rudypoochris Posted January 9, 2008 Share Posted January 9, 2008 I have recently decided to upgrade my rear brakes to the 4 piston Wilwood setups which, as you all know, are not E-brake capable. So I have been thinking, what about adapting a bicycle disk brake, go kart, mini bike, or dirt bike mechanical caliper to mount on the front of the differential to clamp on a metal disk that mounts between the differential and the driveshaft flanges? I have not given thought to clearances yet, and this setup would not be for E-brake sliding. Would this be strong enough to hold a car on a hill though? Any input or ideas are appreciated. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted January 9, 2008 Share Posted January 9, 2008 There used to be kits very similar to this in the street rod world. So yes, it can be done, and with the right parts hold on a hill. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 9, 2008 Share Posted January 9, 2008 You probably need to do some math to determine the load on the caliper and disk when parked on a worst case 15 degree incline - unless you live in San Francisco. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 9, 2008 Author Share Posted January 9, 2008 You probably need to do some math to determine the load on the caliper and disk when parked on a worst case 15 degree incline - unless you live in San Francisco. Well I live 15 miles from San Francisco, but i don't park there. I am drawing up a basic design in CAD. It looks like it will require welding though or be prohibitively exxpensive to machine, from the current design idea anyway. I will do some equations to find the load at 15 degress and say 25 degrees. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 10, 2008 Author Share Posted January 10, 2008 Calculated load on 15 degree incline, 2640lb car, 3.54 gears, 26" OD tire, and 3" brake disk radius: (1200kg*9.81m/s^2)*sin(15) = 3046.8 N of force trying to move the car. 3046.8N*(1/3m) = 1015.6 Nm -> 749.0 ftlbs at axle. 749.0ftlbs*(1/3.54) = 211.6 ftlbs at flange. 211.6ftlbs*(12in/3in) = 846.3 lbs loading the caliper. At 25 degrees (not shown) = 1381.9 lbs loading the caliper. Calculated load on a bicycle using 1 brake disc at 4" radius to stop at .5g, 29" OD tire, 100kg total: (100kg*.5g*9.81m/s^2) = 490.5N of force at tire. 490.5N*(14.5in/39in per meter) = 182.4 Nm -> 134.5 ftlbs at axle. 134.5ftlbs*(12in/4in) = 403.5 lbs loading the caliper. Did I do these calculations correctly? If so it might be wise to use two bicycle calipers per car or source a stronger caliper. I think the real limitation will be the bolt diameter to attach the calipers to the differential. Does a bicycle brake at more than .5g? Quote Link to comment Share on other sites More sharing options...
TONY C Posted January 10, 2008 Share Posted January 10, 2008 Are you trying to stay away from hydrolic? How about a motor cycle caliper and master cylinder? You could make it self contained. no need to plumb into the braking system. And still light enough. 1 Good front caliper off a newer sport bike should do it. masters are small too. now you got me thinking.... Quote Link to comment Share on other sites More sharing options...
boodlefoof Posted January 10, 2008 Share Posted January 10, 2008 There are several pinion mount E-brake kits for Ford and Chevy differentials. They are faiely popular with the hot rod crowd. They typically use a solid rotor and a single piston mechanical caliper that is cable actuated. It seems like you could modify one of these kits to fit pretty easily, provided that you have adequate clearance for the rotor. On a side note, what Wilwood rear kit are you planning on using? You should pay close attention to the piston diameter of the calipers. Some of their rear kits use very large piston diameters, which can cause the rears to lock up berofe the fronts. You typically will not see this problem until you are in an emergency stop scenario (when you least need a problem). Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 10, 2008 Author Share Posted January 10, 2008 ^ Thanks. I have 1.75" 4 pistons in front and 4 piston 1.38" rear. I have a proportioning valve as well. I was wondering exactly what you stated, which is why I created a thread two weeks ago. No one replied though. http://forums.hybridz.org/showthread.php?t=128619 Calculated my range of distribution to be from: 83.9%F and 16.1%R and 62.5%F and 37.5%R I think that is most likely an acceptable range, but I digress. ---- Any chance at a link to those axle mounted parking brake setups? I would like to stay away from hydraulic as the main issue was that these systems are not designed to hold line pressure for extended periods of time. People wishing to do this could use the Wilwood calipers and a line lock. Quote Link to comment Share on other sites More sharing options...
boodlefoof Posted January 10, 2008 Share Posted January 10, 2008 If you search google for "pinion mount" "emergency brake" you will find some kits. I think one site that has them is springfieldstreetrods.com. The piston area on your setup comes to 4.8 sq. in. front and 3 rear. This gives a 1.6:1 ratio, which is within the range I've seen cited as acceptable. However, I have seen people with heavier cars running similar front sizes and still say they have problems with rear calipers of that size. Wilwood has started selling 4-piston calipers with piston sizes of 1" and 1.12" that some have switched to. I am not an expert in this area, but am also researching it presently, which is why I mentioned it. Rotor size front to rear and pad material will also impact the f/r brake performance. Quote Link to comment Share on other sites More sharing options...
torynich Posted January 10, 2008 Share Posted January 10, 2008 http://allprooffroad.com/index.php?option=content&task=view&id=33 here is how toyota trucks do it...just to give some ideas... Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 10, 2008 Author Share Posted January 10, 2008 The piston area on your setup comes to 4.8 sq. in. front and 3 rear. This gives a 1.6:1 ratio, which is within the range I've seen cited as acceptable. However, I have seen people with heavier cars running similar front sizes and still say they have problems with rear calipers of that size. Wilwood has started selling 4-piston calipers with piston sizes of 1" and 1.12" that some have switched to. I am not an expert in this area, but am also researching it presently, which is why I mentioned it. Rotor size front to rear and pad material will also impact the f/r brake performance. Yep yep. I noticed that too. I would really appreciate if you typed whatever findings or thought you have into my other thread linked above. I think alot of people probably wonder these same things. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 10, 2008 Author Share Posted January 10, 2008 http://allprooffroad.com/index.php?option=content&task=view&id=33 here is how toyota trucks do it...just to give some ideas... Thanks! That looks almost exactly how I want to do it. Although I can't seem to figure out how that caliper mounts or functions in the lower picture. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 10, 2008 Share Posted January 10, 2008 I don't see where a Z car has room to mount a brake on the front of the diff. Maybe a halfshaft, but the input flange of a long nose is pretty tight. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 10, 2008 Author Share Posted January 10, 2008 I don't see where a Z car has room to mount a brake on the front of the diff. Maybe a halfshaft, but the input flange of a long nose is pretty tight. Ya. I worried that much too. I guess I will have to look once the rear end is put back together. Quote Link to comment Share on other sites More sharing options...
boodlefoof Posted January 11, 2008 Share Posted January 11, 2008 I'm out of town at present, but will try to go back and add some of my findings to the other post (re: brake balance and selection) when I'm back at home. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted January 15, 2008 Share Posted January 15, 2008 are you completly against using a line lock? Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 15, 2008 Author Share Posted January 15, 2008 are you completly against using a line lock? Pretty much. I'm open to ingenious suggestions though. Quote Link to comment Share on other sites More sharing options...
jeffer949 Posted January 15, 2008 Share Posted January 15, 2008 why not a hydraulic hand brake? like this one http://www.ultrarev.com/product.php?productid=42594 Quote Link to comment Share on other sites More sharing options...
Lunar240z Posted January 15, 2008 Share Posted January 15, 2008 I don't see where a Z car has room to mount a brake on the front of the diff. Maybe a halfshaft, but the input flange of a long nose is pretty tight. It'd probably fit with a shortnose r200 or r230. I've thought about this for a while as well. Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 15, 2008 Author Share Posted January 15, 2008 why not a hydraulic hand brake? like this onehttp://www.ultrarev.com/product.php?productid=42594 I think the whole issue with the hydraulic brakes is that they just don't seem that safe and they can lose pressure. When they do the car rolls. Is this correct? At least I thought it was an issue... With a mechanical setup the caliper is held shut using a ratcheting mechanism and can only fail really if the cable snaps, which pretty much only happens when you are applying the brake itself. Quote Link to comment Share on other sites More sharing options...
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