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Topic: Brake Pipe Routeing... (Read 3265 times) previous topic - next topic

Brake Pipe Routeing...

Touched on this elsewhere when I recently picked up a master cylinder with 4 x outlets.

The cars original only has 2 and utilises the brass junction pieces on the bulkhead to split the feed to the back.

I'm now at the point were I'm going to be tackling this and have looked into it a bit more.

The below are links / images from 7zap for 1991/92 models.

Front brakes - FRONT



Rear brakes - REAR



If I've understood these schematics correctly, they show the routeing for a system using the 4 x outlet MC.

The original MC worked fine and is in good nick.

I've blanking plugs (pictured) for the new 4 x outlet MC which will convert it to operate as the original but since I'm re-doing everything why not go the whole way and use them all... unless someone can see a problem?



Re: Brake Pipe Routeing...

Reply #1 –
I'm using all 4 on mine, could get a bit tight against inlet depending on what engine your fitting.

Key is to keep the opposite corners on the same chamber.
NSF with OSR and OSF with NSR

Re: Brake Pipe Routeing...

Reply #2 –
Very good point... I'm fixating on if it's technically OK, but be sods law that even it is, it won't fit.

It's 7zap that's thrown me a little - even you go back through the model years they show the 4x outlet MC when we know the came with 2.

I was reading (without fully understanding yet) about cylinder diameters / brake calipers / reservoir size etc. and how they all impact on the correct choice of MC.

Makes sense I suppose if you add to the total pipe length, your adding to the volume of fluid in the system which could have a knock on effect on pressures and capacities.

Brakes are too big a deal to be working on without totally knowing what you're doing. Even on a practical level, if the set up didn't work as well as hoped, imagine the hassle changing everything back to standard once the car was finished - think I'll go with the standard MC again - tried and tested.

Re: Brake Pipe Routeing...

Reply #3 –
Length of brake lines shouldn't effect brakes as long as bled properly and enough fluid in reservoir. Granted may need more fluid but the pressure applied should be the same.

Re: Brake Pipe Routeing...

Reply #4 –
The reason for the 4 outlet master cylinder was to give some braking effect in the case of a pipe failure in one line. One system left at least gives a braking effect on one front wheel and the opposite rear wheel, giving reduced braking but at least in a straight line, As sly_gti writes I can't see why if the brakes are bled you would need more fluid as you are only compressing the fluid in the lines.
scs 

Re: Brake Pipe Routeing...

Reply #5 –
The question of GTI model rear axle pipe routing was raised recently on our Facebook page.  It is years since I removed my rear axle so when I was at MK2 Spares recently I photographed a GTi rear axle for reference.  I posted this picture on Facebook and somebody confirmed the pipe routing:



I kept all of the old pipes so can offer them up to make new.  I was surprised to find a completely different routing.  My pipes turn and run on the inside of the rear axle:



They then run through a clip before turning to run along the radius arm.



They are secured by a second clip before terminating at a steel bracket:



I have a feeling both routes are correct dependent upon year.  My car is an 89 8v GTI.  Any ideas?

Edit; I've turned up a routing, and a very good job it is too, partially based on the routing I photographed for reference:


at least two axle designs too
Also a fourth routing looking completely original:



The correct route appears to be determined by the position of clip pegs on your axle.  Thoughts?

Edit, There are at least two axle designs too.

Re: Brake Pipe Routeing...

Reply #6 –
Early and late cars (with rear disc brakes) had different rear callipers.

Hopefully, I've got this the right way round and I think I'm right with the details, but I might not be 100% with it all so feel free to add any corrections - or dismiss my information completely  ::) 

On early ones, the handbrake mechanism was at the bottom of the calliper. Therefore the handbrake cable fed into the top of the calliper. Now to the best of my knowledge some time around 87/88 the callipers were redesigned and the handbrake mech was moved (I presume so it picked up less road crud) ... as we all know rear callipers are still troublesome so this solution wasn't perfect.

I don't know for certain but I think it's fair to assume if the handbrake cable was re-routed then the pipes would also need to be re-routed to move them out of the way of the new cable position. It's also therefore safe to assume any beam manufactured after the change could have multiple mounting points to cater for the pipes and cables in either position.

On my 86, it had at some point been fitted with later callipers and I remember the handbrake cables were cable tied to the bottom of the beam as there were no fixings.

I know we break down the models to a basic 3 variations; early, later and finally big bumper (90 spec) but it's also good to remember that each year of production the car was relaunched with new improvements and upgrades (and some downgrades as costs were kept down). Much of this may not be documented. VW continued learning from customer and service department feedback, seeing the issues users experience in real-world use, finding out what parts were being replaced under warranty etc. This led to ongoing development and many subtle differences over the years. Combine that with often multiple third-party manufacturers supplying parts, it likely parts changed ever so slightly if supplied by company A or company B.

Re: Brake Pipe Routeing...

Reply #7 –
I believe part of the redesign was to make it easier to bleed the calipers.

I think on early calipers they had to be taken off and turned upside down or something like that.
That's going by something I read somewhere, so could be absolute ******.

Re: Brake Pipe Routeing...

Reply #8 –
@Eddypeck the handbrake  cables are a further source of variation. I know there are at least two lengths and at least two methods of fixing. I have a welded on steel loop to retain the cable. Other designs have clips. I’m sure the changes are due to design evolution.
@sly_gti calliper bleeding could be one of the reason for changes. Taking the calliper off is mentioned in Hynes. On an 89 car I’ve never had to do that. Also the routing has changed due to axle design, my car has quite slender radius arms which allows the direct pipe routing. Other cars I notice have reinforced radius arms so the routing changes. I don’t know if Mk2 axles evolved or if some cars had MK3 axles?
I commented on the thread initially to invite comment on my routing. The variants I saw convinced me mine was correct for my car and year. I thought I’d stick with the post because this is a common question on Facebook; what are rear axle pipe routes? At the moment the answer is; it depends which axle you have and that may not be the one your car left the factory with.
Ill post pictures of mine when finished.
 

Re: Brake Pipe Routeing...

Reply #9 –
Both wrong, I made them some 25 years ago.  The way I did it was to take the originals to a motor factors (Pudsey Motor Spares, for anybody who recalls them) who measured the pipe with a bit of string.  They the added a few inches (as it was in those days) and supplied a pipe with a connector on each end.  The excess pipe took account of the lack of sharpness of hand bent pipe and what was left or not was lost or gained in the last couple of bends.  The result:



Does any body have a picture of the factory bends please?  Ideally like this?