I spent the weekend finishing the mods to my chassis to accept the dedion axle that i collected on friday.

I have also fully welded in my rollbar which is a normall straight sided hoop from the mounting plates, with a diagonal and 2 long backstays that go to the bottom rear corners of the chassis where it is fully welded to 3mm plate that is fully welded to the sq and curved tubes in the corners. i really should have taken a pic, but my camera was out of batteries

I have all of the other 'book' tubes on my rear end, but do I really need w1 w2, as the rollbar must be far stronger for the strength of the chassis?

thanks all,

Ned.

ps page 38 of jim mcsorleys pdf plans shows the tubes I'm on about for those that don't have their bible handy..

Ned,

I'm no expert but to me it looks like the effect would just cause a change in the angle the load is transmitted in. Other than the load from the fuel tank and rear body work I cant think of anything else these bars would be supporting other than a little bit of torsional stiff ness due to there angle.

Basically as far as I can see the load would just transmit through the roll bar rather than the O tube, the rear bulkhead tube. As long as the roll bar stays & bar itself are of greater strength that tube O I can see any adverse effect.

As said, I'm no expert.

Simon.

[Edited on 22/3/04 by PioneerX]

Ned, settle an argument, wat age are u? My mate thinks ur old and i think u are young. Please let me know so i can claim my tenner! Cheers Ned, goodluck wit ur car

looks like you're owed a tenner.

Ned.

I think this area of the car is not well designed, all the loads from the rear suspension are directed up into the 4" square plate which is only secured on one side to the transverse upper tube of the seat back panel. The X and W tubes must help to a certain degree, and a triangular plate fixed to the top of the X tube may help a little more. My roll bar will help a bit more as per Ned's layout.

Any comments?

Agree totally!

Going the de-dion route has the shock bracket in a different location....well it does on the GTS jobbie....it is tied into the diagonal going into boot,the 4"plate then gusseted with all this linked tickty boo with 16swg rhs....nowt like book but same if that makes sense!!

Got any shots?

I will take some tomorrow and if i can make it work post them in here.

Mark

Mark,

look forward to seeing the piccies, my axle is nearly ready to go on now and was wondering about where to mount my shocks.

One question i did have Mark(triton) is that my axle doesn't have the reinforcement plate bit in the centre where the 2 halves of the dedion tubes are welded. i see from others pics that they have. is there any reason for this?

thanks,

Ned.

The suspension top plate should be panelled in so that loads are spread out into tubes O/W1/W2. Don't rely on just welding the suspension top plate to tube O. Check the picture on page 62 of the book. Loads put into W1/W2 find their way back into the chassis sides via tubes RU1/RU2 so the W tubes do do some real work in the chassis.

I always figured that w1 & w2 were in tension and didn't help the roll bar at all. If you think about a full tank of petrol (8 gallons?) hanging over RU1/2, then W1/2 are in tension to keep the boot from sagging. This would explain why Ron chose 3/4" tubing for W1/2... you don't need much cross section when pulling on steel.

Cheers,
Jim M.

quote:

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Originally posted by jbmcsorley
I always figured that w1 & w2 were in tension and didn't help the roll bar at all. If you think about a full tank of petrol (8 gallons?) hanging over RU1/2, then W1/2 are in tension to keep the boot from sagging. This would explain why Ron chose 3/4" tubing for W1/2... you don't need much cross section when pulling on steel.

Cheers,
Jim M.

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extra weight only. You can work out how much, probably around 25% for comparable lengths. When i did the equivilent (sp?) bit on my car, i used mostly 19mm 18 or 20g tubes, as it has next to no real structural function (on mine at least...).

I changed my mind over my nice simple hoop bolted rollbar, because of this. I wanted to...

1, Increase the rear crash resistance of the car and protect the fuel tank.

2, I needed somewhere to put my upper seat belt mounts, so needed triangulation for these

3, I did not believe that the upper shock mounts wount not fatigue fracture after a few thousand mile on Cornish bumpy roads
Rescued attachment WTube.JPG