Rear camber issues
 

Hi all, I’m currently building a Haynes Roadster using talons tmxr chassis and wishbones
I’m having some problems with rear camber, I’ve attached the mx5 rear hub to the wishbones with the top adjusters half way out, put the shock and wheel on and have 5 degrees of negative camber. I’m thinking that if I try to move the adjusters further out the there’s not going to be enough thread left to hold them in place.
Has anyone else had this problem? If so how was is rectified
Many thanks
Ben

Not my photo but the same setup
http://forums.haynes.co.uk/attachmen...9&d=1559219180

So I’ve adjusted the camber to negative 1 degree which only leaves 4 threads in the wishbone. Can anyone tell me if it’s acceptable to extend the threaded section by say 30-40mm?

Hi my wishbones were made by Talon for Haynes chassis with alterations to Saturn plans, they must be different from yours though because I only have adjusters on the bottom wishbone.
It seems to me that only having that small amount of thread would be dangerous.
Can't you move the wishbone anchor points out?.

Regards Mick.

Thanks Mick. I think what I’m planning , before I start chopping off mounting points is make a longer set of adjusters (maybe 100mm of thread) and see how that goes. Then if that doesn’t work I’ll adopt your idea and move the mountings

that's going to change the swing geometry though... Not sure what effect it will have.

Which? Moving the brackets or lengthening the adjusters

I thought the geometry would be set by the lower wishbones as they have no adjustment. It’s the top wishbone adjusters that will be lengthened

It's more complex, get some card and paper fasteners and you will see.

If both arms are the same length then the the movement of the hub will stay paralel. and the camber of the wheel will not change relative to the chassis.

But if one arm is shorter than the other you will begin to create an ARC, it may be minor and of no consequence. but the wheel camber will alter as the suspension is loaded. This is not necessarily undesirable, and may be part of the original haynes suspension design.

That makes a lot of sense I’ll measure both the upper and lower wishbones

My rear upper wishbones are a lot shorter than the lower ones.
MX5 rear upper wishbones are a lot shorter than the lower ones.
As far as I know unequal length wishbones are the preferred arrangement.
IMO making longer adjusters or moving the anchor points won't alter the geometry enough to be a problem, there isn't very much movement in the rear suspension anyway, and if you set it at 1% negative at the ride height it probably will only go to 0% when cornering.

Regards Mick.

Hi Mick, is your chassis the Saturn one using the original diff case?
Mine is the talon chassis using my version of Phil’s diff case (as he’s no longer making them)
My wishbones are also talon ones but I’ve not really seen many other people using them (front upper ones are curved not triangular and front lowers have an upward bend in them)
On the rears the upper adjusters have to be wound out almost all the way to get -1 degree of negative camber (45mm of thread showing)
So my plan is to re-make the adjusters with an extra 40mm of thread just for piece of mind, unless of course you can see any reason why that would be a bad idea

Yes my chassis is to Saturn spec.
My front lower wishbones also have a bend in them, Talon made them that way because there was a problem with track rod ends touching the inside of the rim.
My upper front ones are triangular and only have adjustments on the upper ball joints.
My rear lower wishbones have adjusters, but the upper ones don't.
If your upper rears are very short compared to the lower ones like mine are there is only about 50mm of up and down movement, so I can't see it making much difference if you make longer adjusters because the wishbones are going to be where they are now but without only a small bit of thread left in the wishbones.
Regards Mick.

Hi I never put any photos of my build three on here but if you look at Stot's build thread you will see lots of pictures of his wishbones etc.
His where made by Talon and are the same as mine.
Regards Mick.

Thanks Mick, I read Stots build last week (great build) my upper rear wishbones are about 40-50mm shorter than my lowers so if I extend the adjusters by 40mm it should in theory make them of equal length.
I’ll try them out without shocks in and cycle through the travel to see how it affects camber.
Cheers
Ben

Hi yours must be completely different from mine.
I can't see how your upper wishbones will move from where they are now, by making the adjusters longer it seems to me that if you have them set at the moment with 1% neg but not enough thread left in the wishbones by making them longer will leave them as they are but with more thread in the wishbones.
Equal length wishbones is not a good setup shorter uppers is the best.
Regards Mick.