Wheel Failure - Scary Time...
Discussion
Few years back we found some old BBR alloys from a Sierra Cossie in the back of the bodyshop - they seemed in OK nick and so we threw em onto eBay
Much interest - decent price raised - buyer collected (a condition so they could inspect the wheels before buying) - left happy.
About 2 months later they emailled some pics - 2 of the wheels had fractured around the hub - cracks running between the boltholes. The other 2 were still OK (the ones on the front I guess!)
The car he was using them on had 500bhp and he admitted to using the car for timed runs etc. - he was angling for a refund but we reminded him he'd inspected the wheels and they had been OK - the pics we'd used were good enough to show no cracking when they were taken.
So it's not actually hard to kill a wheel and it seems that age is likely a factor!?
Much interest - decent price raised - buyer collected (a condition so they could inspect the wheels before buying) - left happy.
About 2 months later they emailled some pics - 2 of the wheels had fractured around the hub - cracks running between the boltholes. The other 2 were still OK (the ones on the front I guess!)
The car he was using them on had 500bhp and he admitted to using the car for timed runs etc. - he was angling for a refund but we reminded him he'd inspected the wheels and they had been OK - the pics we'd used were good enough to show no cracking when they were taken.
So it's not actually hard to kill a wheel and it seems that age is likely a factor!?
Face for Radio said:
Not necessarily.
Steel is very strong in compression and tension, but it would be expensive to use it for everything. In construction for example, depending what you're doing it is concentrated in areas where high tension is occuring, and where high compression occurs much cheaper concrete is used. Concrete is FAR stronger in compression than tension.
Yep, and what do they use in tension to apply compressive loads to reinforced concrete?Steel is very strong in compression and tension, but it would be expensive to use it for everything. In construction for example, depending what you're doing it is concentrated in areas where high tension is occuring, and where high compression occurs much cheaper concrete is used. Concrete is FAR stronger in compression than tension.
I don't think the 'stocky beam/column' applies to a wheel spoke that will be undertaking lateral loading at the same time as tensile loads when exiting a corner either, it already has buckling forces applied.
HellaflushGT said:
They were in the words of the guy...
Cooked to remove coat overnight, blasted, prepped, coated and cooked again at 184'C.
if the coating has been removed by cooking it will have been at 450c.if left overnight looks like they at least made an attempt at letting them cool slowly,the burning cycle is usually around 3 hours.Cooked to remove coat overnight, blasted, prepped, coated and cooked again at 184'C.
wc98 said:
HellaflushGT said:
They were in the words of the guy...
Cooked to remove coat overnight, blasted, prepped, coated and cooked again at 184'C.
if the coating has been removed by cooking it will have been at 450c.if left overnight looks like they at least made an attempt at letting them cool slowly,the burning cycle is usually around 3 hours.Cooked to remove coat overnight, blasted, prepped, coated and cooked again at 184'C.
wc98 said:
the first thing you need to establish is how the old coating was removed from the wheels prior to the refurb.i do not know how commonly its known,but a lot of powder coating firms use burning ovens to burn off the old coating at temps around 450c prior to a light blast to remove the carbon deposits.the burning ovens used generally see the wheels stuck in and removed at high temps,so thermal shock occurs.knowing how many wheels are out there that have gone through this process,i am surprised this is not a more common occurence.
as has already been stated ,the actual stoving temps for the powder coating process are 180 to 200 c,but generally 180c....
Jesus.as has already been stated ,the actual stoving temps for the powder coating process are 180 to 200 c,but generally 180c....
Edited by wc98 on Wednesday 8th May 23:39
If ever there was a good reason for making a thread a sticky at the top of the board that's it.
Anyone getting wheels refurbed needs to know about what questions to ask.
Herman Toothrot said:
Nothing like those temperatures just from braking, constantly being cooled by ambient airflow, 60/70 oC at the most, I can certainly touch my wheel and not get burnt straight of the track.
And if someone's wheels actually were getting up to 180C-200C, I wouldn't want to be anywhere near their exploding tyres.wc98 said:
i am in scotland mate,so not the same one.i would definetly be finding out what stripping process was used though,if the old coating was burnt off he will have a very good case.thin spoked alloys seem to be the worst,could be the shrinkage/expansion rates during heating or cooling during the burning off process,it doesnt seem to happen to meatier spoked wheels,though personally you couldnt pay me to fit wheels to a car that had been in a burning oven,nor wheels over 18 inch no matter who makes them.
Ok being totally ignorant now - why not 18"+?irocfan said:
wc98 said:
i am in scotland mate,so not the same one.i would definetly be finding out what stripping process was used though,if the old coating was burnt off he will have a very good case.thin spoked alloys seem to be the worst,could be the shrinkage/expansion rates during heating or cooling during the burning off process,it doesnt seem to happen to meatier spoked wheels,though personally you couldnt pay me to fit wheels to a car that had been in a burning oven,nor wheels over 18 inch no matter who makes them.
Ok being totally ignorant now - why not 18"+?Gassing Station | General Gassing | Top of Page | What's New | My Stuff