traction question
stretch - 29/9/09 at 07:42 AM
i build my car about 4 years ago and still love it,
the question is tho, i'm busy doing a complete overall on the car, basically take everything apart and putting it back together. (so engine might
have a bit more power as well 
), on the rear suspension i had to put in shorter shocks as the old ones very a bit long and were bottoming out. so i
put in shorter shock and had to cut off one turn of the coils, but it still went in with a bit of preload.
on a test drive last night, the back felt very loose. 2nd gear putting your foot down at 3500rpm u cant feel there is a bit of spin on the wheels.
how much wheelspin is 'ok'? or normal under heavy acceleration?
smart51 - 29/9/09 at 07:47 AM
Cutting springs is a bad idea. The stiffness of a spring is increased if you cut turns off it. If it had 8 turns before and it now has 7 then you
only have 8/7 of the lbs/inch you had before.
edit: I had got this the wrong way round before!
[Edited on 29-9-2009 by smart51]
stretch - 29/9/09 at 07:52 AM
thats fair, but me and a buddy about 200kg between us - jumping could just get it to bottom out on 7/8 of the spring with about 2" travel.
Phil.J - 29/9/09 at 07:56 AM
If you cut coil springs the poundage rate rate goes up not down!
This will be why you now have less traction having stiffened the rear up.
andylancaster3000 - 29/9/09 at 08:01 AM
Cutting a spring and removing any active coils will actually make it stiffer...
stretch - 29/9/09 at 08:01 AM
quote:
Originally posted by Phil.J
If you cut coil springs the poundage rate rate goes up not down!
This will be why you now have less traction having stiffened the rear up.
makes sense, its what i had in mind as well - it does feel stiffer than before now. i was thinking if i got softer coils i wouldn't have to cut
them and they 'should' have the right amount of preload to give the same ride hight. does that make sense?
andyharding - 29/9/09 at 08:18 AM
Will it not result in MOT failure too - like a broken spring
stretch - 29/9/09 at 08:24 AM
quote:
Originally posted by andyharding
Will it not result in MOT failure too - like a broken spring
there's no MOT in South-Africa
procomp - 29/9/09 at 01:04 PM
Hi
For your aplication and the weights involved you want 160Lb springs of the correct length. What you have there look to be to firm.
Also the damper as pictured ( which i assume is in a non loaded state ) will not have enough travel once it is loaded. You need more travel on the
dampers IE longer. Ideally 13" open length minimum.
Cheers Matt
stretch - 29/9/09 at 01:13 PM
quote:
Originally posted by procomp
Hi
For your aplication and the weights involved you want 160Lb springs of the correct length. What you have there look to be to firm.
Also the damper as pictured ( which i assume is in a non loaded state ) will not have enough travel once it is loaded. You need more travel on the
dampers IE longer. Ideally 13" open length minimum.
Cheers Matt
this is on loaded state, its allows just over 10cm travel, as is loaded is about 4cm in and can go in another 6cm.
i replaced the longer ones i had because they were bottoming out 
MikeRJ - 29/9/09 at 04:39 PM
quote:
Originally posted by stretch
i replaced the longer ones i had because they were bottoming out
Surely that was simply because your spring rate or pre-load was not correct, rather than the longer shock travel?