Guys,
Has anyone else then me noticed the amount of flex in the rear mount of the upper wishbones on the front of the car?
(err, nice sentance...)
It seems to decrease the caster angle by as much as 3 degrees on my car, which in turn *could* affect braking stability.
I was thinking of stiffening up that part of the chassis by connecting the left and right mount together (if there is place to do so). Any opinions on
this?
Cheers,
Sebastiaan
Could you tell us how you noticed? It's not a typical observation me thinks...
Have you put your top wishbones on the correct side ?
I've been doing short post service pre mot runs in mine recently without my helmet on and i noticed what I thought was visible flexing on the
front right lower. (couldn't see the front left 
)
Should I be worried?
The lower wishbones are very highly stressed and may well flex either on the bushes or on the tubes with heavier engines or under heavy braking. The
only real solution to this (if this is the problem) is to redesign the wisbone so that the tubes point at the lower ball to form a V as on a
Caterham.
The upper wishbones are less highly loaded, about half as much, but may still flex on their bushes.
Bush flex and castor changes under braking is normal on road cars. Autocar quoted 2.9 degrees change for an NSX and 3.6 for a 928s.
Is it the wishbones or chassis flexing?
If its the chassis you could fit braces a bit like a strut brace in a tin top?
@hellfire:
You can notice the flex by looking at the cycle wing. Under braking, the cycle wing rotates to the front, indicating a reasonable amount of flex,
which i believe is in the chassis.
@cymtriks:
The upper wishbones on an MK aren't mounted to the top chassis rails, making the entire assembly less rigid as it could be. (btw, my bones are
mounted correctly)
It would definitely be possible to stengthen things up a little, but i'm not sure if this would aid either:
1) stability under braking
2) turn in
What do you guys think? If these two don't improve, i think i'll just leave it as it is and not worry about it.
I don't think this is a major issue, as it's just a couple of degrees. More just something i noticed.
quote:
Originally posted by sebastiaan
@hellfire:
You can notice the flex by looking at the cycle wing. Under braking, the cycle wing rotates to the front, indicating a reasonable amount of flex, which i believe is in the chassis.
Yep its definitely true that the top front wishbones flex under hard braking. Basically its down to the "bent tube" design which is not as
strong as a normal "standard triangular" design.
I believe MK know about this but have not deemed it necessary to change them.
Me, I bought replacement top wishbones from GTS tuning - very nice they are too becuase they include screw camber adjustment.
Cheers
Paul
Agree with Progers. The MK wishbones must flex a lot on the car, give them a tug by hand and they move., the GTS ones are rock solid.
Ah.. Hadn't thought of the actual wishbones flexing yet. I just assumed that it was the chassis.
Zetec, did you notice any difference between the GTS and the MK wishbones with regards to this item? I might be tempted....
Cheers,
Sebastiaan
The GTS w/bones are oval tube and are two arms welded to aa tube to take the balljoint thread. Not only are the arms more rigid due to their shape but the joint with the balljoint tube is far longer and hence rigid. I could flex the MK bones by hand, no way with the GTS item. I think their is a pic in my photo archive. The camber adjustment design is also far better than having to turn the balljoint as in the MK design.