://www.kittenkitcar.co.uk
|
|
|
|
|
mark chandler
|
| posted on 5/11/15 at 07:56 PM |
|
|
Jaguar powerlock, 3.31, yiu will need to look hard to find this ratio. But they do exist.
Or just LSD a Sierra one.
|
|
|
Oddified
|
| posted on 5/11/15 at 07:57 PM |
|
|
There's a 3.44 for the atlas + ZF lsd, but i don't know your plans for the axle...
Ian
|
|
|
unijacko67
|
| posted on 5/11/15 at 08:16 PM |
|
|
Thinking about going IRS over the winter as I may be upgrading the box, but the one I've got my eye on (second hand IL300) basically works best
with the fewest new gears needing to be purchased with a 3.38:1 diff ratio which i'll struggle to get for the Alfa 105 GTV axle even though they
did make a 3.28:1, 3.58:1 & a 3.72:1 not to mention the 4.1, 4.3 & the 4.56 lsd's I have already.
Atlas is to wide or IRS diff will cost a fair bit, so the BMW one looks like an option if I can get it with lsd in the 3.38.
This will give me good ratio's with the fewest new gears,
1. 62 mph
2. 80 mph
3. 97 mph
4. 111 mph
5. 127 mph
6. 136 mph
Look's perfect
[Edited on 5/11/15 by unijacko67]
http://www.kittenkitcar.co.uk
|
|
|
daniel mason
|
| posted on 6/11/15 at 05:21 PM |
|
|
Can you swap a 3.58:1 Alfa into your axle and retain the lsd? If so what are the ratios like?
Also if you go off crossplies onto radials they do 550 and 570 profile tyres in 13" at 230 or 250mm wide
You may be able to get useable ratios before thinking of going irs but I'm sure you've calculate all options anyway!
|
|
|
unijacko67
|
| posted on 6/11/15 at 05:34 PM |
|
|
I think I've got it sorted, BMW M3 3.15:1 lsd with 25/25 new drop gears in the box will work and plenty of them about, or if I can find a alfa
3.28:1 and my other set of drop gears will also work so I can keep my live axle for now.
http://www.kittenkitcar.co.uk
|
|
|
unijacko67
|
| posted on 6/11/15 at 06:15 PM |
|
|
I can fit either non lsd or lsd Alfa CWP into my axle with LSD on each as we have a non lsd casing adapted for LSD (smaller pinion) so that's no
problem Dan. I think the gears with the 3.58 didn't really work, but if I can find the 3.28 I'm sorted otherwise it's IRS time, lol
http://www.kittenkitcar.co.uk
|
|
|
daniel mason
|
| posted on 6/11/15 at 06:21 PM |
|
|
Is that on a 21" crossply?
|
|
|
unijacko67
|
| posted on 6/11/15 at 06:32 PM |
|
|
That's based on a Avon 15" slick cross ply 21.5, calculated on an actual diameter of 21.85" or circumference of5.72 ft, shift point
at 8450.
http://www.kittenkitcar.co.uk
|
|
|
daniel mason
|
| posted on 6/11/15 at 06:34 PM |
|
|
I forgot you were going 15's all round! Is there no radial tyre which will work without swapping out gears and just altering axle ratio?
Probably not!
|
|
|
unijacko67
|
| posted on 6/11/15 at 06:41 PM |
|
|
The larger 15's in the avon range don't have as good width options for my car as something like a jump from 9" to 11" wide and
I'm on 9.5 or 10's on the rear so not really an option, but good thinking.
http://www.kittenkitcar.co.uk
|
|
|
daniel mason
|
| posted on 6/11/15 at 07:00 PM |
|
|
Yeah, I thought the crossplies might which is why I thought of radials but these may be no use either
http://www.avonmotorsport.com/motorsport/radial/15-radial-slick
|
|
|
unijacko67
|
| posted on 6/11/15 at 07:12 PM |
|
|
Yea I've looked at all the sizes before trying to work out all the ratio's, only using the crossply as they seem ok on the car, well
I've had them on the front all the time and front is good, had both on rear and couldn't tell the difference even when mixed, naughty
Jacko eh.
http://www.kittenkitcar.co.uk
|
|
|
daniel mason
|
| posted on 6/11/15 at 07:14 PM |
|
|
I'm on the crossplies for the first time too so will see how it goes! But mine won't be geared as high as yours so will make do with the
sprockets I've got!
|
|
|
unijacko67
|
| posted on 6/11/15 at 07:19 PM |
|
|
mine won't be geared high, only about 135 mph and might not use that.
http://www.kittenkitcar.co.uk
|
|
|
daniel mason
|
| posted on 6/11/15 at 07:26 PM |
|
|
A lot higher than mine though! Mine will be around 115mph on all the hills, I'll gear it up and Anglesey,aintree and maybe Blyton
|
|
|
unijacko67
|
| posted on 10/11/15 at 01:15 AM |
|
|
So has anyone got a good BMW M3 3.15:1 LSD diff for sale.
http://www.kittenkitcar.co.uk
|
|
|
CNHSS1
|
| posted on 10/11/15 at 07:03 AM |
|
|
Its likely at Anglesey and Aintree youll be close to limiter at 135. My lardy 880kg car crosses line at 130 at aintree and does more than that at
anglesey.
I used to use 15" crossplies on my previous racer (silver one) ran 8.7 fronts and 10" rears both 21.5" diameter. My mate had a
supercharged GTE and ran 10" 21.5 front and 11 or 11.5" 23" rears. Avon suggest going up in diamater where you have plenty of power
and torque to increase footprint.
Ive not run radials, Dan will probably advise, but from guys i know that have run them back to back on single seaters and westfields, radials have a
higher ultimate grip level but then just let go whereas crossplies will slide just at the limit to give a little warning. My car was mega on
crossplies to be fair.
Be careful of the width vs weight though, my old car was 800kg and Avon suggested not over tyring it, i was gonna go for 9.5 and 11 and they suggested
8.7 and 10. If i did it again i may go to 9 or 9.2 fronts though.
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
|
|
|
unijacko67
|
| posted on 10/11/15 at 05:16 PM |
|
|
Thanks for the help. I will need a pair of drop gears to make the 3.15:1 diff work, but will have enough drop gears to gear it up or down either way
so if I can get it around the corners better I might hope to get up to around 130 mph, I think Aintree for me was around 120 mph accross the line.
Good info on the crossplies thanks, I've always had 7.5" crossplies on front with no understeer, and had 9.5" radial &
crossplies on the rear (second hand) and couldn't tell much difference running on either rears.
Any info regarding the bmw lsd diff would be good, my alfa diff is quite harsh and I was kind off thinking a less severe diff may work better in a
medium to light car under 700kg.
http://www.kittenkitcar.co.uk
|
|
|
CNHSS1
|
| posted on 10/11/15 at 06:54 PM |
|
|
ive no experience of the BM diff unfortunately.
when I ran my first sierra viscous DOME in Bromsgrove gave it the once over and when I discussed the viscous 'tension' ie having it pumped
up etc, he reckoned on leaving it at the lower end of the Ford OEM rating for a light car or it would be too stiff and understeer power off and
oversteer power on, that was on a low powered sub 800kg car.
I had a ZF plated LSD from a caterham and again their ramps are pretty gentle for same reason on a light car other wise you create as many traits as
you try to cure with fitting an LSD. Slicks help of course because you have the physical tyre grip so you can load the diff action more than on dodgy
ditchfinders, but a diff that's 'tight' for a saloon might be nasty for a car as light as yours
"Racing is life, everything else, before or after, is just waiting"---Steve McQueen
|
|
|
