Special Front Caliper Pistons

[John]

Would anybody be interested in purchasing any new pistons? I have been searching all over the web, and they just aren't out there, but I have met a machinist who says he can turn out a batch. All he needs is a sample, and I have that. The cost of just a couple of pieces may be expensive, but the more we order, the cheaper it will be. Hopefully, there won't won't be such as small limited amount, like with the reserviors. That was a bummer, not being able to provide one to all that wanted one. I am going to meet with him tomorrow, and we will discuss his making some. I have no idea yet what the price may be, but if we were willing to payalmost $40 for a piece of rare plastic, then we shouldn't any trouble ponying up the cash for the pistons. The XS 750-850 Specials also used the same caliper, so there may be some intrest from them, also.
Let me know what you think.
Thanks guys

[sixtysix]

There was a guy a 3-4 years back ( Tom Dickerson ) who made pistons for all who wanted them, they were $10 each. Then T-Kat made a few from stainless steel.....he laughed at $10 and sold them at cost for about $40 each (if I remember right), he actually provided test samples to make sure they would work. It not a new idea, there's just not usually a lot of interest. There are two sizes you need to make, the rear of special is different than front, but luckily same size as standard. They need to be stainless or coated or something to prevent contaminating the fluid.

I wish I still had all the old emails I could save you some work, T-Kat gave up all the secrets to making them.

[John]

The rear caliper on the Special is the same as all three on the Standard, and the pistons are still available. I'd need 2 but would like to have 6 my self and I know of another member that needs a couple. I'll bet that most bikes that have been neglected/parked for a long time will need the pistons replaced if anyone ever tries to rebuild the calipers. If the price is right, it would be sorta like cheap insurance.

[sixtysix]

Yep it is a good idea - I actually bought 4 of those $10 pistons 'just in case'. (Now Marty has 'em) Almost every XS I have restored, the pistons were rusty under the seal or inside the caliper. Out of 10 calipers I could only hope to find two pistons I could use. I think the originals were chrome plated, but I could be wrong.I think it a great idea for somebody to make these.

[newmaac]

If the price was right, I would be interested in two.
I am in the process of re-doing my front brakes,(again). Maybe if I had replaced the pistons two years ago, when I re-worked the calipers the first time, I would not be back in there tonight??

[John]

The pistons were just as obsolete a couple of years ago as they are now.
If I can't generate enough interest here, I think I'll still have a batch made and put them up on ebay...two at a time. They may be more expensive there. They will also fit the 750-850 Specials.

Originally posted by newmaac
If the price was right, I would be interested in two.
I am in the process of re-doing my front brakes,(again). Maybe if I had replaced the pistons two years ago, when I re-worked the calipers the first time, I would not be back in there tonight??

[randy]

I know this is a thread for the Specials, but for those of you who may need to know,
Mike's XS has new pistons for the Standards (and therefore the Special rears) for $24.00 each.

His part # is #29-0516

Just don't tell him it's for an XS11, cause he'll swear they won't fit. They do, trust me, I've got three of them in Swamp Thing. The 77-84 XS650's use the same calipers as the XS11 Standards.

Hope this helps.

[TopCatGr58]

Hey Folks,

Was wondering if anybody has the specifications/measurements for the Special caliper pistons, the outer and inner diameter, overall length, location-depth-width of the O-ring groove, and the depth of the depression on the pressure side, the inside that is against the caliper housing!?

I can then use these to create a machining template with E-Machine program. Thanks in advance!
T.C.

[Ken Talbot]

Outer diameter 42.80 mm
Inner diameter 32.50 mm
Height 33.15 mm
Inner depth 26.50 mm

Groove for rubber boot 27.00 mm from bottom
Diameter of groove for boot 36.70 mm
Width of groove for boot 3.75 mm
Diameter of lip above boot groove 38.90 mm

Depth of depression on bottom 0.50 mm
Diameter of depressed area on bottom 28.00 mm

Need a pic?

[trukleon]

pic

Yes,, send pic too!!!

[Ken Talbot]

Please forgive the quality of the dimensioning info:


And, a bottom view:

[xswilly]

hey topcat

at work i generate cnc programs
for our machines using a program called mastercam

I don't have access to the machines themselves
but if you need some code written
I could do it

anything to help

[TopCatGr58]

Hey Ken,

Thanks for the Xsellent diagram/dimensions!!

XSWilly, thanks for the offer, but I have a program that was posted about called E-machine, that I use a CAD type interface and create the item to be machined, then I submit it to the company via ONLINE, and it provides an estimate on production costs and such!

I haven't played with it in many months, will have to RELEARN it, and tinker with it quite a while. Those chamferred edges will be fun!!
T.C.

[newmaac]

Ken, are the pistons in your oics the stock parts, or is that a stainless steel aftermarket item?
I just disassembled mine and was wondering about the "ss" markings on the head of the piston.

[Ken Talbot]

Those are the stock pistons, Mike. They're a bit rusty and have a few small nicks, but they're still serviceable. I won't do much more than a fine touch with some 800 or finer grit on the sides, but I'll give the groove and pad contact surface a good blast in the glass bead cabinet..