Technical Cinq rear brakes help needed please

[East Mids Neil]

My sons 1st car, bought privately last year with a 12 mth main dealer mot is due again soon. How it got through the last one beggars belief with a rear end knock & a iffy handbrake. The knock was a split rear suspension bush (N/s) which I've changed, but I'm having a problem with the brakes on that side. With the rear end jacked up and the handbrake ON 2 / 3 clicks (very tight) the O/side wheel locks up but the N/side doesnt. The linkage on the N/s also travels much further than the O/s. With the handbrake OFF the N/s linkage seems sloppy compared to the O/s. Having had the linkage off to replace the bush I know it's not seized. The footbrake performance is aslo low on the N/s and the odd thing I notice is that the drum comes off easily (normally they can be difficult to pull over the wear lip on the drum) so I guess it's a problem with the self adjusters. I had this problem years ago on the wifes Uno but cant remember how I fixed it. Does anybody know the most likely cause i.e. worn linkage, loose friction adjusters, stuck hydraulic cylinder.... the shoes are not worn out by the way... thanks in anticipation

 

[rallycinq]

The cylinder has nothing to do with the handbrake, have you checked the service brake operation.

The adjusters are friction type, so need to be tweeked manually before putting the drum on.

Further thought is a seized cable.

The bits are really cheap so its probably better giving it a full overhaul.

Cheers

PD

 

[East Mids Neil]

Thanks for that, as mentioned in the o/p the footbrake (service brake) is also low on the n/s only (engine on/son in car/me in the garage pit). Correct me if i'm wrong but I thought adjustment is done automatically after a few applications of the brakes - although I'm now tempted to prize them out a little to see what difference it makes. The drums by the way ar in good condition and hardly any wear lip

 

[fingers99]

I'd guess -- nothing more -- that the actuator on the other side may be seized (or partially). But a buggered casble is also likely. If fitting a new cable, squirt some motorcycle chain lube down inside before fitting. Check also the condition of the shoes.

As Rallycinq says, the parts are dead cheap, so replacement is the simple solution. An easy afternoon's work should sort it.

 

[East Mids Neil]

Thanks, I'll take a look at the other 'good' side maybe tonight. The handbrake cable seems free enough. With the handbrake FULL ON I can rotate the n/s roadwheel by hand but the o/s locks solid

 

[fingers99]

What can happen is that the cable seizes on one side (the teflon wears off the inner, the lining rubs off the inside of the outer, metal to metal contact and corosion, etc). As it's one cable operated by a pivot, it'll act as two seperate mechanisms if one side seizes.

Another thing that can have the strangest consequences is putting the springs on the wrong way round (top for bottom).

 

[rallycinq]

What can happen is that the cable seizes on one side (the teflon wears off the inner, the lining rubs off the inside of the outer, metal to metal contact and corosion, etc). As it's one cable operated by a pivot, it'll act as two seperate mechanisms if one side seizes.

Another thing that can have the strangest consequences is putting the springs on the wrong way round (top for bottom).

You on the dial up again?

Cheers

PD

 

[rallycinq]

Thanks for that, as mentioned in the o/p the footbrake (service brake) is also low on the n/s only (engine on/son in car/me in the garage pit).

Sorry, missed that in the first read through.

Cheers

PD

 

[fingers99]

You on the dial up again?

Cheers

PD

Yep. Bloody Beta quality server software, says I! This is the only forum it happens with, ever!

 

[East Mids Neil]

Still doesnt explain why the service barke efficiency is low on the n/s. i.e. rear end jacked up, engine on, my lad in the car with his foot on the footbrake I can rotate the n/s wheel by hand, also on this side theres one heck of a lot of cable travel compared to the good side which has less travel and locks solid

 

[fingers99]

Yep. Pads, mechanism wrongly assembled, parts missing, upside down springs, etc.

I'd not entirely rule out the possibility that there's a fault on both the hydraulic and cable (handbrake) sides. On the footbrake side, check the shoes and assembly -- if those are OK, slave cylinder is a good bet (less than a tenner).

But -- shoes and common parts aside -- you are probably best treating the 2 systems as independent.

 

[East Mids Neil]

There's plenty of life left in the shoes (also tried roughing 'em up with sandpaper & the drum). The drum assembly is similar to the wifes old Uno which I seem to recall was near impossible to put the springs on incorrectly because one has a straight section between 2 coils to avoid fouling the stubb axle but will check this too. My money is on the self adjust mechanism - and I'm thinking that by the time the 'free play' in the shoes is taken up the master cylinder has maxed out, and when the footbrake is released the slave piston fully returns.

 

[rallycinq]

Could be worth a bleed too, when was the fluid last changed?

Cheers

PD

 

[East Mids Neil]

It was the handbrake cable! Although it had free play in normal use, when I removed the drum an operated the handbrake lever (making the cable travel a little further) it siezed solid! Thanks for your help and suggestions.

 

[East Mids Neil]

I fitted a new handbrake cable (Bendix / Honeywell £18) and took it for the MOT - the h/b passed with exceptional efficiency.

 

[fingers99]

the h/b passed with exceptional efficiency.

You should frame it and put it on the wall -- that's a historic document!

 

[East Mids Neil]

Exactly! The engineer said the wheels locked on the RR! The rear o/s drum failed on footbrake efficiency. I traced this to a stuck salve cylinder piston and freed it up sufficient to get a pass on the re-test. For the sake of a tenner I was going to replace it but the brake pipe nut & bleed valve are rusted solid, as is the nut on the suspension arm. The test engineer says it's possible to patch in a short length repair - can anybody tell me what I need please. The hydraulic pipes are in super condition.

 

[rallycinq]

You'll need a flaring tool. Better probably to get the plus gas on it for a week or two before attempting the repair.

Cheers

PD

 

[fingers99]

I've heard of this being done, but, personally, I'd forget. You need pretty damn good swaging tools to do it right. Lots of penetrating oil (not WD40) might free up the brake line/slave nut. Then take a 6 sided brake spanner to it. For the other nuts and the bleed screw I'd do the same or use the dreaded heat spanner. I'm lucky in that all the deep sockets in my sets are 6 sided, so they can often cope with these horrors where a 12 sided would just round them off.

You should get a bleed nipple free with a new slave cylinder (I think). If you really come unstuck I have a metal rear pipe (tell me which side) you can have for a (very) few quid plus postage.

 

[East Mids Neil]

Thanks for the tip about the 6 siders - I have a set but didnt think to use them. I shimmed the gap on the open ended spanner to prevent it slipping and rounding the pipe nut and was able to exert quite some pressure but it wont budge. I've tried using heat but still no movement, so I'll give the long term plus gas method a go. Watch this space!