I moved this thread from the Builds Forum

As the title indicates, I am about to test my new 200R4 Overdrive. But need to replace my old single string brakes with modern system, while my front end is off. I just bought a universal frame mounted power brake system. It looks great but does not fit because I had to install a new mid-crossmember to hold the rear of my 200R4 Transmission.

I remember a 12 port news article about hollowing out an old Chevy master cylinder and the brake peddle in its current mounting location on the frame. A long shaft or threaded rod would go through the vacated cylinder to activate the modern booster and dual brake master cylinder. This idea lets you place the booster and master cylinder where they will not be in the way of other structures. I would like to find a reference to that old 12 Port News article. and the author.

Hi Frank . . .

I am running the Buffalo Conversion. I believe that the Filling Station is still reselling them through their catalog. I see that parts123 site still has the photo online: parts123.com

Of course the old access plug isn't big enough, so you need to create an access hatch in floor for servicing.

regards,
stock49

PS the conversion assumes the 4 top screw style master cylinder. Not sure what year it was introduced. You might need to find a newer style core.

Thanks for the tip about the master cylinder. I will give the Filling Station's version a try if I can't get my current system to work.

My current system has a vacuum cannister and a remote master cylinder mounted on the passenger side where the Battery use to be located. The old Chevy master cylinder drives the remote booster. I will try another old Chevy master cylinder today.

We are now driving my 40 Chevy with the 200R4 behind the 302 GMC. It drives great with smooth takeoffs and no more shifting. One problem remaining is the GMC rocker arm cover is leaking oil at the rear. I put on a new cork gasket but it's still leaking. We also put the cover on a sheet of glass to check out and fix any high and low spots at the base.

Does anyone know if a rubber gasket is available? Seems like that would work better the cork.

Does anyone seal the cork gasket to the head or rocker arm cover , or to both ?


Any suggestions will be appreciated.

Frank Hainey

You could always run a bead of RTV let set before installing and see if that helps.

I have had a 270 in my '53 Chevy pickup since the '70s. This has always bee an issue. Once I used a product called the Right Stuff. I sealed it just fine but was a #@%& t get off the next time. Now I have a cork gasket from BEST gasket. I noticed two things #1 it was new #2 it was thicker. I ran a bead of RTV on the cover when I installed it so the gasket would come off with the cover the next time. It works very well. Now it just blows some out the breathers. I have other leak issues that need attention.

If you have the original master cylinder it would be a simple matter to remove both end plugs and install a brass bushing for a piece of solid steel rod to slide through. Then the booster or dual line master cylinder could be mounted on the frame behind the crossmember. It's a simple machining project for anyone with a lathe. I can do that job- - - -send me a PM if you're interested.
Jerry

Thanks for the replies to my brake problems. Currently I am running the old single string system with the old master cylinder feeding pressure to a remote vacuum powered booster located on the passenger side. The amplified pressure line is split to feed the rear drums and 11 inch disk brakes.

One new thing I added was a brass pressure modulator replacing a simple "T" fitting to slow down the feed to the disk brakes. It works as advertised, giving the rear drums more time to react and apply the drum brakes. The car seem more in control especially during panic stops.

I want to change gears and ask for advice on my recent 200R4 overdrive installation. I swapped out a Borg Warner 5 speed manual transmission for the 200R4 behind my 302 GMC. I am having problems with it shifting down as the car slows when the shifter lever is in overdrive. It seems to not want to down shift automatically. Once the car slows down to about 25 mph the drive train starts to lug and vibrate. I have to manually move the shift selector to Drive(3rd, 2nd and 1st gear) to stop the car and the lugging in Overdrive. I assumed that the 200R4 would be smart enough to do this on it own.
I know there is an electrical relay that controls torque converter lockup which is tied to the brake light switch. That lets you unlock the torque converter at slow speed by taping the brake to activate the light. It seems to work ok but it still does not shift out of overdrive.
.
Any ideas on how to solve this problem. Thanks __Radar