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Rear brake cylinder

Posted: Mon Jul 24, 2023 7:11 pm
by Larry 1300
Hi I have a dolomite 1300,1980.
The brakes were poor when my wife drove her yesterday.
I had a look under the car today. There is brake fluid on the nearside back wheel. I am partially sighted.
I only saw one brake pipe going into the near side what I presume is the cylinder at the bottom. And what looked like a bleed nipple.
While on the offside there are 2 brake pipes.
There is still some fluid in the reservoir.
Any advice would be appreciated. I was going to order new brake cylinders but noted that there is a single one and a dual one for the 1300. Thanks
Laurence

Re: Rear brake cylinder

Posted: Mon Jul 24, 2023 7:34 pm
by ClassicFan
I only saw one brake pipe going into the near side what I presume is the cylinder at the bottom. And what looked like a bleed nipple.
While on the offside there are 2 brake pipes.
Brake pipe goes from the 'flexi' to the offside cylinder then across to the nearside which has the bleed nipple for both rear brakes so it's a single circuit system part GWC1110 - James Paddock have them for less than Rimmers https://www.jamespaddock.co.uk/wheel-cy ... inegwc1110 but there are other suppliers

Re: Rear brake cylinder

Posted: Mon Jul 24, 2023 10:25 pm
by Larry 1300
Hi thanks for your help 👍
I have ordered it.

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 12:15 am
by Carledo
ClassicFan wrote: Mon Jul 24, 2023 7:34 pm
I only saw one brake pipe going into the near side what I presume is the cylinder at the bottom. And what looked like a bleed nipple.
While on the offside there are 2 brake pipes.
Brake pipe goes from the 'flexi' to the offside cylinder then across to the nearside which has the bleed nipple for both rear brakes so it's a single circuit system part GWC1110 - James Paddock have them for less than Rimmers https://www.jamespaddock.co.uk/wheel-cy ... inegwc1110 but there are other suppliers
Don't like to rain on your parade, but ALL Dolomites have that stupid and potentially dangerous "to and through" axle brake pipe design. A 1980 car of any model should have dual circuit brakes, they were introduced on the Sprint on the series IV cars (VA30,000>) in late 78 and other models followed virtually immediately after. For check, dual circuit master has 2 pipes coming out and a single circuit car only one! :twisted:

Steve

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 8:36 am
by ClassicFan
Carledo wrote: Tue Jul 25, 2023 12:15 am Don't like to rain on your parade, but ALL Dolomites have that stupid and potentially dangerous "to and through" axle brake pipe design. A 1980 car of any model should have dual circuit brakes, they were introduced on the Sprint on the series IV cars (VA30,000>) in late 78 and other models followed virtually immediately after. For check, dual circuit master has 2 pipes coming out and a single circuit car only one! :twisted:

Steve
Hmm I stand corrected, how that is true dual circuit though, where both rear brakes are connected is not. It's a 'Tandem' arrangement.

The alternate cylinder is part GWC1202 again available from James Paddock, Rimmers etc. Both were used on the Spitfire and other models so readily available.

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 8:44 am
by xvivalve
You are correct, the Dolomite range was NEVER fitted with a dual circuit brake system, just a tandem master cylinder on later cars.

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 8:48 am
by Larry 1300
Hi if I was to order a brake cylinder for the off side rear would I order the double one please?

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 7:33 pm
by Carledo
xvivalve wrote: Tue Jul 25, 2023 8:44 am You are correct, the Dolomite range was NEVER fitted with a dual circuit brake system, just a tandem master cylinder on later cars.
I'd argue that! True, the system used is not like the modern diagonal split which is universal today and has been since the early 80s, still it's a dual (dual meaning 2) circuit system, it just has a distinct front circuit and a distinct rear circuit, rather than a diagonal split. But there are still 2 completely separate circuits, each serving 2 of 4 wheels and each capable of functioning alone if the the other fails.
The only hydraulic bit shared is the reservoir.

Though, I will admit that, from experience, the braking effort generated by a dual circuit braked Dolomite if only the rear circuit is working, is marginal at best and the pedal only JUST above the carpet! The saving grace of this is, I would say more than 90% of failures involve rear wheel cylinders so the likeihood of you being left with ONLY the rear circuit is very low! And it's still better by far than a single circuit system where only a single point of failure can leave you completely devoid of brakes!

Steve

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 7:36 pm
by Carledo
Larry 1300 wrote: Tue Jul 25, 2023 8:48 am Hi if I was to order a brake cylinder for the off side rear would I order the double one please?
The wheel cylinders are both the same, the threaded holes are both 3/8" UNF, so it doesn't matter if you have 2 pipes, or a pipe and a bleed screw.

Steve

Re: Rear brake cylinder

Posted: Tue Jul 25, 2023 9:47 pm
by Larry 1300
Hi that's great thanks 👍