Brake Master Cylinder for ABS Delete

[belize1334]

My brake master cylinder appears to have crapped out on me. Brakes were really squishy yesterday (halfway to the floor on the first pump and then firm but getting bad again after a minute or so of driving) and upon inspection the brake fluid level dropped about 2 inches in as many days and there's some seepage on the front of the brake booster and the pain is coming away. This seems an obvious sign that the master cylinder needs to be replaced.

I went to rockauto.com and they list different master cylinders for DSMs with and without ABS. Is there really a difference? Since my ABS has been removed I want to make sure that I get the right one for the current configuration.

 

[belize1334]

Nobody knows if the ABS Master Cylinder differs from the Non-abs version?

 

[curtis]

Get one from a early 90's Q45 infiniti It has the largest bore of any import master and bolts right up, rod in the booster has to be adjusted and the lines have to be repositioned but that's about it. I did a right up on it click me

 

[belize1334]

^^ If I go that way, how do I determine the correct adjustment for the rod? Also, aside from just making the pedal pressure lighter, what's the advantage of the larger bore? After my ABS delete I thought the braking already felt great ... right up until my slave gave out.

 

[CP]

What will that do to the bias?

 

[Muskrat]

Brake System's Book

I'd suggest this. Lots of good info, and good introduction to brake systems in general.

 

[belize1334]

^^ Except that I'm not looking to wright a paper on brake systems. I just want to replace my dead master cylinder with a new one that is appropriate for the application. As I understand it, most people who do the non-ABS conversion don't bother to switch out master cylinders. The fact that Mitsu offers a different master cylinder for cars w/o abs suggests to me that maybe we should and that maybe that is why mine failed. I'm just wondering if anybody can say for sure that the ABS mc is different from the non-ABS mc so that I can understand why I should prefer on to the other.

 

[curtis]

Quoting belize1334:
^^ If I go that way, how do I determine the correct adjustment for the rod? Also, aside from just making the pedal pressure lighter, what's the advantage of the larger bore? After my ABS delete I thought the braking already felt great ... right up until my slave gave out.



Adjustment for the rod can be figure by either pedal feel or just put a dot of grease on the end of the rod and put the master in place and pull it back off. You just want it to touch. Larger bore is a big difference the more volume in the bore the faster the system ramps up pressure so if before you move your foot 1/4 inch to stop from 60 to 40 you may only need 1/8 inch. etc

Also I read that the q45 have more front bias built in. Its a really impressive mod and want put anything else back on the car.

 

[Muskrat]

Quoting belize1334:
^^ Except that I'm not looking to wright a paper on brake systems. I just want to replace my dead master cylinder with a new one that is appropriate for the application. As I understand it, most people who do the non-ABS conversion don't bother to switch out master cylinders. The fact that Mitsu offers a different master cylinder for cars w/o abs suggests to me that maybe we should and that maybe that is why mine failed. I'm just wondering if anybody can say for sure that the ABS mc is different from the non-ABS mc so that I can understand why I should prefer on to the other.



I was replying to the post above me.

But if you want to size components properly, instead of just going on what other people say, it might be a good idea to do some research. That book can't be more than 60-70 pages and it's a good primer to what really goes into and affects your brake system performance. It will also walk you through a good basic level brake system analysis - which include MC sizing.

The only difference I can imagine, performance-wise, is the bore size of the MC. The FSM should tell you if there is a difference. I kinda doubt it.

 

[belize1334]

I found this master-cylinder on RockAuto for $29.99 closeout price. It's listed for a '91 Eclipse GSX w/o ABS but it also lists the output size as m10x1.5. This is odd since every other mitsu part I've found is m10x1.0. Can anyone confirm what size it should be and whether any 1Gs had a different fitting size?

 

[belize1334]

^^ Update on that MC. Raybestos says that it's a cataloging error (since it lists m10x1.5 on their website as well) and that the part is indeed m10x1.0 just like all the rest of the Mitsubishi stuff. As such, there will be two left at that price after I've ordered mine.

 

[CP]

I did the ABS delete, kept the stock master cylinder (replaced it with a new OEM unit) and never had any problems. I had a Stoptech kit on there for a few years while I was tracking the car and didn't have any issues with the stock master cylinder. Don't go messing with things that don't need to be messed with.