1973 3500s- front caliper pistons

Quagmire

Active Member
#1
I need to rebuild the front calipers on the red rocket as the driver's side has started to drag occasionally, and the pistons look past their best.

I have seen various places doing rebuild kits with pistons, but seems there are variations with different diameters?

Is anyone able to confirm what the diameters are of both the large single and smaller double pistons please for a car of my vintage? I could go and take the wheel off and have a look but it's absolutely filthy weather here this evening... :(

Many thanks!
 

quattro

Administrator
Staff member
#2
I wasn't aware there were different types.

I have a pair somewhere which I rebuilt with stainless pistons shortly before removing them.
 

jp928

Active Member
#3
Mine is also a 74, chassis 482...D, had the calipers rebuilt last year. Best I can measure the corroded old dead one, large piston is 57mm, smalls are 40mm.Havent seen anybody list alternatives. Pretty cheap IMHO.
 

Quagmire

Active Member
#7
Well the stainless piston and seal kit I ordered from biggred fitted perfectly. The calipers looked rank when I took them off, and the pistons were shot, but thankfully the bores were fine. The old piston boots had perished and I think were holding moisture on the pistons. Now rebuilt and I have refitted them on the car, but need to bleed before I can go for a road test and say what kind of improvement there is:
 

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jp928

Active Member
#12
Watched an old US Wheeler Dealers yesterday, on a '65 Volvo Amazon 122. Caliper overhaul reminded me of something here.....what was it ?
 

jp928

Active Member
#13
And on another US wheeler dealers on a Cayenne Ant opined that they were lucky the bores in the disk calipers were in good condition. Wrong! The bores do not do any sealing - that is all done by the square section O rings and the piston walls. They need to be clean, but surface damage is not relevant.
 

harveyp6

Well-Known Member
#14
Ant opined that they were lucky the bores in the disk calipers were in good condition. Wrong! The bores do not do any sealing - that is all done by the square section O rings and the piston walls. They need to be clean, but surface damage is not relevant.
The more he says the more stupid he makes himself look. That's probably why the content of that part of the show has diminished to almost nothing.
 
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