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MG Midget and Sprite Technical - Front disc caliper banjo fluid seepage

I converted the Frogeye to front discs by refurbishing some used calipers I acquired. I re-used the banjo bolts but fitted new copper washers. I thought I'd got all surfaces smooth enough but, after a few days, there is very slight fluid seepage at the outer joint of both bango bolts, either washer to hose or washer to bolt head (more likely). Should I buy new banjo bolts and washers or try re-cleaning/ surfacing the bolts? I've tightened as much as I dare, including loosening and re-tightening. I don't want to lose too much fluid as it is new silicone DOT5. To confirm, it is very slight annoying seepage only showing on a finger after a few days.
Bill Bretherton

Bill,
have a look in the Archives here or on MGB as this has been covered a few times before, IIRC it's been - wrong washers, to re-anneal the copper washers, wrong depth to banjo or threads, (split at caliper(?) and stuff I've forgot.

Did you buy new rubber flexi hoses, bolts, washers from x-suppliers or the Goodridge type, are they matched to your calipers and system.

Good thing is if it's only a weep if you're not using the car it's not urgent as silicone won't be striping any paint. A squeeze and bung or double bung should stop all but a little more loss.
Nigel Atkins

There was an issue with some aftermarket calipers not having the sealing surface to receive the banjo a a true 90 degs to the thread. But if these are original, refurbished calipers that seems unlikely.

I would try annealing the copper washers by heating to cherry red and air cooling, slowly. It often seems to do the trick as new copper washers often don't seem to be soft enough.
GuyW

Nigel
New rubber hoses and copper washers from Moss.

Guy
May try annealing the washers if no joy with re-tightening.
Bill Bretherton

The process of stamping out the copper washers can work harden them.

Anneal by bringing to cherry red and dunk straight into water - i.e. quench - or slow cool - no difference for copper unlike some steels.

Maybe worth just rubbing the washers on a flat file to check they don't have raised edges from the punching.
richard b

New rubber hoses and copper washers from Moss - I couldn't possibly comment.

But if you can risk squeezing off the rubber hose there's not much fluid to be lost after that.
Nigel Atkins

The banjo bolts unless really corroded don't usually need replacing. Annealing the washers usually does the trick. Check the sealing face of the caliper is flat and clean
Bob Beaumont

ETA: Richard posted as I was typing, both he and Guy say a couple of the things I forgot, now Bob has posted a third.

Mainly all boils down to new parts quality.
Nigel Atkins

Interesting that speed of cooling doesn't influence the copper annealing process. I have done it so many times, yet never realised that Richard!
Live and learn.
GuyW

Richard, Bob, thanks.

I didn't know you could quench copper when annealing.

Hoses are clampable Nigel. It'll stop well enough with standard hoses I reckon.
Bill Bretherton

Bill,
13 years ago I didn't buy my Goodridge hoses for pedal feel and the only improvement to braking would have been that there weren't of possibly piss-poor rubber that I'd already experienced for years at that time (and for many years after and still(?)), they were for fit and forget, work and last reliably (unlike the rear brake cylinder rubber seals). :)
Nigel Atkins

If you have new hoses from Moss, depending on what sort, I have seen some (very recently) where the hole is slightly too small for the larger shoulder of the banjo bolt and thus won't tighten up properly.

I forget the excuse they gave, but it was something along the lines of "they are supposed to be like that, the hole is actually tapered (?!?), blah blah". BS. They have a bad batch they are trying to fob off.

Malc.
Malcolm

My secondary school metal working education (which was to many years ago to think about) taught me that copper and steel are opposite when it comes to annealing.
Rob
MG Moneypit

This thread was discussed between 21/11/2020 and 23/11/2020

MG Midget and Sprite Technical index

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