Source for caliper pistons??

[Dirtcrasher]

I have some calipers to rebuild, and many pistons are identical.

I found Moose at a price of 13$ a piston, but they don't list one (at least I didn't find it yet on Ebay) for the 350X dual piston front caliper.

I have about 2 dozen calipers to rebuild.

I'm considering making my own, I can order the phenolic material that Honda used sometimes.

Anyone have a source by size? Or just a suggestion on where else to search??

Thanks for any help!!

[deathman53]

I read somewhere that the piston used in 85/86 atc250r, 86-89 trx250r and 85/86 350x(front only) is the same as pistons for early 2000 cr250r front caliper pistons. Well, except for the parking brake piston.

[Dirtcrasher]

I've been digging everywhere, crossing part numbers and so on without a ton of luck.

None can be found by size, only steel or phenolic is mentioned; Which, BTW, I can buy a foot and machine up my own pistons.

Other thing is Moose, Moose seems to carry tons of caliper pistons for about 11$ each which is great. I just can't find one for the 350X, ATC or TRX.

I did read some year CRF230L may use the same size piston...

[Troyg25]

Im in the same situation. Looking for 2 sets. Looking up by part number I found the follow machines that use the same piston.

This Honda 45107-MG3-016 PISTON fits the following models and components:

Honda ATV 1985 ATC350X A Front Brake Caliper (1)

Honda ATV 1986 ATC350X A Front Brake Caliper 2

Honda ATV 1986 TRX250R A - FOURTRAX 250R Front Brake-Caliper

Honda Motorcycle 1984 XL600R A Front Brake-Caliper

Honda Motorcycle 1983 XL600R A Front Brake-Caliper

Honda ATV 1985 ATC250R A Front Brake-Caliper

Honda ATV 1986 ATC250R A Front Brake-Caliper

Honda ATV 1987 TRX250R A - FOURTRAX 250R Front Brake-Caliper

[Dirtcrasher]

Thanks Troy, I did find that as well but I can't find the XR pistons either.

Maybe one of those websites for XR's only...

[deathman53]

Im in the same situation. Looking for 2 sets. Looking up by part number I found the follow machines that use the same piston.

This Honda 45107-MG3-016 PISTON fits the following models and components:

Honda ATV 1985 ATC350X A Front Brake Caliper (1)

Honda ATV 1986 ATC350X A Front Brake Caliper 2

Honda ATV 1986 TRX250R A - FOURTRAX 250R Front Brake-Caliper

Honda Motorcycle 1984 XL600R A Front Brake-Caliper

Honda Motorcycle 1983 XL600R A Front Brake-Caliper

Honda ATV 1985 ATC250R A Front Brake-Caliper

Honda ATV 1986 ATC250R A Front Brake-Caliper

Honda ATV 1987 TRX250R A - FOURTRAX 250R Front Brake-Caliper


brake pistons for most cr250 and cr125 will work for them, they are slightly different, as they are lighter and made of the different material.

[Troyg25]

brake pistons for most cr250 and cr125 will work for them, they are slightly different, as they are lighter and made of the different material.

Can you please tell me what years and are the sizes the same for front and back pistons for the cr125/250? Are the internal seals also the same?

Thank you

[TSpencer]

I just got 2 OEM pistons from rocky Mountain last week but now it looks like they are unavailable. I boogered up the caliper bore trying to get the old ones out as the top metal portion fell off and the rest of it, I guess that phenolic material, was seized in there good. Rocky Mountain said they could get me the caliper body but it was backordered. I'm hoping but not holding my breath. Any chance one of those caliper bodies is for sale if Rocky Mountain doesn't come through? I have the bracket and rebuild kit, I just need the body with the bores.

[gaby]

I read somewhere that the piston used in 85/86 atc250r, 86-89 trx250r and 85/86 350x(front only) is the same as pistons for early 2000 cr250r front caliper pistons. Well, except for the parking brake piston.
If the pistons on the front and rear calipers on a 1985 atc250r are the same size I think I found something. I know the rear caliper pistons are 25.3mm

[gaby]

Boomerangsports.com made by nissin

[Dirtcrasher]

I just got 2 OEM pistons from rocky Mountain last week but now it looks like they are unavailable. I boogered up the caliper bore trying to get the old ones out as the top metal portion fell off and the rest of it, I guess that phenolic material, was seized in there good. Rocky Mountain said they could get me the caliper body but it was backordered. I'm hoping but not holding my breath. Any chance one of those caliper bodies is for sale if Rocky Mountain doesn't come through? I have the bracket and rebuild kit, I just need the body with the bores.

Next time put a solid bolt in the brake line hole. Loosen your bleeder and the end of grease gun, it will op on and you can push them out safely, just messy.

They will not always come out even if it's a dual piston, you have to get creative to stop one side while pushing the other until you can wiggle them out, it's easy...

[badasskfx]

I’m a parts unlimited dealer do you need me to price any parts? I need to rebuild the brakes on my 350x. I have no problem ordering a couple to measure if you think something might work.

[Dirtcrasher]

I’m a parts unlimited dealer do you need me to price any parts? I need to rebuild the brakes on my 350x. I have no problem ordering a couple to measure if you think something might work.

I'm definitely interested in the cost of pistons. I think many of them are just a standard size and will work fine.

There's a dude on Ebay selling pistons and valve buckets for thumpers, he's making bank!! He must have some great resources, sometimes we just stumble upon things...

Does PU go by size in mm's? or by model?? Thanks Shaun/Sean/Shawn - I forget now :lol:

[Allstock]

Any updates on sourced parts??

In measuring an 85 front and an 85&86 rear.. The front 250r pistons are .001" less than the rears in diameter. The difference must be due to the expansion if the steel being greater. Aside from the parking post the rear pistons are almost .035" shorter in height.

Why not just use the front phelonics in the rear, shave them down .035" and enjoy the weight savings..

[oldskool83]

I used trx450r ones in my 350x caliper, no issues and delrin.

[Dirtcrasher]

Any updates on sourced parts??

In measuring an 85 front and an 85&86 rear.. The front 250r pistons are .001" less than the rears in diameter. The difference must be due to the expansion if the steel being greater. Aside from the parking post the rear pistons are almost .035" shorter in height.

Why not just use the front phelonics in the rear, shave them down .035" and enjoy the weight savings..


Long read but hopefully helpful...

I wonder if the measurement difference your getting is just because steel is harder than phenolic and the micrometer tip just bites in a bit more, or did you use calipers? There very well could be some thermal expansion going on with that material. How did you come up with a .035 difference for the rear?? Did you mean .039 or 1MM?? Doesn't matter, just trying to be on the same page as everyone. Anyway, it's always hard to hold any type of plastics in a lathe and I don't have a phenolic piston in front of me but I believe the phenolics are solid with a short relief in one side but it's not like the "bucket" of a steel caliper. A bucket you could hold the inside on a lathe and turn off 1mm or whatever the spec is, but a Phenolic, being a harder type of plastic that flexes far more, there would be no way to hold one and take off that whatever >1mm dimension and half and half always sucks.

I don't know of any Delrin being used by Honda in their calipers but some other manufacturer may have used it. Although, It has self lubricating properties which means it has absorbed oil and gives it up when it gets warm, hence why Delrin is considered "self lubricating", so brake fluid wouldn't be too friendly with it. But the material I priced, and that was with me being aware that I'd try to lose less than 4mm's when cutting them off to length after machining, was still expensive.

The dudes selling the rebuild kits must be using K + L or a similar Japan or Taiwan vendor because it's a good kit, or it seems to be. The rubber stuff and the bolts/pins are very Japan looking rather than China, but I could be wrong there too!!?? The new calipers and masters that are cheap are definitely China, we all know that buy now but someone is buying 18$ front master cylinders - crazy... Unless you see "Nissan" avoid whatever they try to sell you for a replacement, it's better to rebuild your OEM stuff. Most of our OEM stuff is bad because any of us hoarders - we don't always use all of them and or the parts all year round, or they sat for many many years, but what I'm saying is that often none of the metal parts are out of spec, the OEM stuff typically needs a total tear down and rebuild with all new rubber stuff, pins and bores cleaned up, caliper painted or coated, new bleeder and cap, and they're like new. I think I mentioned I bought a China caliper for 40$ just to see the guts. They seemed to be a drawn cup steel piston that was then coated but the diameter was weird, not .001 either, more like .05 or half of on mm different diameter. The China brake castings are very rough, there is no secondary operation to ensure the castings are clean. They blast that casting out quickly, they must cut half the operations out of the fine tuning and finish. The amount of cast aluminum barely hanging on was quite a bit, the finish on every piece is rougher, less round, poorer tolerances, misaligned and I doubt the steel and aluminum were quality metals either.

The pistons on Ebay (2) for 49.99 must also be from K + L , Parts Unlimited or somewhere similar, IDK what those guys pay. If we aren't dealers we may still have to pay quite a bit ourselves even if we could use them. I'd turn them on a lathe but I'd need exact sizes, thermal expansion rates (unless we figure out whether that matters) and a much longer piece of material that's much more expensive. I think I priced it off of an 8" or 12" piece and I could not make them inexpensively.

Anyhow, I look at valve buckets and there cost and I say to myself that they aren't made too much different than a brake caliper piston!! Who knows...

[Allstock]

Were these oem pistons or did someone make them? Are you sure they were Delrin and not Phelonic? The Phelonic can appear to be a hard plastic. It is what was used on the oem 85 fronts.

As for measuring I used a micrometer. I measured 2 sets of rear steel pistons and 1 set of front phelonics (oem 1985). The difference of .035" was measured with a caliper as it is greater than the one inch limitation of the micrometer I have on hand. I wasn't concerned with exact accuracy on that measurement anyway because that difference was in the height it would not be an issue except for pad and rotor thickness as to whether or not the piston could sit in the caliper deep enough to allow the pads sufficient gap for the rotor without dragging. In addition, it can be shaved down (insert side) without precision (except for enough to cause side loading in the bore) as it has no bearing on the precision of the O.D. that the seal rides on.

[oldskool83]

like i said, i use trx450r ones, yes they are phenolic and about never wear out. A lot of old XR ones are the same. Go on partzilla.com look up the part number, find the machine go buy what you need.