bassett
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| posted on 17/4/10 at 01:15 PM |
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Bent Hub - Advice?
Hi, Today ive been tinkering with the car and found the cause of my slow speed on and off grinding. It looks like it is the alloy hub being un true by
about 0.2mm which in turn makes a larger impact on the disc by running 1-1.5mm untrue. It is definitely the hub having swapped hub and disc to the
fine one and tried on both uprights. Is it possible i could have bent it from standard road use and it has never been dropped by myself or could it be
a manufacturing defect or from when the races/studs were set in at the factory as id like to know if im owed a replacement or need to shell out on a
new one. The car is an MNR Vortx which uses the Cortina setup so the disc bolts to the back of the alloy hub.
Thanks in advance.
Adam
My MNR Blog Updated Jan 2010 - Track Day Prep Begins!
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daviep
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| posted on 17/4/10 at 01:43 PM |
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Don't think anybody will be able to advise on where/when the distortion has occurred.
Do any of the faces run true?
Is the hub of consistent thickness?
Have you checked that the bearing are properly seated?
Would it not be possible to take it in to your nearest machine shop and have it trued up? Once they get it setup in the lathe they will probably be
able to tell you whether it has been machined incorrectly or has been bent.
Just a suggestion
Davie
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dinosaurjuice
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| posted on 17/4/10 at 03:13 PM |
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i think cloudy on here had a similar problem, turned out to be some grit or similar behind the bearing when it was pressed in.
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bassett
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| posted on 17/4/10 at 06:16 PM |
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Thanks for the replies chaps. Bearings fit in flush and they always go together nicely(tappered roller bearing). I havent checked since we received
them from MNR but there were no visible lines that the races werent in square. Worth a more indepth check although i am looking for 0.2mm and unsure
how/what i will measure against.
My MNR Blog Updated Jan 2010 - Track Day Prep Begins!
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daviep
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| posted on 18/4/10 at 07:38 AM |
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I'm confused, how do you know it's running off by 0.2mm if you've not measured it?
The bearings would make up easily on to the shaft even if one bearing was not seated properly.
I can't tell from the original post whether you have swapped the disc to the other hub to check whether it's a warpped disc?
You need to use a DTI with a magnetic base to measure the run out. Assemble the hub minus the disc on to the stub shaft, tighten the bearings a little
tighter than normal till there is no play in the hub at all. Mount your DTI on to the hub so that the pointer can read the face you want to check, try
to get it as square as you can. check all the faces that the wheel or disc bolt to.
Davie
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bassett
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| posted on 18/4/10 at 10:00 AM |
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Hi Davie, What i have measured is the difference between disc to upright and hub to upright with a digital vernier. I know this is not strictly
accurate but certainly shows a level of movement around 0.2mm. The varying movement was found only in the hub. I have tried both discs on both hubs
and that showed the discs to be fine on the good hub. I then tried the hubs on both uprights and one hub was always giving varying readouts no matter
which upright. The tapered roller bearings make it extremly difficult to see if they are entirely flat. Having swapped bearings over the results
remain the same so it is only one hub that has an issue and not the bearings although it is possible it is the race but because of the way the hub is
it is very hard to tell if the race is off as there are no edges to get the vernier to sit on. Ive checked the MNR site for replacement cost and a set
is £200 so hopefully a individual item would be half of that which would be a better alternative than the reengineering as the only place i know of
and have used before(bensham engineering) are extremely expensive on small jobs
Thanks
Adam
My MNR Blog Updated Jan 2010 - Track Day Prep Begins!
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daviep
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| posted on 18/4/10 at 01:01 PM |
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There are a few guys on here who do machining you could try one of them.
Davie
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