1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Replacing Clutch Master Cylinder - do I need to remove dash...?

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Old Mar 4, 2020 | 10:06 PM
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Replacing Clutch Master Cylinder - do I need to remove dash...?

85 FB GSL Manual...

I think my MC needs replacing, but want to avoid anything drastic like a dash removal...seems like it's not necessary but can someone comment?

Any special tools required?

Sorry, basic question, I'm just nervous about getting stuck halfway with this thing, or risking breaking more things than I need to...

Helpful comments appreciated.
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Old Mar 4, 2020 | 10:21 PM
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Please tell us you're just kidding.

Yeah, it's 2x12mm nuts on threaded shafts attached to the firewall side of the Clutch MC, and they're admittedly hard to reach laying on your back, but that job gets easier if you take out the drivers side seat. It only takes about 5 extra minutes to do so, and makes the job a lot easier. Aside from that, the Clutch MC should come out easily. Consider changing your Clutch Slave Cylinder at the same time, because more likely than not, as soon as your new part is in, the older part will fail.
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Old Mar 4, 2020 | 11:03 PM
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Originally Posted by LongDuck
Consider changing your Clutch Slave Cylinder at the same time, because more likely than not, as soon as your new part is in, the older part will fail.
and the flex hose too.
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Old Mar 5, 2020 | 09:36 AM
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From: https://www2.mazda.com/en/100th/
the top nut is not very fun to reach, pulling the dash would not help
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Old Mar 5, 2020 | 07:03 PM
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From: KC
Also inspect the studs on the MC and ensure the threads go all the way down to the MC body. If not, use some washers.
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Old Mar 5, 2020 | 08:28 PM
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Thanks to all for indulging my question and the helpful replies!
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Old Mar 6, 2020 | 11:00 AM
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From: https://www2.mazda.com/en/100th/
Originally Posted by KansasCityREPU
Also inspect the studs on the MC and ensure the threads go all the way down to the MC body. If not, use some washers.
i had to remove the studs from the old master, and use them on the new master
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Old Mar 6, 2020 | 01:14 PM
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I switched to using bolts for that. The shank on the studs are always too long and I never had the proper studs to start with (or so I think, I'll have to check). It is a pain to get to, but it's not too bad once you get going. I just lay upside down on the seat/footwell; works for me.
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Old Mar 18, 2020 | 08:47 PM
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Just thought I’d add an extremely helpful thread from the 1st Gen Archive; this gave me great guidance on the entire process:

https://www.rx7club.com/1st-gen-arch...-slave-873427/

And an additional observation re: bleeding the brand new line--my experience was that the initial manual pumping of the pedal to fill the line can easily take 100+ pumps until fluid starts coming out of the bleeder screw.
I find access to the bleeder screw also to be a significant challenge given the confined space (and my large hands). I found this type of wrench to be particularly useful:

100-position flex-head ratcheting wrench set. Bleeder is 8mm.

Last edited by demongo; Mar 19, 2020 at 01:12 PM. Reason: Adding helpful information and link.
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Old Mar 18, 2020 | 08:56 PM
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And just to vent: the MC bolts on the inside were satan’s own butthole to remove and replace. Fundamentally my hand was too large to manage this step without significant blood and scarring. And even tightening it with a ratchet was a challenge.
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Old Mar 18, 2020 | 11:27 PM
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They suck, indeed. Hope that new MC you put in is good quality, haha.
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Old Mar 19, 2020 | 08:30 AM
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One note: when installing the top stud nut, I had the best luck using a standard depth 3/8" drive 12mm socket placed onto the nut first, then barely sticking the wrench on the backside so the square was inside the socket just enough to turn but the socket wasn't clipped in. This helps because you need a deep socket to fit over the stud, but most deep sockets are too deep to actually fit. You need just the right length to have enough room to turn the wrench. Once I figured out this trick the job became easier. I highly recommend replacing with bolts though
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Old Mar 19, 2020 | 03:51 PM
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When I meet rotary fans, that's how I can tell how long they've owned an Rx7 - based on the scars on their right hand, when you shake hands, count the lasting scars and multiply by 7 and you get 'X' years of ownership. On average, you get 7 yrs of use out of a Clutch Master Cylinder which makes the math easier.

HI, how are ya?!?
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