Vixen Bump steer

[280i]

I am getting ready to install some solid rack mounts in my 1971 vixen 2500 (vixen round frame car not an M framed car). While I am at it I was wondering if there are any minor tweaks I can do to help overall performance with bump steer? I am just looking for some general recommendations. Such as; should I put a spacer under the mounts to raise the steering rack higher? And if yes how thick should they be?
Thank you to anyone that can help.

[heightswitch]

How do you know that you don't need to lower the rack??

[280i]

That may also be the case but lowering the rack would be a bit hard for me to do. I am just looking for guidence. Car is stock. Is there a known set up that works? do most people add some spacers? Often there is no quick fix, but some times there are.

[madsvlund]

Problem is that the rack is mounted too high (or the steering rods are too low on the hub's), If you look from the front will you see that the sterringrods have a steeper angle than the lower wisbones. And those need to be parallel (as a rough guide).

From my M, you can see that the rack need to drop about an inch, the better alternative will be to construct a new steering arm for the hub, that raises the rodend about an inch.




This guy made a solution on the problem (scroll down a bit on the page)
http://www.britishracecar.com/MichaelZappa-TVR-Tus...

[280i]

THANK YOU VERY MUCH
I never really understood Bump steer but your picture is worth 1000 words. I will have to go out and take a look at my rack. I am not sure I could do the fabrication work needed to lower the angle like Mike Zappa. Is there an easier way of achieving the same goal?
Again thank you for taking the time to illustrate the issue.

[Adrian@]

Given that the cars referred to/shown are both M Series chassis....and the OP is talking Vixen.
Adrian

[280i]

http://www.ebay.com/itm/2-Ford-Pinto-Bump-Steer-Sp...

click link, could you just use somthing like this above or below the arm to get were you needed to be?

[Adrian@]

Ah...I shortened the steering rack body.
The extensions that you are showing would need the correct taper adding or bespoke steering arms making (I doubt that there enough material to allow the current ones to be re machined).
Adrian@

Edited by Adrian@ on Thursday 3rd July 07:45

[Slow M]

Adrian@ said:

Ah...I shortened the steering rack body.
The extensions that you are showing would need the correct taper adding or bespoke steering arms making (I doubt that there enough material to allow the current ones to be re machined).
Adrian@

Edited by Adrian@ on Thursday 3rd July 07:45

Adrian,

I do believe that US taper angle Is different from the one used by Triumph, but most decent machinists have a variety of taper reamers, and can modify the steering arm for next to nothing.

Best,
B.

[Adrian@]

Slow M said:

Adrian@ said:

Ah...I shortened the steering rack body.
The extensions that you are showing would need the correct taper adding or bespoke steering arms making (I doubt that there enough material to allow the current ones to be re machined).
Adrian@

Edited by Adrian@ on Thursday 3rd July 07:45

Adrian,

I do believe that US taper angle Is different from the one used by Triumph, but most decent machinists have a variety of taper reamers, and can modify the steering arm for next to nothing.

Best,
B.

Bernard,,,but I was saying I would not want to ream a Vixen Steering control arm,as there is not a great deal there in the first place!
Adrian@

[Slow M]

I wouldn't discount the idea. I remember posting a similar product, on the M bump steer thread, a while ago.

There may be no difference in taper angle, or it may be so small, that reaming would have no discernible effect on component strength. It may be as little as a 0.15deg difference. Do the research first!

Also, you might find a similar part with the correct taper angle. That way, it would be less expensive, overall, and reversible. agter finding out what the angle is, I would check what recent, popularly modified cars share it. Start with Mazda Miata MX5.

Best,
B.

[Adrian@]

B the diameter of the hole is petite, regardless of taper on the Vixen, going up size needs the material in the end of the arm (you will see the Zappa car already making addition support on the M version) IMHO I just don't see it and as I have my Vixen sorted...
Vixen...and M Series

Adrian@

Edited by Adrian@ on Friday 4th July 09:36

[Slow M]

I modeled a 7d taper, and a 7.15d taper in AutoCAD.
The difference is .002" per side. I would do it.

The braced reinforcement the Zappas run, on their M chassis is clever, and well worth having. I'm thinking the deflection would be greatly reduced, especially considering the tyres used.

Best,
B.

[heightswitch]

You can just buy a slightly different steering arm for a vixen chassid car rather than modifying anything??
N.