Brake Booster SV

[Eleven]

My braking performance is poor. Have rebuilt both calipers and the rears with new everything. Running a stock Master Cylinder (cannot remember the size). Like stepping on a rock. Can get it stop okay with a good shove but doesn't inspire confidence... For such a small car, am surprised how below average it is with a non-boosted set up. Been over it several times and with someone who knows and apparently it is how it should be.

I do not have a booster. I am wondering if there is a viable alternative to the ones used by Rootes that is also not as costly. From what gather, getting a used booster is a crap shoot due to corrosion. I also do not have a mounting bracket. My car came without a booster.

 

[DanR]

Running a stock Master Cylinder (cannot remember the size).

|Tracy, YOu definitely need the piston size to determine where to go!

Here is a link to a discussion on the Forum that may be of some help: V6 2.8 clutch cylinders?

Read on down till you see Barry's input.

Also, Barry Knight is one of the most knowledgeable on hydraulics here! I rely on his opinions greatly....

 

[65beam]

Our series 4 and series 5 have non boosted brake systems. I use the 700 master as used on series 1 & 2 Alpines with the self adjusting wheel cylinders on the series 5 . Brakes are fine. The series 4 has the 700 master and stock rear wheel cylinders. Victoria British does sell a Lockheed booster kit for use on the Alpines.

 

[husky drvr]

Bill Blue also developed a modification to change the pedal ratio. You might want to contact Bill to discuss the pros and cons.

 

[RootesRooter]

Check the Victoria British catalog. They have (or had) one that fits and doesn't cost a fortune. Often on sale as well! I have one that I bot a couple of years ago. Installation is on my to-do list this summer.

 

[Alpine 1789]

I have had one of the Lockheed replacement - which is what VB used to sell and presumably still does - for about 20 years and it has served me well. For even less expensive alternatives, this thread might be interesting: http://forum.sunbeamalpine.org/index.php?threads/new-brake-booster.27454/#post-190338. That particular booster is no longer available, but VH44 boosters seem to be pretty plentiful and inexpensive. I have no idea if they fit, so buyer beware.

 

[alpine_64]

A lot of the PBR production was moved to China a few years back with the inevitable QA control issues initially, probbaly been sorted by now.

The PBR vh44 are very popular here.. I have one on my SI. They have manu ratios available, iirc the. One offered for 60s mini cooper was compatible for sunbeam.. There was also a holden ref cross over but the model escapes me at the moment.

 

[65beam]

Victoria British shows complete replacement kits for replacing both the 5" Girling and the 7" booster. The 5" replacement is $127.95 and the 7" kit is $151.95. Sunbeam Specialties also shows the Lockheed boosters for replacing the original Girling booster.

 

[Eleven]

Thank you all! I very much appreciate your help this!

 

[Eleven]

Our series 4 and series 5 have non boosted brake systems. I use the 700 master as used on series 1 & 2 Alpines with the self adjusting wheel cylinders on the series 5 . Brakes are fine. The series 4 has the 700 master and stock rear wheel cylinders. Victoria British does sell a Lockheed booster kit for use on the Alpines.

I just went through my old records and find I have a 7/8 MC. You are running a 700? I have to really shove mine to get moderate stopping, do you think the smaller MC will give more pressure? I am not sure how to phrase this so it makes sense. I raced a friends SII with no boost years ago and do not remember any brake issues. With my Spitfire (much lighter car), I also raced with no booster. The Spit had metallic pads and stock shoes, the Alpine I don't know but believe they were stock. This is why I believe I should be able to run my Alpine without a booster and still get decent braking performance.

 

[Barry]

Tracy,

Series Alpines with a brake booster had 0.875" (7/8") master cylinders. Series Alpines without a brake booster had 0.700" (Series I / II) or 0.750" (Series 3 / IV / V) master cylinders.

To get "normal" pedal effort, you need to either use a brake booster with your current 0.875" master cylinder or use a smaller (0.700" or 0.750") master cylinder without a booster.

 

[Tom H]

do you think the smaller MC will give more pressure?

Tracy,

Like Barry says, no booster requires a smaller diameter master to get easier pedal with no booster. It's all in the hydraulic "lever". A .875 dia master has an area of 0.60 sq in. ( A = R sqrd x pi). If you step on the piston with 50 lbs of foot force you crate a pressure of 50lbs /.6 sq in = 83 Pounds per Sq Inch (PSI).

Use a .700 in piston = 0.38 sq in . Same 50 lb foot means 50/.38 = 131 PSI . Big gain. Pedal moves a bit father as the brake pistons move, but big gain in pressure.

Doing the math just now I must say I find the PSI gain of 58% surprising, but math and physics are always fun

Tom

 

[Eleven]

Thanks Berry, you made my decision for me! And no Tom, math is never fun!!!!!
Take care, thank you and all who helped!

 

[Alpine 1789]

Something always puzzles me in discussions of removing the booster: Rootes started the Series Alpines without a booster and then added it with the S3 and kept it through the end of production. Since this had to be a non trivial addition to the costs, I assume they found it improved braking performance. I wonder if the archives contain any background on the decision-making process at the time?

 

[Tom H]

My guess is that they figured out they could appeal to more females if the car was more tame. From the very beginning I think they were aiming to have a car with more modern style and more modern amenities to appeal to a broader audience. Tail fins, roll up windows, convertible top, roomy trunk. I just looked up Graham Robson's book "Sunbeam Alpine and Tiger - The Complete Story". On pg 79, in the chapter on Alpine III and IV, it says "The last significant chassis change was to specify larger front disk brakes and to specify a brake vacuum servo as standard. That, at least, put a stop to the early complaints that the brakes were too heavy, especially for lady drivers who made a significant portion of the Alpine clientele."

While scanning through the book I was surprised to see that the head of the styling team on the Alpine design, Kenneth Howe, was once a member of Raymond Loewy's group in London, New York, and Indiana and worked on Studebaker designs. I shouldn't have been surprised!

Tom

 

[Warren]

As yes like the Mustangs being the US secretaries car
How about the annoying ad title how much can Karen take....

 

[Alpine 1789]

My guess is that they figured out they could appeal to more females if the car was more tame.

Making the car easier to stop would seem to make sense to me. I can believe that it was done so that less pressure would be needed to stop the car and make it more appealing to women, but the general consensus here seems to be that putting earlier master and wheel cylinders on a later car results in comparable brake pressure. I've never driven a SI or II, or a later car with earlier cylinders, so I have no direct comparison. Still, I still have to wonder why Rootes went to so much trouble and expense for no discernible benefit. It seems like there has to be more to the story, although no one may know that "more" today.

 

[65beam]

We were at the Fall vintage races at Watkins Glen a few years back and the Penske Sunoco Camaros were there. I watched Donohue and Revson race these cars in the late 60's and I was taking photos of the cars and I noticed there was what appeared to be a Girling brake booster mounted in the right front foot well. Joel was part of Revson's crew so maybe he might be able to answer whether the cars originally had the boosters and the reason for it or was it something installed by the current owner.

 

[Eleven]

Wrap up. Got the .700 MC installed. Yikes! I have brakes now!! Thanks all for your help and advice!

 

[BEpine]

Tracy,

Like Barry says, no booster requires a smaller diameter master to get easier pedal with no booster. It's all in the hydraulic "lever". A .875 dia master has an area of 0.60 sq in. ( A = R sqrd x pi). If you step on the piston with 50 lbs of foot force you crate a pressure of 50lbs /.6 sq in = 83 Pounds per Sq Inch (PSI).

Use a .700 in piston = 0.38 sq in . Same 50 lb foot means 50/.38 = 131 PSI . Big gain. Pedal moves a bit father as the brake pistons move, but big gain in pressure.

Doing the math just now I must say I find the PSI gain of 58% surprising, but math and physics are always fun

Tom

Tom,

On my series 3, I'm restoring, I got a .750 Wilwood girling style master cylinder and a VB 5" lockheed booster kit. Will this combination work well.
Ive rebuilt the front and rear brake system with original parts.