Front brake disc seal replacement

[Pdv]

Hi all,

I am going to fit new parts seals etc to my calipers, first how do I  remove the seized or just stubborn, pistons, not on the car I am sorry to say and should I replace the pistons as well  regardless.

Second how do I  identify which type of caliper ie 12 or 14.

Thanks

Steve

 

 

[Pete Lewis]

what car ???? 

type12

 

Type 14

[Pdv]

Hi Pete,

Should have said it is a 13 60.

Steve

[PeteH]

Piece of wood between the Pistons and appply 100+psi of air via the pipe connection, It worked on my P-107, a month or 2 back?. Once you get them moving Plumbers pliers will often get them out. If you plan to replace the pistons you can get even more brutal, if not, care and teasing should limit any marking to the extreme edges.

Pete

[Peter Truman]

I had to revert to a grease gun the compressor didn’t develop enough pressure the grease. Was easily cleaned out of the calipers piping and piston/bores.

I thought type 14’s had 4 bolts holding the two halves together, type 12 had 2 bolts, I stand to be corrected.

[johny]

Think thatll have type 14 but it should have it cast into the caliper itself. As said, compressed air can be used to force out any pistons that are stuck and then they and the bores can be inspected for any damage.

I just sent my calipers off for exchange at Canley (probably better than getting reproduction new ones as there have been problems) as I didnt know what I was going to find inside...

[DanMi]

those pics Pete sent are both type 12, type 14 have 4 bolts holding the halves together type 12 only 2. If a 1360 they will be type 14. I have to agree with Johny, the cost of the recon callipers is so little more than the cost of pistons seals etc, so probably best to go that route. To free a seized piston I normally bang the piston in with al long pole and hammer, then lever out with a couple of screwdrivers (off car), or hold one piston in with a g clamp and force the other out by pushing the brake pedal (still on car). Levering etc will damage the piston but if seized it needs replacing anyway.

[Colin Lindsay]

48 minutes ago, DanMi said:

 I have to agree with Johny, the cost of the recon callipers is so little more than the cost of pistons seals etc, so probably best to go that route. 

Check the previous threads on the quality of modern replacements first. Some of them are causing problems.

The problem with removing pistons is that they meet in the middle before they'll drop out; you need to wedge one then remove the other, and then block up the hole it came from in order to get enough pressure to remove the other one. I find that stuffing the piston chamber with cloth works, but often has to be held in place by hand so watch the other piston especially if using compressed air - it'll get you on the back of the knuckles and boy does it hurt.

[DanMi]

18 minutes ago, Colin Lindsay said:

Check the previous threads on the quality of modern replacements first. Some of them are causing problems.

That's why I said recon rather than new, just get someone else to do the work for you

[Pete Lewis]

1 hour ago, Peter Truman said:

I stand to be corrected.

2 bolt  12s  and  4 bolt  14s      Pete  im sure youre correct but those were just copied from a site that should know  'better'

struck me they were just a generic shot of a caliper 

heres a shot of a 4 bolt 14

 

 

[Peter Truman]

I’d just refurbished a set of what I believed to be type 14’s ex Escort as that was all that was available here, fortunately they mount on the Spit vertical links ok and fit the disc’s too.

They we’re a bit of a gamble but at $60 plus new pistons/seals a good deal.

[chrishawley]

There's seized and there's SEIZED ; so a lot depends on particular circumstances. But in general it's the outer quarter of an inch of the piston which is the problem on account of the hard chrome breaking down under corrosion. Once a piston can be persuaded past this corroded rim the rest of the movement is usually relatively free.

Worth immersing calipers in diesel for a few days if poss; improves the chances a bit.

If one or more pistons won't budge with air pressure or hydraulic pressure (as above) then other methods are needed. Options might include:

• On some calipers there's enough space around the body to get mole grips on the piston and rotate the piston in the bore to and fro. Once it's moving, a combination of rotating and prising will release the piston

• Avoid any method which involves hammering anything - a stuck piston gets more so if it's clobbered out of round.

• Since forever it's been standard to say that calipers shouldn't be split into their two halves. But this can be done and will make the piston readily accesible to mole grips/Stilsons etc. But halves musn't be mixed up and it's crucial to replace the o-ring between between them.

• For the most intractable cases (esp where the unit is rare or expensive) my own method is to weld 1/2 mild steel box section across the piston. Through this a long 10mm bar can be inserted providing all options of levering/rotating. Damages the piston, of course, but if it's that stuck it's probably going to have to be replaced anyway. TIG better than MIG for this sort of welding.

Sometimes exchange/recon is the more cost effective way to go if units cheap/readily available.

 

 

[Colin Lindsay]

3 hours ago, DanMi said:

That's why I said recon rather than new, just get someone else to do the work for you

Apologies! You're way ahead of me. Need more coffee....

37 minutes ago, chrishawley said:

There's seized and there's SEIZED

Sometimes you just gotta go heavy duty... this one took a lot of chiselling after the caliper had been split to allow better access.

 

[Pdv]

Hi All,

Thanks for the replies.

Chrishawley mentioned that it has been standard not to split the calipers into their two halves.

Providing  the o ring is replaced (which comes with the kit) both faces are clean and the bolts are torqued correctly what could be an issue.

By the way they are type 14.

Thanks

Steve

[Pete Lewis]

cant see a problem with splitting the halves when clean and new 0 rings  after all they were put together by humans on the assy line 

Pete

[Colin Lindsay]

Keep them clean, replace the seal (part CS1 at Canleys) and tighten up - there's no torque figure for the bolts that I've ever found so really really tight seems to work.

[daverclasper]

21 hours ago, Pete Lewis said:

cant see a problem with splitting the halves when clean and new 0 rings  after all they were put together by humans on the assy line 

Often wondered that, when you can do cylinder rebuilds, without it appearing to be a "no no"?.

[Pete Lewis]

there is always a resistance to tamper with parts designated as safety critical  but they are all assembled on a production line to a process by humans 

Pete

[PeteH]

The ones on my 13/60 are (aparently/allegedy) "new". So fingers crossed there. The P-107`s where done a few weeks ago using the "Air" method of piston removal, new seals etc. the braking with new pads, was a revalation!. I`v now learned to put less foot into it!