I’m looking at my drum brake system and I’m wondering what effect having wheel cylinder diameter the same on all 4 wheels might be. I’m asking because the front drums (MT products 39 Lincoln) have wheel cylinders that are 1 1/8” diameter. The big Ford drum brakes on my Winters quick change are 1” diameter. Changing them out with a pair of wheel cylinders the same as the front will simplify my brake plumbing. My first thoughts are that it should probably work fine, I’m also installing a SSBC adjustable proportioning valve. So, wheel cylinders the same size front and rear with 4 wheel drums, will I be okay? As far as I know Derek at Boling brothers uses the same parts when they set up a 4 wheel drum brake system using their Lincoln brakes.
The size of the wheel cylinders depends on the size of the shoes, and that depends on the weight on the axle. In other words, give is more info about the whole system, maybe we can offer some helpful suggestions.
The car is my 26 T RPU I’m just building. The front drums are brand new mt products 39 Lincoln brakes with 2” shoes. http://www.mtcarproducts.com/Brakes.html The rears are brand new big Ford brakes I ordered with my Winters quick change https://www.speedwaymotors.com/Ford-Racing-11-Inch-Drum-Brake-Kit-2-1-2-Offset,2001.html 4 wheel drums with a 1” bore dual master cylinder. SSBC adjustable proportioning valve 700-16 rear tires with 500-16 fronts.
going to a slightly larger wheel cylinder will give you a 'power brake' feel. The price you will pay is slightly longer brake pedal travel. I think its worth it. The rears are smaller than the front. The Bob Wilson Lincoln brakes on my avatar have 1 3/16 front cylinders and self adjusters. I use 15/16 masters and 1" on s0me of my cars. The law of hydraulics dictates smaller masters give the 'power brake' feel to your pedal
The front brakes have 2” shoes and the rears are 2 1/8”. Same diameter. Wondering if the 1 1/8” wheel cylinders that the front has will work on the rear or if I’ll have problems with all 4 the same size. The rear brakes came with 1” wheel cylinders.
One way to learn more about sizes is to look at autoparts websites and learn what sizes a 56 Ford half ton used...or a 64 Impala..or whatever example you choose
I'm going to call Derek at Boling brothers tomorrow and ask him if they use the same sized wheel cylinders on their Lincoln rear brakes when they set up a 4 wheeled drum system. But in the meantime keep the info coming guys. Larry.
How is the weight distribution on the car? If it's pretty well balanced, the front brakes will need to do more work, and if you have the same size wc on the back and front, the rears will probably lock up before the fronts. If you want to have some fun and make it like a race car, you can get a dual side by side master cylinder, with a balance bar, and adjust the brake pressure on each end of the car that way.
I’m not sure, what is the typical weight balance of a steel bodied T RPU? Don’t forget about the adjustable proportioning valve. Unless my thinking is way off base I think I would be able to adjust the rear pressure to compensate for the change
Up above you said you had Lincoln style fronts (12") and a link to the newer Ford rears (11"). Not the same diameter. But isn't the true way to measure by calculating the total square inches of shoe? That sq. in. difference front to back is probably more important than the diameter.
You may be over thinking the "problem". I would just get it going with what you have (unless the Boling Bros have a significant change), drive it and evaluate the performance. You may like the way it is after adjusting the prop valve a little. You may find the pedal effort to high or to sensitive, same with the stroke, then you can decide what changes to make. My roadster has excessive pedal effort with a 1" master due to a screwed up pedal ratio, I'll be changing the pedal if I can and maybe the master but with a bunch of mismatched brake system parts I had to start somewhere.
True enough I wasn't paying attention, I thought they were the same diameter. Close anyway Once I find out what Boling bros uses for the rear wheel cylinder size, I should have a better idea. The 1" master cylinder I am using is the one that Boling recommended, it's what they use on chassis they build and set up. The main reason I want to go with the different (larger and same size as the front) wheel cylinder is because the way the brake line (in this case hose) attaches to the wheel cylinder is different than the rear wheel cylinders which are set up for hard line. I don't want to run hard line on my quick change rear end, I want to tee the hard line for the rear brakes one line to each side and then run the same hoses as on the front to each rear brake.
Gotcha..... I think Speedway and others offer adapter fittings so you can use factory style, AN, or banjo ends on almost any wheel cylinder. What type of flex hoses were you thinking of?
Most factory systems use around 1/8" to 1/4" bigger cylinders on the front for a reason. If the rear is over braked, handling can be interesting just when you don't want it.. Mixing drum sizes makes anything a guess. Be conservative and aim for a sizing that the factory may have come up with. A look through the brake parts books can often help with the decisions. Not hard to change rear cylinders after the car is driving. The aim is to have the rears lock up AFTER the fronts Garpo .
The hoses I would like to use are the same as the front hoses (Old style rubber Raybestos hoses) which go into the front wheel cylinders with a 7/16"-20 thread and seal without a tapered seat, they use a copper washer. The rear wheel cylinders use a 3/8" -24 thread with a tapered seat for a hard line connection. I suppose the easy way out would be an adapter to go from the wheel cylinder to the hose, or a hose with the tapered seat and the other end to a frame tab fitting which accepts the chassis hard line. Trying to avoid the hard line on the rear end and use the same type of hoses seems to be a challenge
It’s true the rear will brake a little more aggressively with bigger cylinders but that’s what he proportioning valve is for, you will be able to adjust the split point where you like it. That’s the point it begins to limit pressure to the rear, from there on you will have less pressure to the rear than the front to avoid the rear locking up first Sent from my iPhone using H.A.M.B.
Well here goes. After hours of searching wheel cylinder sizes and hose end sizes ( which are not easy to find... ) I believe I have my answers. 1) MT products (Boling Bros) use a 1" bore wheel cylinder on the rear Lincoln brakes just like what I presently have. ( Information I managed to find on the Ford Barn) So my thoughts on using the same hoses due to the way they fit the wheel cylinder goes out the window because it seems like all of the rear wheel cylinders available in the 1" bore size come fitted with 3/8"-24 inverted flare ports for hard line. I have to keep the 1" rear wheel cylinders. 2) So, the next step was a long and frustrating exercise in coming up with brake hoses that have one male 3/8" -24 inverted flare end to go into the wheel cylinder, and on the other end a female fitting to go to a frame tab with a female 3/8" -24 end to accept the hard line. That way I can do as I planned and hook up my rear brakes without any hard line on my quick change, rather just a hose to each side. After a long tiring search I came up with the appropriate hoses with the correct ends. https://www.summitracing.com/int/parts/dhb-h11146/overview/ And since I prefer Raybestos parts their number is BH11146 https://www.brakepartsinc.com/raybestos/en-us/catalog-part-search Have to love it when a plan comes together.
In the end it may seem like the solution was a simple enough one but I only wish it was easier to come up with. Thanks for all the input.
I'm like you; I want what I want, and sometimes I have to agonize over it before a solution finds me. These little things seem unimportant to most people but invariably some savvy car guy will see it and appreciate the effort you put into it. Glad you found your hoses.
Thanks, the process is never easy when you are trying to stay with a vision of how you want the details to be accomplished. Plus I’m probably a little stubborn too and don’t like to give up Maybe all this might help someone else in the future.
On the last two cars I built, 33 Ford Coupe & 32 Ford Roadster, both with Lincoln brakes. I used the stock 1 1/8" front wheel cylinder on the front and 15/16" on the rear worked the best, after trying a 1" and a 7/8" on the rear. Wheel cylinders are cheap, and I didn't need a proportioning valve.
Of course I had this info on my computer at work, it originally came from the Hamb, but I couldn't find it when I needed it. Isn't that the way it usually goes
Not that I am in need of this info. but this is why tht HAMB has no equal in this little universe we exist in. In this day and age just having some applications and part numbers for those hoses that have been verified to work makes such a difference. It's like having the numbers for radiator hoses that someone else has done all the legwork for you. Probably seems insignificant to those that don't need it but priceless to those that do. I love this place!
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