Currently, my Mk2 is running G40 brakes with a Lockheed remote servo. I understand the Lockheed servo is designed for cars with a single circuit braking system; the Polo is a dual circuit. I noticed that the person that fitted it has joined the pipes (via a T-piece)  for the front brakes from the master cylinder to a single pipe which connects to the servo. Once the brake line leaves the servo, these are then T-pieced back out to each of the front brakes. If my understanding is correct, I think this renders the dual circuit braking setup useless in the event that part of the system fails. If this is the case, I'd like to remove the remote servo altogether.

 

I have a few questions:

 

First of all I'd like to check, can anyone confirm, is my understanding correct? Does the current setup remove the redundancy in the braking setup?

 

Secondly, I have the parts required to upgrade the brakes to a 256mm setup. How are people's experiences with Mk2's with 256mm brakes and no servo assistance? Is it decent enough? What's the braking effort like compared to a modern car?

 

Finally, the pipes from the master cylinder that have been joined are the one from the bottom, front and the one from the offside. If I return to a servo-less setup and want to feed those lines directly to each front wheel, does it matter which one serves which wheel? If it does matter, does anyone know which one goes where?

 

Many thanks in advance :)

Edited 21 November, 20169 yr by dabigginger

I think that I must have had a late night last night, as I keep re-reading this, but I'm still not sure that I have grasped what you are saying.

First of all, yes, the Lockheed remote servo is for a single -circuit braking system.

From your master cylinder, there would originally be two outlet pipes, one to the front brakes and one to the rear, the rear one normally feeding the brakes via a pressure regulator valve (variable load valve) mounted between the body and the rear axle - this REDUCES pressure to the rear brakes when the car is lightly loaded.

Are you saying that BOTH M/C outlets are 'T' ed together? If this is the case, how are the rear brakes connected?

If both outlets from the M/C are joined in this way, obviously there is no protection at all, should there be a loss of fluid.

 

When REAR wheels lock up under braking, the car will tend to do an about turn, as locked wheel ALWAYS try to get to the front (the principle of a 'handbrake turn') - that was the reason for fitting the rear pressure regulator valve.

With the above in mind, it MIGHT be possible to retain your servo, connecting it to the front wheels only, connecting the rear brakes directly to the master cylinder.

Note here that I say MIGHT, as this is something that I have never attempted  - it could result in over-braking of the front wheels, but at least the car would be more likely to stay in a straight line - and it would certainly surprise the MoT man when he got your car on the rollers!

 

Unable to comment on the 256 question.

 

It would be most dangerous to connect individual front wheel to the TWO master cylinder outlets - Just think what would happen if there were a fluid loss on one side - the car would pull so hard to one side  that it would pull you either across the road or into the hedge on your N/S.

 

If I have got the 'wrong end of the stick' with your question, please let us know, and we will have another look at the problem.

 

NB An alternative way of connecting a split system, is to split it DIAGONALLY  (N/S front to O/S rear and O/S front to N/S rear) but then you would not be able to use the pressure regulator valve.

 

Regards

Thanks for your help. In my understanding, the Mk2 has a diagonal dual circuit (the front o/s wheel and rear n/s wheel are on one circuit and front n/s wheel and rear o/s wheel are on another one). My master cylinder has 4 outlet pipes. The ones for the two front brakes are T'ed together. I've attached a drawing demonstrating this. My understanding from this modified layout is that if there were a loss of pressure in either front one, this would take out the other, is that correct? 

 

Also, I don't think the Mk2 has a brake pressure regulator.

 

I've found a dual circuit remote servo which I'm going to get, but as suspected, it will be important to plumb the front brakes to the corresponding master cylinder outlet. Bearing this in mind, do you or anyone else know which of the two outlets on the master cylinder are for the front o/s and front n/s brakes? The two that were t'ed together were the connector on the o/s and front, underside. 

my mk2 has a brake pressure regulator near fuel tank, but being LHD it has a dual circuit servo as standard.

 

http://www.pkwteile.de/ersatzteil/bremskraftregler/vw/polo-86c-80/8054

(http://www.buycarparts.co.uk/vw/polo-coupe-86c-80/8053/10137/brake-power-regulator)

 

in fact even the 0.9 litre 39hp had one in Germany

http://www.pkwteile.de/ersatzteil/bremskraftregler/vw/polo-86c-80/6234

 

I'll look tomorrow which master cylinder connections lead where.

 

 

 

 

Edited 27 November, 20169 yr by dvderlm

doesnt matter what way the connections go ...as long as its an opposing pair of front /rear on the back 2 ports and the other on the front ...so if it fails you get a left rear and right front or right rear and left front if you get me

 

never do it so its all on one side 

@dvderlm Thanks for checking the connections, I appreciate it. I'll also take a look for the brake pressure regulator. Thanks!

 

@steveo3002 Thanks for your comment. Unfortunately, I don't know which connections on the master cylinder relate to each circuit. There are 2 on the front (top and bottom) and 2 at the back (one on each side). The rear brakes connect to the top front connector and rear o/s connector on the master cylinder, so I really don't know which of the remaining ones is supposed to go where as they were T'ed.

 

right 

 

your m/c will have 4 outlets ...one for each wheel , early polos had a pipe to each wheel /later ones used a t peice , i would run a pipe to each wheel for the true benefit of the fail safe should something go wrong

 

the 2 rear most ports on the m/c are a pair

the 2 front ports are the other pair

 

each pair needs to be connected to a diagnonal front and rear wheel ...so in the event of something failing hopefull you have the use of one rear wheel and the opposite front  

   

Perfect, thanks :)

Dangit, sorry, still not managed to look under the bonnet in daylight. Was late and had to scrape ice.

 

what servo did you find for it 

 

i have a mk1 golf linkage id planned to try and fit one day 

@dvderlm If you get the chance to get some pictures, it will still be helpful. I'm not in a massive rush, so whenever you remember :)

 

@steveo3002 It was a Lockheed remote servo sourced by a local garage some 13 years ago. If you have a Google around, there are a fair few results for them. However, as they're single circuit only, I'm going to go for a dual circuit remote setup. I'll have to find somewhere for it to live though as space in the engine bay is tight. I'm considering the possibility of mounting it in the passenger foot well.

do you have a link for the new one ?  wouldnt mind doing something with mine 

Sure, this is the dual circuit one I'm interested in: 

http://www.vwjim.co.uk/ourshop/prod_2110864-Brake-Servo.html

 

Also, the Lockheed one for comparison: http://www.ebay.co.uk/itm/like/381171648852?lpid=122&chn=ps&adgroupid=36084540643&rlsatarget=pla-266373423547&adtype=pla&poi=&googleloc=9045803&device=m&campaignid=698615505&crdt=0&ul_ref=http%3A%2F%2Frover.ebay.com%2Frover%2F1%2F710-134428-41853-0%2F2%3Fmtid%3D1673%26kwid%3D1%26crlp%3D159563030297_563391%26itemid%3D381171648852%26targetid%3D266373423547%26device%3Dm%26mpre%3Dhttp%253a%252f%252fwww.ebay.co.uk%252fitm%252flike%252f381171648852%253flpid%253d122%2526chn%253Dps%26adtype%3Dpla%26googleloc%3D9045803%26poi%3D%26campaignid%3D698615505%26adgroupid%3D36084540643%26rlsatarget%3Dpla-266373423547%26gclid%3DCjwKEAiAjvrBBRDxm_nRusW3q1QSJAAzRI1tdttZy-R0G7BPcX2d3oz04WFts_Z4HUY3yYtkegUMvhoCDB7w_wcB%26srcrot%3D710-134428-41853-0%26rvr_id%3D1132343225664 I cant promise it's the exact same one I have, but it looks exactly like it.

 

The dual circuit one is quite a bit more expensive, but I think it's money well spent for piece of mind.

Edited 30 November, 20169 yr by dabigginger

pictures

side and both bottom outlets and brake light switch

Other side outlet and brake servo and hose and one way valve to inlet manifold. Reservoir with level sensor.

 

Looks like outlets furthest away from servo go to front left and rear right.

Outlets nearest servo go front right and rear left.

 

Rear pipes a little hard to tell because the bias valve is not very visible with car on the ground

Why a dual servo rather than two singles? Is it a space problem?