I had my first Spa Francorchamps track sessions last week-end, and my 300ZXTT turned the switch to "full pleasure"!

 

After the second 25 minutes run, having pushed a little closer to the possibilities, but still staying far from using full 500 Bhp power, everything whent fine, including the StopTech brakes, Tein suspension, and even T1R toyos.

But then, partking the car on a slight slope on the Datsun-France stand, .... I could not close my driver door correctly!

I put it back on flat zone, and even with this situation something had moved, and I continued with the locked door... entering the passenger side! :mellow:

 

So now: Is this coming from the lack of rigidity of the body?

The car is lowered, on coilovers, with 19" wheels, and the suspension was on "hard" adjustment with the dry track. The behaviour was great, staying absolutely flat on bends, so I suppose that the efforts on the body were maximum. The good news is that the windscreen did not broke!!:cool2:

 

The front strut bar was disassembled when I drove the car back from Manchester, and I did not reinstalled it as there were marks both on the engine and on the inside of the boot. Is this a fists step to consider?

There is no strut bar at the back, and I had the sheet roller at the back out of its place once. The rear strut bar is to consider for implementation also?

 

I suppose the maximum rigidity will be achieved with a true full cage, but this is not yet in my plans for the moment.

I have seen that extra bars can be implemented inside the car, so what is the best solution to improve the body rigidity, apart from the swaybars that are already implemented?

 

Thanks for your experience on this, as I would like to reinforce the LWB targa that I know is not the best compared with a SWB slick top of course!

Have you tried lifting the car on one corning, this may give you a clue on how much the chassis is flexing.

 

Paul

My understanding is, that with coilovers (especially on 'hard' setting) a front strut brace is mandatory. There is so much flex between the sus towers.

 

Not sure how this would affect the doors though, but they do sell a Front wing A-Frame that connects to the door hinges (?) so this might be a good option for you.

 

As first step, put the strut brace back!! :D

if you make the car with no flex in it you will take away the handling from the car ...

thats the main reason the car does twist/flex its not all to do with the suspension setup

 

having the car to low and hard springs will make the car flex/twist more then it should under normal use or OEM setup

I'm suprised this has happened tbh. I always thought the zed had a pretty stiff chassis considering its a t top!

These are the frames that Olliezx is referring too, and one that fits across the tunnel.

Edited May 29, 201312 yr by 300_zedx
Name change to Olliezx

if you make the car with no flex in it you will take away the handling from the car ...

thats the main reason the car does twist/flex its not all to do with the suspension setup

 

Chassis movement is an unknown quantity, surely you need a chassis with minimum movement and let the suspension control body roll and contours on the track surface.

 

I would have thought this is best way to dial a chassis into a track.

 

Paul

Maybe I should state the car mods that could play a role in the deformation...

My car is BazzaJG prepared car with the following on the chassis (remember 500 BHP on the dyno!)

 

Stillen engine damper brace / Amortisseur couple moteur Stillen

19" Staggered deep dish alloys (8.5"F 10"R) / Jantes 19" 8.5" devant et 10" derrière

Pneus Toyo Proxes T1-s 235 35 19

Pneus Toyo Proxes T1-r 285 30 19

Tein Flex Coilovers / Combinés filetés Tein

Tein EDFC / Réglage de dureté suspension EFDC

Stillen sway bars / Barres antiroulis Stillen

PowerTrix Rear rear control arms / Bras arrière de controle Power trix

PowerTrix Adjustable tension rods / Barres de tension ajustables Power trix

CZP Adj rear stabilizer links / Jonctions stabilisatrices arrière CZP

Stillen Hicas Eliminator / HICAS eliminator Stillen

Energy Suspension Hyper Flex bushes / Bagues de suspension Hyper flex Energy

Stoptech 332x32 Front disks and calipers, cross drilled, zinc plated / Disques et étriers avant Stoptech 332 x 32

Stoptech 328x28 Rear disks and calipers, cross drilled, zinc plated / Disques et étriers Stoptech arrière 328x28

 

I think that my first mistake is to have left the front strut bar away!

I will reassemble it and check by lifting a corner slightly...

You want the chassis as stiff as possible so in turn you can make the suspension work harder ie work all corners of the car, put a stiff setup on weak chassis and it will shake and break it!

 

Sounds like there might be a weakness somewhere and the track session has exploited it. Get the car checked over as it shouldn't have happened

check the usual place, one is the front radiator support bracket a weakness on uk cars and also there is somewhere in the middle like under the back seats that can go?

 

hope it isnt too much of a problem as i know a lot of time and money was spent on that car

I'd avoid them 3 peiece strut braces I think they flex get a one peiece one carbing is good make and well made but can be expensive but worth the money if it stops flex between strut turets .

I once made a custom set of fender braces for my S13, they made the car so much stiffer it understeered right away. But what you do have to consider is the fact that the crush zone of the car lies there, if you get into a front end collision things could turn out pretty bad. I highly doubt though that fitting one like it will reinforce the center section of the car.

 

If the door got jammed this could be due to chassis flex, however, if it got so bad it should be visually noticeable that the door is misaligned. Like someone said, jack up the car underneath an original jack spot and try to close/open the door.

Thanks for the feedback. I will look at the door position on rest flat and lifting a side.

The door lock is quite sensitive, so that could be a lot of noise from a limitit position of the lock, and just the right position to find.

I will check the other areas if anything is wrong.

If its only the drivers door that is giving you trouble, I would suggest its the door that's moved and not the chassis of the car that's bent. Track driving I would say is far smoother than fast road driving, although the speeds might be higher there is less chance of shock traveling through the car.

 

Could well be that in your enthusiastic driving you have lent heavily on the door and strained the hinge/lock mechanism?

 

Does the car have proper seats and harnesses?

You want the chassis as stiff as possible so in turn you can make the suspension work harder ie work all corners of the car, put a stiff setup on weak chassis and it will shake and break it!

 

Sounds like there might be a weakness somewhere and the track session has exploited it. Get the car checked over as it shouldn't have happened

 

 

Im 100% with jaffa on this