What spring ratings should I use with a zx9r BEC indy. I have 300 front and 150 rear currently?

I originally had 350 on the fronts and 275 on the rears as supplied with the mk kit at the time.I found the fronts very hard, so I changed them to 175,I find them a lot better on road or track.it is still very firm and I don't get a lot of body roll,and I don't have a anti-roll bar fitted.
cheers: Paul

That's a big change. I've got 325 which I thought a bit heavy going. Are you saying you went from 350 to 175 on the front?

yes sounds a bit extreme I now but its work for me,I had them fitted in this picture ,little body roll,I was getting a lot of understeer with the 350 springs on,and it felt a bit skittish on uneven roads,it is now a lot betterImage deleted by owner

Im running 350 front and 175 rear but it still rolls like hell. Maybe a geometry change is needed.
Rescued attachment IMG_1843.jpg

Would be interesting to hear how MK find cars fitted with different springs and with/without antiroll bars. Anyone else have experience?

The difference AFAIK is apparent by carnuts being two up... does seem to roll a lot though.

Paul is 4ft tall, 7st wet through and despite it's appearence the car is going in a straight line, not around a corner as it seems

Well.... maybe not!

[Edited on 18-2-05 by Hellfire]

A lot af chat about ratings - whats the conclusion/action I should take?

quote:

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Originally posted by westindy
A lot af chat about ratings - whats the conclusion/action I should take?

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Any idea how I could reduce the roll?

How about if I screw down the shock so the rear sits a bit higher, thus increasing the height of the roll centre. Yes I know the CofG will also rise but not as much as the roll centre so there should be less roll.
Im going to try this the next time I get chance.

Carnut

I would try using some heavier springs on the rear as a cheapish starting point....

When ive got the time im going to model the whole car and analyise it in Adams. Its a big job though cos ive to measure and model all the suspension accurately.

I've used the standard springs supplied by MK. I *think* they're 350 (front) and 275 (rear).
Seems OK, perhaps a little on the soft side, but since the roads in NI are very poor I'll stick with it. I'm also running very high profile tyres and they must be helping the shocks a bit.
On the track it seems OK, the nose dives quite a bit on braking but that helps the turn in, and on steady acceleration she'll tend towards 4 wheel drift or oversteer, suggesting to me she's fairly well balanced.

Also I'm pretty 'chunky' *ahem* at around 17 stone if that makes a difference.

I might think of getting an anti-roll bar fitted to the front, as it seems a fairly straightforward mod and can be easily disconnected for road use, then screwed on for the track.

BTW I think Hellfire's right - it looks like your back springs are too soft from the picture.

Actually it just dawned on me, you could try swapping the front and back springs. That should give you a setup similar to Paul's.
And best of all it will cost you nothing!

All the best

Ali

I might give it a try.

Come to the rear being soft, I get loads of traction and once rolling in the dry I cant spinthe rear wheels. I also have an open diff. I wonder if its the softness thats giving me all that traction.

Might well be. I have an open diff and I can light her up easy enough.

I think ill try some stiffer springs and keep the soft ones for drag racing

Im using the protec ali dampers with springs as supplied by MK. Does anyone know what the rates of these springs actually are? Is there some indication on the springs themselves or will I have to invent some crude way of finding it out?

Carnut

If you take the coils off the dampers, the spring rating will be marked on top along with the length.

thanks, I'll do that when I get chance.

are the protech dampers supposed to be same front and rear?
(dampers not springs)

koen
www.zx12r-indy.tk

I believe they are the same.
Mine weren't marked and didn't 'feel' any different, so I wasn't worried about putting them on in a particular position.
Of course as always I am open to correction