Howe dual piston calipers?

[chris71]

"When I spun it, it looked like maybe the wheel was bent, so I don't know. You may have to run a then spacer to get the stock wheels to fit."

i suspect the wheel is getting hung up on something on the caliper and not sitting flush, try another wheel and see if you get the same result. i hope everything works out okay for you. It looks like these may not be the solution for us guys running 15's. regardless, thanks for keeping us informed. just food for thought that tape on the pins made me a little weary. floating style calipers are supposed to slide across those pins to contact both pads to the rotors since the pistons are only on one side of the caliper, if there is tape there the calipers may get hung up when they try to "slide". i would do some more research here to nail this one down, maybe sign onto a circle track forum and ask the question with video clip, or send the vid clip to Howe, i wouldnt want those calipers to either not release or not engage properly your first stomp

[Ackattack]

Originally Posted by chris71

"When I spun it, it looked like maybe the wheel was bent, so I don't know. You may have to run a then spacer to get the stock wheels to fit."

i suspect the wheel is getting hung up on something on the caliper and not sitting flush, try another wheel and see if you get the same result. i hope everything works out okay for you. It looks like these may not be the solution for us guys running 15's. regardless, thanks for keeping us informed. just food for thought that tape on the pins made me a little weary. floating style calipers are supposed to slide across those pins to contact both pads to the rotors since the pistons are only on one side of the caliper, if there is tape there the calipers may get hung up when they try to "slide". i would do some more research here to nail this one down, maybe sign onto a circle track forum and ask the question with video clip, or send the vid clip to Howe, i wouldnt want those calipers to either not release or not engage properly your first stomp

I know what you're saying about the tape. I did grease the pins, so that should help. I may take the tape off completely and see what it is like with out it. Ideally I was thinking some sort of delrin press fit bushing would be ideal, but I'd probably have to make those myself (or have the made to my specs.

[Brad]

I was just thinking about this again and I wonder if you can get a machine shop to either make bigger pins (major $$$) or perhaps just press fit bronze bushings that fit inside the caliper? I'm looking forward to seeing this tested.
So do you still think a 15" wheel won't work? Have you had a chance to get another one to test?

[NC Cams]

Here is the whole explanation behind why the Howe calipers may rattle around like they do.

Back in the 70's, Ed Howe adapted the then new and comparatively inexpensive sliding caliper D52 GM caliper to oval track racing. There wasn't much available in the way of pad materials at the time but the calipers could be had for peanuts at junkyards all around the Midwest states where he raced and eventually sold his cars. As his business grew, he made race specific adaptations of the same stuff he formerly gleaned from junk yards. THe DP caliper is one such upgrade from the 2.94" Gm caliper. but it is still a little shy of the MASSIVE 88mm D52 truck caliper that Gm came up with a bit later one. THe motorhome guys use this a lot wutg 1.125 or 1.25 or 1.312 truck MCs..


WHen you look at the OEM caliper setup, it is NOT mounted in flat, "blade" like caliper brackets that the aftermarket guys offer today. THe OEM caliper brackets were actually fitted to/with "hooked over" brackets that had a tab folded over that guided the caliper and also absorbed F and R braking forces.

ALthough not readily known or followed anymore, the clearance between the D52 caliper and caliper bracket is CRITICAL to the quiet operation of the system under braking.

Here's how it works.

THe caliper clamps on the rotor, THe rotor slams the caliper into the "hooked over " caliper bracket. WHen properly clearanced at about 0.003 to 0.007", the caliper relies on the bolts/pins ONLY to keep the caliper positioned into the "Hooked" caliper bracket. The rubber bushings take up the slack and keep the thing from rattling or "cracking" when the calipers move around as braking occurs with a properly clearanced bracket/caliper. Brake forces are applied directly to the bracket and NOT so much thru the pinds or busings.

NOw, delete the "hooked" bracket and use a "blade" bracket.

WHen the caliper clamps, it now clamps well outside of the now "point source" reaction point of the blade bracket. Since the clamp point is outside of the reaction point and no "hook" is there to absorb the brake reaction force, the caliper both twists and slams against the blade bracket.It can't help but rattle around as its twists and turns and shimmies, especially without the O rings that the race caliper lacks

Since the early HOwe adaptations were used in hard core racing, they often saw rotors get CHERRY red in/during service. At those temps, the factory O rings in the calipers would literally melt out whether you liked it or not.

Hence, for racing you could leave out the o rings and the calipers would still work. Since noise was not an issue, and the headers blanked out any rattle or cracking sound of the calipers, nobody cared. I bet even Howe will argue that their calipers are RACE calipers and not STREET calipers.

TO reduce fab costs, the "hooked" brackets were then replaced by "blade brackets" and the parade rolled on.

Fast forward to 2008.

The Chevelle and truck crowd uncovered what was essentially a HD suspension that was initially developed from A and B body and truck GM hardware by Ed Howe, This is whey so much of the Howe stuff bolts on. HOWEVER, there is a reason why RACING is Howe's middle name - it is race car stuff that has eliminated street needed features that hampered performance in a harsh racing environment.

For inexpensive reliable race calipers, HOwe's are hard to beat. However they aren't suitable for street use -even Chas HOwe will surely state this when/if you talk with him directly about it as I have done on occasion..

How to fix it, no pun intended.

First, get a "hooked over" factory style caliper bracket. Tighten up the "hook" so it has 0.003 to 0.007, 0.005" preferred caliper to bracket clearance. Do this by bending the "hook" down so the flat nose of the blade makes clean even and square contact with the caliper. Use silencer shims behind the pads and the lube goop as well.

THis should MINIMIZE rattle potential until or unless you can find a way to replace the O rings which take out the final rattle potential.

Now, if you really want trick aluminum calipers, look at Willwood. They sell GM III"s with the anti rattle Orings. HOWEVER, I don't believe you can get them for an 11.75x1.25 HD rotor - they only come on calipers for 1" or thinner rotors.

The real issues seems to be that many/if not most of the aftermarket caliper brackets are the quick and dirty flat "blade" type brackets that don't have the "Hooked" over section that is/was intended to absorb a lot if not most of the braking forces in the oem design. This doesn't mean that that the blades won't work, they clearly do but one might experience rttel or shake noises as defiend above.

HOwever, this omission of the "hook" allowis the caliper to move/rotate around more than it was intended. The fact that no O rings are present to dampen and support caliper positioning, simply assures the potential for sloppy, unsupported and rattling and cracking caliper sounds.

BTW the above clearance specs were found in an obscure GM TSB that I used at the time for warranty reimbursements while working at a GM dealer in 1972. IMagine me, a snot nose kid of 21 having to explain that there ARE caliper clearances and they ARE critical to elimination of caliper cracking to flat rate mechanics of the day.

It all came down to "do it the factory way" and you'd get paid for the noise fix, Don't do so, and you'd not only not get paid but you'd get have to do the comeback for FREE.

37 years later, the same laws of physics and mechanics apply as so should the solutions to the vagaries of this particular caliper design.

Flame away but I've already proven to guys well my senior at the time that this noise fix would work time after time. THe other choice is to uncork the headers and let them rattle. Thats what the racers did -and they also readily replaced the worn calipers and/or caliper bolts due to what was actually "abnormal" metal to metal contact due to deletion of the O rings.- simple maintenance Items on race cars that any good racer would do after every 200-500 laps or so, depending on how hard the brakes were used..

To those who propose the use of "bushings", try this: machine and heat treat bushings out of O6 tool steel. It is PERFECT for non lubed bushings due to its graphitic content. Flash plate the pins/bolts with 0.0002 to 0.0003 of chrome. go for a net bush to bolt clearance of about 0.003 to 0.005. Add a bit of caliper lube and you should be set to go.

HOWEVER, without the "hooked" or properly fit brackets, the braking force will be now be applied to the bolts and they can then shear due to flex --- after all they were never designed to absorb the braking forces directly - the "Hooked" caliper brackets were supposed to do that - besides the D52's were never intended to be used with "blade" brackets anyway.

One more thing, if you go the bushing route, inspect and maintain regularly, Grease attracts dirt and dirt will wear metal to metal contact tween the busing and pins. GM engineers were pretty sharp to use the O rings, were'nt they???l

[NC Cams]

RE 15 inch wheel fits with these calipers.

GM had a bunch of different wheels made by Kelsey Hayes when the D52s came out. They had different offsets and different DiaMETERS on the caliper side and different ID steps too. NOt all rallyes are the same and for these same reasons.

Example. Rallyes should not fit 90 camaros with PBR 12 inch brakes. I had 15x7 M/C rallyes and 3 or 4 fit perfect, one rear made some noise until the small nub that was hitting wore off. Upon inspection, you couldn't even see where the rub was on the caliper even though there was a rash mark on the wheel.

IT don't take much bend in a wheel to take up 0.050 clearance. More importantly, even the OEM runout specs stamped wheels was pretty liveral. SPecs I've seen allow as much has 0.040 TIR. Add some axle float for a C clip rear )easily 0.030( and you can almost guaranteed somthing is gonna rub.

Hope this helps the effort

[love my 72]

Man i would love to have this ^ guy for my neighbor!