Potential problems of shortening a wheelbase w/o changing geometry/track?

[CoryM]

Hey guys,

I am getting seriously antsy for a fun car this summer. Problem is I have too many other expenses and things to save up for to spend any real money. This leads me into my current (sick?) frame of mind. Buy a rusted 2nd gen camaro, pull out the engine,trans,subframe and rear susp and use it to build a very simple, fairly light 2 seater with a much shorter wheelbase (my version of a locost I guess). Use the factory brakes, pedals, rad etc etc to keep the costs low. Im thinking 2nd gen because they are cheap and I know the cars fairly well. To connect the bits I would use a simple four tube chassis with rollbar and bang out some panels to keep the wind/rain out. Make it just pretty enough to keep the police happy.

The thing I wonder about is the drastic change in wheelbase. Stock is 108" and I would want about 95" or so, although I could run it longer if I had to. What would I run into as far as handling changes? I know my roll axis would change, and I would need different springs/shocks/swaybars for the lighter car but what else would you expect to see as far as required suspension changes? I dont plan this thing to be a real racecar, just a light car that I can bag on for a while somewhat safely.
Cheers.

[astroracer]

"buy" the time you rebuild all of the rusty stuff you'll have a good chunk of change into your "cheap" build. If this is something you have to do I would suggest picking up an old S10... You'll have a full frame which can be easily shortened, parts are cheap and a small block can be swapped in. You'll still have the issue of old rusty parts but I feel the truck would serve you better towards your goal.
Your concern with geometry is justified although shortening is not as detrimental as narrowing. The only real concern with a shortened suspension is anti-dive and where it will end up after the surgery.

[CoryM]

Well, one reason I chose the 2nd gen is because of the bolt on subframe. Get some solid bushings and bolt it on to my chassis. I would add some bracing to stiffen it up a bit though. For the cost I would just buy some steel bushings, adjust the steering box and I should be good. I will try to find one with tight steering so I dont have to replace idlers, tie rods etc as those can add up. I get replacement parts for about 40-50% of retail as well so that helps. The 2nd gen also has a 8.5" rear gear which will be invincible for this car, although pretty heavy compared to the sprung weight.
Good point of the anti-dive. I wouldnt expect it to be a major deal though as the car will be lighter, and have a lower CG. I can also tweak it a little if I need to. I was also thinking I could just leave the wheelbase almost stock and just have the wheels at the very corners of the car. Might look kinda cool and not screw up any geometry. The rear leafs would force the tires further in on the back though so maybe not.
Any more input guys?
Thanks again.

[David Pozzi]

What you are talking about is building a whole car almost from scratch!
You aren't going to do this cheaply and if it's just quickly thrown together it won't be worth doing or the cost in my opinion.

I think you'd be better off just using a second gen and doing some things to lighten it up and improve it. Maybe use a glass front end and roll cage for stiffness.

[CoryM]

if it's just quickly thrown together it won't be worth doing

This is what I am trying to figure out. All I am after is a light car that corners OK. Not great, not spectacular, just not scary. So long as its predictable I will be happy. This is why I am asking about what all is going to change in the geometry rather than if its a good idea . The way I see it is the donor car will supply 90% of the parts I need. Then I need tube,sheet steel, fuel cell, harness, some steel bushings. Will see what comes of the springs/shocks but those wont be high dollar peices either. If the brakes have pad material and are not warped.... Im not going to replace them, same goes for every other part. If its servicable, I will leave it. I know this will be a lot of work, but I dont see the major costs involved. The steel will be the most expensive part I think.

[boodlefoof]

I say go for it!

As far as handling changes, the shorter wheelbase will make for a little more "flighty" steering. You may need to go with a slower ratio gearbox.

I'm currently in the planning stages of building a custom space frame and custom front and rear suspension and grafting a modified early Datsun Z body onto it. In stock form the Z only has about a 91'' wheelbase. I'm still undecided as to whether I'm going to elongate the car. I plan on widening the track width about 8-10'' front and back...

For inexpensive parts that might help out in your build... check out the following...

http://www.speedwaymotors.com/Default.asp?wc=true
http://www.colemanracing.com/catalog/index.php

Good luck!

[CoryM]

Thanks boodlefoof (that name is, uh.... interesting btw)
That is one more reason why I opted for the 2nd gen. Dirt track parts! Just in case I decide the car is worth putting some more $$$ into later on. As for the steering I felt the stock high ratio box was too slow on my camaro so that shouldnt be an issue. So far all I can think of is antidive, roll axis and ackerman angles that will be changed but those can be dealt with some easy tweaking. Any other angles? I am basically just going to measure the stock car and leave all mounting points the same height and lateral position but move them towards the centre of the car a bit. I really dont think I will need to shorten it that much, maybe 5" or so.
Cheers.

[PAI Racing]

Go and buy yourself a beat up IMCA modified. It is a stock stub front clip, tube chassis car with aluminum panels. It is cheap and exactly what you described for a lot less work. The cops are going to hate it either way...

[wally8]

Good luck putting one of those on the street!

PAI is right though. We're shopping for one right now and you can get a pretty good roller (no motor, tranny or gear) for under $3500. This would be perfect for an occassional open track car. Of course you can get a late model (fully fabricated, no stock stub) for about the same price.


Wally

[CoryM]

Thanks guys.
I have been looking at the IMCA mods for frame ideas. They do any of that around here so not going to find a car. I would want to make it a little prettier and it can't be open wheeled to pass a vehicle inspection so I was looking at front fenders like a plymouth prowler has. It is actually a little scary how easy it is to get a car on the road legally here. It just has to pass a VI which is just basically making sure the light,brakes,suspension are in good working order and then apply for a VIN number. We do VI at work so I know what it takes to pass, I would have another shop do it though, looks a little seedy if I do it ;) . Anyhow, I will play with some more ideas and see where I end up.
Cheers.