Brake Calipers

[Moparnut72]

The font calipers on the semi basket case T3 I am rebuilding are trash, badly rusted. I think I have found that the '76 Lemans used the same calipers. This came up in AI which I don't trust. It seems that F08 calipers are kind of rare, a few of the ones I have found are in Germany and very expensive and exorbitant shipping and beyond my budget for this disaster. Can any of you guys very that they will fit. I have found a listing for these at a reasonable price. The T3 takes F08 calipers and AI says the Lemans does also. I want to be sure the seller doesn't take returns and these are a bit pricy but not bad. I couldn't find anything in Guzziology about the Lemans. It does say F09 will work though but the master cylinder to caliper ratio isn't very good.  This project that I took on to give me something to do this winter is turning in to be more than I wished for. If it gets any worse I may park it for awhile. I hope tis all makes sense. Thanks in advance.
kk

[73 sport]

     MG Cycle in Wisc. has both left & right FO8 calipers.

[Antietam Classic Cycle]

All early big-block Guzzis used the same F08 calipers on the front end. The F09 was used on the rear of some 1000SPs. If you can find F08s with the single 10 mm bleeder, those are the best as they usually have anodized alloy pistons instead chrome-plated steel ones. The 10 mm bleeder is also much less likely to twist off.

F08 calipers aren't what I'd call "rare", they were widely used on Guzzis, Ducatis, Laverdas and BMWs. The F09 is sort of rare.

If you're looking at the same ebay calipers as I am, then $250 for a pair that might need to be rebuilt is a bit high IMO. 

[yackee]

I found that it was worth the money and less hassle to buy new F08s from MGcycle rather than try to rebuild the existing ones. The chrome pistons tend to rust quite a bit if neglected and it can be a hassle to get them out and clean out the existing caliper. But my budget constraint may not be yours. You can use the F08 in the rear, the F09 is hard to obtain. I used an F08 on the rear of my T3, it works great.

You will probably also need to replace the master cylinders, or rebuild them. I rebuilt the front M/C, but still couldn't get pressure, and just bought a new one. The rear is harder to replace.

And the lines themselves--probably worth replacing with stainless-wrapped new lines.

[Antietam Classic Cycle]

New calipers at MG Cycle: $185 for the right-side/rear (price may not have been updated to reflect the tariff yet) and $266 for the left-side. Both are $200 ea. at Harper's.

The T3 would have had F08s from the factory, only the 1000SP ever had an F09 on the rear.

The front master cylinder is $224 and the rear is $232 at MG Cycle.

[n3303j]

Brake calipers on the T3 are aluminum and do not rust.

Mine sat for 18 years before I bought bike.

New Teflon coated aluminum pucks are available to replace the rusted chrome plated steel ones.

Split the caliper. Clean the bodies thoroughly. Replace all the rubber bits (including small o ring between two halves) and you will be set for another 100K miles. A lot cheaper than buying new ones.

https://store.bevelheaven.com/Brake-Related-Parts/Brembo-F08-Piston-Seal-Kit-38mm/

The caliper bore only guides the puck. All sealing is done by the square cross section O Ring. As long as the O Ring groove isn't damaged installing a new seal will work excellently.

[Moparnut72]

Thanks for all the advice. The pucks are rusted in so solidly I have been unable to remove them. I plan to continue with that. I planned to do that but this road block has me rethinking the project. Spending this much money for just brakes may just put it over the top. I have already purchased forks, carbs, lighting and other misc items and more to go. I will also have to rewire the whole bike. The previous owner(s) went through it with wire cutters. I also have a parts frame which I picked up later and thought I could recover some bits that were missing but no such luck. I am not a quitter so I will push through but probably on a delayed schedule and just ride my V7.
kk

[n3303j]

Pressurize the caliper half with a grease gun. That should drive the piston out. Numerous people have shown ways to install a grease fitting in one of the ports.

[Moparnut72]

Thanks, I will give that a try. I was thinking something along those lines but this is a better idea.
kk

[jhem68]

I had a caliper with the piston stuck so bad that after a week of trying everything I could think of, I finally tried the grease gun method, and it worked. Bit of a mess to clean up but I don't think there is another method that can exert more pressure on the piston. That caliper is still in use today ten years later.

Good luck!

John H

[n3303j]

...and a note from my FWIW department.

Both master cylinder bores on my T3 were heavily pitted and useless. 18 years sitting parked.

The master cylinder bores on the T3 are specified in metric numbers. Those numbers translate to exact fractional sizes (color me surprised)!

https://tinyurl.com/5duz237t

These people make seamless brass tubing in fractional sizes with fractional thickness walls.

So I bought the tube that matched the old pitted bore and the reamer that matched the tube OD. I reamed the cylinder and bonded the brass tube in place with RC680 Loctite. Then cut off the excess tube, drilled through the cross feed holes and polished the burrs from inside the tube. I finished the project with a new piston and seals. That was over 100K miles ago.

Cheap way out for anyone with a drill press, vise and a bit of patience.

I did finally replace the front cylinder after I cracked the mount in a high side. Still worked, but moved around the bars.

[Moparnut72]

I got the pistons out of all three. The pistons and bores all look good although I haven't cleaned everything up. I got them out using a propane torch and a pair if vise grips. It was congealed brake fluid that had everything stuck. A guy on MGNOC has an article going into this very subject, he said to use the oven. That wasn't going to go over well at my house. I was going to use the bbq grill but the hose developed a leak. I moved the torch around but concentrating on the side opposite the pads worked the best. Basically liquified the congealed brake fluid. Need to look at the master cylinders before I order rebuild kits. I took a break and worked on the shifting pedal and linkage which came a couple of days ago.
kk

[Antietam Classic Cycle]

I got the pistons out of all three. The pistons and bores all look good although I haven't cleaned everything up. I got them out using a propane torch and a pair if vise grips. It was congealed brake fluid that had everything stuck. A guy on MGNOC has an article going into this very subject, he said to use the oven. That wasn't going to go over well at my house. I was going to use the bbq grill but the hose developed a leak. I moved the torch around but concentrating on the side opposite the pads worked the best. Basically liquified the congealed brake fluid. Need to look at the master cylinders before I order rebuild kits. I took a break and worked on the shifting pedal and linkage which came a couple of days ago.
kk

New anodized alloy pistons are only $27, I would not reuse the original chromed-steel pistons.

MG Cycle currently doesn't even list the caliper rebuild kits and they're out of stock at Harper's as well. I ended up buying 2 from OPP Racing for my CX1100 project.

[n3303j]

Bevel Heaven lists the whole kit for $43.
They have yet to do me wrong.

[Antietam Classic Cycle]

Bevel Heaven lists the whole kit for $43.
They have yet to do me wrong.

https://store.bevelheaven.com/Brake-Related-Parts/Brembo-F08-Piston-Seal-Kit-38mm/