I'm replacing the whole braking system

[Crescent Fresh]

As some of you are aware, I have about had it with the brake system on this car. I already have the Wilwood calipers on the car, and the Wilwood master cylinder and proportioning valve have arrived via UPS. I will be taking out the stock master cylinder (which is leaking), the accumulator and the pressure switch (both are suspected to be bad), and going to a regular brake system.

My mechanic can't get to it until April 10th which gives me time to learn of hints and tips.

Anyone ever did this before? I have searched the forums and found nothing.

Is anything (besides ABS) tied in to the brake system?

Any hints, tips, suggestions, or rude comments that may help the mechanic and I make this transition a smooth one?

Scott

EDIT: It is a twin master cylinder that I'm going to.

Edited April 16, 2008 by Crescent Fresh

[V8Esprit73]

I've done just that, only on a V8.

Not sure how relevant it would be to you but if there's anything you think i may be able to help you with just drop me a pm.

I removed the abs system, servo etc. Converted the original pedal box to a twin master cylinder (front and rear circuits separate) with an adjustable balance bar.

One of the main things with the V8 was the wheel speed sensors send info to the abs ecu, a signal is then sent to the engine ecu which uses the wheel speed to limit the boost in first and second gear. I'm not sure if the S4 has anything like this (sure someone will be along to enlighten us!) but it isn't too difficult to sort out......

You'll definitely notice the difference with your changes! Are you intending to use a servo?

[Crescent Fresh]

V8, I don't even know what a servo is .

So, assuming all goes well of course, I won't have limited boost in 1st & 2nd? Sweeet!!!!

Servo...what is that and do I need it?

[V8Esprit73]

I think the s4 has the electric servo system? - The one with a much talked about pressure switch that causes no end of problems?!!

Servo reduces the effort required on the brake pedal. - The V8 has a vacuum powered servo.

Without a servo the pedal can feel very stiff (can be altered with the piston size in the master cylinder). Generally gives a lot more feel to the brakes but requires more leg effort!

I don't think the limited boost is relevant to the s4..... u can't just junk the wheel speed sensors if it is though, otherwise you'd have limited boost in ALL gears!

[Jonathan]

Yeah the S4 will have a wheel speed sensor on the drivers side rear hub for the speedo (umm actually IF it is a digiatal speedo, the early S4's might not have this) - You're right in that it also has a pressurised 'boost' chamber which causes a servo effect and that's a lot of the problems.

Other than that you're fine - it's something I was thinking of doing if pushes came to shovels, the GT2 (if I finish it) will have this kind of setup in it as well for track use).

The way to overcome the servo is bigger pistons on the master cylinders (oops someones just said that lol), you've gone some way to that already by having a twin system, you're effectivly doubling the surface area of the piston. You'll find out how good it is when you drive it really - no real way of predicting it.

The S1 Elise has a very basic braking system which proved really you dont have to have magic brakes to drive the car - even when you locked a wheel the brakes were incredibly controllable - just takes a bit of getting used to.

Nothing to really add - good luck with the install and testing.

What are you going to do with the old parts ?

You should sell them up, they might be handy to make 1 good unit for someone else.

[Vulcan Grey]

I know some here in the States have removed the GM ABS and gone back to the master cylinder that came on the SE's (one big reason I bought the 89SE, no ABS)

For the servo, you might consider the mechanical vacuum pump from the SE's (its about $100 from local parts stores)

or an electric pump with a reservoir.

The SE's Bendix master cylinders are pretty much un-obtanium these days... I think my friend bought the last one that I could find anywhere (including the UK sources).

But if you find another that works, let us know...

I searched Amazon.com's master cylinders and some Honda Accord master cylinders looked similar...

[98GT3]

The way to overcome the servo is bigger pistons on the master cylinders (oops someones just said that lol), you've gone some way to that already by having a twin system, you're effectivly doubling the surface area of the piston. You'll find out how good it is when you drive it really - no real way of predicting it.

Pretty sure you need to go the other way i.e. smaller master cylinder bore if you are trying to achieve a better mechanical advantage - take a hydraulic jack, they enable you to lift great weights by using a small piston pumping fluid into a larger one. The trouble will be getting enough mechanical advantage without running out of pedal travel, taking up slack in the system - one reason they use a larger piston and a servo.

Phil

98GT3

Edited March 25, 2008 by 98GT3

[andydclements]

Yep, if not using a servo (or other assistance) you either need smaller master cylinder bore, or large bore calipers, assuming you don't have the right foot of an elephant pushing on the pedal.

[Crescent Fresh]

Well, all 4 calipers are dual piston, and the master cylinder the mechanic had me order is tiny. After it's all done, the Lotus will have the same brake setup as my mechanics race car...the EXACT same setup.

Can I just leave the wheel sensors where they are, or will this cause massive chaos?

[Jonathan]

Pretty sure you need to go the other way i.e. smaller master cylinder bore if you are trying to achieve a better mechanical advantage

Ugh - you're probably right, always get the force and area mixed up. For some reason I keep thinking pressure is force x area.

[Tony94S4]

Scott,

I hope ur mechanic did his home work right,

what he has doesnt mean it will work the same for u

if the bore is to small and ur calipers larger ur pedal

travel may be all the way to the floor,

if bore is large it will be very hard to press,

if it was me I would use duel smaller bore masters

I will probably take that route,

also did u get a chance to feel the brakes on ur mechanics car

it will take getting used to it from servo to no assist brakes

[Crescent Fresh]

He knows about brakes....and Chevy, Ford, Honda...etc..etc.. He's fixed my cars for 17 years. However, I will not have him work on any other part of the car, as he's never worked on Lotus before. But, going to a mechanical braking system, I think he'll be OK. He's predicting 2 or 3 days to do it right.

[okspeedsix]

How is the brake system replacement progressing?

[CarlC]

To my knowledge this hasnt been tried before and Im very interested to see how you get on. Im sure like a number of S4 owner the brake system really lets the car down in a massive way. It would be brilliant if you are able to get a effective system to replace the current crap system. Keep us posted. B)

[Crescent Fresh]

The vessel goes in tomorrow. He is estimating 2 or 3 days. I'll let you know how it goes.

[Tony94S4]

The vessel goes in tomorrow. He is estimating 2 or 3 days. I'll let you know how it goes.

Scot,

have u checked any insurance laws,

do we need to let the ins. companies know

that we no longer have abs?

just dont wana a get in trouble if accident hapends

good luck with the project

tony

[Crescent Fresh]

Got it back....Totally Sweeeet.

100% mechanical. No assist at all. It'll just take some getting used to. Turbo seems to be spooling higher, but that might just be all in my head.

Wilwood Racing dual master cylinder and proportioning valve - under $200.

Labour - $1500.

No more weak link in the Esprit......

I highly recommed this.

[Jonathan]

Good stuff - take a pic or 2 when you get a chance, like to see the install etc.

On a side my brakes are now seemingly OK once I bled the master cylinder under new instructuions - I also drained the accumulator and have those pipes off for a few days, so whether this is an air in the system, I dont know, nice and wooden again hehe.

[Crescent Fresh]

Link to pics. I have taken 2 pictures of the old parts to give you an idea of the size difference. The box with the old parts is rather heavy.

http://s21.photobucket.com/albums/b257/Bor...k=nav_tab_album

The ABS module on the passenger (U.S. model) side...are all the wires in it ONLY for ABS? Can I remove this?

Edited April 16, 2008 by Crescent Fresh

[Paul93Lotus]

From looking at the ABS schematic....the only outside wires from the abs controller go to the lamp driver for the abs fail light, power and ground wires for the abs. Probably the only thing that MAY occur by disconnecting and removing the controller is having the ABS light on all the time (which a bulb disconect can fix).

Not sure about the relays near there though....

[Crescent Fresh]

Can someone let me know if the link to pics works, please? (2 posts up)

Thanks

[Paul93Lotus]

Work for me. B)

[hast2]

Link works for me aswell.

[Jonathan]

Looking at this again, did yu use this component ?

http://www.wilwood.com/Start/Products/006-...TIRMC/index.asp

I take it all that was needed was an adapter plate and job done.

Are the fronts being served by 1 port and the rears by the other via a proportinal valve ? Thats what it looks like.

Not sure how this will work with my setup but it looks neat - how did you come to the conclusion to use this particular master cylinder ?

[MartinL]

Hi, I have looked into going this route to replace my S4 crap system, all looks a straightforward fitting and set up but do you know the master cyl. diamater??

Various sizes available off the shelf but would like to try and get it right first time.........