The Turd v2.1
- Thread starter owelly
- Start date
I'm sure the front can be made to work without too much effort. I'll make a pair of bottom wishbones and et it up as I would a normal track car and see how the mop flops. The K-series has enough power for now but I made sure there's enough room for a turbo should it need a bit more poke...
I was running sticky track tyres on the front but had to revert to some crusty old Teflon Ditchfinders on the rear. I was thinking that as the front was so light, I'd need to make sure the pointy end went where it was pointed. As it happened, they were too sticky.
I was running sticky track tyres on the front but had to revert to some crusty old Teflon Ditchfinders on the rear. I was thinking that as the front was so light, I'd need to make sure the pointy end went where it was pointed. As it happened, they were too sticky.
Lilspeed
Member
owelly":3ur1dgu0 said:
Quite surprising how much front end grip is available considering the weight balance. I found that using positive camber on the front gave a less agressive turn in and stopped the back end flailing around.
Results of my handling "experiments" here;
viewtopic.php?f=10&t=2702
15psi hot in the fronts and 18 in the rears.
Having had a bit of a twiddle and a measure, I don't think I'm too far away with the geometry! I think the main problem was the very sticky front tyres and white rears.
The rears are toe-out slightly and the coilovers at that end are very stiff. I'm going to get some fittings for the hydragas and take the coilovers off and set a bit of toe-in. I'll do a full set of readings on the front throughout the travel and see what occurs.
Having had a bit of a twiddle and a measure, I don't think I'm too far away with the geometry! I think the main problem was the very sticky front tyres and white rears.
The rears are toe-out slightly and the coilovers at that end are very stiff. I'm going to get some fittings for the hydragas and take the coilovers off and set a bit of toe-in. I'll do a full set of readings on the front throughout the travel and see what occurs.
With another trackday looming, I decided to have another look at the buggy. I drove it off the trailer after the last event and left it there.....
The main issue is the steering geometry so this morning I took the front dampers and springs off to see why the bump steer was so nutty. It's more nutty than squirrel poo.... Throughout the suspension travel, the top arm rotates enough to move the top ballpoint over 20mm!!! So as the suspension dips, the top of the hub moves inward which pulls on more steering lock. The only way I can see to rectify this without a complete redesign is to make the suspension stiffer and set the top arm as level as possible....which puts the bottom arm at a jaunty angle. Time to find some proper coilovers and see what springs I have kicking about in the shed.
In other news....: I found a matching set of medium compound cut slicks in my shed. Old but better than the old hoops of coal I had on the rears at the last outing. Now the front hubs have been drilled to match the MGF PCD I can have matching rims too!!
The main issue is the steering geometry so this morning I took the front dampers and springs off to see why the bump steer was so nutty. It's more nutty than squirrel poo.... Throughout the suspension travel, the top arm rotates enough to move the top ballpoint over 20mm!!! So as the suspension dips, the top of the hub moves inward which pulls on more steering lock. The only way I can see to rectify this without a complete redesign is to make the suspension stiffer and set the top arm as level as possible....which puts the bottom arm at a jaunty angle. Time to find some proper coilovers and see what springs I have kicking about in the shed.
In other news....: I found a matching set of medium compound cut slicks in my shed. Old but better than the old hoops of coal I had on the rears at the last outing. Now the front hubs have been drilled to match the MGF PCD I can have matching rims too!!
It suddenly occurred to me that the angle of the top damper bracket was all wrong! The whole Jonny is reverse-progressive!! At rest, with only the weight of the car on the suspension, the damper is at right angles to the bracket which is welded to the top suspension arm. As soon as the arm starts to rotate, the damping and spring reduces in effectiveness. I need to drop the inboard mountings to under the original mounts.
Faffing about with the front suspension certainly helped at the recent trackday! I binned the daft 'damper-through-spring' setup in favour of a pair of proper coilovers and mounted the inner ends in a more geo-friendly place. The bracketry I crafted was adjustable to enable me to do some mods in the paddock. I reverted the rear end to hydragas and took along my £5 Chinese pump to make adjustments at that end.
The first three low-speed sighting laps showed silly bump-steer again so I raised the front to put the top suspension arm in a better place so the travel didn't move the top of the hub inwards. It made a massive difference and the buggy was now drivable! I left the rear as it was but it could've done with being lifted a bit too as it also tended to oversteer under compression.
Here's a little vid:
https://youtu.be/duKfbqOqaLI
The first three low-speed sighting laps showed silly bump-steer again so I raised the front to put the top suspension arm in a better place so the travel didn't move the top of the hub inwards. It made a massive difference and the buggy was now drivable! I left the rear as it was but it could've done with being lifted a bit too as it also tended to oversteer under compression.
Here's a little vid:
https://youtu.be/duKfbqOqaLI
Mini Mad Max
Active member
Good to hear that you've had some success in reducing bump steer. I'm interested in seeing the mods you've done - any pictures? 
Another trackday....another day of spins. The mods I've made are making the buggy better but I have a few more ideas to implement and test
https://youtu.be/C08xVoCcQBI
https://youtu.be/C08xVoCcQBI
I'm getting there with the front suspension....but I have a bit of redevelopment to go..... https://www.youtube.com/watch?v=UcCu7nAIYdY
