New member - brake servo question

[Rob Booth]

Hi all.

I'm currently building a Royale Sabre with a Rover V8 engine.

Using this engine means the Ford brake servo won't fit, so I'm going to have to use a remote servo (or two) for the Sierra-based brakes..... discs all round. 

Anyone have specs or information as to which remote servo(s) would suit? 

I'm thinking of running two, as most of them are single line and/or designed for drum brakes. 

I assume the original master cylinder will send the correct bias to the front and rear circuits, so shouldn't need separate adjusters ?

Any help appreciated.

Cheers.

Rob

[richyb66]

Ford Ka master cylinder and no servo. You'll get used to the increased braking effort.

Why complicate things overly with one, or worse two servos.

[Kerry]

I will go with what Ricky has said,Ford KA  master cylinder work perfectly 

[Rob Booth]

Cheers folks.....which is the one without the servo......or do you mean delete the servo ?

Edited March 24 by Rob Booth
Added feedback

[Sparepart]

I'm rebuilding an Exmo. The original brake master cylinder from a Sierra is all seized up, replacement is expensive. So I have gone down the Ford KA path. I have purchased a complete unit with reservoir and servo, not new, there are many on offer from breakers. Here is a picture of what I have bought.

This part is also common with models of Fiat Panda. Here are some old links to eBay ads.

 

https://www.ebay.co.uk/itm/226996062974

https://www.ebay.co.uk/itm/256831165194

https://www.ebay.co.uk/itm/226368975525

https://www.ebay.co.uk/itm/157493628002

 

You will find I think that the common part number is 51866500.

I have discarded the servo, as both the Sierra servo and the Ford Ka servo get too close to the exhaust manifold. Obviously I have had to make a new push rod from the pedal box, and clip to hold the rod in the top of the brake pedal. This rod is threaded at the pedal end so that I can adjust it. I have only just got the car mobile on a short driveway, it does stop, however it feels like I am going to need quite a lot of force on the pedal compared with when servo assisted. The other challenge is the height of the fluid reservoir. As it is I cannot place the bonnet on the car because the reservoir filler tube is too high. I need to get the car up to a good speed somewhere to try the brakes for real. If they are good enough then I will fit a remote reservoir. If the car won't stop without needing me to really stamp on the brakes then I'll.....welll... back to the drawing board I guess.

Note the Ka MC has two output points. On the Ka these are connected to each diagonal slave cylinder, Front right and Rear left, Front left and rear Right so there is no bias in the pressure. I am using the two outputs as Front pair and Rear pair. This might sound iffey but even with the Sierra MC I had discarded the bias valve and was not getting a rear lockup on hard breaking. Fingers crossed on this.

 

 

[Rob Booth]

7 hours ago, Sparepart said:

I'm rebuilding an Exmo. The original brake master cylinder from a Sierra is all seized up, replacement is expensive. So I have gone down the Ford KA path. I have purchased a complete unit with reservoir and servo, not new, there are many on offer from breakers. Here is a picture of what I have bought.

This part is also common with models of Fiat Panda. Here are some old links to eBay ads.

 

https://www.ebay.co.uk/itm/226996062974

https://www.ebay.co.uk/itm/256831165194

https://www.ebay.co.uk/itm/226368975525

https://www.ebay.co.uk/itm/157493628002

 

You will find I think that the common part number is 51866500.

I have discarded the servo, as both the Sierra servo and the Ford Ka servo get too close to the exhaust manifold. Obviously I have had to make a new push rod from the pedal box, and clip to hold the rod in the top of the brake pedal. This rod is threaded at the pedal end so that I can adjust it. I have only just got the car mobile on a short driveway, it does stop, however it feels like I am going to need quite a lot of force on the pedal compared with when servo assisted. The other challenge is the height of the fluid reservoir. As it is I cannot place the bonnet on the car because the reservoir filler tube is too high. I need to get the car up to a good speed somewhere to try the brakes for real. If they are good enough then I will fit a remote reservoir. If the car won't stop without needing me to really stamp on the brakes then I'll.....welll... back to the drawing board I guess.

Note the Ka MC has two output points. On the Ka these are connected to each diagonal slave cylinder, Front right and Rear left, Front left and rear Right so there is no bias in the pressure. I am using the two outputs as Front pair and Rear pair. This might sound iffey but even with the Sierra MC I had discarded the bias valve and was not getting a rear lockup on hard breaking. Fingers crossed on this.

 

 

Isn't the two outlet version for cars with ABS ? The three outlet version has two fronts and one rear, from what I can see ?

[Sparepart]

I'm not an expert. As I see it ABS or not ABS is a red herring here because both have a master cylinder operated by a brake pedal (and servo) the pressure generated by the master cylinder may or may not then go to an ABS component which can regulate the pressure to individual wheels to avoid lockup. The Sierra master cylinder did have 3 outlets, one for rear and two for front, however the two front ones were driven by the same piston, I know because I took it apart, I assume that it had two outlets because it's cheaper than having a single outlet and then a separate splitter to go R or L at front of car, whereas the single rear outlet means a single pipe to the back and then a splitter near the rear subframe. One annoying thing about the Sierra master cylinder apart from replacement cost is that the outlets are on the engine side, so the pipes emerge right above the heat of the exhaust manifold. (by the way this is the same on LHD sierras, so if buying a replacement a LHD version is worth considering and might be more available) Anyway, before you go to sleep reading this (I am), 2 or three outlets doesn't matter to me, what matters is that the master cylinder has two pistons that can provide a DUAL circuit system with an output for each. I am going for a front back split for the circuits, but a diagonal arrangement could be possible. The icing on the cake about the KA MC is that the outlets are on the other side from the exhaust manifold which means the pipes are far less exposed to heat.