Powdercoating calipers

914GT · 07-29-2003, 06:09 PM

I picked up a pair of BMW 320i calipers this afternoon for fifty bucks, and now getting them cleaned up and ready for machining. They look good as-is and I don't know if I'll rebuild them yet. Anyhow, I was reading a PP tech article about painting calipers and it said they sent them off to be sandblasted and powdercoated with the pistons still in the calipers. I'd like to powdercoat these but I hesitate to stick them in the oven and risk damaging the rubber parts. I know brakes get hot, but I don't think calipers get THAT hot. Is this a safe thing to do or should I just use some high-temp paint?

Tidybuoy · 07-29-2003, 07:21 PM

I'm not sure if the rubber will survive the powder coat traatment.

However, I'm writing to say that I think you should go ahead & do the rebuild. I put 320i calipers on my car last weekend & the rebuild kits were only $12 each from the dealer. It took about an hour to clean & install everything & it was very simple.

My brakes are working great with tremendous improvement over stock.

..............................................Vern

914GT · 07-29-2003, 08:40 PM

Vern - I agree. One is already apart. I decided I'm not putting them on without seeing the insides and having new seals on. Plus I can bake them and easier to machine the surfaces. By the way, what did you do? I plan to do something different, we'll see how it works out. I am glad to to hear that this conversion worked out well for you.

my15window · 07-30-2003, 04:32 PM

tne powder coater I took mine to said they have to be completly dissassembled and cleaned because any brake fluid will contaminate the proccess , so I painted mine with Pep Boy's caliper paint $

Tidybuoy · 07-30-2003, 05:25 PM

As far as the rebuild, I simply poped out the pistons & cleaned everything with brake cleaner (you will need 3 or 4 cans to get them really clean). I scrubbed the bores with a 3m scratch pad to get rid of any surface rust. I bought rebuild kits from the BMW dealer (rubber seals, retaining clips, & pads) plus I changed the bleader valves to speed bleeders.

As far as the machining, I had the inside parts where the calipers bolt on ground down to the proper specs. I used my stock calipers for comparison & just made sure the very center - to bolting surface was the same as the stock. I also did a trial fit & you will notice that the center of the calipers (where the two halfs are joined) should line up to the center of the rotor.

I also had to change the metal brake lines. I used 8" lines & bent into an "S" to fit but I plan on replacing with 5" lines as soon as I can find some.

Thats it. I didn't paint the calipers but I might some day. I also replaced the rotors & bearings since I needed to do that anyway.

I plan on adjusting the proportioning valve since my front brakes seem to lock up really easy & I think that the back brakes can be allowed mor fluid with the stronger 320i fronts.

You will know that your brakes are working better because of the sudden appearance of brake dust. I never had that problem before but the BMW brakes definately put out the dust.

.................................................. .Vern

914GT · 07-30-2003, 09:21 PM

Well, my calipers have to go on the back burner for a few days. The clutch slave cylinder went out on my daughter's car (an Acura), then after replacing that this evening I noticed a coolant leak from a plug on the rear of the block. Of course, both of these are in about the most inaccessible regions of the engine compartment. Hopefully I can get back to the 914 in a couple days.
Tomorrow I'll pick up the BMW rebuild kits, they're only $12 each. What a surprise. Something for a German car that's about in line with Chevy parts. I'm going to get those mounting pads shaved down, dunk them in lacquer thinner one more time followed by hot soapy water, then maybe into the oven for 10 min or so to drive off any moisture or oil residue. Then mask off the critical areas and put on some bright yellow powder that matches my paint job. Into the oven they go and watch them bake while I open a cold beer. My kind of cooking...

neilca · 07-31-2003, 05:24 AM

I have a couple of questions on powder coating calipers.

1. Can you use regular powder coating material? I thought the brakes would get too hot for this.

2. Can the little O-ring between the caliper halves take the bake temperature, or do we need to disassemble the whole caliper?

I am looking at powder coating M calipers for racing purposes.

Thanks,
neilca

914GT · 07-31-2003, 08:12 AM

Neilca

I'm using regular powder, I think that'll be fine for street use. But for racing maybe the high-temp powder would be good idea. I would expect the powder to handle high temps better than the rubber parts normally on the calipers though. They must not get that hot, it's the pads and the rotors that take the brunt of the heat. The calipers are heat-sinked into the struts (wonder if the mounting bolt points are a good spot for some thermal grease?). I've disassembled mine, I'm going to replace with new and not take the chance with 20 yr old rubber, baked or not.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

The calipers get more than hot enough to boil water... Or wet brake fluid. (Ask me how I know this??

)

--DD