C4 master cylinder bore size(s)?

69427

69427

The Artist formerly known as Turbo84
Joined
Mar 30, 2008
Messages
3,077
Reaction score
38
Location
Clinging to my guns and religion in KCMO.
I'm currently visiting relatives and am away from my shop books and technical manuals. Anybody know the m/c bore size, or sizes, of C4 units? Just doing some thinking while I'm away from the garage for a while.

thanks,
Mike
 
I think its 7/8, I have one...the bore is smaller than 1". Too small so I canned it. i had the 2 reservoir one. It also has an internal prop valve and 2 front ports. I would get a C5 master, they're 1" and bolt on. The C4 ones are not bolt on, the holes need to be slotted.
 
Twin_Turbo said:
I think its 7/8, I have one...the bore is smaller than 1". Too small so I canned it. i had the 2 reservoir one. It also has an internal prop valve and 2 front ports. I would get a C5 master, they're 1" and bolt on. The C4 ones are not bolt on, the holes need to be slotted.
Click to expand...

Thanks for the C5 m/c suggestion. Along with the C4 suspension, I've been looking for other ways to take a little weight out of the '69. The stock '69 m/c weighs a bunch, and the damn paint keeps bubbling off it. I'll start taking a serious look at the C5 unit.

Thanks a bunch,
Mike
 
Twin_Turbo said:
I think its 7/8, I have one...the bore is smaller than 1". Too small so I canned it. i had the 2 reservoir one. It also has an internal prop valve and 2 front ports. I would get a C5 master, they're 1" and bolt on. The C4 ones are not bolt on, the holes need to be slotted.
Click to expand...

Did you find tube adapters for the C3 to C5 ports?
 
I thought they were M12x1 & M12x1.5 I then contacted a shop in Germany who had installed a C5 master on a customers car, they told me they were M10x1 & M10x1.5, so i bought adapters and whaddayaknow, they WERE the M12s. So, I had custom hoses made. V-Twin 160$ down (and another 50 for the adapters and a couple more for the unf to an adapters from summit) so in the end the master was cheaper than the lines :cussing::devil:

Here's the C5 master, IMO it looks better than the C4 one, and the lines exit on the outboard side, not inboard like the C4.

548220452c3352.jpg
 
Thanks for the picture. I was concerned about the height difference between the stock m/c and the C5 unit. Do I understand correctly that the car in the picture is a C3? If so, then the height issue isn't a concern for me. Also, is the C5 unit a unique part? At first glance it looks similar to some m/c units on other GM platforms. Unique part?

Thanks again,
Mike
 
Yes, that's V-Twins 77

I'm not sure if it's a unique part, might be shared with other cars. The black fluid level switch is shared with other cars so maybe the MC too.
 
Took a look at the m/c on my '05 Silverado this afternoon. Damn if that thing don't look just like the picture you provided. A used pickup m/c ought to be a bit cheaper than paying the premium that always happens when buying something that was taken off a Corvette.
Thanks again for the suggestion of this type m/c. It looks like it will do the job, and save me some fabricating work in the process. :thumbs:
 
The C5 master has been a little spendy (just under $200) until just recently. Rock Auto has a listing for Dorman M630023 that is about $90. I don't know if that includes the reservoir.

I assume you are putting the C5 master on the C3 booster? Do you need to mod the pushrod?
 
Will have to check, looks like it's bolt in, will test & report. Depth looks to be very similar to C3 stock and other old cast iron MCs.
 
It's almost identical. Bolts right up, no issues with brake pedal sofar. Still have to do road testing. installation was completed with custom flex lines.

548387c75a5fef.jpg

The additional brake fluid level switch is available from many sources like rock auto. The connector used is:

PART NUMBER: 12162193
DESCRIPTION: 2 Way Black Metri-Pack 150.2 Sealed Female Connector Assembly
12162193-hbl.gif
 
You must log in or register to reply here.

Latest posts

Back
Top