MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MG Y Type - YA wheel cylinder spring.

In cleaning up cylinder internals ready for new seals etc, I notice that although the front and rear cylinder bores are (correctly) different at 1 1/8" and 1", my springs are all the same size. Thus (at their widest point) they are a tight fit in the rear cylinder and a looser, sliding fit in the front. These are the replacement type springs, I long ago lost the originals which I seem to recall were a sliding fit all round. Is there a right and wrong, or does it not matter? Thanks all.
John.

J P Hall

I'm thinking you might have all front ones---If they're already a tight fit in the rear, being a coil they'll expand and jam when they're fitted/compressed
William Revit

That's exactly right, Willy. I suspect that the rear cylinder springs have indeed been stuck in the bore, with the obvious effect on my (Joanne's) rear brakes. I nearly said rear end. At the same time, inactive pistons have gathered more moisture and hence rust spots, than the fronts.
I have asked on at least 3 forums/forae/fori, whether there is such a thing as a slightly smaller diameter spring which is sized to fit the 1" bore. Any help appreciated. John.
J P Hall

lots of cars ran/run 1" rear cylinders Holdens did in HQ's Rodeo's If you've got a brake repair joint near you they might have some old cylinders you could nick the springs out of, even 15/16 or 7/8 would be ok, all the springs do is keep the cups/pistons out against the shoes.
William Revit

Good thinking Willy. I notice that Moss list (admittedly for TC not YA, but same principle) two different product numbers for front and rear cylinder springs (Front is 180-865, Rear is 180-855). Again these are the one-piece modern version. I've emailed Moss to see whether their springs are 2 sizes.
In the meantime, I ferreted out one of my sleeping TC's rear cylinders (7/8" bore) - unfortunately to find the original type spring, with nothing else but the rubber cup at each inner end and the piston at the outer end. The spring is 1/2 wide, so plenty of clearance between bore wall and spring.
It would be good to know whether the new type spring, with its wider "waist", is still supposed to have enough clearance to move inside the bore. I can't see how the cylinder would work properly otherwise. In which case, as you say, my YA has the correct spring in the front but the same (wrong) size in the smaller rear cylinder.
It seems to be getting harder to elicit advice on pesky little points of interest these days - thank you for being there Willy!
Anyone have experience in this area?
John.


J P Hall

Um--I 'think' TC front cylinders are the same cylinder as the Y rears --1" and TC rears are 7/8"
IF you've got spare TC front cylinders laying about maybe you can use the springs from them--or use that 1/2" one you show there, it'll just sit in the cup, it can't go anywhere. Don't overthink it, it's just a spring
As your TC is modded it might have twin leading shoes on it so maybe if you got spares with it the old single leading shoe cylinders(1") might be there somewhere.

If you've got a 4WD workshop anywhere near you they'd have some old rear cylinders off Hilux's or something laying about that you could rob the springs out of

These fellas are advertising reco'd exchange cylinders, I'd imagine they'd be fitting new springs in them, might be worth sending an ask to them--South Aust. but closer than Moss and I'd reckon a whole lot cheaper-

https://www.powerbrakes.com.au/shop/mg%20y%20rear%20wheel%20cylinder%20assembly%2025.4mm%20diam%20%281.00%29/mgy/mg/vehicles%20h-p/page/shop/flypage/offset/0/orderby/size1?
William Revit

Yep I thought I might just put my spare old parallel springs in the rears for now Willy, espĺecially since I'm having trouble clarifying what the intention of the "improved" springs is. And yes, I've sent a query to the Powerbrakes mob - it seems they do a thorough job on the cylinders, but they don't put new pistons in (!). Not sure about springs - I'll ask them.
John.
J P Hall

The so-called new improved springs are sold as supposed to hold the lip of the seal against the bore--but it's all snake oil. They're called expander springs and the new type with the cone winding on the end would sit in the cups nicely IF the cups are the matching shape, some are tapered cone inside and some are more of a square section which wouldn't be quite as compatable with the new style springs--
The parrallel 1/2" springs you have will be fine, originally they would probably have had thin star shaped flat washers on each end to centre them and protect the cup from being mauled by the end of the spring--I'd imagine they've been rusted out and given the flick. If the springs are nice and smooth on the ends I'd just use them as is and forget about them--or make them smooth and use them anyway-- Don't overthink it they only hold the cups/pistons out against the shoes so that you get a good solid/reliable brake pedal, any light spring will do the job.
William Revit

That makes total sense about the "expander springs" theory - and the potential difference in practice, depending on which cups you have. AND - no way will the expander spring, if it's a tight fit in the middle of the bore (like the ones I found in the rear cylinders of the YA),effectively push outwards against the cup at each end. The cup will be left stranded until hydraulic pressire builds up again. So - into the 1" bore rears of the YA, go my spare (robbed from the TC) parallel springs.
Hey ho and away we go.
Thanks as always, Willy o' the South.
J P Hall

This thread was discussed between 19/07/2026 and 23/07/2026

MG MG Y Type index

This thread is from the archives. Join the live MG MG Y Type BBS now