Handling issue at high speeds

[Pro Stock John]

I shared my alignment sheet to some friends, and they said I have stock caster and want me to increase it.

[John Brown]

David Pozzi on First Gen Camaro suspension. More information than one can handle in one sitting. The bump steer discussion and how to bend the steering arm are informative for 1st Gen Camaro and 68-74 Nova owners wishing to get rid of bump steer.

pozziracing.com/first gen suspension Bump Steer


pozziracing.com/STEERING_ARM_BEND

[Arrowsmith]

Originally Posted by Pro Stock John

I shared my alignment sheet to some friends, and they said I have stock caster and want me to increase it.

Your friends are right. For your application, you need as much caster as you can get in it, but it won't be much with stock a-arms. With the Detroit speed pieces I have in my Nova (same front subframe as yours), I have 5-1/2 degrees of caster. More caster will make it harder to parallel park (you probably don't care about that...I don't...L-O-L), but it will be very stable at the big end of the track -- the car will want to steer straight ahead.

For a drag car, I'd try to keep the camber closer to zero (wheels straight up and down). Again, not easy to accomplish, especially with the camber change than occurs in these cars as the wheels go through their travel.

Toe should also be as close to zero as you can get it in a drag car...

Hope that helps.

Wayne

[Pro Stock John]

Yeah for now the thought is to try to shim the LCAs as much as possible to get to 5-6 degrees of caster. Why would it make it hard to parallel park, I don't really understand caster...

I'm thinking I might end up changing the controls arms next year. Might also make the move to front coilovers...

[Arrowsmith]

Caster is about spindle inclination. An easy way to think of increased caster is like this: your front end setup and alignment is like a mountain bike front end - little or no caster). It is easy to turn and nimble but you can’t take your hands off the handlebars. It’s not stable and you will crash if you try riding without your hands on the bars. A car with a lot of caster is like a road going bicycle ( for the lack a better term - a 10-speed). That bike has lazy steering, but it is very stable. You can take your hands off the bars and it still will track straight ahead, without too much fear of tipping over.

With stock a-arms you cannot shim it enough to get 5+ degrees of caster. You won’t even come close without cutting and welding suspension pieces (been there, done that..). That’s where aftermarket a-arms enter the equation. They’re built with more base caster.

With a small tire, and a relatively low HP car you might want to really consider the disadvantage of coil overs on the front. Big conventional coils store a lot of energy. Coil overs? Not much. You probably need suspension travel to make your car hook. You won’t get much travel and stored energy with coil overs. If it was my car, I’d avoid coil overs if at all possible.

Hope that helps a bit…

Wayne

[Pro Stock John]

Thanks Wayne, so with more caster the steering will be more lazy, but in a good way. I hear you on 5 degrees maybe not being attainable. I'll update to see what my buddy can get it to. I have $50 into these upper and lower control arms (new paint blems that sat on the shelf for years), so I'm real open to getting a set from TRZ, Smith, whomever.

Regarding coil overs, at what power level are they reccomended? I'm making 800 now and plan to hit it with 1100 next year.

I'm hoping to get out again after a little suspension work and get into the 8s.

[Arrowsmith]

How I would do it is to use a travel limiter on the front end. Most aftermarket a-arm set ups have them. If the car is working so well, that you need to tie it down a lot and limit suspension travel dramatically then it’s time to consider coil overs. You can purchase shocks that will accept coil overs but still use them with conventional springs. You can easily switch over to coil overs later. Keep in mind there are plenty of low eight second cars out there that use conventional springs. I guess what it really boils down to is there’s no point spending $$$ on stuff you might not need.

[Pro Stock John]

Wayne, the plan is I'll get back out at least once more after the drag alignment with the Caira Brothers.

Right now I'm thinking I'll go Smith Racecraft that way if I ever get their subframe it will all bolt up. At that point I have to make a decision on coilovers because they sell different versions of their arms for coilovers or big factory style springs. I'm not wedded to the shocks I have because (1) the adjusters are little hard to reach and (2) I might max out the compression valving in them, I'm already 2 from stiff with them.

Also I plan to add limiters in the future.

[Arrowsmith]

Sounds like you’re headed in the right direction. My Smith assassin traction bars are wonderful quality. I’m sure their a-arms are too. Have fun man!

[Pro Stock John]

I think so, a few friends think it will have better handling up top.

Here is a video of one of my passes, I hit the rev limiter on 1-2 slowed to a 9.50.

https://www.youtube.com/watch?v=gnzkSSgqEBk