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Improving power brakes

junkpile

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Has anyone here ever used a Leed Brakes "bandit" vacuum pump to supply the power booster?

My current setup is working and I want to improve my stopping ability. My 440 has a 484/284 cam with low vacuum. I run a line from the intake manifold to a Summitt vacuum can with a check valve and then to the bendix booster. The master is 1-1/8" bore and I have Cordoba 11-3/4" rotors with slider calipers out front, drums on the rear. The breaks grab nicely and consistantley but are short of locking up. I want to know if adding a vacuum pump to supply the can with more vacuum will improve the brakes so they will grab easy and lock up when I want them too. The breaks are working correctly and have no air in the system. I am just looking to see if anyone has used a vacuum pump and if it gave an advantage over the vacuum can alone. Without the can I could not use the power booster, with it, it has worked fine but i know it can be better.
Thanks for any info. I have not performed a vacuum test at the booster yet but I will when I get a chance. I will supply that info if needed. The can has a vacuum gauge on it and it usually rests between 15-18 but I can not read it when it at idle in gear.
 
Not too sure why you are having these braking issues. My cordoba 440ci (about same weight as your 69) has all stock brake components with no add-ons. Front disk, rear drum, booster, master, all stock. I use to have the same cam in it you are running, changing it 2 more times now each with higher duration and lift. Never an issue with braking (as I knock on wood). Always lock up if needed, no noticeable difference in pedal feel or slowing performance. My latest cam is a Hughes cam. Very wild. I was worried about the effects on my brakes but didn't make a bit of difference. I don't know what vacuum I'm getting because never needed to know.
 
The best way is to put a brake pressure gauge in and see what you get pressure wise.
The simple thing to do is put in better pads. I used Hawk HPS and they are very good.
You could then reduce the size of the master a bit to give you more line pressure.
On a street car you probably would be taking a step backwards if you make the brakes so powerful they overcome the traction of the tyres too easily and lock up.
Some folks do not realise the brakes are only as good as the grip of the tyres to the road surface.
 
Thanks. I have new rotors and ceramic brake pads all new put on in september. Car stops better than if did before with the 10" rotors. I have always used the 1-1/8" master and never had an issue. I was looking to see if anyone has used a vacuum pump to improve the brakes function. When i had a stock 440 this set up would lock up the brakes when panic stopping and hold the car during a burnout. since the engine build and new cam i have been fighting to get the brakes back, i even used manual for a while. since i added the vacuum can, i can use the power set up again but it is not like before so I was wondering if a pump would improve the system.
 
I have never used one myself but friends have and they do work although they are noisy and a bit hard to mount.
If you really want good brakes maybe look at hydro boost?
I would tend to go this way myself and you could almost guarantee a good result.
 
Hunting down lax brakes with my front disk conversion, a few things to check is possible air in the MC (if you may not have checked this). Before this, another check is adjusting the prop valve adjustment. Another is assuring you have the proper booster to MC gap...due to some modification hassles, I found out my rod travel was a tad short. Another check, while this shouldn't be a problem (though have encountered this) is assurance your pads aren't binding at all in the calipers. A shop did an install for a buddy and didn't assure there were no burrs and didn't lubricate the guides causing binding. Yes, vac checks are easy to do if you have a pump/gauge...
 
Forgot to include...checking your drums, among the gremlins I've had is a self-adjuster canted not mating with the star. In one case, my drums were old and maxed out so got new ones. I mentioned air in the MC, reason is you can bleed the brakes forever; but if there's air in the MC, only an MC bleed will get it and air can be a cause of lax or no lock up. Will include I had a booster in a car that wasn't compatible with the system, smaller size, getting a larger one made a diff. As you mention you need to check what the vac is at idle of you have a gauge...reserve tank (I put one on one of my cars) if it's under 15" a reserve tank can work; but they only get you a few inches at best and can die off with repeated braking to regain ample reserve. More aggressive setup like a hydro-boost has been a fix. Just tossing out some 'checks' with brake hassles I've had in case helpful.
 
I will try to get a vacuum test later today on the car and post a reading for everyone. There are no vacuum leaks. Brakes have been bled properly, rear drums are functioning correctly, Master cylinder was bench bled, dual diaphram booster (bendix (tapered front)) working with no leaks, and the push rod from the booster to the master was gauged to have the correct depth without binding. I have looked into Hydro boost, and that is out of my budget and looked at the silent pump by master power brakes but at 580 bucks that is crazy. Leed brakes has a silent pump called the "bandit" and its a little cheaper. I just want to make sure before spending the money that it is worth trying. Adding something extra to the engine bay will suck but if it improves braking....it must be done. either that or return to a stock cam, in which case I would need advise on a cam to use for a 30 over 440. :) I would have to mount the pump near the horns on the passenger side since the drivers side if not an option. Like I said, assuming everything else is working correctly (and I will recheck everything again, including re bleding all the brakes in the spring) would higher vacuum numbers help the booster to clamp the brakes.
 
Sorry to sound repetitive but I truly think you have other issues within your braking system. You already have a can and everything seems new. Your cam isn't crazy radical either. Seems like you will be compensating a problem with more add-ons without correcting the problem. Good luck in your search and please post the final results of your problem.

Edit: Reminds me of my braking issue with my 71 Cuda (has same cam as yours). New everything, 4 wheel disk, mc, lines, prop valve, everything all Wilwood. Same issue as you are having. No brake lock up. I find out I needed a different size MC.
 
Forgot to include...checking your drums, among the gremlins I've had is a self-adjuster canted not mating with the star. In one case, my drums were old and maxed out so got new ones. I mentioned air in the MC, reason is you can bleed the brakes forever; but if there's air in the MC, only an MC bleed will get it and air can be a cause of lax or no lock up. Will include I had a booster in a car that wasn't compatible with the system, smaller size, getting a larger one made a diff. As you mention you need to check what the vac is at idle of you have a gauge...reserve tank (I put one on one of my cars) if it's under 15" a reserve tank can work; but they only get you a few inches at best and can die off with repeated braking to regain ample reserve. More aggressive setup like a hydro-boost has been a fix. Just tossing out some 'checks' with brake hassles I've had in case helpful.
Also don't assume that since you have self adjusters, you don't have to keep them adjusted. The more the back is out of adjustment, the more the front has to do the job and the less effective the total system is. When I had my 94 1500 ram, I adjusted them at every oil change. Its amazing just how far you have to crank them up. You have to figure that almost 100% of your driving is forward and less than 1% is backing up. The adjusters only work backing up therefore getting out of range.
 
There is a video on YouTube of a guy that fits one of the Leed units to a truck and he is happy.
That video should provide all you need to know.
 
O.k. I finally got to work on the car a little. All the brakes are bled and adjusted, push rod to master cylindar is adjusted and there are not vacuum leaks. The vacuum resivoir hold 20" when the car is reved up but after two or three pumps of the pedal it reads 8" vacuum, with the the car idling in gear the vacuum reads 8". I do not want to change the cam in this finished, good running engine. I have had manual brakes in the past (do not like the feel) but have all the pieces to put back. If I go with a vacuum pump to increase the vacuum to 21" I believe it will solve the problem but I want to know if anyone has used LEEDs bandit pump, and what they think of it. Master Power brakes has what appears to be a nice vacuum pump system that will do the same thing but they are way out of my budget at just under 600 bucks.
 
Hopefully someone here will be able to answer you on Leeds. No doubt ya know 8" is way low and a reserve tank won't come close. I've heard of some home grown vac assist setups and I know a guy (if I recall correctly that did this on his roadster). Until I finally solved my ills, I was really thinking of just dumping the power brakes as guys have manual that are fine. I didn't have power before the conversion and it wasn't a hassle. Good luck on your question.
 
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