Body diferences betwen B3 and B4 quattro coupe

[Albert]

I'm thinking of of preparing a new body for my track car project. This time it will be hardcore light.

I was searching trough some www pages and somewhere I have found information that the body of S2 is reinforced more than the B4 quattro coupe body thus weights more.

Did any of you have heard that ? If yes the normal body should be lighter.

Also lighter than the B4 should be B3 body .... could somebody verify that ?

I have went trough etka but did not seem to find any prof.

Bout it could be true as for body of Astra GSI vs the 3dr standard version was significantly lighter

[Nuvo]

The Coupe was only available in a B3 shell throughout it production. There is no B4, I'm sure the b3 shell remained unchanged regardless of year.

[mcandmar]

S2 had a few variations over the other models, there were two small braces added from the bulkhead to the front wheel arches, and the front strut brace to join the two arches together. Only other difference i know of is the relocated battery box, and the subframe mounts uses larger diameter bolts. Its possible the mounting points were beefed up too.

But as above they were all B3 bodys.

[stiglet]

I've also heard about the chassis reinforcements on the S2. Would account for the massive increase in weight as the only other difference is a gearbox and a turbo.

[SteveH]

I've spoken to someone that re-shelled an S2 with another coupe body shell, they said the car was nowhere near as stiff once the rebuild was complete. I believe there is more reinforcement in places that cant be seen until you cut the body shell up. Perhaps someone that has broken a few cars could comment- Sal or Chen?

[Albert]

when making a car that total weight (race ready) goal is 1000kg ( ~ 2 200 lbs ) every kilogram counts.

[robert_n]

when making a car that total weight (race ready) goal is 1000kg ( ~ 2 200 lbs ) every kilogram counts.

Even at the expense of chassis stiffness? (and possible impact on handling).

Will be good to see what how this project turns out if i was building a race car (as I will when I have time/money) I would also go the lightweight approach.

If you really want to keep weight down I hate to say it as they are expensive but a Carbon helmet will even make a difference. (and the driver going on a diet......)

[stiglet]

Even at the expense of chassis stiffness? (and possible impact on handling).

Less weight, softer springs, less stiffness needed.

For a 1000kg car the standard coupe shell will be fine. Plus I assume you'll have a rollcage which will do far more for chassis stiffness anyway.

[Albert]

Less weight, softer springs, less stiffness needed.

For a 1000kg car the standard coupe shell will be fine. Plus I assume you'll have a rollcage which will do far more for chassis stiffness anyway.

Yes, the cro-moly cage will be connected to all of the suspension parts.

[robert_n]

Yes, the cro-moly cage will be connected to all of the suspension parts.

Cool, I was just concerned you would loose stiffness if the cage was only in the passenger compartment. Which cro-moly are you using? Heat treating welds would be a pain in the middle of a chassis.

[Albert]

that is a long way form now, will start a new thread about the project when it starts

[Error404]

Can't see anything in the FA with extra chassis strength on the S2, but i agree they feel stiffer than an ordinary coupe, half of that is the strut brace i'm sure! In the CQ I recon you can measure the deflection in inches under hard cornering load in the !!

I'm planning on welding some brace pick-ups under the tunnel and between the front and rear chassis rails on my CQ to stiffen up the chassis without having to install a cage. The amount of underbody bracing on my GFs RX8 and my mates RX7 is telling, and they both have great chassis to start with - will make a big difference i think, and pretty cheap and easy to do - also gives you the opportunity to mount a proper removeable splitter / front undertray which should help with understeer on track

[Flat on my back]

Dont forget...

Seam weld all the internal panels...should increase stiffness no end without too much of a weight penalty.

[GazzaG60]

i must say the s2 coupe is the least stiff car i have ever driven other than my rover 620 sdi.

id hate to drive a cq if they are more jelly than S2.

[lind4hl]

yep as flat_om_my_back says seam-weld all, that will make an huge diffrence