I'm starting to think it might be nice to have a functional parking brake...
Got any tips for me before I get started?
Note: my MGB has a Ford 8.8 axle and drum brakes. Ten or twelve years ago, when I installed the axle, I rigged up some Mustang cables. They've never worked properly. Apparently my rigged system had too much friction in the cables and not enough leverage or travel at the pull-handle. My budget for improving the system is modest. What has worked for you guys?
Are you looking for an emergency brake or just a parking brake? If all you're after is a parking brake, you can get hydraulic line locks. I did a quick search & only saw the electric servo type used by folks doing burn-outs, but there at least used to be manually controlled locks as well. Essentially a fitting that had a knob on it similar to a proportioning valve but way smaller & with a way smaller knob that you could turn to close off the line thereby holding the pressure.
Now, if you want an e-brake, that's a whole nuther story.
The ford axle probably has a coble going into each backing plate. That system does not have the compound leverage that the MG brakes provide, so the key is in multiplication of leverage. One way to do that is with a pivoted lever having the drum cables attached part way down to the pivot.
Jim
Jim,
If you switch to Ford/Mustang based disc brakes for your 8.8, I can help you! My e-brake system uses the original MGB lever/cables/pivot and attaches to the Ford e-brake cam on the caliper.
If you decide to go this route I can take some pics.
....damn, my previous post should have been addressed to Curtis........
Graham,
I should have elaborated a bit more. This solution is a lever which is pulled by a cable or link from the existing e-brake lever and is easier to construct under a longer wheelbase vehicle, but if you could move the cable attachment point on the existing handbrake lever up towards the pivot you could get a better job of it. How much to move it is the question. Maybe you could try a couple of spots.
Jim
Oops, should have addressed that to Curtis.
I'm sorry that I've been so slow to come back to this thread. Thanks for the good advice, guys. I'm definitely thinking of new cables (not a line-lock this time) to work with my existing drum brakes. I'll leave discs for when I rebuild the whole rear suspension some day. I think I understand what Jim is saying about building a mechanism to compound leverage... I guess I need to take some measurements and figure out how far things need to move, etc.
I'd bet someone has fabricated this sort of mechanism for an MGB V8 already, but I know there's no photo of it on this website yet.
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My good news is that I finally got to drive my car on its new tires/wheels this weekend. I made fitting 205/50R15 tires look much more difficult than it should be. When I narrowed the axle (~12 years ago) I didn't narrow it enough. I don't know what I was thinking at the time, but the axle ended up about 52 3/8" wide. The logical solution would be to accomodate this by buying wheels with more negative offset. I already had tires mounted on new Panasports before I realized/remembered my old mistake. So, I took the new wheels to my neighborhood machine shop and had them mill the offset from +22mm out to +26mm, and I also had them turn the hubs of the axles from 10mm down to 7mm. (This forced me to track down different lugs too.) I also ground the fender lips back into the spot welds and a little bit more. The only remaining problem is tire scrubbing on the Adco front sway bar on tight turns... and Graham has shown us one good way to fix that.
The sticky new tires make it all seem worthwhile!
Curtis, I've rigged up parking brake cables on several street rods, it's not too hard usually. First you need to figure out how much linear movement is necessary for the Ford brakes to acutate when properly adusted, then compare that with the linear pull of the MG handle assembly. If the MG pull is too short you'll need to build some sort of bell crank to increase the pull. All you need is a piece of steel strap with a 90 degree twist near one end. Drill the end away from the twist for a pivot bolt, drill another hole for the pull rod from the MG handle near the middle (that point determined by the ratio necessary) and then drill and notch the twisted end for the two cables from the rear brakes. You can make the rod between the MG lever and the bell crank adjustable by using a rod end or clevis so you will have some adjustment. For the GM brakes on my Midget I didn't need a bell crank, there was enough movement in the stock MG lever.
The Moss Europe front sway bars are bent to clear the tires, unlike the ADDCO bars. Surprisingly, the European bars (including shipping from England) cost about the same, or even less, than the ADDCO bars, and come in sizes up to 1 inch in diameter.
In case you're curious for a follow-up report... here's where it stands.
I bought some Lokar cables, but decided to make my own bracket.
BrakeCables-A.jpg
Here's how the bracket and cable jackets will look. (Actual cables cores aren't fitted yet, obviously.)
BrakeCables-B.jpg
The car is still on jackstands for other mods. It'll be a week or more before I get to test it.
Okay, here's what it looks like installed...
(http://www.britishv8.org/MG/CurtisJacobson/CurtisJacobson-ED.jpg)
After the first trial use, I found that the lever (under the floor) simply wasn't long enough. I cut it and extended it by about 3/4 inches... and now I get enough travel for the emergency brake to work. Actually, it seems to work just fine as a "parking brake", but the engagement force is way too high for convenient handbrake u-turns. I'm very disappointed by that... Maybe one day it will piss me off enough that I'll extend the lever (inside the car.) Or, is there something to be done back at the hubs to improve this situation?
"handbrake u-turns"
Now, Curtis, you used to live in the South. Everybody down here knows that that is properly called a "Bootleg Turn". ;-)
Maybe 3/4" was too much to add to the bottom arm?
Jim
Curtis, if you're planning on making those "bootleg" turns you should convert the pawl and ratchet assembly to fly off operation. Embarrising when in the turn the brake locks on and your car continues to pivot on around off the road!
Ah. Good advice, and another new "word of the day" as a bonus! I'm actually a pretty mild-mannered driver, although all bets are off in a rental car.
Jim, you're probably correct that my extension (~3/4") was a little too long. I'm gonna have to put off tinkering with it (cutting/welding) until after the meet. I wish making the lever adjustable was a simpler proposition!
One thing though... I had the drums turned recently. Perhaps the e-brake will work a little better after the shoes wear to match the larger radius. Maybe?
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Here's a general question. What symptom might one expect if they had a slightly bent backing plate or two? I don't have noise or vibration issues in the rear brakes, but the backing plate rims don't have a nice even clearance to the drums all the way around and I've always wondered if that might suggest a problem. If they were moderately bent (from a previous owner's accident, or from abuse in the junkyard before I bought the axle) might that increase e-brake engagement effort?
On my wife's Toyota Sienna minivan, there is a piece called an 'equalizer" that looks pretty close to what you have there, or at least part of it. Might have saved you some work if you had known.