Dual Circuit Master Cylinder on 600D

[903cc600D]

Hi Everyone,

I've run into some issues while installing a dual circuit master cylinder on my 600D and I'm hoping that someone who's been through this before can help me out.

First, here is a picture of the original master cylinder and the new one

You can see that the new one is quite a bit longer than the original. For test fit purposes I mounted it using the rear hole so as to keep it in the same position relative to the brake plunger as the original as shown below.



Trouble starts as the pitman arm now strikes it while turning left:


This was solved by using a pitman and idler arm from an 850:


The two issues remaining are that the sector shaft strikes the front inlet and I'm not sure what I should use for the link rod and inner tie rods.



Can anyone provide me with some guidance or show how you installed your master cylinder?

Best Regards,
Aaron

[pheyden]

Aaron,

I would make the following suggestions.

1. The new master cylinder looks to be slightly narrower than the original. I would say try using s spacer (maybe 1/2 inch) to space the new cylinder out from the chassis rail. This will move the cylinder away from the idler arm.

2. Once you have done this the push rod will also align better. This may allow you to shorten it slightly, allowing you to move the master cylinder back some.

I recognize that this is a problem. Let's hope someone else give some input as well. It is the generally accepted m/c that is used, so there must be a solution.

Unfortunately on my car the whole pedal arrangement has been modified, so I cannot model it myself.

Regards,
Paul

[903cc600D]

Paul,

Thank you for your response.

In regards to your suggestions, I had the same ideas. The new m/c is narrower. By spacing it away from the chassis rail by 3/16" it lines up very well to the plunger. Also, I'm locating a smaller banjo bolt to give me a little more clearance. Finally, I will try putting some thin spacers behind the steering and idler arm box to move them forward just a bit. If that doesn't give the inlet enough clearance, I will move the m/c back a bit.

The m/c should be in it's final position this week.

Regards,
Aaron

[pheyden]

Aaron,

I know you are good at documenting things, so I would be grateful if you would post a message here with some photos showing the what you finally came up with. It will be of value to others making the same modifications.

Regards,
Paul

[903cc600D]

Everyone,

In installing the new master cylinder I was hopeful to find a way that would require a minimum amount of modification, fabrication and replacement parts. I believe that I found such a way. Here is my solution for installing the dual circuit master cylinder in my 600D.

Starting with the m/c mounted using the rear-most hole, I moved it back toward the rear of the car 23mm and drilled two new holes. As mentioned above, it is just a bit narrower than the original, so I spaced it away from the chassis rail 3mm to line it up to the plunger more closely. (It's not perfectly lined up, but spaced away any further caused clearance issues with the brake pedal.) I used two 90mm legnth bolts, fender washers, and nyloc nuts to secure the m/c to the chassis rail.




Moving the m/c toward the rear causes clearance issues with the brake plunger, so it necessary to remove a similar amount of material from the plunger. The plunger also was orginally installed with the curve upward. With the m/c so much closer, I found it fit much better installed with the curve downward.



If left as-is, the sector shaft clears the inlet, but the 600D pitman arm will still strike the front of the m/c. You can use the 850 arms to solve that problem, as mentioned above, but that would really change the steering link geometry. I didn't know how that would affect the car's performance, so instead I put spacers behind the steering box to move it forward about 6mm. The combination of moving the m/c back and the steering box forward allows the use of the original 600D pitman and idlers arms.




Lastly, I wanted to note that all original brake lines stretched to fit the new m/c with the exception of the driver's side front, which is much too short. My solution to this was to use one of the two 850 lines that run from the m/c to the brake failure sending unit. Each 850 has two of these lines and, since they are well protected, they are usually in good shape.



I'm very happy with how this installation turned out. It was relatively straight forward and not too dificult. If anyone has any questions or comments, please let me know.

Aaron

[pheyden]

Aaron,

Congratulations !! Very well thought out. This is a great write-up, that I am sure will be helpful to others wanting to do the same modifications.

Regards,
Paul

[gil]

Aaron, thanks for posting your excellent write-up and photos. I have a dual circuit m/c for my 600 that is for a Zastava 750. I had assumed that it would be a straightforward swap.... I wonder if there is any way to get some photos or info. on how they are installed in a Zastava? It seems rather drastic to have to use 850 steering parts to get the clearances. Could the Zastavas really have a lot of changes in the steering, mounting of the m/c, etc. to accomodate the longer m/c? I wonder if some Zastava parts might make this swap easier?

For what it's worth, "hecgre" on ebay sells an adjustable pushrod. Not sure if this would improve anything on the swap. I bought one and thought it would be helpful anyway.

Gil

[903cc600D]

Gil,

I wondered about most of those same things while I was doing the swap. The gentlemen here at www.yugoparts.com may be able to shed some light on the Zastava setup. They seemed knowledgable about them but said most parts are near impossible to get anymore. (He said it was due to the Americans blowing up Zastava factories in the 90's.) I didn't ask many questions after the 5 minute speech... You may want to keep the conversation away from parts and keep it on m/c installation/diagrams.

If I had to guess, I would say they used 850 steering arms, inner and outer tie rod ends, and a unique center link. Your adjustable center link would be perfect here and make the swap a breeze. I was tempted to make an adjustable center link using two long 600D inner links.

Good luck with your swap. If you come up with a different way, let us know.

Aaron