Brake Caliper Pistons

**Frontier1** · 21st April 2007, 09:17 AM

Hi All,

'93 Disco' v8i.

The front driver's-side brake caliper has a leak on one piston sleeve. I bought a kit for the entire caliper and put in new seals in the one leaking but it continues to leak.

If it is the piston, (there is some pitting, etc), can I replace one piston only or will that create a difference in pressure on that one brake pad?

Can these pistons be cleaned up with emery paper or will that make the tolerances worse?

Since all four pistons are the same, can't I swap them around to confirm whether it is a piston issue or something else?

The idea of changing all 4 pistons even though only one is leaking seems a bit expensive too when I have been told that they are at least $70 each.

Option 2 I guess might be to buy a good 2nd-hand caliper...

Any advice will be appreciated guys.

Cheers, Pete'

**Reads90** · 21st April 2007, 09:26 AM

Not really that expensive . Just have to hunt a bit
Here is a set of 4 for the price you were quoted for one

http://cgi.ebay.com.au/LAND-ROVER-DE...QQcmdZViewItem

Or this one which you can buy and they will ship them over for you and they take paypal as payment
This is a set for a 93 V8 Disco
http://www.land-rover-parts-shop.com.../20/78/660/863

**Frontier1** · 21st April 2007, 09:49 AM

Hi Reads90,

I must have missed the first one on ebay and the 2nd one I didn't even know about so thanks!!

I have emailed the ebay post to ask whether those Defender ones will suit the Disco too.

This will probably be the way I'll go then but I am still curious about the questions I had, especially about the emery paper solution and whether it would work as a stop gap.

Anyway, thanks for the sites!!

Cheers, Pete'

**PhilipA** · 21st April 2007, 11:26 AM

I think they are chrome plated so the emery would probably not work.
I do not think replacing one would be a problem, as long as the others were perfect.
I would probably try it!!
Regards Philip A

**Frontier1** · 21st April 2007, 01:11 PM

Well now I have swapped two of the pistons over and it still leaks from the same bore even with a new seal so now I'm really confused.

If it is still leaking at the same spot with a different piston then it must be the bore right? Not the piston?

Pete'

**4bee** · 21st April 2007, 02:37 PM

Wouldn't it be one of the two seals then or a buggered piston? The piston metal actually slides in the O rings which are proud of & fit in the grooves of the cylinder wall. Maybe you have got a twisted seal & needs refitting or a daggy piston. Certainly worth having another look.

I wouldn't be using Emery Cloth, I would be using say, 400 grade wet & dry.

**ladas** · 21st April 2007, 02:38 PM

Originally Posted by Frontier1

Well now I have swapped two of the pistons over and it still leaks from the same bore even with a new seal so now I'm really confused.

If it is still leaking at the same spot with a different piston then it must be the bore right? Not the piston?

Pete'

I would have come to that conclusion -----

You may need a replacement caliper. What does the old one look like inside ?

**Frontier1** · 21st April 2007, 05:45 PM

Hi Guys,

Well even though I again took out the caliper, removed the pistons, checked all the seals including the new ones that I put in the initial leaking bore, put it back together, etc, etc., it still leaks.

I don't have the energy to take it apart again tonight but I guess I'll give it another go first thing in the morning. Plus while I was doing this, I had done the wheels bearings on my boat trailer and had a go at braising a leak with solder and a small blowtorch on the side on the Disco's radiator which had a leak too, but I think I need to use lead as solder probably has too low a melting temp.

Damn, I was going to go fishing tomorrow!

Cheers,
Pete'

**4bee** · 21st April 2007, 06:18 PM

That's most unfortunate, Pete. Maybe it is the piston surface or one of the seals was damaged when fitting it. Wouldn't take much to bugger the edge. As there are 2 seals in there, it does appear unlikely it would be that imho, so next is the pitted surface of the piston.

Ah well. Good luck in the morn.

**Frontier1** · 22nd April 2007, 07:32 AM

Yeah, I totally agree that the best option in all cases is to replace with new, I was simply looking at an option that would allow me to continue driving while I ordered in the new part.

But that's the thing here, is it worn pistons (they all show pitting/wear & tear) or is it the caliper itself? Why does one bore continue to leak even when different pistons are put in with new seals? If all the pistons are shot why are all the bores not leaking?

My point with all this is am I going to have to order new pistons or a new caliper? If it's a new caliper, I'll need new pistons as well.

As mentioned I'm taking a look at it again this morning, one last time.

Pete'

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