Guys, I think for the most part I have this thing whipped. I narrowed the batwing 10" overall and will beef it up with 1/4" 6061 plating, tig welded to the outer portions covering the inner webbing. Narrowed each side 3". Installed the VPB lower camber links and Denny's half shafts. Have an idea for mounting the QA1's. Now for the questions.

Suspension travel: without notching the frame, the first thing to touch is the toe links, with 2 3/4" of travel up (compression) from rest. Should I alow more. I have a feeling I should have allowed more stroke, the trouble is, I was worried about ripping my fenders off so I went with the shortest QA1 with 4" of stroke....giving me about 2" of up travel (comression). Any thoughts?


QA1 mounting: I'm told, not to mount the QA1's off the factory shock mount, which makes sense to me. I have seen people make a sort of plate mount using the two bolts that support the dog bones (trailing arms). The trouble is, I really cant use the top bolt because it nearly touches the frame when the suspension is fully compressed. Its like a 1/16" away from frame. I could notch the outside of the frame slightly but I was wondering if it would work using the lower dog bone bolt and the factory shock mount instead, and just leave the upper bolt alone. Anyone mounted thier coil-overs this way?


Camber change: This is strictly an eyeball way of checking camber. Used a inclinometer. My camber tool is on its way. With the face of the rotor at 0 degrees at rest. On full compression of the suspension, 2 3/4" upward (compressed) motion, I lose 1 degree of camber and lose the same 1 degree when moving down 2 3/4". Total of 5 1/2 " of overall suspension travel. Is this acceptable? Any thoughts. New poly busings throughout already installed. I also noticed the forward bracket for the dog-bones flex a little. Not much but they do flex some.

Any thoughts would be appreciated.

Thanks,
Dave

 

Dave,

I narrowed mine, also. Other than being a bunch of work, there hasn't been many issues. I'm confused about your camber question. For good cornering and handling purposes, there has to be camber change with suspension movement. Unless you're making a drag only vehicle (where you would want no camber change with suspension compression), I'm unsure what the problem is that you are seeing. Can you give us more details?

 

I'm eager to hear some answers to this too. Keeping the camber/caster/toe aligned with suspension movement sounds tricky. QA1's are the adjustable shocks, right?

 

I guess I'm confused. LOL's. It happens often.

I thought that during the compression of your suspension it would be ideal if you could maintain the same camber you had at a rested state? It may be time for me to learn more about suspensions...camber, toe, etc. I use to have a book called Doorslammers which is riding around in my memory...so yes....its based more on straight-line conditions. I do need to think more along the lines of cornering conditions. Can you steer me toward a good book thats not so in depth that I lose interest. I'm ADD and OCD. My attention span wanders. LOL's.

It depends. I think QA1's can be bought with-out adjustment. Not sure. I know they have a single and double adjustable. I went ahead and bought the doubles...for compression and rebound adjustments. I was told it really wasnt all that necessary but I thought it might help me tune the IRS for my application better if I had some adjustment.

Thanks all,
Dave

 

Get Herb Adam's book. There's a lot of books out there, but Herb's is more geared towards the enthusiast, versus the chassis engineer.

 

Awesome. Looking for it now. So now I'm thinking...maybe I dont have enough change in camber...oh ratzzzz. LOL's. The reason I asked....I was concidering an additional link suspended off a ring which would mount aroung the pinion....over to hub assembly...with coil-overs mounted off of it close to the hub as I can without rubbing. What you said makes perfect sense because during compression it does indeed have negative camber. Now....even though I'm bald....I am showing my blonde side. LOL's. Sorry and thanks so much.

Dave

 

Most street and road racing applications seek 'camber gain' during jounce. That is, the camber will be more negative under compression than at static ride height. This helps keep the tire contact patch more level when the chassis rolls (along the roll centers) during lateral acceleration.
Looking at most street double A arm applications, see that the upper arm is usually shorter than the lower. Draw those two arcs on some paper and see what happens to a line drawn between the end of both lines does.

The less the chassis roll, the less the camber gain required.

 

I will have some chassis roll. But shouldnt be much in the rear.....truck...and light...and the addition of a NASCAR style sway bar. Now the trick for me is....to figure out how much.

Thanks. I do understand the need for camber change now. I was being nieve.

Dave