Brake servo and MC on driver's side

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redcar
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Sun Apr 08, 2012 4:07 pm

Image Good deal of adjustment present on the s14 servo. Also more adjustment at the master cylinder end of the servo.

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Image 80 mm

Image 60mm...so 80x60 mounting holes?

Image Servo distance (80mm) + MC distance (150mm) = 230mm total length

Image 150mm
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Image Thickness of servo is 80 mm. This was measured as shown, by sitting a straight bit of cardboard flush with the bulkhead mounting point, then another piece of cardboard flush with the MC mounting point, and then recording the distance between the two. Was very difficult to hold all that gear + aim a camera at it! :D
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Imageshows how close the mc is to the turret even on an s14!
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redcar
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Sun Apr 08, 2012 4:15 pm

The BM-57 MC only has two outputs on it, so a T-piece must be used. As shown on the pictures of the R33GTR MC and servo in the s14 engine bay.
GeoffBob
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Sun Apr 08, 2012 5:11 pm

redcar wrote:The BM-57 MC only has two outputs on it, so a T-piece must be used. As shown on the pictures of the R33GTR MC and servo in the s14 engine bay.
Better that than trying to get down the righthand side of that servo :eek: I've had my fingers in some fiddly places but that would not be fun.
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redcar
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Sun Apr 08, 2012 5:14 pm

GeoffBob wrote:
redcar wrote:The BM-57 MC only has two outputs on it, so a T-piece must be used. As shown on the pictures of the R33GTR MC and servo in the s14 engine bay.
Better that than trying to get down the righthand side of that servo :eek: I've had my fingers in some fiddly places but that would not be fun.
:D

What do you think of the pics etc. as shown. As you said, best to look for a small jap servo? Or modify the BM-57 to fit the clio servo?
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Sun Apr 08, 2012 5:38 pm


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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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redcar
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Sun Apr 08, 2012 5:44 pm

Ok, that's very interesting Geoff, i see what you mean now about having a smaller servo rather than a larger servo which could be difficult to use.
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Sun Apr 08, 2012 5:53 pm

Redcar, keep in mind that F0xy only requires a 17/16" M/C due to the fact that he has larger callipers and discs. Don't copy his setup unless you have the same. With stock brakes the 23mm Clio M/C should be just fine.
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redcar
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Sun Apr 08, 2012 6:05 pm

GeoffBob wrote:Redcar, keep in mind that F0xy only requires a 17/16" M/C due to the fact that he has larger callipers and discs. Don't copy his setup unless you have the same. With stock brakes the 23mm Clio M/C should be just fine.
Yeh, makes sense. I would be looking to run e38 4 pot brembos up front on a 312mm disc with stock brakes on the rear. What would the situation be then...27mm master cylinder?

Also, what's the stock master cylinder. ATM my braking system is ALL 325i stock setup...I think that a combination of RHD e30 with all those pivots and linkages/joints etc. as well as the too small a stock MC leads to an interesting pedal feel. The pedal actually travels a fair bit before it does anything.

Although, having driven brand new VW Golfs, corsas and polos, basically modern hatchbacks i feel that their brakes are MASSIVELY over assisted. I actually felt it very very difficult to make a controlled smooth stop coming upto a roundabout. I've also driven new shaped BMWs, like e90s and e60s and the pedal feel is MUCH MUCH better. The pedal isn't over assisted and i can control and feel it easily. I suppose it boils down to personal preference, but for me, I like to really press the brakes and feel what they're doing, but at the same time have a servo/MC setup.
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f0xy
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Sun Apr 08, 2012 6:25 pm

Nice pics/details on the servo. Right then...

Clio Servo Depth - 85mm
Clio Servo Diameter - 220mm / 8.66in
Clio Master Cylinder Depth - 110mm

Clio Servo Mounting Points (Bulkhead) - 73mm Square
Clio Servo Mounting Points (Master Cylinder) - 60mm

Clio Master Cylinder + Servo Total Depth/Length - 195mm


The main deciding factor on the servo is its total diameter. 220mm is the MAX that will fit, its pretty much sat on the inner arch. The servo is as far over to the center of the car as it will go (retaining the standard clutch MC position), otherwise you'l have to re-fab all of that.

As I previously mentioned, the maximum total depth is 200-210mm, otherwise the end of the MC will hit the strengthening part of the front turret. I could probably get around it with a bit of work but im trying to stick to that length.

I only need two outputs, as I have a single line running through the car to the hydraulic handbrake/bias valve and then a double banjo bolt on the other output for both front lines.

Looking at the pictures and measurements, the R33 MC is 150mm long. Add that to the clio servo (85mm) and you get a total of 235mm. Could be a bit too long. Compare that to an S14 servo and R33 MC which is 230mm its pretty much the same.

With regards to the servo-to-chassis mounting, the clio holes are 73-75mm in a square. Im sure I could modify it again to fit the S14 servo, but its pointless really considering they are the same thickness and the clio is a double diaphragm inside. What was the diameter of the S14 servo? It could be too large width ways to fit anyway..

In short it would be ideal if the R33 MC could be made to fit the Clio servo (and length wasn't an issue), even better that the holes come out on the engine side. Could you get me a picture looking at the master cylinder end on from the back, so I can see how much material there is to play with inwards of the current (80mm) holes?

I've got a feeling the S14 servo has too large of an overall diameter to fit in the space looking at it.

Good shout on the Megane Sport master cylinder Geoff, I know quite a bit about those. The 2005> models (R26, R26R and another) had a increased master cylinder from the factory when they were released, it was mentioned in the details when they had a spec sheet up first going on sale. Not sure on the size though! They did have 4pot Brembos and quite beefy calipers on the rear mind.
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Sun Apr 08, 2012 6:38 pm


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redcar
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Sun Apr 08, 2012 6:44 pm

Ok, Diameter of the S14 servo is exactly 240mm, so out of the question really.

Here are lots of pics and measurements of the BM-57 MC...I think it will work as there is space for modification to have two holes 60mm apart to fit the clio servo.

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ImageReads 20.16
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f0xy
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Sun Apr 08, 2012 7:30 pm

Cool.

Well after seeing that and you checking the dimensions of the part that sits inside the servo is should be a perfect fit with the holes re-drilled. The whole assembly of the Servo and MC may be a tad long but I'l have to come to that once its offered up to the car.

Luckily the Clio servo has an adjustable rod inside, so it can be wound out to match the BM-57 MC. Il have to get the MC mounted in the mill and either drill two holes 10mm further in, or slot them sideways until it slides onto the servo. Will get hold of one and give it a try.
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redcar
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Sun Apr 08, 2012 7:31 pm

Well...Seems the best way to go is to modify the BM-57 MC to fit the clio servo. After a few measurements of the clio servo by F0xy, the conclusion was that the BM-57 MC would fit the servo with only the two mounting holes requiring modification.

F0xy, wuold it be better to just drill two holes 10mm further in...will probably be a better idea than slotting them.
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f0xy
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Sun Apr 08, 2012 7:38 pm

Well the holes would be very very close to overlapping on their edges anyway if they are 8.3mm like you say, i could always drill it and see how close they were I suppose.
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redcar
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Sun Apr 08, 2012 7:44 pm

Yeh, could drill it...then if too close i suppose you could slot it anyway.
Last edited by redcar on Thu Apr 17, 2014 5:45 pm, edited 2 times in total.
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f0xy
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Sun Apr 08, 2012 7:46 pm

Im guessing its cast alloy and not steel, so would really need a TIG to weld it up. I only use MIG, plus I guess you'd have to be careful with the high temps involved and MC seals..
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redcar
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Sun Apr 08, 2012 7:52 pm

Yes, it's cast alloy so TIG. Oh yeh, didn't think about the seals etc. Hopefully slotting or drillling new holes that overlap will be strong enough as long as the two bolts are done up nice and tight and a nice big washer over those holes are used :D
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Sun Apr 08, 2012 8:47 pm

Definitely dont weld :eek: Will likely distort the bore!

The way I'd do it is as follows:
Secure the M/C vertically on a mill. Drop a slot-mill (8mm by the looks of it) down into one of the mounting holes. Mill 10mm towards the axis of the bore. Then do the same on the other hole. Will still be plenty strong enough. Washers won't hurt when mounting.
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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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Sun Apr 08, 2012 9:27 pm

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f0xy
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Sun Apr 15, 2012 1:56 am

Machined the BM-57 MC earier, wound the rod out on the Clio servo and it fits well. Put it onto the car and there is just enough room, perfect really!
GeoffBob
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Sun Apr 15, 2012 6:00 pm

f0xy wrote:Machined the BM-57 MC earier, wound the rod out on the Clio servo and it fits well. Put it onto the car and there is just enough room, perfect really!
Well done mate :thumb:
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"It is amazing how many drivers, even at the Formula-1 level, think that brakes are for slowing the car down." - Mario Andretti
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