Hi all, am undertaking front caliper rebuild on my 2002 Triple 955i. All good so far, but the top of the pistons (the pad end) is a little pitted and will not polish out. I am sure it is pitting not caked on crud. As this pitting is 'above' the hydraulic seal (ie the outside side of it) are new pistons necessary? The rest of the pistons (90%) are mirror finish. Or, as it's brakes....it'll be £150 well spent...?
If you mean the ‘rim of the bucket’ it is inconsequential provided it bears pretty flat on the back of the pad. They should get a smear of brake grease on re-fitting to forestall further corrosion. Brasso is pretty good for polishing the important bits! Just clean it off well as it is a fine abrasive.
DanielB Yes I would fit stainless pistons. I did think they had stainless. I have in the past sanded rough bits out and uses super glue then sanded back again. Regards & Ride Safe Joe.
DanielB. They are goners stick them in the metal skip and treat your self to some stainless. Regards Joe.
You should find your bits here: https://www.triumphparts.co.uk/prod...rts/triumph-all-parts-stocked/triumph-brakes/ Personally I don’t think stainless confers any particular benefit given the service life you probably seek.
When doing caliper refurbs I always use red rubber grease and a nice smear of it around the outer seal where the exposed piston shows,i found as the pads wear more of the piston is proud and prone to the elements this trick has worked for me for many years.
It is the flowing pattern you get from twisting and working strands of steel with heat and hammers to create strength with elasticity. Found in swords and 19C shotguns.
I think it's the reflection of the paper/cloth the piston's are sitting on ... ? Polish up the piston's on a cloth polishing wheel ! Those pit's will still be there but very minor ! It's the rust that's sticking proud that will cause the most issues. I did the piston's on my America and the brakes are fine ! That pitting is right on the edge of where they start working. The sealing ring is several mm's back ! So all should be fine with new pads and rubber greased as mentioned above ... ! ... ?
As you have overhauled the rest of the braking system and for the small nominal cost of replacement pistons replace them, it will give you peace of mind, plus 1 on the red grease.
Thank you all....new pistons are on their way. I agree...I am sure it'll be all ok, but I may as well, seeing as I'm elbow deep and hundreds of pounds in (valve adjustments, steering bearings etc) I may as well replace the pistons then loose no sleep over it.... Just to confirm....where am I putting the red grease? In the seal grooves? On the seals themselves? Does that include the little seals between the caliper halves? Lightly on the pistons themselves? On the bleed screw thread or is that copper grease? What about on the bolts that hold the caliper halves together, copper grease?
OK apologies for confusing you with misplaced humour. The photo is of Damascus shotgun barrels. You achieved a similar effect with reflected paper towel and fine buff marks. Grease - red brake variety. A light smear on the inner fluid seal for ease of assembly but brake fluid would be my preference. Light smear to fit and seat outer dust seal but minimal as it will attract dirt. A more obvious smear on ‘bucket rim’ where it bears on the back of the pads and on the opposing fingers (or pistons as the case may be) The calliper gallery seals need no lubricant but you can use a light dab to keep them located during assembly. Bleed screws and calliper shell clamping bolts use copper anti seize. It resists corrosion rather than lubricates and impedes air leaking back up the thread during bleeding.
I myself I have never used grease I just smear them all with the brake fluid. Used this method for years and its never let me down. All the other bits like bolts and bleed nipple I apply anti seize grease or copper slip. Regards Joe.
No apology needed... I just worried one of us was going mad... Thank you, and to others, for your continued patience and explanations. Really appreciated and a huge help on my motorcycle maintenance odyssey!
