rodgling
|
| posted on 13/3/13 at 07:49 PM |
|
|
Modifying hubs
I'm looking at getting some custom bells made so I can fit a light-weight brake setup. Unfortunately, my hubs are off a medium size car and the
discs are small, obviously - this means that it's very very tight getting enough space between the rotor mounting bolts and the wheel bolts on
the hub.
So I probably need to take some metal off the outer edge of the hub. If I leave myself 0.25 mm clearance next to the rotor mount bolts, I will need to
take the hub down to leave 4.3 mm of metal between the wheel bolts and the edge of the hub. Does this sound like enough?
|
|
|
|
|
v8kid
|
| posted on 14/3/13 at 09:02 AM |
|
|
A pic would be worth a thousand words here.
However generally you do not need as much pad area with a lightweight car as a saloon. With a smaller area the pad will get to operating temp quicker
and pad life is not really an issue.
So you can fit brake pads that are not so deep which leaves you more clearance for your bell.
As a bonus the mean radius is further from the center giving more braking torque for free!
Cheers!
|
|
|
britishtrident
|
| posted on 14/3/13 at 03:47 PM |
|
|
The size of pads on modern cars is a lot to do with getting pad life to match extended service intervals, these days tin top pads are expect to last
the 20,000 to 30,000 miles between services.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
|
|
|
rodgling
|
| posted on 14/3/13 at 04:04 PM |
|
|
Crappy diagram of the hub / hat / rotor:
Basically the "wall" of the hat (the orange circle) needs to be there so it clears the hat-rotor bolts (six small circles). Which means
the hub diameter needs to shrink down a bit so the hat can fit over it.
I am assuming by the lack of replies telling me I am an idiot that this sounds like a reasonable idea?
|
|
|
motorcycle_mayhem
|
| posted on 14/3/13 at 04:41 PM |
|
|
A picture would help here a lot. I can't see (with 100% confidence) what you're doing here.
However. I would imagine that whatever you've got in mind will be OK, doubly so on a BEC (if you have that).
If the hub is driven or is the freewheeling (or turning) end of the car, then that may play a part if it gets marginal.
Production stuff is massively over engineered for a kit. Westfield (for example) machine down (well, GKN do it actually) hubs quite a bit.
|
|
|
rodgling
|
| posted on 14/3/13 at 04:49 PM |
|
|
It's the non-driven end.
Can't provide a picture as the hats haven't been made yet, this all stems from the hat mfr telling me that given the position of the rotor
bolts and the hub wall thickness, my hub diameter is more limited than I would like.
As an aside, the hubs were originally 5x120 PCD, which I've redrilled to 5x114.3. This means I've got an extra 3mm of metal around each
stud over stock. It turns out that I need to remove exactly this amount to fit inside the hats, so from this point of view I think it's probably
good.
Of course the next problem is how do I modify them while they are pressed onto the upright. Current plan is to use an angle grinder which will
simultaneously spin and grind the hubs so I get an even result... a bit of a bodge but I think it will work?
|
|
|
v8kid
|
| posted on 14/3/13 at 07:41 PM |
|
|
Yup that pic is what I thought you meant.
What I said before is OK. The limiting factor is going to be the calipers.
If you use single pot (or dual if operating both sides of the disc) the radial width will be greater than if using 4 pots and I think this may be
where the problem lies.
Check out wilwoods design site - it is a bit "I'm cleverer than you" but I found that reading it a few times and reflecting in
between it made sense. After that it was a matter of trolling the manufacturers specs. AP were the most forthcoming but I bought Hitech cos they
squeezed a bit more out of what was going at the expense of fairly iffy service.
Good Luck and enjoy the search!
PS I bought my clutch plates from AP and in my case the service was not any better!
[Edited on 14-3-13 by v8kid]
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
|
|
|
rodgling
|
| posted on 14/3/13 at 07:56 PM |
|
|
Too late, I've already got the calipers (Wilwood powerlites) :-) Fortunately they will clear the hats fine.
I've done a lot of measuring of all the other dimensions and I think they should all be fine (although obviously I can't really test that
out until the hats arrive).
The Wilwood site is indeed so bad I wrote a script to pull the data off it and make a spreadsheet that I could search properly...
|
|
|
rodgling
|
| posted on 14/3/13 at 08:36 PM |
|
|
Just measured them again... the caliper bolts (they're radial calipers) are exactly the same distance apart as the holes in the uprights, so the
two bolts are going to hit each other. Bugger. I think I can fix this by reducing hat offset to move the caliper-bracket bolts further outwards away
from the upright-bracket bolts, if not then I've got a problem...
|
|
|
v8kid
|
| posted on 15/3/13 at 06:48 AM |
|
|
Yes it's really annoying how that happens Inmade two rough fixing blocks before I got it right and made the finished article
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
|
|
|
rodgling
|
| posted on 16/3/13 at 05:23 PM |
|
|
Gosh hubs are made of hard stuff. Took me several hours to grind off 6mm diameter from the hub. I suppose it is 300g of steel per hub though so
that's a fair bit.
|
|
|
