Rear and Front Dunlop Brake Pistons/Caliper

[richard btype]

I fitted 4 new rear brake piston units about 30 months ago, (the original Dunlops were seized with heavily corroded bores) however one of them on the diff side has just started leaking. It has been very difficult to work out what is wrong, for after removing the piston there was no visible sign of damage on the bore or to the rubber seal.

On inspecting the original Dunlop items they are a one piece casting, whereas the replacements appear to be two piece and possibly bonded I believe it is the two mating faces where the issue might be found - I wonder if anyone else has experienced such a problem?

It has been my intention to get the original Dunlop items refurbished and wonder if anyone can recommend a company for this work? I believe I recall that some companies re sleeve the bores in stainless steel to get back to the correct diameter?

Finally, might anyone have a spare pair of the original front Dunlop calipers that they would be willing to sell, condition unimportant as they could all go together for refurbishment...

[Heuer]

Angus Moss offers a service to reline the calipers - he did mine for me.

[richard btype]

Thank you David...

[Philippe-J.]

Not sure to be in the proper thread for this, but anyway: I am considering re-sleeving my brake caliper cylinders. I found a company in NY, USA, that use brass sleeves. What about brass as opposed to stainless steel?
I must admit it is not straightforward to find a guy able to do this in France. Could one of you indicate a british mechanical that would do it properly with friendly costs? I mean, less expensive that changing for new .
Thanks!

[mgcjag]

I checked a couple of machine shops to resleeve cylinders last year...its was cheaper to buy new replacements...Steve

[Boris64]

I work for a solution in France,
If you can wait September…

[Philippe-J.]

Excellent news Boris. Sure I can wait, I was just trying and anticipating the next activities, I don't intend to start them at once. Anyway it is now time for hollidays, isn't it?

Steve: new replacement is an option, but only if refurbishing original parts is not worth the expense, which I am trying to figure out (not to mention feasibility).

Philippe

[Desmo]

Hello Philippe,

Have a look here:

www.ccparts.nl

Best regards
John

[abowie]

You might consider https://mossmotors.com/8777-2-cp-cobalt ... r-axle-set

I've not used them but they are well priced and a better design than the original.

[typea59]

Hi Philippe,

You can ask Uryk Dmyterko who machined mine from the originals.
Regards

[dxke38]

I've used Past Parts ltd in Bury St Edmunds for resleaved Dunlop brakes, excellent service.

[Philippe-J.]

Thank you all for your answers. The good news is that there are several companies to do the (good) job
As a french man I have to regret that such a job seems to be such an issue for the french companies I contacted, as opposed to the English companies you cited for whom it is "normal work". Unless Boris's solution proves to be ok in September?
This example gives the explanation (or the consequence?) why oldtimer restoration is one or two levels higher in England.
Anyway, whatever my choice they will have work to do, as I couldn't avoid to break part of the shouldered tops of the wheel cylinder when I extracted the almost sized pistons:



OK, it was a really crude way , and it resulted in:



The machine worker will have to be well skilled.

[mgcjag]

A machine shop will re sleeve but I doubt repair that damage....Steve

[Philippe-J.]

Then I'll try to re-weld the shouldered edge prior to send them to the shop.
I know, this sounds to be quite hazardous but after all these edges just hold the brake dust seals, so they don't have to sustain mechanical constrains, do they?

[mgcjag]

To be honest if it were an early or special car then keeping all the original parts is ideal....but I would be thinking of new replacements at less cost than to repair would be worth thinking about....I'm sure you have bigger things to sort out than calipers....Steve

[Philippe-J.]

Thank you Steeve, good point, my car is far from deserving an history correct restoration. I'll give thoughts to your opinion.

Philippe