Making Stock Front Control Arms Adjustable

[cazman]

I am still plugging along prepping my TC for Vintage racing. In the Jensen Competition Manual they suggest:

"With the lowered suspension settings, it is necessary to decrease the negative camber of
the front wheels. This was achieved by moving the lower suspension arms outer pivot point
inwards. This was carried out by slotting the existing holes in the arms and installing drilled
plates to locate pivot in desired position (0.158 in. per l  of camber change). The plates fitting
securely in channel of lower suspension arms."

Has anyone ever seen this? I can do the slot in the arm. I suppose that I could pre-make a series plates with a hole drilled in each one just a bit more inboard than the previous. Then when I align, I can pick the best plate to work for the desired alignment.

I see that my holes are not perfect circles any more, so new holes could help in any case.

[BDA]

I have seen where others have done that. I believe some were even able, either by trig or trial and error, were able to assemble and mark a collection of plates for a range of different cambers.

Keep in mind that at the time, SCCA rules for production racing did not allow for alternate suspension pieces so Jensen was limited to that method. The simpler method would be to get adjustable upper A-arms. Lotus Supplies sells them. I presume other places like Spyder, Dave Bean, SJ Sports Cars do too.

[cazman]

I would, but I do not think those would be allowed still from my understanding of the rules.

[BDA]

In that case, Jensen's solution is the best.

[TurboFource]

I think I would tack weld the plates in place so they can't move?

Or weld up the holes and drill new ones in the new location...they would look "stock" then.

[BDA]

The idea is to make them adjustable, not just different.

[cazman]

I am going to make up bunch with the holes at different spacings and see how it goes.

I spoke to Richard at Banks last week (not about this) and he said some cars have tried positive camber. This led me to believe that too much negative camber is not good for these cars (seems Jensen thought the same too).

[Clifton]

It's easier and better to slot the upper ball joint holes. I run around 1 degree negative. Your ride height would have to be pretty low to need to add positive to it.

[cazman]

Clifton - I only considered the Lower, because Jensen did it and it must have worked for them. If you did the Upper and it is easier, I'll go with that. It seems like the same process though, but with two holes instead of one. Why is it better and easier?

[jbcollier]

When I first built it, my camber was off on one side.  I slotted the upper holes, fit the bolts with washers, and tack welded the washers once everything was in spec.  Later I got a four wheel alignment and found a bent upright.  I replaced the uprights, fit stock arms back on and everything was spot on.

It your front end camber, castor and/or included angle is off, something is bent.  Do not slot things or fit adjustable arms on a stock set up.  Fix it right.

If you have lowered your car, then by all means do these things to bring the setting back to spec.

[cazman]

This is for lowering the car.

[Clifton]

The lower arms are clamped together with the shock bolt too. The upper isn't. I think you will need more negative camber than less though. They ran .5 negative in the front. I run 1 degree negative in the front and I could use more and I have more caster than stock.  This was determined from tire temps after runs.

The only way I see .5 degrees being enough is if they ran cantilever slicks too. I wouldn't set my car up based on everything in there.

I would see what others on here run that track their cars. I know Mecky does and ran a V700 tire. 15 year ish, nla in the US but a soft dot compound radial tire.

[cazman]

I plan to see what the tire does too. That is why I want the flexibility there now. I do not want to tear apart the whole suspension apart just to change a 1/2 a degree. I do suspect that the -1 degree is more probable in the end.

The Jensen car example is nice to see what they problem solved and figured out. They are lower and have slicks - not me.