60 replies to this topic

[dapleb]

Decided to rebuild some calipots that have been lion aboot. Starting to wish I hadnt bothered now!

I borrowed some compressed air and mild heat and eventually managed to extend the pistons as far as they could make it without colliding, then split the calipers in half but even though all the pistons moved out as far as possible with compressed air, I cannot get enough purchase on the pistons to remove the buggers. I have mashed one piston trialling grips with a rag underneath and it didnt budge anyways.

Anyone got any good ideas on how to git them burgers oot? The only thing I can stink of at the mo is an interference fit with the inside of the piston and then pull loike a bassad,

Ugh.

[TinTin]

Its a long time ago since I did it but I got a grease nipple the same thread as the bleed nipple & pumped grease in it till it popped oot.
Mind you it was a single piston one but you could stop one of yours near the end of its travel with a g clamp or summit till the other is ready to pop out.
Air is compressable (obviously) liquids & grease arent.
Well it worked for me

Edited by yamahasam, 31 October 2012 - 05:13 pm.

[dapleb]

Cheers Sam, I am kinda past that stage as they are all extended as far as possible without collision before the halves split. The Heinz suggested removing the seals from one side and then reinstalling the pistons and then repeating on the other side No idea how that could possibly work as you would have a non pressurisablesystem after removing the first seal!!!

I emailed the knowledgeable powerhouse on ebay who sold me the seals and they also sell pistons......phewww and suggested aluminium vice covers, the trouble is the calipot halves are a ridiculous near impossible to clamp shape.

I sure hope a previously working set of calipers are easier than this!!

EDIT: ahhh found an tool available for hollow pistons. Doubt it will cope with how stuck these are but cannae hurt none.

[Rallyist]

Put em in the oven when nobody is looking, about Gas mark 8 230c/450f for about 20 mins and they will fall out will stink a bit tho

[dapleb]

I didnt want to heat em up too much especially whilst split. Heat certainly helped with gettin the burgers to extend. Will defo try some more heat on me next attempt. ta.

[Studley Ramrod]

How about using some o that freeze spray on the pistoons ?

[dmmsta]

How about using some o that freeze spray on the pistoons ?

An "air duster" aerosol can will do the trick held up-sid-doodle.
Will need to be a cheap one tho, as the more expensive ones work either which way...

[dapleb]

How about using some o that freeze spray on the pistoons ?

They have been monkey pissed to the max over the last few days, tried shock and unlock too but it werent a great shock that it didnt unlock. With the calipots split, you can feed spray in behind the pistoon easily too.....I got one out eventually and there is a good 20 years worth of crud in there, plus the seals have grown into the calipers!!! Keen not to damage the seal grooves I hoiked around unsuccessfully with a pencil but then picked up a blade fuse, nice wide contact patch in two areas, in and lever/flip and seals out in a second with no damage.

Now getting on with udder non calipot things until me new piston twirling tool arrives. I did read a neat trick with 2 tyre levers sandwiching a metal bar inside the hollow section to lever outwards and pull out piston.....clever idea.

[dapleb]

Phew, that was ermm fun.

A few piccies of progress so far:

Starting point:
 calipot_start1.JPG   97.56KB   44 downloads  calipot_start2.JPG   111.03KB   66 downloads


Jizerified and toothbrush scrub for a good while:
 calipot_jiz.JPG   98.39KB   68 downloads


Although still attached to hydraulics it wouldn't shift the pistons at all. Even with all others blocked off. So decided it was time to detach and try compressed air and heat which eventually got pistons extended as far as posible (but still rock solid in bores!).


Heat and compressed air FINALLY got me to ear:
 calipot_piston_extend.JPG   144.86KB   64 downloads


Next the calipot half bolts which were previously cracked open, were undone:
 calipot_splttin.JPG   133.11KB   59 downloads


Which left me ear:
 calipot_halves_pistonsin.JPG   114.37KB   66 downloads
Note the lille calipot half 'o'-rings. These were previously not available apparently but now powerhouse sell em as part of a kit on ebay.


After alot of swearing and a combination of heat gun, aluminium vice jaw covers AND a piston removal tool (could have done with an extra pair of hands for this really), oi gots to this stage:
 calipot_halves_pistonoot.JPG   92.36KB   70 downloads


Important to keep organised and luckily found a tray with right number of compartments:
 calipot_orgy_nised.JPG   97.89KB   64 downloads


Getting the seals out with a non scratchy instrument was not going well, kept snappin me pencil. These seals had grown in to the caliper so I picked up the nearest proddy thing (a fuse) and it worked first time. Just push in gently then lever upwards. Perfect and no damage to the seal recessesesesesseseesss:
 calipot_fusetrick.JPG   75.34KB   67 downloads


Next is clean of all the bits and inspection of pistons, I mullered one but the others should clean up ok. There is plenty of cleaning to do:
 calipot_manky.JPG   102.68KB   47 downloads



Also thinking of painting the outers, have some alloy wheel paint somewhere, not normally in to this painting lark so any advice welcome.

[tdm850rider]

Perseverance pays.

[TinTin]

I painted some once. Bled brakes- paint off. Stripped down again & polished the buggers. Kept em shiney for a while with solvol then just rubbed them with scotchbrite now & again to clean them & keep em looking nice. Anodising is the only real option

[stu]

So dappers, are you about to offer a reconditioning service ?

[dapleb]

I wouldn't want to deprive everyone of the "pleasure".

Having said that you know oid do anything (well nearly) for you. If I survive a good testing of these then mayhaps.

The rebuild of calipers is not really very economical since a set of boo spots would probably work out the same as the rebuild kit. Of course they might need rebuilding too. I don't need or particularly loike the feel of boo spots, hence the choice of rebuild.

[Studley Ramrod]

Coming to bits noicely !

Was it a build up of crud that stopped the pistons coming out ?

Also, do ya reckon them o rings could be had without buying the kit ?

Godda spare set o calipots mesel, so might have a go at 'em

[dapleb]

Yup I'm sure it was the 8 tons of crapola, the skank in the seals and being stored for years without moving that were stopping em comin ooot. This is a spare set, which if/when finished oil bung straight on the boike...at which point I will store the set that come off in DISMANTLED form until they are required. I wouldn't rebuild a set until you need em as the pistons sat still in the bores for long durations prolly aint no good ferrum.

I am sure you could get seals without the kit. Since I had collected one calipots worth of OEM seals over a year or so, powerhouse were kind enough to sell me one full kit and the calipot half o rings and bits n bobs only for t'other side.

Also on the trail of affordable replacement wubber hoses...will report bacon that wan.

[Matlock]

The pistons seem in remarkably good nick considering the crudification and subsequent removal shennanigans.

[danceswithmopeds]

Any chance of a link to that Powerhouse place?

[dapleb]

I have been getting stuff through ebay from em ear: http://stores.ebay.c...=p2047675.l2563

I have just ordered a coupla pistoons, if you want me to enquire about Carpe discount will happily give it a whirl. Either way, they have been pleasant and helpful peeps to deal with.

EDIT: If you donut see what ya want listed then send em a message and if they gots it they will put you up a listing.

[danceswithmopeds]

Thanks, stored for future use.

[dapleb]

Me calipot halves are soaking in jollop at the moment and I have scrubbed with toothbrush but still some skanky bits in the seal grooves. Any good tips for cleaning in this confined area without scratching bits please and thank you?