Master Brake Cylinder Advice Please

[richardm6994]

Hi folks, I'm after some information surrounding brake master cylinders, in particular converting my current set-up from the sierra servo set up to a non servo set up.

 

I'm not going to lie...I know bugger all about how the servo works..all I know is that the inlet manifold vacuum operates it as when the vacuum pipe once melted on my exhaust, the brakes felt like glass!!!

 

My reason for asking is that I've got to get rid of the brake servo on the exmo because of the sudden lack of space now that the v8 has been plonked in.

 

Can I use just the master cylinder on it's own (i.e. remove it from the servo)or will that not work very well because it relies on the servo to assist therefore it would be just like when my vacuum pipe melted...?

 

I've also read that the ford ka master cylinder is an option, & I've seen these on ebay with servos and also without servos.

 

I suppose what I am trying to ask is....are there two different types of master cylinders....i.e. those that are fitted with servos and those which are designed to be used without servos???

 

Any advice would be greatly appreciated...and lessons in servos for a greater understanding

[Grim]

non-servo master cylinders have a smaller diameter so they can exert more force (needed since you're losing the servo). The standard m/c will not be much use with the servo removed, as you've found.

 

The check the diameter of the KA one, i'd be surprised if it was non-servo. The standard sierra one is 7/8" (22.2mm) so you need something a fair bit smaller.

[richardm6994]

cheers andy. I thought the m/c I've got on the servo would be no good, but just needed to ask before I chuck it away. Adding an extra 100bhp and removing the brake servo does make one feel a little apprehensive so I want to get it right!

 

It looks like the dia of the ka m/c is 20.6mm which I suspect will make bugger all difference? So what do people use because Im guessing non-servo set-ups are fairly common....it's just I've never come across them or had any need to ask about them.

 

As well as m/c piston dia, i'm guessing changing the pivot point of the brake pedal makes a difference too? I'm hoping the forum comes to the rescue and someone divulges how they've done it and what parts were used...

[speedtripledan]

In my RH I used the standard sierra m/c on a zero pedal box but had to play around with the pivot point to get enough force also used mintex m1144pads standard pads were ****. when i took the servo off the RH on the standard pedal box it was no good as the pedal ratio was wrong. If it were me id get a complete new pedal box with wilwood m/c's either floor mounted or hung as before. with all the money you spent so far a pedal box is peanuts

 

Modifying the existing will never be much good and as rob said the engine braking on the v8 is massive, on the road you wont be using the brakes much

[Guest Ian & Carole]

On my car I had to remove the servo to get the 4age engine and webers to fit.

Bought the "Tiger Racing" push rod and just refitted the Sierra M/Cylinder, with decent pads the brakes on mine are fine with much more feel, the harder I push the more it brakes.

Always found the Hood to be very "over braked" in standard guise,I would regularly lock all 4 wheels under heavy breaking. Think what the weight of the Sierra compared to the Hood.

Really doesn't need a servo.

The "ICE" feeling that you had when the servo pipe melted gave you a feeling completly different to the one with the servo removed.

My 2 penth and what has worked for me.

Tiger push rod is about £11.00

http://www.tigerracing.com/zencart/index.php?main_page=product_info&cPath=59&products_id=278

[richardm6994]

Cheers guys.

 

I don't really want to have to make a new pedal box with twin m/c's etc...because I've got all on with the engine and I want to be completed by March (just in case of an early summer again) so if there's a simpler solution to hand that will work...I'll take it!

 

Ian, I have read that you can't use the master cylinder without servo, but I have also read that you can use the sierra master cylinder without servo (which is why I'm getting a little flustered), but for it to work you have to remove the servo completely, not just disconnect the vacuum. I'm glad you've confirm this "ICE" feeling isn't what I'll end up with when removing the servo & I think I'm going to follow in your foot steps and see how it goes!.....also why would tiger do a shortened push rod if it didn't work without a servo?

 

I'd still like to keep the floor open for other people's thoughts & comments

[Guest Ian & Carole]

Ian, I have read that you can't use the master cylinder without servo, but I have also read that you can use the sierra master cylinder without servo (which is why I'm getting a little flustered), but for it to work you have to remove the servo completely, not just disconnect the vacuum. I'm glad you've confirm this "ICE" feeling isn't what I'll end up with when removing the servo & I think I'm going to follow in your foot steps and see how it goes!.....also why would tiger do a shortened push rod if it didn't work without a servo?

 

I'd still like to keep the floor open for other people's thoughts & comments

Rich

The Tiger push rod is of a length to compensate the removal of the servo.

Un bolt the M/C from the servo, remove the servo and FIB it and the push rod you have, bolt the M/C onto the bulk head where the servo was using the new push rod.

Thats what I did 8 years ago and never looked back. Been to Europe 4 times lap of "The Ring" and I love the way it stops, much more feel IMHO.

[fry61]

Fitted a Ka m/c at first build;thought that mine was 19mm bore?? Running standard pads/shoes(loads of meat left so tight git me said use)Braking is fine,can still lock wheels in the "we need to stop NOW" moments. This set-up also passed IVA.Pedals were just straightened & re-welded.

Sierra m/c changed to Ka 20.6 = CSA reduced to 86% = 116% line pressure for same effort

-----"---- " " " 19mm + CSA " " 73% = 137% " " " " "

 

All the above don't add up to much unless you are happy with braking performance, both Mo & I drive Florin;with & without unbraked trailer tent in tow & we are.

 

 

All the above is rubbish -- second thoughts are -- shouldn't the wheel cylinders/calipers/tyre footprint be a match to the extra power your engine upgrade will bring??

[Guest snotfart]

sierra master cyl without servo,modified peugeot pendant type pedals(I will get you the dimensions if you get stuck)sierra vented front discs and calipers with greenstuff pads,sierra drum rear,bog standard.nice progressive brakes with good "feel" will lock all four wheels if I try.don't worry about the extra power as the car will be a little lighter than before and miles lighter than the sierra they were designed to stop.Dave.

[stevedohc2b]

I am using the standard Mc from serria and the zero pedals fitted some new braded Hoses and green stuff pads stops fine.

Also using the rod from tiger with a slight mod.

 

Hoses fitted when i got the shed to tow made a noticable diffrence.

 

Stephen

[Guest tiggertom]

_{my 2b was 1.8 cvh with servo ,front locking before retarding any speed,gone to st 170 on carbs had to go to gbs pedal box new sierra m/c no servo mintex 1144 in front lot more feel and less stoping distance .a big inprovment, i have a brand new ka m/c it would not fit gbs pedals if you want to give a try it was only a £5.but on other hand my brother has a cobra rep with 6.2L V8 jag brakes front and rear with transit m/c and servo which is very good you need harness to hold in under braking.}

[theduck]

I am reliably informed (and will be purchasing myself) that the fiat 124 mastercylinder is the ideal replacement and is available here http://brakeparts.co.uk/ for around 17quid

[Guest alfaGTA]

Richard, I had non servo'd sierra master cylinder with sierra discs and calipers with sierra pads and did not like lack of feel or bite, this was with bog standard everything (fluid was well past its best though)........ I rectified the issue with wilwood powerlite calipers, drilled and grooved disc's and mintex 1144 pads and new brake fluid. The car now stops very very quickly with no drama, slowing from speed on track is just a hard stamp on the brake pedal, speed is wiped away then turn into corner and away.

 

I chose this option because it involved no messing around with master cylinders trying to find the right bore to match the cylinders and no pondering over whether it'd fit or not.

 

Many will say the wilwood powerlite set up is vastly overkill on a lightweight kitcar and they may be right but I know I have made the right investment. If I decide to sell the car I can easily replace the originals and sell the wilwoods all day long for a very small loss.

 

I will PM you the price I paid for the whole set up.

[richardm6994]

cheers keith, can you pm me where you got the calipers from....could be a secret upgrade!!