I have the original single pot in my 64 and picked up a Raybestos MC36338 after reading some swap stories and recommendations. After examining the part I noticed there are not two screw holes for the push rod retaining "stop" plate. Does this new dual cylinder have some way of capturing the rod or do I need to get a different dual cylinder for the swap? -Todd
1964 Valiant Single to Dual Master Swap Question
- Thread starter T0dd
- Start date
-
Use the same rod. Just unbolt old and bolt on new master cylinder. no need to touch the rod. The stop plate and boot are on the inside side of the firewall.
Early Valiant Barracuda Club - dual master cylinder
Early Valiant Barracuda Club - dual master cylinder
Last edited:
The MC is a power brake unit but will work fine with the rod. They use the clip to hold the piston in and the same rubber ring to secure the rod. Use a new rubber ring on the tip which might not have come with the unit but should be available.
If you want to use the boot/spring retainer you would have to drill and tap the 1/4-20 holes. (carefully) I just did this last weekend.
If you want to use the boot/spring retainer you would have to drill and tap the 1/4-20 holes. (carefully) I just did this last weekend.
Rapid Robert
Well-Known Member
For manual brakes, the tapered rear piston "thimble" just needs to have a circular "recess" about half way down for the snip of neoprene slipped on the end of the pushrod to lock into. if it is a smooth taper with no circular recess then this MC will only work for power brakes. If the MC did not come with it then a piece of vacuum line from your parts house works fine.
Thank you all for your bits of wisdom. I see you say "if you want to" does that mean it is not necessary to use the boot/spring retainer if I don't want to drill & tap? User 64conv65hard suggests I can un-mount the single pot and leave the push rod in place and just drop in the new?
If it isn't clear I have never messed with an MC before so I am just trying to plan out as much as possible before I disable the brakes in the car for the swap.
When I did mine, I followed the article I posted and did a direct MC swap. Have done it on all of my 64's and 65. Took about 4 hours with most of that time at the parts store finding the correct fittings.
You should be able to reuse your old pushrod. The pushrod has a "retainer" ring the fits into a groove, then seats in the groove in the master cylinder to lock. You must use a new retainer on the new m/c.
When I did mine I think I yanked back on the brake pedal to unseat the old pushrod from the m/c. Then unbolted the m/c, cleaned up the firewall and made a gasket to fit. Bolted on the new m/c, ran new lines, then bled the m/c. Don't forget to bleed the new m/c to get the air out.
Can't remember which m/c I used, but I ended up buying an adjustable pushrod and new retainer from Dr. Diff. The original was a little too short.
The hardest part of the whole thing was making the new brake lines!
When I did mine I think I yanked back on the brake pedal to unseat the old pushrod from the m/c. Then unbolted the m/c, cleaned up the firewall and made a gasket to fit. Bolted on the new m/c, ran new lines, then bled the m/c. Don't forget to bleed the new m/c to get the air out.
Can't remember which m/c I used, but I ended up buying an adjustable pushrod and new retainer from Dr. Diff. The original was a little too short.
The hardest part of the whole thing was making the new brake lines!
whitepunkonnitro
Well-Known Member
I have the lines and distribution block listed on here, if you need them
If you are serious about safety, it was touched on in that informative article, The brake system components including the hard and soft lines are older than most guys driving them. Replace it all. Metal lines, hoses, cylinders, brake hardware kits. Better yet, do a disc brake upgrade. Kits are covering more cars now and they are reasonable. The cost is not prohibitive if you value your life and the safety of others. A brake failure is something that I hope nobody experiences.
Yes I did this same conversion twice using Erik's write up and help from EVBC. I used the manual MC from 67 Valiant and did not have to make any modifications to the MC. A new Retaining Grommet for the pushrod came with
First step to safety as MoparLeo stated is upgrading. I did the MC swap first. If you're running 13" tires than that must be converted over to 14" when doing a Disc brake swap. Took me a couple years to save up for complete rim, tire swap along with disc brake parts (found everything on this site). But definitely do the MC swap first and it can be used for the disc swap so you're on the right path.
The MC you pictured has the clip holding the piston. The original MC does not have this clip. The stop keeps it from pulling out. The push rod also needs the ring/grommet/retainer at the tip holding it in the piston. It will most likely tear when you pull it out. I used the 67 manual MC10-1323M . It has the holes for the bolt and stop and they include the retainer.
BillGrissom
Well-Known Member
Since you already bought the MC, I would run with it. I would tap the holes to mount the dust bellows & stop. If you prefer an alum MC and can return your new MC, see what I did in my 64 Valiant:
Alternative for power brakes , post 28.
Re plumbing. You can buy the 1/4 to 3/16 adapter and 3/16" plug for your distribution block at Autozone (bubble packs). Nice to add an adjustable proportioning valve in the rear circuit.
Alternative for power brakes , post 28.
Re plumbing. You can buy the 1/4 to 3/16 adapter and 3/16" plug for your distribution block at Autozone (bubble packs). Nice to add an adjustable proportioning valve in the rear circuit.
Great info, thanks so much. I will be sending my MC36338 back as upon unwrapping it the casting looks to have been skidded across a warehouse floor a few times. Still undecided if I will go with another MC36338, get a stock 67 valiant or one of the aluminum ones as you show. I kind of like the look of those.
Finally got my replacement. I went with a MC36221 this time around. Seems like a more popular option. Do I unscrew the little pointer? I assume that is holding the piston in until I screw on the boot and stop?
Here is my existing Brake Block. I have a new brass one on the way made for dual bowl conversions. As I need to replace lines and I want to keep things looking stock, what are those old style flex brake lines called? Can they still be had?
-Todd
Here is my existing Brake Block. I have a new brass one on the way made for dual bowl conversions. As I need to replace lines and I want to keep things looking stock, what are those old style flex brake lines called? Can they still be had?
-Todd
-
