Jamco dual master cylinder and booster conversion

[JamesR]

Hi. I've posted this recently in the modified flairbird forum at VTCI, but I thought I'd also post it here because this forum gets a lot more traffic and time is rather of the essence with me getting some feedback.

https://www.jamcosuspension.com/product ... -pbb6566tb

Do any of you have experience with the Jamco dual reservoir and smaller booster conversion? It looks like it might be a way to avoid the headaches of trying to put something together that will have both the dual reservoir function and enough clearance for my aftermarket valve covers. (The Jamco booster is a 7" diameter unit. I believe the original booster is around 9" or so.)

ALSO: I just talked to a Jamco rep and he said that the dual reservoir MC does NOT require cutting or modding the under-hood brace from the shock tower. IF YOU'VE USED THIS CONVERSION, please let me know if that's accurate or not. He also said I can use the Russell proportioning valve (that I've already purchased) with this Jamco conversion.

So, if you've installed and used this conversion, please let me know what you think, good or bad. How was the installation? How was the function and braking performance? Thanks for any reviews you can give. - Jim

[maxismile]

Jim, I'm interested to know if you proceeded with the install of booster + MC from Jamco. I'm also interested in doing the conversion for my 1966 convertible but won't get to it until spring. I was curious about the actual length of the Jamco booster + master cylinder and had them measure for me. The attached pic is what they sent me a few months back. It does seem like it'll fit in my 1966. -Mark

[paulr]

I was curious about the actual length of the Jamco booster + master cylinder and had them measure for me. The attached pic is what they sent me a few months back. It does seem like it'll fit in my 1966. -Mark

It's great you got that pic. I wanted to ask them for specs on the "dual diaphragm booster" and get the bore size on the MC. When I clicked their email icon all I got was a blank page over and over again. I'd like to know the specs of the system as it compares to stock.

[stubbie]

That page worked for me Paul. Try this info@jamcoparts.com

[paulr]

Thanks Stub, your link worked. (The page link doesn't work for some reason.) I asked em for spec sheets on both parts. I wonder if the ports face the block like in the picture? The tape measure is perfectly in the way. I like the downward facing port. I know that pic in their ad might not be the actual cylinder. Block-side lines don't sound so great; hopefully they're on the fender side.

[stubbie]

The ports look to be block side.

[Yoda]

I recently purchased the Jamco dual master cylinder & booster conversion kit for my 65 convertible:
https://www.jamcosuspension.com/product ... -pbb6566tb

The kit appears to have the proportioning valve built in for front disc/rear drum. So I just have one front port and one rear port as you can sort of see from the picture in the link. These ports are a wider diameter than the stock line fittings.

Has anyone else completed this conversion? If so,
1. How did you handle the plumbing/connections? Pictures would be much appreciated.
2. Do you happen to know the stock fitting diameter and female fitting diameter at the ports on the dual master cylinder?
3. Did you unbolt the entire assembly by loosening the 4 nuts on the inside side of the firewall? Is this best done with the drivers seat removed?

I'm guessing I'll need some sort of manifold/tee to joint the front left and right lines. I could probably cut/bend/flair some small sections of line or possibly try to find some short lengths of a flexible line. I'd like to make this look as 'clean' as possible.

Funny how a leaking rear drum cylinder can turn into an entire brake job. Ended up replacing the entire fuel line too as it was extremely corroded. Lots of mission creep on this one.

Thanks!
-Brian

[redstangbob]

The Jamco picture shows a booster and master cylinder, I have to believe the prop valve is separate and not shown. The master cylinder should have a residual valve built in if you select disc front/ drum rear. JMO, Bob C

[Yoda]

Thanks Bob. I'll snap some pics of the unit I received, but the front/rear ports appeared to be integrated into the MC and there was not a separate proportioning valve. If the valve was supposed to be separate hardware, it's possible that the hardware received was incomplete. There were no instructions.

Just for reference, the thread in the Modified forum discussing this kit (and the ABS system) is here:
viewtopic.php?t=18708

-Brian

[redstangbob]

download/file.php?mode=view&id=6498
this picture shows the valve underneath, is this what you have? Their site shows it has to be ordered separately depending on your application. Have fun, I'll be doing something like this on my 59 one of these days, but maybe hooked to a Grand Marquis front clip

[Yoda]

Here are some pics.

[Terry64HT]

I see in Yoda's photos that both bowls of the master cylinder are the same size and in the Jamco photos they are not. When I got the kit to convert my 64 to front discs, the master had same size bowls and, with the proportioning valve and residual valve, things seem to work fine. I've seen quite a few disc/drum setups like mine.
Any comments on the need for different sized chambers?
Terry
64HT

[GRNTHNDR]

I will be doing this conversion on my 66’,too. Not sure which company to go with. Waiting to see more reviews and opinions. Thanks to all that have contributed good info on this topic. I’m looking forward to getting this car on the market with the dual bowl conversion.

[jtschug]

I don't see anything in that master cylinder that makes me think there is a proportioning valve integrated into it. Looks like a pretty standard dual master cylinder. A single front port and a single rear port is all you need. Plumb the rear port through the prop valve for the rear brakes. Use the front port for the front brakes. As long as you are using stock discs in front and stock drums in the rear and your original prop valve works and doesn't leak, then there is no reason not to use it with this master cylinder.

[JamesR]

I started this thread a couple years ago and another on the same topic in the modified 4th gen forum to get as many perspectives as I could on these conversions. For those not following the other thread, a link is below. FWIW, I didn't use the Jamco conversion, I used the ABS conversion. I suspect whatever issues I've run into are installation errors, but haven't had time to to dial things in. Info on that will be in the other thread:

viewtopic.php?t=18708&start=15