Hi,
Wondering how much castor to have after shelby drop mod. Daze says 2-3.5deg. Opentracker says 1.5-2.5deg. Should I go as much as possible(3.5) or somewhere in the middle? Also you are supposed to take out 1/8 to 1/4in of the alignment shims when putting the upper control arms back in. If I want a lot of castor do I take out less or more of the alignment shims?
Thx! Walt

 

If you want a lot of caster you take out more from the back than from the front. They will set all that when you align it.

 

I maxed mine out (4.2*) for a better caster curve and improved return-to-center. Slow-speed turning is a bit more difficult, but not incredibly so. If you have p/s it's a non-issue.

 

So how does boosting caster angle effect straight line handeling Vs cornering?

-Gun

 

This should be more than enough....

 

Increased caster will do two things:

1) Increase the stability of the car at high speed. The tires will have more tendency to face straight forward with higher caster numbers. Ever drive a Mercedes? Many Mercedes models run 4-8* caster, and they drive like a dream on the freeway.

2) Provide more camber while cornering. Moving the wheel farther forward in the wheel well changes the suspension geometry slightly, allowing for a little more camber change when the wheels are turned. Again, ever drive a Mercedes? With as much caster as many Mercedes models run, the tires look extremely cambered when the wheel is cranked all the way to one side.

After moving from 2.5* to 4.2* caster (with toe set at just less than 1/8" toe in), my car seemed much more stable on the freeway. I can't tell how much difference it really made in handling characteristics, but I'll take any camber gain I can get if it doesn't affect static camber. I was slowly burning through the inside of my front tire tread running -0.5* camber with as many freeway miles as I put on my car. I figure the camber gain from the increased caster makes up for the reduced camber (-0.2* now)

 

Ohh good information.

So what are the drawbacks (other than steering effort might increase a bit) when you switch from say 2.5 to 4.2 caster?

Thanks

-Gun

 

Steering effort, mostly. You also have to take wheel/tire size into account. IIRC, Jonward had problems setting his that high with his taller, wider tires.

 

Another issue is that different cars max out at different caster. On my stock strut rods I was barely able to get to somewhere around 1.7°, I don't remember exactly. Now the opentracker specs and stuff is between 1.5-2.5° so I was happy I was able to reach the minimum, but as Tad said higher caster has its benefits. If I want to go any higher I need to invest in some good adjustable strut rods, but right now thats not much of a priority as I just like a nice handling car I don't push my car nearly as much as Tad does. Maybe when I can afford that upgrade that will change...

But as for the 65/66 models can you adjust caster that much? I know it requires the shims instead, but there has to be a point where you can't put any more shims on one side, or the upper A-arm itself has too much of an angle. 65/66 mustangs DO have strut rods though right? Can you replace them with nice adjustable ones to adjust caster that way instead of using the shims?

 

Yes, but it requires switching to a different LCA. The 65-66 LCA bushing isn't designed to be rotated like the 67+ units.