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1990 300zxTT Master Cylinder Swap Complete


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I purchased the 17/16 bore 89-91 brake master cylinder today for $89. It was not too difficult to make it work. I decided to do it right so I disassembled my brake booster. Don't bother trying to screw it off as designed. The rubber prevents this. I bent back all the tabs with nice pliers and then removed the halves. With the bare cover I then drill through the studs from the backside and pulled them off with pliers. Took it this morning and had the holes welded up solid and then ground off on the outside. I then took the new master cylinder and created the new hole marks. The are about 1/8" further inward. Drilled and tapped them 5/16-18 and put bolts in from the backside. I welded the bolt in from the backside so it would not come out and to maintain a vacuum seal. I then had it powdercoated black which only took about 1hr. Now, before I powder coated it, with the guts removed I attached the 2 halves back together and used a screwdriver hammer to knock the tabs back into place. When reassembling, I used Dow Corning 'High Vacuum Grease' on all the rubber seals and this also allows you to screw the base to the front cover without the rubber seal sticking. I had to shorten the rod for the master cylinder, but no big deal. The cylinder bolts directly to the booster and does not use the spacer. BTW, I have a 73 Booster.

master1.jpg

master2.jpg

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James

 

dont you think you could have slotted the master and use it on top of the original spacer? and cut the vertical studs off.

 

yours looks nice but i'm not sure if i want to take my booster apart///

 

i was wondering if the 91 booster would fit easily...

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Very trick. The gent that owns the orange Z with chrome side pipes has this mod in his car--he claims it works VERY well and he wouldn't do anythign else again. I am partial to this mod and I hope to do this sometime as well. Thanks for the excellent description!

 

Davy

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SCCA, Yes the spacer can be used, but it would have to be bored out about .065" on the diameter. If you remove the spacer it fits right in. This would only require that you slot the holes and shorten the rod some. What I have done was very easy and took all of 2hrs total. The advantage it gives you is a much cleaner look and allows you to have the casing chromed or powder coated. I would have just slotted the holes, but I had no good method for slotting them besides using a grinder which would look like dung. I can tell you this, the pedal hardly moves now. I will try it out tomorrow when the car is running again and give a comparison over the 7/8 one I was using.

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Guest Anonymous

Where did you get the master cylinder from. $89 seems like a boneyard price around here. Or did you get it from a auto store? I would think that a master from a 300zxtt would be pricey thanks

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