Lagondaforum

Subject: Brake cylinder pistons seized; how to free?

---

Well, these are actually on my LG6, but of course the same brakes as the V12 (but not LG45 etc, hence posting here).

I last drove my LG6 in 2001, so predictably, all the pistons are seized; at least in the rear brakes. Not too surprised, I found the pistons on my V12's brakes could be stuck after just 6 months lay-up.

The cylinders are cast iron, whilst the pistons are aluminium...perfect combination for electrolytic corrosion. The pistons are recessed to accept the shoe push-rod, so have nothing to grasp to twist. I recall dealing with a stubborn one on the V12 many years ago, ending up using a hammer and punch...that did the job eventually but didn't do the soft aluminium any favours. Really want to be kinder this time round!

So does anyone have a neat and reliable solution to dealing with stuck pistons?

Laurence

Subject: Re: Brake cylinder pistons seized; how to free?

---

A thought for the future .There are a few outfits over here that will sleeve the cylinders with stainless and I think use brass pistons.

---

Subject: Re: Brake cylinder pistons seized; how to free?

---

Laurence

I had the same issue with stuck pistons and badly scored cylinders on two wheels and in the end had to replace the whole thing as the aluminium pistons were not salvageable. I found replacement units at PowerTrack Ltd
Tel/fax (01753) 842680 International +0044 1753 842680. Although this will surprise anyone who has done this sort of job, the replacement item was identical and fitted perfectly - a direct swap. What a nice surprise that was. Although I prize my car's originality, there was no choice other than replacement and perhaps on braking components I am more happy to compromise. The refurbishment of the removed cylinders and pistons is still at the bottom of my jobs list after 10 years.

This was done nearly 10 years ago so these contact details may not be helpful.

Alistair

---

Subject: Re: Brake cylinder pistons seized; how to free?

---

Laurence;
I once dealt with a stuck caliper piston by removing the caliper from its mounting, then pumping the brake pedal until the piston was pushed out of the cylinder. I think something similar would work for you if you removed the drum and shoes from one wheel at a time, then pumped enough to get the piston moving. This assumes your master cylinder is still operational!
Alec

---

Subject: Re: Brake cylinder pistons seized; how to free?

---

They are still in business, based in Windsor http://www.powertrackbrakes.co.uk/

---

Subject: Re: Brake cylinder pistons seized; how to free?

---

You may want to try these people in Bury St. Edmonds, Past parts.

I can recommend, excellent work and reasonably priced.

http://www.pastparts.co.uk/contact.htm

01284 750729

Simon

http://www.Lagonda-Rapide.com

http://www.DB-Lagonda.com

---

Subject: Re: Brake cylinder pistons seized; how to free?

---

Hi,
Remove cylinder from car,
Place cylinder in a bench vice with a socket or similar for a rod, close vice jaws forcing piston to move inwards,
Repeat with cylinder turned the other way,
Keep repeating until pistons are quite loose,
Tap out gently.
Front cyls are 1 1/4" dia and rears 1 1/8" you can by seal kits easily if the bore is not bad.

Past parts are a good bunch if not.

Regards,
Julian

---

Subject: Re: Brake cylinder pistons seized; how to free?

---

Thanks all for replies. I hadn't realised that one could still buy correct replacement cylinders. I did know about stainless sleeving, but these cylinders are pretty tolerant of some rust pitting, from experience with my V12.
The cylinders have different markings side to side, yet one at least is a perfect match in all respects to one I have off my V12, so they probably are all original.
In the end I used Julian's method with a few tweeks:

Removed boots, scraped out most of the rust with blunt pointed knife, then kitchen scourer wire wool. Then sprayed with WD40. Found a socket a nice close fit to the bore, then as Julian, in a vice, tighten, tap cylinder casing (not too hard) with hammer, retighten. Let WD40 soak overnight. Repeat again.

With one cylinder, I connected a tyre pump compressor to the bleed valve (bolt in brake fluid inlet), and one of the pistons popped out; easy to press the other out.

With the second cylinder, must have been rustier, that trick wouldn't work. Sprayed with WD40 frequently, gradually wound each piston in, until eventually, first one, then the other, freed off enough for the internal spring to return the piston. Eventually one was free enough to force out by pushing the opposing one in. By this method, although it took longer, there is no damage to the spring or seal spreaders (neither of which are supplied in seal kits).

AS an aside, I did try banging the cylinder vertically downwards on a flat steel plate, hoping that inertia and the return spring pressure might free a stuck piston...probably a forelorn hope given the light weight of the aluminium pistons. What did surprise me is that this did slightly crack the boot flange. So...don't try that!

Laurence

Laurence