remote brake servos...

[Karan]

i've got everything to start on my project car with e34 m5 engine now, just have to sort the plenum to brake servo clarance issues....

now i did think of taking an angle ginder to te plenum unntil i loooked further into the compledities of teh s38 engine, anmd that it has a resonance flap or something in the plenum that rotates and creates waves and creates a passive form of superchargiing or something.....
so i cant cut up the plenum....

now ive heard of remote vacuum servos but how do they work... but how do they work if they are not placed directly between the rod from the pedal and the master cylinder.... do mods need to be made to the rod and positiong of the mastre cylinder

also, does anyone ekse know whats involved in using old 7 series components... as i believe ian uses these on his s50 conversion to good effect and a bmw looking finish. ill probably use this unless the remote vacuum servo method is easier...


any help or insight greatly appreciated

cheers
Karan

[Toby_Unna]

this won't help you in the slightest, but what have you done about the exhaust manifold vs steering column clearance issue?

just curious!

the m30 powered e28 and (i think) e23 7-series use the hydraulic brake servo that runs off the power steering pump - are you talking about the later e32 seven?

got my e34 lump wired and plumbed in today and the car goes like a bloody rocket now!

[Karan]

toby i have a bit of cash set aside for a visit to hayward and scot to carry out exahuast manifold work, although at present im not sure exactly what needs to be done to it..


glad to hear u got a sweet engine in there now,,,,

go and gtech it and check the difference.. cheers for the vids.. that e46 goes with ease doesnt it!!

im not sure which seven's components to use but will prob email Ian, who's been great in the planning so far.

cheers
Karan

[Toby_Unna]

would gtech it but i have a slight charging problem, the charge light isn't coming on but after half an hour it died and wouldn't restart, put a different batt in and it worked fine but then died again, probably a buggered alternator on the new engine... i have a spare one though!

it started immediately first turn of the key, i couldn't believe it!

[Toby_Unna]

ps your avtar thing rocks! i could sit for hours laughing at that!

m3 was quick but a bit uneventful, if will bang in 5.3 secs all day long but there isn't much skill involved.

[Brianmoooore]

Have fitted remote hydraulic servos to minis, years ago. They were just bolted anywhere convenient, with the front slightly up to avoid airlocks.
They had a pipe from the single circuit master cylider, and a pipe out to all four brakes. ie. were just cut into the existing brakeline. Only other connection was a vacuum line from the inlet manifold. Don't know if anything similar is still available.
An alternative, on right hand drive cars, is to move the brake master/sevo sideways until it's up against the inner wing.
You need a metal plate either side of the bulkhead to blank the original hole and provide fixing for two of the servo bolts. The bracket above the glovebox will need drilling, the bracket from the transmission tunnel will need an extension piece, and the rear corner of the glovebox will need surgery.
A longer pullrod is also needed. This came from the same 525 as my engine.
I used a similar technique for the steering shaft as well, moving the bulkhead bearing slightly outwards.

[Karan]

cheers brian, i guess moving the whoole assembly to the left is an option...

however i did not understand what u mean by remote 'hydraulic' servos, how are these different to vacuum servos...

cheers
Karan

[Brianmoooore]

By the hydraulic bit, I meant they are triggered by hydraulic pressure from the master cylinder instead of a mechanical link. Boost is still provided by vacuum in the conventiional wat.

[ian332isport]

im not sure which seven's components to use but will prob email Ian, who's been great in the planning so far.

Hi Karan,

Not sure if you have e-mailed me, but I can't currently pick up my work e-mail at home (problems with the software I use to dial into the company network).

I used the hydraulic servo/booster from an E23 7 series. This is similar to the one used on the E32 7 series, but gives more clearance in the engine bay. Here's a picture showing the difference:



As you can see, the booster is actually the same length, but the mounting flange is in a different place. This puts some of the booster length inside the car, and get's more clearance (lengthwise) in the engine bay. I'm not sure if lenght will be an issue with the S38 plenum, but it was with my S50.

This booser will bolt straight in the E30. The bolt pattern is exactly the same as the vacuum servo you have currently. It also hooks straight up to the standard linkage under the dash, although I think I had to cut a few threads off the booster rod as it was a bit long.

The heart of the hydraulic system is the valve block/pressure accumulator. This splits the hydraulic pressure from the power steering pump, and feeds some to the steering rack, and some to the booster. It also stores a quantity of high pressure fluid to provide instant response, and also a bit of backup if you stall the engine.

You will find the biggest problem using this system, is finding places to fit things. The valve block/accumulator needs a home, and the fluid reservoir also needs fitting (this is much larger than the E30 one). I made a bracket, and mounted the valve block on the side of the booster. It's right in the corner, sort of down below the fuse box, so it does not get in the way. I mounted the fluid reservoir where the three relays used to be mounted on the inner wing. You can sort of see it all in this picture:



Once you have all the components mounted, you need to get the plumbing sorted. Unfortunately, you probably won't be able to use any standard BMW pipes, so you will need to get them made up at your local hydraulic place. I found my local branch of Pirtek to be very helpful with this.

It's a lot of work to get it all fitted, but I'm really happy with how it looks and performs.

Cheers,

Ian.

[Karan]

woohoo Ian to the rescue (again-lol)
im thick and even i understood all of that-cheers
that looks like great reliable setup, how does the servo assistance compare to the old system... also i'll be running minus abs, will this have any detrimental effect?

ill be on the lookout for e23 bits then i think, in fact i think pacerpete has a couple opf 745i turbos that hes stripping so i'll steal their bits

cheers once again Ian!!!

Karan

[Frenchguy]

Some of the issues I can see with remote servos are first that they're not compatible with dot 5.1 brake fluid, and secondly that they were mostly fitted to small and light cars, so they may be undersized for an E30.

[ian332isport]

how does the servo assistance compare to the old system... also i'll be running minus abs, will this have any detrimental effect?

Karan,

It feels great, but there again, I do have fcuk off great big brakes, so can't comment on how it would work with regular calipers etc. To me, the assistance feels about the same as the vacuum servo, but there was about 6 months between driving with each system, so it's hard to say for sure.

Running without ABS should make no difference.

Cheers,

Ian.

[Karan]

cheers Ian...

i guess u t-pieced the existing pas pipes then and took a feed a a drain back into it, what kind of pressure?(bar) is present in the pas pipes, as this will be required while ordering pipes

cheers
Karan

[jph78]

I'm using a dual-circuit remote servo on my S50 conversion.

It's made by a spanish company that supplies servos for JCB among others so they're pretty good quality.

It's also quite compact so there are various places it can be mounted.

This is a much simpler (and possibly cheaper) system than using 7-series components but saying that, Ians setup is very neat and looks almost factory.

Regards,

Jon

[Toby_Unna]

ian that's a really nice job you've done there, it must have taken a lot of work! i've had the hydraulic servo system off my m535i and there's a lot of heavy bulky bits and pieces to fit in!

much respect to you, i don't think i'd have had the patience to do that good a job!!

karan the brakes on my 528i and m535i did/do feel different to all the other (vacuum servoed) cars i've had, shorter pedal travel and a bit less progression (more on-off), but these are with standard brakes. get used to them very fast and now don't really notice swapping between 316 and m535.

[Karan]

jon do u have any pics of ure setup and how it is all laid out please
cheers
Karan

[SVBMW]

Just a guess from what I know about accumulators from work

The accumulator has a diphram/bladder inside, so you would have brake hydraulic fluid one side and presurised power steering fluid the other. (I guess thats where Frenchguys comment comes in)

The PS fluid pushes on the diaphram and thus provides pressure to the brake system. (the brake fluid sied of the accumulator would need brake fluid in it)

If I'm right then there wouldn't be a feed back to the PAS pump, just a vent to make sure there is no air in the system.


Tris

[Karan]

argh got ya

[ian332isport]

Nah, you're all wrong

Firstly, the accumulator has absolutely nothing to do with the brake fluid. The hydraulics for the booster, and the hydraulics for the braking system are totally independant of each other. The booster hydraulics are purely ATF/Power steering fluid (same as standard E30). The brake hydraulics can use your favourite brand of brake fluid. I'm currently running Dot 5.1.

The booster hydraulics go something like this:

High pressure output from the power steering pump feeds directly to the valve block/accumulator. The valve block splits the pressure between the steering rack and the booster. It also stores some pressure in the accumulator (sphere).

You have two high pressure outlets from the valve block. One runs to the input of the steering rack, and the other feeds the input of the booster. There are also three low pressure return lines back to the reservoir. One from the rack, one from the booster, and the other from the valve block.

I believe the sphere (accumulator) has a rubber diagphram inside it. One side of this is Nitrogen, and the other side is the hydraulic fluid. The fluid is pumped into the sphere, and compresses the Nitrogen. This pressure is held until required by the system.

Cheers,

Ian.

[Karan]

arghhh yes, that makes sense know as to why u have input into the valve block and then splitting from there as opposed to a 't' section, as if turning the steering while braking, i guess ud get some odd braking assistance cos of the loss in pressure when pas is activated....

i think i'll go with the 7 series method , as to be honest i dont get how the remote servo system works, and i suspect there will be fabrication and machining involved... although if someone could explain id be very grateful as id like to weigh up the pros and cons of both methods

cheers
Karan

[jph78]

The remote servo set-up is much simpler, and in theory shouldn't require anything more complicated than a bracket to hold the unit, and some new brake pipes.

A stock non-ABS E30 brake system works approximatley like this.......

The only differences are that the diagram shows a front circuit and a rear circuit, whereas the E30 has a diagonal split system (1 front brake and 1 opposing rear brake in each circuit. Also there is no item 6 on an E30 either. Oh and i don't think you'll be using drums!

What i am planning to do is remove the servo & M/C assembly and then re-mount the stock M/C to the factory linkage.
This setup would work fine but would require lots of pedal pressure to stop so is not suitable for a road car.
Next you plumb the remote servo into the the brake lines. The servo has 2 inputs, and 2 outputs, so it just 'lives' somewhere in the brake lines between the M/C and the 'Tee' pieces where the lines split to the individual calipers. Oh and it runs off the factory vacuum line which goes to your stock servo.

I hope that made some sense!!

The remote servo itself works in just the same way as the factory servo, it just lives in a different part of the brake circuit.

I've built several cars using remote servo setups like this and haven't experienced any problems using them so far.

There is a chance that the factory M/C will require some machining to mount directly to the stock linkage but this will not be a problem, and i'm willing to help out with any maching work that others may need if they choose this setup.

Cheers,

Jon.

[Karan]

cheers for that excellent description jon!

have u started doing ure brake setup yet?
do u have any pics and any recommendations as to which remote servo to go for for this application

this does admittedly sound a lot easier, but i guess it depends on the machining required for the master cylinder to mount to the pedal rod assembly.

in remounting the master cylinder... would it not be possible to retain all the original 'rodwork' inside the servo/booster assembly, so as to reduce machining and then simply cut off the actual round diapragm part of the vacuum servo?? so as to give the engine the clearance required??, i guess this would reduce the strength of the whole linkage assembly between the rod and the master cylinder though, but this could probably be strengthened by welding strengthening of some form onto it, but as you say it would in fact be neater to just move the master cylinder backl towards the bulkhead and remount it there.

cheers
Karan

[jph78]

I forgot to mention in the earlier post that there is a problem when using the 7-series brake booster setup with an S50 engine than Ian forgot to mention.

Have another look at the pic of Ian's engine bay thats posted above...

See how close the end of the M/C is to the rubber plenum boot?
Well thats not a stock Plenum chamber Ians using! (sorry if i'm revealing some of your secrets Ian!)
The outer face and flange that the rubber boot mounts to was cut off and then moved both further forwards and inwards, toward the engine.
It was then welded and painted to give a factory appearance but if it was left stock i believe the mounting flange would sit about 1-1.5 inces futher back (toward the bulkhead) and about 1/2-1 inch further out (toward the N/S inner wing).
I cant recall if Ian said it wouldn't fit at all with a stock plenum, or that it would but he didn't want it touching and looking non-factory on his car.

I'm not sure if this is gonna be an issue for you Karan with the S38, but it's something to bear in mind. I can always take some measurements of my S50 so you can compare it to your S38 if you like?

I haven't started on my brakes yet, but i have bought the remote servo i'm gonna use. Again i can send you measurements, pics etc if you want.

As you say, you could prob keep the original rod connections within the factory servo but the M/C would be too far forward within the engine bay and would foul the plenum intake of the S50.

I don't think the mods to the M/C (if necessary) will be too major tho.

Regards,

Jon

[Karan]

cheers jon i noticed that rather tight clearance before actually....

the engines are clearly very different, but the intake into th plenum from the rubber boot on the s50 appears to be very elongated.. whereas this is not the case on the s38...



id appreciate it if u could send me some pics of this unit and details as to where i can get one from and how much it costs etc to
'hp3899(at)bris.ac.uk'

let me know please when u start on ure brake setup aas id be interested to know, and may have to call on ure expertise for the machining side of things..

cheers mate
Karan

[jph78]

Sorry for the slow reply mate, i've been trying to find the invoice for the remote servo but it's currently hiding somewhere in my 'office'

From memory the single circuit type (this is the type i've always used before) are about Ԛ£175 +VAT but you'll need 2 of these.

The one i've gone for is a dual circuit (ideal for the e30) which is about Ԛ£225 +VAT IIRC. Obviously if you use this type, you'll only need to buy 1.

When i've found the invoice i'll post up the supliers web addy.

I'm planning on moving the battery to the back of the touring, and positioning the servo in the original battery position. I'll see if it fits this weekend and take some pics if it ever stops snowing/raining.

PS, i found some pics of an S38 in an E30 and although it's not very clear, it appears it still has the stock servo and M/C assembly. Although saying that, you can't tell if it's a smaller servo, or if it's been moved further out toward the nearside of the car.

If i were you i'd prob wait till the engine was in, then decide!

[Karan]

hi jon cheers for the help

do u have that pic by any chance....

thing is with my engine is i'll be putting it quite far back in the bay in position 3 so this may be an issue...

cheers
Karan

[jph78]

I'll sort some pics out at the weekend mate, it's dark when i go to work, and dark when i come home at the moment!

[Karan]

cheers guys!

does anyone know if the iX ran a hydraulic brake booster as this thought seems to be stuck in my head......


Karan

[ian332isport]

cheers guys!

does anyone know if the iX ran a hydraulic brake booster as this thought seems to be stuck in my head......


Karan

Hi Karan,

No ,the iX still ran a vacuum servo, but it was a slightly different size to the regular E30 servo. I believe it was a smaller diameter, but a bit thicker front to back.

Ian.

[Karan]

hmmm i think i could get away with that maybe.....

but i reckon findong one could be an issue.. sorry to bother u again ian.. but do u know how much these are new from the dealer, and i guess they could fit to the standard master cylinder..

cheers
Karan

[ian332isport]

hmmm i think i could get away with that maybe.....

but i reckon findong one could be an issue.. sorry to bother u again ian.. but do u know how much these are new from the dealer, and i guess they could fit to the standard master cylinder..

cheers
Karan

Karan,

I just checked my ETK, and it was only actually the facelift iX that had the different servo. The early ones used the same unit as the rest of the range. The later one is a Girling unit, so is not going to match with your current ATE master cylinder.

New from the dealer, you are looking at around Ԛ£256 for the servo, and Ԛ£237 for the master cylinder

Cheers,

Ian.

[Karan]

hmmmmmmmm

cheers mate for that

i think im gonna get the engine sitting in first then see clearance, as the s38 does tend to leave more room that side than ure m50 does as the s38 appears to be longer rather than wide like the s50, also the whole intake side of things like the plenum is wider on the s50....

ian, apart from cutting off a few threads did u have to do any other mods inside the car to the linkages?, or was there similar travel on both systems

cheers
Karan

p.s-sorry it must really piss u off with me asking all these questions, i tend to copy and paste all ure replies and save em on my laptop-lol , in case i forget!!

[ian332isport]

ian, apart from cutting off a few threads did u have to do any other mods inside the car to the linkages?, or was there similar travel on both systems

cheers
Karan

p.s-sorry it must really piss u off with me asking all these questions, i tend to copy and paste all ure replies and save em on my laptop-lol , in case i forget!!

Hi Karan,

The linkage inside the car is totally untouched. I didn't even have to adjust it. All I did was to cut some threads off the booster rod, and screw the thingy (can't think of the correct term right now ) back on.

One of the main requirements for my conversion was that I did not want to modify the car itself. Everything I did during the conversion was done without cutting, drilling, hammering or any other sort of 'ing'. You could unbolt everything I did, and bolt it straight into another E30 shell. You could also fit an M20 back in my shell and never know it once had an S50 fitted.

Feel free to ask as many questions as you like. I know how hard it was to find info when I was doing my conversion, so I'm more than happy to help. Your not the first either. I have helped several people in this country with S50 conversions into E30's, E36's, and even helped a guy in Sweden fit an S50 into an E39 520i.

Cheers,

Ian.

[Karan]

cheers Ian

I know what u mean.... my iS is a really clean car with 60k on it.. i dont think i wanna be messing it up big time, i think im gonna get the e23 setup

although i will have to give the bulhead a bit of beating with the position im using , but i guess that wont be visible anyway.

cheers for the help again
Karan