Replacing front brake cylinders

[renoir cigar]

Apart from ordering the wrong size rear brake cylinders, (DOOP!) I have front Franzose replacements to go back on, (re sleeving was too expensive by far).

Now a little problem has developed where I can't access the plate to put the two holding bolts back on, can't rotate the plate around due to the shoe adjusting knobs, it seems like the only option is to rip off the axle so I can get to the bloomin back of the plate. I bought 24 mm Bendix (Franzose part 84125-84126) which fit correctly to bolt holes etc, the car is a 65 R4L. So frustrating, took hours to get the hoses off too.... I kept thinking there must be an easy way to do this, it's French, logique, logique! mais ou?

maybe I need a smaller piston? still can't access rear of plate though....

BTW do you need copper washers on brake hoses? With clips in there's no space to fit them.I look forward to some brilliant advice!

Cheers

Steven

 

[malcolm]

That's normal. You can get enough access by loosening the 4 bolts that secure the backplate to the upright and then tipping it outwards. I don't remember at which point the hose goes on. Probably before the cylinder is tightened to the back plate. I think there should be copper washers.

 

[simonandjuliet]

Brakes

On the Sinpar rears I have the same problem and the only way to do it is to withdraw the hub and wheel bearing,take off the backplate and put it all together on the bench along with shoes (much nicer to do anyway) and then refit - worth trying ?

Plus I always use copper washers

 

[renoir cigar]

thanks guys, erm, I removed bolts off backplate and still not enough room with rotating forwards, backwards, the cylinder is the 23.8mm and there just isn't enough space left to wriggle everything around, the shoe adjusters hit the axle arm, I think I either have the wrong size cylinder or I genuinely have to remove the axle to free up the front cylinder plate....

Steven

 

[benchseat]

I had a problem recently when ordering new (rear) brake cylinders : the correct cylinders (according to the parts number) were too big, and I eventually found that incorrect brake shoes had been fitted and were so large that the previous owner had fitted much narrower brake cylinders to compensate. Once the correct shoes were located the cylinder fitted without a problem.

So it may be worth checking to make sure the shoes are correct. I am not aware whether dimensions changed over the years, but yours is a pretty early model and a previous owner may have bodged a repair.

 

[Geoff in the Gully]

Steven,
I've just completed this very task on a '65 R4L last week. I'm with Malcolm as to the method.
With the backing plate bolts loosened you tilt the backing plate outwards until the wheel cylinder comes up against the wheel hub. You don't rotate the backing plate to try to gain access.

Tilting the plate gives you enough room to slip a 'small headed' ring spanner onto the wheel cylinder bolts to loosen them. BUT don't try to undo the bolts all the way with the ring spanner because as the bolt comes out the clearance to get the spanner on and off goes away. Once loose, I used an open-ended spanner. I could have used one from the beginning but they're not so good on tight bolts and can round the head.

Once the bolts are out, you then push the backing plate back into position so that you have enough clearance to get the wheel cylinder between the plate and the hub.

Here is the secret that took me ages to realise: You need to remove the bleed nipple otherwise the cylinder won't tilt enough.

You don't need to remove the brake hose. Won't hurt if you do though. I had one that had been rounded and I couldn't loosen when it was in place.

This job is indeed a fiddle but there is in fact enough clearance to get the buggers in and out.

Which reminds me, it's just as difficult to get the wheel cylinder bolts back in. You can't get your fingers in behind the backing plate to hold them. I tried needle-nose pliers but had difficultly then getting a spanner on the bolt head. I ended up using some long tweezers. And make sure the bolts move freely on the threads in the cylinder before putting it back in - you want them to go in as easily as possible.

Good luck, Geoff

 

[jonigel]

Malcolm is correct just undo the 4 bolts and pull the plate forward, but the wheel cylinders should be smaller on the earlier models,in fact they are not available for one sid had one machined down by a fellow member in Italy,and you have to reline the shoes.
And you need copper washers on the flexis. Heat your old ones to cherry red then quench ,good as new. Bon courage.

 

[angel]

Be aware that although you can fit these wheel cylinders to your backplate, and the piston diameter is correct, you may experience clearance problems between the brake shoes and the wheel cylinder bodies, after fitting the shoes. These are the long-bodied wheel cylinders (in fact the only ones available now), for the post-67 200mm or 228mm drum brakes and are not compatible with the 180mm drums you have.
Both jonigel and Geoff pointed this at some time earlier, you can find the relevant post if you search in the forum.

 

[orsome]

quench

. Heat your old ones to cherry red then quench ,good as new. Bon courage.

**a question: quench with time or rapidly with water?

I just opened my 77's drums and found 1/4 liter rust dust inside each.All sleeve cylinders migth be jammed.
I also ordered all new parts, shoes+assembly kits+rubbers-let's see what i will get.

Ps-tomorrow to paint shop!
:smile:

 

[jonigel]

Either,but i use water as i only do it when i need to reuse them,it is the heat that anneales them.