BC

Has anyone ever quantified the differences in bodies between the early and late cars with reference to which is better for the forces of racing?

Things like how the body changed at the suspension pick up points, or how its welded at the seams.

One main thing is the front of the rear lower arm - it went from welded bracket to a much beefier three point subframe - this was obviously for a reason.

I have noticed slight changes on the front end where things are welded together.

Any other input? Anecdotes? First hand or 4th hand knowledge?

Rob Edwards

Won't the addition of a proper cage reduce any structural differences in early v. late unibodies to rounding error?

BC

I have seen online (which makes it true always) that people will seam weld the car for stiffness while they put a cage in.

The cage, however, moves the car from drivable on the street (safely and comfortably) to not-so-much.

Rob Edwards

Everything on the internet is true, and PET is never wrong.

IcemanG17

this is an extremely simple answer........OB all the way....why....its much lighter....and cheaper....track cars by nature are disposable....S4+ cost more.....its simple math....

My perspective...my professionally built Black Widow (1989) was almost 2850lbs with an empty tank...Casper is nearly 2625 at the same standard....why?? Can two extra cams weigh that much? Need another example.... Kiborts racer (32V) off track weight is almost 3000lbs....mine 2825lbs....both cars are properly prepared (we both weight about 200lbs)

More info....16V engines are MUCH cheaper....and more plentiful.....and can make nearly the same power with minimal mods (euro cams)..... I have 3-4? engines in my shop that are 16V....all cost almost nothing (parts cars)....

Need an ANOTHER benefit.....while you are learning the lower HP of a stock 16V is a HUGE BENEFIT....honestly....any 32V is too much while you are learning the game.....

BC

I can agree with the first part if we had some info as to why, but I disagree with the second. The later engines, once the oiling is dealt with, are much better for power and tunability.

So lets focus on the body still. Early bodies are cheaper to GET, but what needs to be done to them for stiffness. You can stick a cage in, but that is for good safety - I am not so sure it affects the suspension.

Can anyone even tell? Even F1 drivers are notorious for "being fast" or "being slow" but they have no idea WHY or what's causing it.

Massa was recently slow in the F car, and they changed the entire monocoque and he was faster.

Dave928S

For dedicated race cars (not 928's) I've blasted the whole shell back to bare metal, which lightens the car by a huge amount, preps it for strengthening plates and seam welding, and allows you to see everything. Then full seam weld and plates and gussets in high load areas, then full roll cage. Then paint and put back on and in only what you need for racing.

I'd always go for the latest model shell that I could get, with no previous impact history = less years of incremental fatigue at any high stress point, less chance of any corrosion, and body to factory chassis jig points.

If I was prepping a 928 I'd go for the latest I could get, unless I could find a straight low mile early shell with caput mechanicals.

A good multi point roll cage integrated into the car will not only add to safety it stiffens any car a HUGE amount .... 928's do flex and you can remove that totally with a good cage, and get precise suspension performance and control. Not much point setting up a car with a correct alignment if it aligns itself differently, as a consequence of flex, every time you throw it into a corner.

If you have a properly setup and caged race car on the jack stand points, you should be able to jack it up at any of the points a bit further, and the other point on that side will lift off the stand too .. try that with a non caged car and it will flex.

BC

Thanks Dave. That's one of the possible realities for one of these cars.

Mark Anderson

Been there, did that,
Now it's up to Rob E

BC

More pointedly, has anyone ripped that rear lower arm bracket out of the body? The front lower bracket that was changed in the later body.

Mark Anderson

That was one of my concerns. I've never seen a failure but I'd like to think they had good reason to do so

Vilhuer

I'm quessing rust was issue in early cars. Metal sticking out like it does in old style body is going to rust much quicker.

BC

No rust here. If that's the main issue suggested I could seam weld and secure it more.

I don't think that body will be used in racing but its still something worth looking at.

BC

GregBBRD

Seam welding a car is only necessary if the factory spot welds are popping or cracking. Has anyone seen a 928 do this? I have not.

The Porsche Factory doesn't seam weld any of the Cup Cars or the RSR's.

Why?

Seam welding a car that is galvanized is going to cause more problems than any good it will ever do.

slate blue

I have no idea how you can properly seam weld our cars, welding them in general takes lots of prep and don't dare breath the fumes. There is no way I would go down the seam welding route either.