Scaffolding poles + old VW bits + Rotary engine....
Discussion
A very steep faced jump, so it clattered off the bumpstops front and rear for anyone going over at any speed.
Odd combination of it being just tall enough if you slowed down and rolled over it you'd be doing 10mph and lose more time than just hitting it and holding on, but not a smooth enough ramp that you could just hit it with the throttle flat.
Odd combination of it being just tall enough if you slowed down and rolled over it you'd be doing 10mph and lose more time than just hitting it and holding on, but not a smooth enough ramp that you could just hit it with the throttle flat.
Still don't ask. This is completely normal and 100% not a scary lash up, honest.
But at least they're back flat now:
So these discs warped when they were hot zinc plated, and the plan was originally to heat cycle them gently to get the stress out of them, then take them off the car and grind them flat before the car got used in anger.
That obviously never happened and because they were getting hot spots they got worse and worse lately - the things had more bow than a pringle in them.
Ground them back flat in a seriously Heath Robinson manner for now, just to get the brakes back, as it's been knocking the brake pads back and needing the pedal double pumping at higher speeds - they were half a mm out of true (discs should generally be under 0.05mm)
Obviously not good, so this is a temporary fix for now, and then we'll get some more cut either out of cast iron plate if we can manage it (which I originally wanted but our parts are so small you have to wait until somewhere has some spare offcuts basically) - or probably have them done out of 10mm thick plate next time, stress relieve them and then machine them back true to 8mm thick (these fronts are only 6, they were designed for the old tiny little 2-pot Wilwood calipers we used to run) - I've already got a jig for it as we made one to do the discs originally before we got carried away and forgot
But at least they're back flat now:
So these discs warped when they were hot zinc plated, and the plan was originally to heat cycle them gently to get the stress out of them, then take them off the car and grind them flat before the car got used in anger.
That obviously never happened and because they were getting hot spots they got worse and worse lately - the things had more bow than a pringle in them.
Ground them back flat in a seriously Heath Robinson manner for now, just to get the brakes back, as it's been knocking the brake pads back and needing the pedal double pumping at higher speeds - they were half a mm out of true (discs should generally be under 0.05mm)
Obviously not good, so this is a temporary fix for now, and then we'll get some more cut either out of cast iron plate if we can manage it (which I originally wanted but our parts are so small you have to wait until somewhere has some spare offcuts basically) - or probably have them done out of 10mm thick plate next time, stress relieve them and then machine them back true to 8mm thick (these fronts are only 6, they were designed for the old tiny little 2-pot Wilwood calipers we used to run) - I've already got a jig for it as we made one to do the discs originally before we got carried away and forgot
Edited by PhillipM on Sunday 2nd July 22:58
Okay, she's back up and running, a few changes, rear torsion bars finally removed now the new springs are in to save some weight, new fuel pump as the old one was making a few funny noises, and the brakes back on.
The brake balance needs setting back up it's a little too front biased now but it feels a lot better for now. Fingers crossed, we should hopefully be off to Walters Arena in Wales this weekend to see how it goes.
The weather looks fairly reasonable so might be a nice weekend of racing.
The brake balance needs setting back up it's a little too front biased now but it feels a lot better for now. Fingers crossed, we should hopefully be off to Walters Arena in Wales this weekend to see how it goes.
The weather looks fairly reasonable so might be a nice weekend of racing.
Okay, after some hours of work, we've traced the problem, which is 90% of the battle - it's no good fixing something if it's just going to do it again - but it looks like the spindle cinch nut had fatigued, and managed to vibrate loose, despite the cinch bolt being tight and loctited - most probably from material fatigue on the aluminium.
Then it vibrated looser and looser until the locking/tabbed washer finally dropped out of it's slot and then that allowed the bearing to spin the nut off, which explains the whole lot suddenly falling off on the last 3-4 corners - and why the right side is fine, the right side would tighten itself while driving from the rotation, while the left loosens. And also why the thread is only damaged on the end of the spindle and was fine in the nut.
Which also means it's a fairly easy fix of switching them out for some stronger steel castellated nuts and roll pins to secure them, and not some sort of issue with the front hub/spindle/bearing assembly we'd previously got away with.
Unfortunately, because of the damage caused when it did come off, that means we need to machine and weld on a new spindle, sort new bearings, fettle a little bit of damage to the brake mounting bells and make new brake discs...so it's not all smooth sailing.
Onwards with the machine work I guess...
Then it vibrated looser and looser until the locking/tabbed washer finally dropped out of it's slot and then that allowed the bearing to spin the nut off, which explains the whole lot suddenly falling off on the last 3-4 corners - and why the right side is fine, the right side would tighten itself while driving from the rotation, while the left loosens. And also why the thread is only damaged on the end of the spindle and was fine in the nut.
Which also means it's a fairly easy fix of switching them out for some stronger steel castellated nuts and roll pins to secure them, and not some sort of issue with the front hub/spindle/bearing assembly we'd previously got away with.
Unfortunately, because of the damage caused when it did come off, that means we need to machine and weld on a new spindle, sort new bearings, fettle a little bit of damage to the brake mounting bells and make new brake discs...so it's not all smooth sailing.
Onwards with the machine work I guess...
Okay, new spindles made, jigged and welded onto the uprights, spare hub fitted and 2 more machined up, new brake bell and finally, 4 new brakes in 10mm material cut, rough machined, annealed in a pizza oven, and finish ground. Everything is back together and the brakes feel a lot better. I think I'm gonna make some changes to the calipers a bit though later on.
Anyway, I was over in Germany so Ed got the car back together ready for a race at Tiverton this weekend:
(apologies for the poor video, I didn't film it, don't blame me
)
As you can see definately bedding them in gently....
Unfortunately, due to heavy rain, after a 5 hour trip today, the event got called off, as some area's of the course are pretty much impassable even being careful with jacked up course cars hooked together on winches, never mind the racers. So it's a long drive home.
Anyway, I was over in Germany so Ed got the car back together ready for a race at Tiverton this weekend:
(apologies for the poor video, I didn't film it, don't blame me
)As you can see definately bedding them in gently....
Unfortunately, due to heavy rain, after a 5 hour trip today, the event got called off, as some area's of the course are pretty much impassable even being careful with jacked up course cars hooked together on winches, never mind the racers. So it's a long drive home.
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