Topic: Blasting brake calipers

[theunrulychef]

Hey, I've got all 3 brake calipers off of my '77 750F2 & pulled apart.  The piston finish & bore of the calipers look great, but there's alot of rust on the inside of the piston & gunk on the caliper.  I searched old threads & found that I probably shouldn't blast inside the bore or on the finish of the piston.  Anyone have any good tips on how to blast everything w/o damaging any of the critical finishes?  Tape, rags, good aim?

I've got new hoses and rebuild kits coming for the calipers, but I can't seem to find master cylinder rebuild kits at any of the usual suspects: ebay, oldbikebarn, cycle-re-cycle, parts n more, jc whitney, dennis kirk etc.  The stealership can get them in 3 days for an arm ($52 for rear) and leg ($43 for front), but I'm feeling the pre-wedding money pinch.  Anyone else have an affordable source for these rare kits w/o having to pay in Pounds or Euros?

Thanks,
Jay in Philly

[eldar]

I have heard of people using a plastic medium instead of sand or glass. I just used sandpaper and time. a dremel with a brass wheel works to get in the small spaces.

[Noel]

I bead blasted mine. Stuck a rag up tight inside and held it in place with my hand while blasting. Still ended up with a bunch of media inside, but no blasted areas, anyway. Blew it out with air, then brake cleaner, then air again, the cleaner again, and a final shot of air. Zero sign of media afterward, so I think it was okay. And it's fookin' gorgeous, if I do say so myself.

I got the master rebuild kit from Z1 Enterprises. http://www.z1enterprises.com/detail.aspx?ID=1373. $22 bucks, altho it doesn't say it fits the '77 750F. Is the master different from '75-'76 to '77? I was under the impression most of the SOHCs used the same master, which is why the Z1 kit worked on my 500 even tho it's not listed.

Hope that helps!

[Noel]

BTW, I also gave up blasting halfway through and gave the paint strip gel a shot. The blasting removed the loose paint, but the paint that was still in good shape was impervious. I had to spend an hour or so with the paint stripper before going back to the cabinet.

Of course, nothing seems to remove brake caliper paint so well as brake fluid.   I'm going to give that serious consideration the next time this job comes up.

[theunrulychef]

Yeah, 77-78 F2 & F3 are different as far as I know.  It used a more powerful MC like the Goldwings for the dual front disc.  I wouldn't be surprised if the rears are similar though.  I'll have to look it up at Service Honda when I get home (their parts look-up doesn't work on a Mac).

Thanks for the info.
-Jay in Philly

[dusterdude]

dual disc mc should have a larger bore.

[Clyde]

I bead blast my calipers with a glass bead and just stuff a rag inside them. Make sure you clean them out thoroughly afterwards.
All K series and F/F1 master cylinders use the same size MC and repair kit.
The Z1 also uses a similar MC.  Although it has some ribbing on the outside, internally it is identical and you can interchange the brake levers, diaphragms caps etc. The Z1 lever did not have the rubber on the ball at the end, but they are the same apart from that.
The F2(77F/78F)  master cylinders I have looked at, use a 5/8 bore which is larger than than the MC used on the single disc bikes.
Some years ago there was considerable debate on this forum about whether you should use a small MC when converting to twin discs. General consensus was that you should use the larger MC, but if you were using braided lines and bled the air properly a smaller MC was OK
The kit Jeff lists on his site (as referred to above) is for the smaller MC. He does list a 5/8 kit for the Z1000 which had dual discs, but I do not know if this is the same as the F2/F3
JC Whitney list a MC kit for the 75 Goldwing which I believe is the same MC as the F2. $34.99 (Need to check that assumption)

[theunrulychef]

Good info on the MCs, thanks.  Never knew it was the bore that was larger, but it totally makes sense.  Looks like Service Honda might have them for around $30 a piece, so I'll give them a ring today to see if they're in stock.

I bead blasted the calipers last night w/ a rag, and taped off the pistons.  Everything came out well.  Now, they'll take their turn on the polishing wheels.  I'll just have to do like you guys say, and make double sure to have all the sand out before I put them back together.

Thanks for your help, everyone!
Jay in Philly

[Noel]

So did the bead blasting take off all the paint?  Maybe time to replace my media...

[crazypj]

If you put a 10x1.25 bolt in the union hole you wont get so much blast media in caliper and theres no chance of damamging the seating.
PJ

[theunrulychef]

So did the bead blasting take off all the paint?  Maybe time to replace my media...

None of my calipers were painted to begin with - don't know if that's stock for the F2, or if someone blasted them in the past (I got lucky there).  I think it might actually be time for me to change my media as well though.  I threw in my top triple clamp & centerstand last night, and the paint's not flying off like I remember on the swingarm or brake disc centers.

If you put a 10x1.25 bolt in the union hole you wont get so much blast media in caliper and theres no chance of damamging the seating.
PJ

I was tempted to do that, but other bolts I've left in while blasting tend to get media in the threads.  I didnt' want to chance scoring them up as I pulled the bolts out.  The rear caliper might be fubar at the union hole anyways.  The banjo bolt didn't want to come out - the whole way out.  The threads are pretty goobered.  I'll have to take a closer look to see if it's repairable once my new lines & fittings arrive.  I'll be putting everything back together off the bike, so it's good that I'll get to do a leak test before my life depends on these parts.

-Jay in Philly

[crazypj]

If you put a 10x1.25 bolt in the union hole you wont get so much blast media in caliper and theres no chance of damamging the seating.
PJ

I was tempted to do that, but other bolts I've left in while blasting tend to get media in the threads.  I didnt' want to chance scoring them up as I pulled the bolts out.  The rear caliper might be fubar at the union hole anyways.  The banjo bolt didn't want to come out - the whole way out.  The threads are pretty goobered.  I'll have to take a closer look to see if it's repairable once my new lines & fittings arrive.  I'll be putting everything back together off the bike, so it's good that I'll get to do a leak test before my life depends on these parts.

-Jay in Philly

If you use a short piece of rubber pipe (fuel or oil line) it completely seals off the threads, blow off the extermal blast media and your pretty much done.  kinda sucks that it takes way longer to mask things off than to do the blasting
PJ