BritishV8 Forum

When my car still had the MGB suspension and front brakes and a Jag rear (a long time ago), I got a remote booster from (I believe) an MGC and installed it on the shelf on the passenger side. The brakes were phenomenal with the booster and now I would like to add a booster with the new setup of the car. I currently have a Wilwood dual brake master setup with a balance bar. I have 5/8" masters and it works pretty well with the Corvette brakes but it takes too much pedal pressure for a max G stop. I found this dual remote booster from Car Builder Solutions in the UK and I was wondering if anyone here has experience with this product or with the seller. https://www.carbuildersolutions.com/content/images/thumbs/0024882_compact-dual-circuit-remote-brake-servo.jpeg

 I believe I have room to install it behind the battery box and in front of the rear suspension. If it won't fit there I could install it in the trunk just behind the bulkhead although I would rather not take up trunk space.





 Any help or suggestions are appreciated

Jim I also have stiff brakes with a 5/8" MC on the front circuit.

Early pedal assy
mechanical balance bar
5/8 and 1" M/C
Jag rear brakes
Outlaw front calipers.
Porterfield R4S pads

The early pedal assy has a 4:1 ratio. Late has 6:1, so I'm going to look at possibly rebuilding the pedal/BB assembly with the 6:1 ratio.

In fine tuning the Roadmaster brakes (late 6:1 pedal assy, Jag rear brakes, Dodge Dart calipers, 7/8" dual M/C.) the booster made an improvement but not nearly as much as going from the Corvette M/C which I think was 1" or possibly 1-1/16" to the 7/8" M/C. I think it was 7/8". In any case it was the late MG (1980) part. I'd say the M/C change made double the difference of just adding the booster. It now runs unboosted and is quite a bit better. The brakes feel like they should. There is no need for any further tuning.

Jim

I have a Wilwood dual master setup with 5.1:1 pedals and 5/8" masters. It stops pretty well under normal braking but I have to really stand on the pedal to get the brakes to lock. The booster I'm looking at has two circuits for the two circuit brakes on the car and has a 2:1 boost ratio which will double the line pressure for a given pressure on the pedal. I'm thinking this should give me the a reduction in required pedal pressure without making the brakes too "touchy". When I had the MGB brakes in front and the XKE brakes in back, the MGC remote booster made the brakes incredible. They were the best brakes I have ever had on a car, they would almost throw you through the windshield.

I've been suspicious of the adjusting bolt on those and the Tilton. What diameter is it and have you ever had any indication of it bowing? I run a 1/2" hardened jackscrew for a bolt in mine and I'm not entirely sure even it is strong enough. (1/2 x 13 thread)

I guess your rear calipers must be quite small to run a 5/8" master on the back circuit.

In my experience the late MGB booster never came close to a 2:1 boost, apparently the MGC one is better? I think they have to go by diaphraghm area and vacuum signal and they look about the same size from what I've been able to see in photos, but maybe not.

I ran Mach-I Mustang calipers for years with the stock rear axle and 3/4" M/C on both circuits. I had the balance bar about 1 turn from being all the way to one side but today I couldn't swear whether that was the front or the rear. But, it was at least in range. The pedal was firmer but it should have been with twice the piston area. (vs a single 3/4" M/C) My best recollection was that the bar was shifted towards the rear.

I doubt any of this helps though.

Incidentally, I found a neat way to use the round Lockheed tin can reservoir on Tilton M/Cs. Unfortunately I presently have 3 very different M/Cs on my assembly but they at least all now use the same reservoir.

Jim

I haven't checked my adjuster for bowing but I will now that you mention it. I think it is a 3/8" rod but I haven't looked at it in quite a while.

My rear calipers are stock '88 and newer C4 Corvette which are single piston floating with a 1.575" diameter (40mm). The 5/8" master works well and stops the car fine in normal driving and has just the right amount of pedal travel.

I have decided not to run the dual servo mentioned above but instead I'm going to use two PBR VH 44 remote boosters that were originally for Australian Ford Falcons, Hillmans, and others. They have a 7" vacuum chamber and 5/8" master cylinder. I was able to buy two of them new for $230 with no tax and free shipping. The unit from the UK was $389 and a bunch to ship it. The VH 44 units came from California.



The rear unit will mount next to the battery box and the front will be below the drivers side headlight. It will reduce the length of fluid tubing by at least 2/3 vs plumbing the dual unit in the rear. I'll have to install one way valves in the vacuum lines to keep the boost out. I'll post the result when I get it running

Sounds like a good plan!

Hope so. I'll let you know how it works out.

I'm a little surprised that by now an electric booster of some sort isn't widely available. But I suppose a catastrophic electrical failure would be a problem.

I've never really looked into how those remote boosters work. Slave cylinder on the pedal end I suppose?

Jim

I don't think so. The only fluid connections are on the master cyl that sticks out of the booster can. In the photo there is a device that sticks down that has to somehow meter vacuum into the chamber when hydraulic pressure is applied. I'll have to read up on how they work.

Just Googled it
 "This vacuum is applied to both sides of the booster. Both the pedal side and the master cylinder side. As the driver presses the brake pedal, the vacuum valve blocks the vacuum source located on the pedal side of the booster"

What must happen in the remote booster is the pedal master applies pressure to the booster master and that movement pulls the rod inside the booster causing the vacuum to be shut off to the back side allowing the vacuum in the front side to assist pushing the booster master cylinder.

Here it is:

https://mgaguru.com/mgtech/brakes/bt201k.htm

Sounds like it might be easier to add one to the front circuit than to modify my pedal assembly. Worth looking into I expect.

Jim

Why don't you use a 5/8" master on the side you have the balance bar biased toward? Easier and cheaper than adding a booster to one circuit.

QuoteThe early pedal assy has a 4:1 ratio. Late has 6:1...

I think you have that backwards, JIm. Early, non power assist would be 6:! and later servo brakes would have 4:1.

Thanks Graham, I'm glad you pointed that out.
Jim, I already have a 5/8" M/C on the front and a 1" Tilton on the rear so while I could go up another 1/16 there it doesn't do any good as presently the balance is only off center by about 20% and the issue is not the balance but the amount of pedal pressure. I really didn't expect the Outlaw calipers to be undersized on the pistons but apparently they are. I'll look into that more closely once I get the car on the lift again.

The optimal solution might well be different calipers. Unfortunately I doubt the spacing will match the new Wilwood Metric calipers, meaning new hats as well to go that route, if the correct size can even be found. So a booster could be the best answer, and possibly even the easiest. On the front only. The rear clearly does not need it. Those boosters you found look like a good choice, I look forward to seeing how they work out.

Jim

My 76 Land Rover 88 had a very good pedal with no servo.
My 74 also has a good pedal, but with servo.
My Rambler has a good pedal, with factory Bendix remote servo.

You could use a 1/2" master, that would make a big difference. But..... and it's a big but, the more hydraulic leverage you have the more the pedal travel.
A servo gives the same effect as a smaller master, but with no increase in travel.

Car Builder Solutions are well thought of over here in the UK.
Shipping is indeed an issue. I just bought a load of parts from Rock for my Rambler, the shipping from the US was not cheap.

Ivor

I have good balance front to rear and pedal travel is perfect. All I want is to generate more line pressure for a given pedal pressure. I received the two servos I ordered today and they are quite small and only weigh 5 # each.

 

They are advertised at 2:1 pressure ratio but if I get a 50% bump in line pressure I'll be happy. I only have to fabricate 4 short fluid lines to hook them up. I think I may fabricate a small vacuum tank to use as an accumulator and then run the vacuum lines to each of the servos from that. I'll put a one way valve on the intake manifold side of the tank so I will have a power stop or two if the engine is off.

Tilton doesn't have a M/C smaller then 5/8" and I suspect any smaller would not have enough volume anyway.

Typically a booster will have a large enough vacuum chamber to make 2 or maybe 3 full brake applications after the engine dies. The check valve in the hose fitting prevents backflow. Then you have unboosted brakes but they still work. So if the engine does die you just make sure your next brake application is continuous until you are stopped. Really nothing new there. Another tank would give you a larger cushion if you felt you needed it but that isn't usually done.

I think a 2:1 bump in my front brakes might be just what I need. Was that price you got per each or for the pair? If for each I may have do do some further research.

Jim

Look up VH 44 brake booster on Ebay. Mine were $120 each or $230 for the pair with free shipping.

That's a fair price. Time to go shopping I expect. First though I'd better map out a place for it to go, it's getting tight around the engine bay.

How soon do you expect to have yours installed? I may wait to see what your results are like.

Jim

I'm probably going to wait until I get my 2 post hoist working. I stepped on a finish nail and it went through my shoe and about 1/2" into my foot head first. Probably a week before I get back into the swing on the hoist. All I have left to do is level the bases and bolt it into the slab and wire it up.

Oh, you will love that! I'm surprised you don't already have one. Very surprised. I wonder how I ever got by without mine. But when you are younger getting down on the floor doesn't seem like that big of a thing. And with what they cost these days... I traded services for mine, an old Rotary from a defunct car dealership. Only mistake I made was locating it on a slightly sloping section of the floor, which causes one arm to be slightly higher above the floor than the other one. Makes a difference with low cars.

A clean finish nail I hope. Lockjaw is no joke. I still remember that achey feeling from my youth and you have my sympathy. We used our sisters' tricycles to get around the house until we could limp/hop to get around. Sat on it backwards.

Jim

The only way I got by when I was building the car was the rotisserie. I built everything on the car using that thing and never had to get on the ground once. After I put fluids in it those days were over. A friend gave me the lift just for removing it and hauling it away. He was replacing it with a 4 post since all he used it for was car storage. It is a rotary also and I had to have one of the motors rewound but that is a small price to pay.

My rotary has a single hydraulic pump, and the motor burned up after I had it awhile. I bought a bigger motor off ebay and modded the end plate to mate them up. I did a little heliarc welding on it and now I don't worry about the frequency of starts anymore, there's no way I'll overload it. I can send you a photo or two if you want. It was a real good mod. I plumbed in a 4 way valve and use the same pump to power my hydraulic press. That's a wonderful thing.

Setup was pretty simple, I used 5/8" x 6 or 7" long tapcons to bolt it down and have never had the least issue even with heavy loads (it's the 9000lb version). Just made sure everything was plumb and level. I've even maxed it out with an uneven load trying to warp one of the the sills on my roadster. Overall a great lift and very reliable.

Jim

Mine has twin acme screws that lift the arms with a motor at the top of each tower. It works well and has circuitry that re-synchs the motors after each use.

Yeah, that sounds like a straight replacement is the safe way to go on that. Probably not cheap, might want to check the brushes on the other motor though if it has them.

Jim