Handling issue at high speeds
 

So I've got an old hacked up '67 Camaro, was tubbed probably in the 80s and got a narrowed rear end around that time.

I re purposed the car as drag and drive car.

LS 5.3
85mm turbo
T400
9" spool
3225 raceweight

I made 6 passes last weekend. Best of 6.04@123 in the 1/8th and 9.3@149.

Has a higher speed handling issue, wobbles.

Anyone running factory rear steering, factory box who has swapped on a TRZ bump steer kit?

Are you running radials on the rear? How much air pressure?

Yeah 325 50 15 ET Street Rs, 18 psi.

I'm planning set up mine like my friend Aarons, check out the spacers below the tie rods:

Can't comment on the TRZ kit but I will verbalize an observation of mine ... your rear coil overs look awfully close together compared to where the tires sit. Spacing them out could only benefit you and, if you don't already have one, a rear sway bar might be a nice addition.

Yeah those being close together probably is not helping. I'm monitoring whether I need to add an ARB, playing it by ear.

I might try to move the car back to leafs next year, will investigate my options.

I don't believe that's enough air pressure in the tires. Radials need more air pressure than bias ply tires. I had radials on the back of my car and tried running 15 pounds. I had a terrible tail wag at just over 100 mph. I increased air pressure to 30 pounds according to Hoosier and it helped a lot. I changed to bias ply slicks and it went away completely.

Yeah if I do the bump steer / camber stuff and it's still somewhat doing this I might up the air pressure maybe even consider a stiff sidewall slick or even a radial slick.

Sounds like rear tires could stand some more air to me. Easiest fix, too. I’m not sure what you mean by “wobbling”, but low slicks will absolutely make the car dance around on the big end.

They are drag radials but I hear you on slicks dancing around, been there in the past.

So from researching around, what's most likely happening is when the nose comes up the toe gets all messed up and the front tires up end up towing out, which is kinda of how the car feels, like it's trying turn left/right/left/right, like micro second turns if that makes sense.

I ordered the TRZ bump steer kit.

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

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

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

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...

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

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.

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.

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.

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!

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

So I ordered some Smith Racecraft upper and lower control arms, have 5 degrees of caster built in and they are also adjustable. My buddies who are running mid 8s to high 7s tell me I'll be happy with 6-7 degrees of caster Went with their coil over setup. I'll be ordering a set of Afco front shocks.

I also have a TRZ bump steer kit to install too.

I need to blow the dust off this thread.

I have some Afco coilover shocks en route. So how these work, the bottom of the shock will slide over a bottom shaft, and the top bolts up like stock. I also have some QA1 tapered springs (300 lb spring rate, 11 inches long).

After I swap out the stuff I installed two years ago (BMR tubular control arms, Viking double adjustable shocks), I'll align it probably myself and then get back out. Looking for a 8.70 / 5.70 1/8 ET.

Car is 3200 without me.

I asked my buddy (former master tech for Toyota and extremely handy guy) how long he would take to swap the front arms, shocks, and tie rod ends. He said 3 hours.

I'm happy to say I got it all done in 12 lol.

Old:
BMR control arms, not adjustable
Viking stock style shocks
Traditional big coil springs
Stock tie rod ends

New:
Smith Racecraft arms, bottom one is coil over style (5 degrees of caster built in)
Afco shocks, coil over bottom, stock stud style top
QA1 tapered coil springs, 300 lb
TRZ bump steer kit

I need to grease the ball joints, generally set toe (got some toe plates over the weekend), hoping to have local buddy do the alignment I don't feel like spending $400 on the tools and turning plates.

Planning to get back out to the track this month, better my current 9.25@150 with something like a 8.7@155.