Brake connections

Zub-911 · 9 Apr 2017

I am in the middle of replacing my 2003 4S rear brake lines from the connection block which sits forward of the nearside rear arch.

The block (996 355 760 31 - connecting piece fourfold) has 4x connections to it... connecting to the rear calipers. 3 of the connections appear to be standard M10 fittings however the one exiting to feed the rear offside caliper is larger measuring around 12mm..

Can anyone confirm this to be an M12 x 1.0 before i order an adapter to M10... ?

I have gone for the ProMax braided over gearbox solution to avoid dropping the box. However this has been provided with M10 connections - hence my question.

thank you.. Neil

wasz · 10 Apr 2017

Sorry can't help but thats a great idea. I have heard of people getting copper lines through with some wiggling and in situ bending though.

This sounds easier

http://www.promaxmotorsport.co.uk/p...ke-hose-996-models-for-over-transmission.aspx

poppopbangbang · 10 Apr 2017

How much do you value your ABS working well on the rear brake circuit?

Braided lines baloon far more than solid under pressure. This increase in system volume under pressure increases volume consumption and increases the amount of control the ABS has to deal with. The most important things when optimising ABS from a mechanical point of view is the stiffest possible caliper with the shortest possible length of flexible line in the system, this combination means the pressure reintroduction into the brake line after wheel lock has cleared is as immediate as possible. If you have soggy calipers and lines which baloon in volume with pressure the ramp in to full clamping load for a given master cylinder output pressure will be delayed, essentially you go from a square wave to a sine wave when looking at the brake pressure trace at the caliper. Ideally you want the ABS to be able to limit braking effort to the threshold of wheel lock/a slip amount optimal for braking effort in order to maximise the time spent braking the car and minimise the time spent coming off pressure to avoid lock, it can't effectively do this if it's constantly dealing with a large volume change in the system.

Bosch specifically recommend rigid lines for ABS, from the M4 Manual "Use rigid steel tubes for the brake lines. Only use flexible lines when you have no
other option available. This keeps the volume consumption low and the ABS
needs less controlling"

It's less of a problem if you've plumbed the whole car in flexible as the ABS simply works poorly on all four wheels but half and half is pretty much worst case as the front circuit performance will be sharp and as per the controller calibration but the rear brake circuit performance will be much less leading to brake bias moving forwards which in the wet when braking heavily will result in the rear braking effort being heavily compromised due to weight transfer.

It will also effect operation of the PSM with regards it's ability to brake a wheel sharply to assist in rotating the car or controlling wheel spin as again the braking effort delivered at the wheel for a given valve pulse width is not reflected at the wheel as it was when the controller was calibrated.

Having said that if you're a driving god and never get into the ABS or PSM the only result will be a very slightly softer pedal at high brake system pressures :lol:

You can do it with copper fed up and over and bent in situ, this is really a far better option that braided lines as it's a lot of flexible line length you are adding.

Zub-911 · 10 Apr 2017

Thanks for the feedback on the flexi poppop ...

I appreciate the issues it may cause, but as it's just a temporary fix for this summmer until the box is dropped for ims/rms, clutch slave lines and air oil sep refresh.. I'll take my chances..

Can I have a shot of your manifold jig?

Thanks Neil ..

Jamesx19 · 11 Apr 2017

I also had larger male union in the connector block. I cannot be absolutely sure, as I didn't measure, but the pitch of the thread was the same as the other connectors 1.0mm and the diameter wasn't 12 mm so I'd say M10 1.0 will be correct.

I reused the old male union as the pipe was still 3/16ths or whatever the rest is 4mm?

Cheers James

Brake connections

Zub-911

Silverstone

wasz

Paul Ricard

poppopbangbang

Nurburgring

Zub-911

Silverstone

Jamesx19

Hockenheim

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