FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: cjshaker on August 08, 2017, 09:26:38 AM
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Last year at Drag Week, on one of the days, I popped the trans into neutral at the end of the 1/4 to save on engine wear. I had enough brake shake at that speed (115) that it made me uncomfortable, so I didn't do that again. It was never noticeable on the street, at average speeds.
I just took my rotors and rear drums (factory disc brakes on front, 2 1/2" drums rear) to have them turned to eliminate that problem this year. Still, it took quite a bit of brake effort to get the car stopped last year, so I've been looking at aftermarket brake systems. So I have 2 questions...
1: I've been looking at the Wilwood systems, which seem pretty nice. Are there any issues with their stuff that you guys have noticed or experienced?
2: Rolling resistance is quite a bit heavier than new cars. New cars have almost zero resistance when you go to push them. I know on older cars, that rolling resistance has to do mostly with the front brakes and the residual pressure in the system to keep the calipers expanded. I know the residual pressure valves are located in the master cylinder, but is there a way to minimize the effect they have on resistance? I know they sell lower pressure residual valves, like 1 pound deals, but how do you get by the stock valves? Is there a negative to doing this? Or....how do you guys minimize the resistance created by the braking system?
After thinking about it, the rear stock system could easily be managed by removing the automatic adjuster system and just keeping the brakes adjusted so that there is enough gap to eliminate the resistance. That's not a big deal, it's easy enough to pop a drum off and do a quick adjustment once a year. But what about the fronts?
Ok, that's like a dozen questions, but they all fall under 2 categories...new brakes and resistance, so...
And yes, I know resistance is futile ;D
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I have Wilwood systems on my race car, my Galaxie, my Mach 1 and my 68 Mustang. I like the Wilwood products, and four wheel discs are wonderful. I buy the four wheel disc setup and the matching 7/8" bore master cylinder, plus their rear brake proportioning valve. I think the Wilwood master doesn't have those check valves that the factory master cylinders have, so you aren't dragging the pads all the time.
I would say that I have never had any problems with the Wilwood stuff, EXCEPT that a couple weeks ago I got a notice from Summit and from Wilwood that the front seal in their 7/8" bore master cylinders may start leaking into the rear circuit and decrease the brake action in the front circuit. They want you to check the date code on the master cylinder and if it is one of the suspect units, to send it back in for repair or replacement. Well, great, I'm not going to tear apart my brake systems on the off chance that one of the master cylinders might be defective; I've had no problems with mine. Hate to see this kind of a thing from a brake manufacturer...
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Thanks for the info, Jay. I assume you don't use a power booster on any of your cars? Mine is a power brake car, but I'm looking at going the 4 wheel disc route and eliminating the booster. Partly for clearing up space, reducing weight and simplicity, but mostly for the fact they don't seem to be needed with a more modern system and properly sized master cylinder.
So you have not had any trouble with the caliper pistons retracting and making the pedal travel excessive?
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I too changed over to Wilwood brakes on all four on my 67 Mustang and like them a lot. I had factory disc up front and I checked the weight difference and came up with 35 lbs. savings on the front end.
I have the power booster also but decided to keep it. Isn't the pedal leverage different on non power cars?
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I have the power booster also but decided to keep it. Isn't the pedal leverage different on non power cars?
Yes, the brake pedal pivot point is different. The power pedal has less leverage built into it if I recall correctly, but that shouldn't be an issue, or is easily changed if it does present a problem.
And just for clarity, I'm considering the Wilwood system for a near future upgrade. I'm looking at reducing resistance with the current system.
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I don't use the power booster on my cars; I like the extra room that leaving it out provides. I do notice that the pedal travel is a bit more than stock with the Wilwood setup, but I don't find it objectionable. Pedal pressure is not excessive.
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Doug, on the Wilwood setup I would check to see how it affects the car's front track; it may be wider with the Wilwoods. That's not necessarily a bad thing but better if you know. On your current setup, seems to me you can reduce rear brake drag with the drum adjustments as you've described. Not sure how you would reduce the front disk drag but maybe you're on to something with the residual valves. As for boosted vs. non-boosted, nearly every newer car I've seen has 4-wheel disks with a vacuum booster. So I guess that boils down to personal preference. :o
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Doug, I believe the 1lb residual valves were ment for systems that have the master cylinder inline or below the the brake plane. This prevents the siphoning effect of the master cylinder on a hill or parked on a hill. I have the residual valves on my 56 F100 as it is equipped with 4 wheel discs and the master is below the floor in line with the brakes. Only time I have had rolling problems is when I stop, the valves seem to hold for a second or two but the minute you move they free up. My brakes are non power by the way.
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Hey Doug I have the wildwood brakes in the rear and the proportioning valve that I dont believe works to well I cant really tell the difference when I turn it. I bought the 7/8 bore master and was having trouble getting a peddle called wildwood and they said they had some problems with a small batch of 7/8 masters so I bought the 1 1/8 bore. I thought bigger was better but i was told thats not the case with masters although my peddle is fine, no drag and no booster. Now I bought new Billet Specialties 15 inch rims 4.5 backspacing and they wouldnt fit with the calipers called Jegs and Billet Specialties and they agreed that they wont work with the wildwoods so I had to get 16 inch rims for the rear. I had an old pair of centerlines that used to be on car with the drum brakes and they wouldnt fit either, I dont know if its just me but inquire about that because I know you like your rims on your car.
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If you guys want a real education on braking systems, do some reading here;
http://www.stoptech.com/technical-support/technical-white-papers
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Doug, on the Wilwood setup I would check to see how it affects the car's front track; it may be wider with the Wilwoods. That's not necessarily a bad thing but better if you know.
Bruce, the Wilwood site shows the hub is moved outward by .090 on each side. That's not much and I don't see it as a problem with my wheels and intended use.
Doug, I believe the 1lb residual valves were ment for systems that have the master cylinder inline or below the the brake plane. This prevents the siphoning effect of the master cylinder on a hill or parked on a hill.
Garry, I wasn't aware of that, but it makes sense. I couldn't see a piston being drawn back in on a caliper, at least not very far. The only thing that could pull or push it back is the rubber boot or flex from high speed cornering. That last one I'm pretty sure won't happen :)
Hey Doug I have the wildwood brakes in the rear and the proportioning valve that I dont believe works to well I cant really tell the difference when I turn it. I bought the 7/8 bore master and was having trouble getting a peddle called wildwood and they said they had some problems with a small batch of 7/8 masters so I bought the 1 1/8 bore. I thought bigger was better but i was told thats not the case with masters although my peddle is fine, no drag and no booster. Now I bought new Billet Specialties 15 inch rims 4.5 backspacing and they wouldnt fit with the calipers called Jegs and Billet Specialties and they agreed that they wont work with the wildwoods so I had to get 16 inch rims for the rear. I had an old pair of centerlines that used to be on car with the drum brakes and they wouldnt fit either, I dont know if its just me but inquire about that because I know you like your rims on your car.
Wilwood has some very detailed info and measurements regarding what rim dimensions can be used with their individual braking systems, so I did some careful measuring and found that there is enough room to fit their calipers inside my front wheels. The rears were no problem. I also think when you try to mix and match parts of different systems, you can get into an issue with things not playing well together. I think I'd opt to go for all 4 corners and ditch the original (complex) distribution valve when I do the swap.
If you guys want a real education on braking systems, do some reading here;
http://www.stoptech.com/technical-support/technical-white-papers
There's some interesting reading there. Thanks for the link.
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When I put the front hubs back on tonight, I noticed how much drag comes just from the grease inside. I considered going to a synthetic instead of using the conventional grease that I normally use, but had some doubts as to whether or not it would hold up to a thousand miles of street use on these older style bearings. I doubt it would be an issue, but think I'll look into that a bit further. I'm sure that would free up some rolling resistance in the front wheels if I were able to use it. For now, all my intermittent scrubbing when turning the wheels, is gone, so I'm confident that the shake will be gone.
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Rolling resistance is reduced to zero on Pro Stock cars with some expensive parts like ceramic bearings.
At Seattle on the weekend I was watching them adjust valves on one of the top running cars and a crew guy plugged in a fan to blow across the work area. The car was jacked up with all four wheels off the ground and the front wheel started turning on it's own with that small bit of wind and gained speed until it was doing about 30mph. It spun for a good ten minutes and only stopped when the crew guy went to that side to do the valves and stopped it with his glove.
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My understanding is that the disk calliper piston retraction is controlled by the square section o ring.
The o ring returning to its square shape retracts the piston enough to minimise drag.
One trick we use on racing bikes is to remove all those vibration and anti rattle plates, we also face the rear of the pads.
The facing removes any unwanted flex, and removing all the plates allows the pads to move off the disc more, note if there is a huge vibration the pads will move a long way from disc, causing the pedal to require a few strokes to apply pads to disc.
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Dough to my knowledge the residualvalves are for drumbrakes
To have some pressure in the lines to ...Compensate somewhat
for the returnsprings for the brakeshoes otherwise you get a
mushy pedal . On the old Volvo PV 544 when we put discbrakes
from Volvo Amazon on them we removed the residual valve from
the bottom of the mastercylinder. Otherwise the discbrakes was
in constant contact. One trick to get the brakepads to retract
more is to not tightening the wheelbearings so tight a little slack
knocks the pads back more
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What about front drum brakes with some of those fancy new brake shoes? I realize it seems a step backward to go to drums, but they do have less drag. You only have to stop once on a drag strip before letting the brakes cool down. Just a thought.
FYI. I'm a hypocrite because I converted my '67 Cougar from front drums to front discs. I never tried the new brake shoes and/or larger drums, though.
paulie
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What about front drum brakes with some of those fancy new brake shoes? I realize it seems a step backward to go to drums, but they do have less drag. You only have to stop once on a drag strip before letting the brakes cool down. Just a thought.
paulie
I actually have some old magazine articles that mention racers that used drum fronts for that very reason. Since my car will have some street miles on it, I'd prefer the better performance of discs.
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Hell man, I didn't actually want you to DO it. I remember stopping my first car, a '69 Cougar, many times from over 120 mph. I remember the brakes fading and I ended up rolling into a red light at an intersection with my foot to the floor, and my right leg shaking with fear. That's after steering back and forth to try to keep the malicious beast between the curbs. Many times.....
Front drums suck dead rhino butt. I just thought you wanted less drag. :)
paulie
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My Fairlane is scary in the shutdown with stock 10" drums at 135mph. A 330mph fuel dragster only needs half the stopping distance I do.
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Today you can get drum brake shoes that absolutely will not fade. They are well worth the money.
I have gotten them hot enough to boil DOT 5 fluid, melt the seals and temper the springs, but was able to reuse the shoes. (Parking brake left on for about 50 miles...)
https://www.porterfield-brakes.com
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I use to have the Granada discs up front and drums in the rear. Never had problems. I switched to aero
space front and rear discs with a manual proportioning valve. It stops ok but need to center the rotors a little more to reduce drag.