Front brake cylinders

[roy0147]

I have just bought a full set of 4 front brake cylinders for my 1.5.
I thought that when fitting new seals the inner surface of the cylinder should be rubbed with new clean fluid and the seals soaked in fluid before fitting. Once fitted the plunger should move in the bore.
However, of my 4 new cylinders one does move easily by hand but the other three are seized and will not move by hand.
Can someone suggest if this is right please? I am worried that by forcing the plungers to move the edges of the seals will be damaged.

[2robert4]

If the cylinders are new old stock they may have been stored incorrectly in a damp setting or the seals are stuck up with dried up red seal grease as this is how they would be fitted upon assembly. Use a low pressure air line or tyre pump fitted with and air bed or similar adaptor to push the pistons out and examine the bores which will be ok I am sure then fit new seals (never take risks with brake components if they are NOS they can degrade over time) with red assembly grease or brake fluid and they will be good to go. I hope this is of some help?

NP

[canuck]

Hello Roy,
You understand well the assembly procedure.   

I will add to Nigel comments.

The guts of these slave cylinder are very basic.




The spring is simply there to assist the seal to remain in contact with the piston.  The hydraulic pressure does the work when you press the brake pedal, and the tension of the brake shoe springs returns the piston (s) enough to free the shoe from the drum. 

In the above photo you can apply a very low air pressure, (as Nigel suggests)  into the open port to 'pop' the guts out to verify the bore & seal integrity.
Of course the bore wants to be free of scoring etc. 



Other than that I have nothing else to add other than when you do get around to bleeding the system keep your eye on the reservoir at the master cylinder. This reservoir doesn't hold a lot of fluid and it is quite easy to run low of fluid and start pumping air back into the system . 
Ensure the cylinders are compressed and the shoes are adjusted to the drum before starting to bleed the system.

Have fun be careful

Bruce 

[roy0147]

Thank you both for your help and I will follow the steps suggested.
Roy

[ozieagle]

Hi Roy,

I don't have a Riley 1.5, but a Wolseley 1500, similar machines.
The Riley, I believe, has Girling brakes, whilst the Wolseley has Lockheed, and I don't know the differences, or similarities. When I replaced my front cylinders, I used Morris Minor ones, but had to open up the holes in the backing plate. They were 1/16" bigger in ID, giving about 7% more braking effort, but at a large fraction of the cost.

Herb

[canuck]

Moggy brakes are very small, with the early cars having 7" diameter drums upped to 8" later models and Ute etc. . 

FWIW the Riley has far superior braking to the MM and the Wolseley.   yeah I know obvious bias. 

See  the table below, from BMC documentation.



While the Riley & Wolseley have same diameter drums, the similarity stops there. 

The brake shoe lining surface area of the Riley tells all. At 78 square inch for the front while the rear being 46 square inch these lining surface areas is  +50% and +10% respectively.   

If one were to 'upgrade' the Riley front brakes with a popular aftermarket disc fitment the braking would not see much improvement, although resistance to dreaded brake fade would be improved much.

In summary,  difficult to improve the Riley braking system without some serious  'outside the box' thinking.

Salut
 
B

[kiwimc]

I'll second the 'low pressure' air comment for when you want to push pistons out.  I made the mistake of using the compressed air gun @ 60 psi...

...took a while to find all the internals

[tonyhosk]

Been there - done that!!

Tony