Brake pedal slop

[toddz69]

In the never-ending quest to get the rattles and shakes out of the rig, I've noticed that I have a lot more slop in my brake pedal than I think I used to - or at least I notice the noise from it a lot more than I used to on bumpy roads, and some not-so bumpy ones as well. I changed the pedal bushings a month or two ago but that didn't really help much. It's tough to stick one's head up there and see exactly how much play there is, but I'm guessing when I move the pedal around, there's probably 0.030-0.040" of vertical play based on my very poor eye-crometer. There's not a lot of rotation going on, of course but that pivot rod is now almost 58 years old and has been moving around for almost 390K miles now - the brake pedal a few years less.

Curious if any of you can check your rig or a pedal assembly you might have in your shop to see how much slop the brake pedal has on the shaft with good bushings in it? Tight? A fair amount of slop?

TIA,
Todd Z.

 

[Bung72]

Hi, Todd. I don't know if you got a stick shift or not, but this is what I did about 25 years ago. Just hooked the two together with a spring. I don't remember if the holes were in the pedals or if I drilled them. I also fitted the pedal bosses with grease fittings. Good luck.

 

[toddz69]

Hi, Todd. I don't know if you got a stick shift or not, but this is what I did about 25 years ago. Just hooked the two together with a spring. I don't remember if the holes were in the pedals or if I drilled them. I also fitted the pedal bosses with grease fittings. Good luck.

Thanks! Mine was a stick shift until about 1999 or thereabouts when it shed that pedal to the left. Good idea on the spring - I was thinking maybe something like that might help my situation too.

I went out and checked the pedal on my '01 Super Duty and it has a surprising amount of play to it too - the only difference is that it seems to fit tightly between the "walls" of the bracket on either side, whereas my Bronco pedal has some space there. Messing around with that pin is hard enough as-is but maybe trying to stuff a washer in there might help a bit.

Todd Z.

 

[Bung72]

I wonder how one of those wavey washers like Hurst used to use on their shifters would work.

 

[toddz69]

I wonder how one of those wavey washers like Hurst used to use on their shifters would work.

I was thinking of those too. I need to investigate those a bit more. @ntsqd posted a McMaster Carr link for them here a few weeks ago.

Todd Z.

 

[nvrstuk]

TZ, I was thinking that if you can just put up with the rattle a "while" longer you'll reach that age (longer for you than me) where you either can't hear those rattles anymore or you can just turn the volume down on your phone that controls your hearing aids... lol

I like the spring washer idea... that or one made of UHMW sized to fit tight...

I'll do an "eye"crometer tomorrow for ya!

Keep us posted on what works.

 

[Brush Hog]

When I replaced mine I didn’t put the nylon washers in or in correctly. Had all sorts of pedal slop and brake light issues. Took it back apart, about stood on my head to get under there and wrestled it back together correctly and it solved my issue.

 

[toddz69]

When I replaced mine I didn’t put the nylon washers in or in correctly. Had all sorts of pedal slop and brake light issues. Took it back apart, about stood on my head to get under there and wrestled it back together correctly and it solved my issue.

Thanks! I did confirm last evening that my bushings are still in there and are correct.

Todd Z.

 

[ntsqd]

If the side gap is small then one of these should work: https://www.mcmaster.com/products/springs/disc-springs-2~/corrosion-resistant-wave-disc-springs/
For a larger side gap you're going to need one of these: https://www.mcmaster.com/products/s...orrosion-resistant-stacked-wave-disc-springs/
I chose the stainless versions because who wants to deal with rusty springs?
If the gap is in between those two than I'd use AN washer(s) as a shim(s)/spacer(s): https://www.mcmaster.com/products/w...ion~army-navy-specification/material~steel-1/

The couple of brake & throttle pedals that I've made from scratch used flanged oilite bronze bushings for their pivots. That let me set both the pin fit and the side to side gap.

 

[toddz69]

If the side gap is small then one of these should work: https://www.mcmaster.com/products/springs/disc-springs-2~/corrosion-resistant-wave-disc-springs/
For a larger side gap you're going to need one of these: https://www.mcmaster.com/products/s...orrosion-resistant-stacked-wave-disc-springs/
I chose the stainless versions because who wants to deal with rusty springs?
If the gap is in between those two than I'd use AN washer(s) as a shim(s)/spacer(s): https://www.mcmaster.com/products/w...ion~army-navy-specification/material~steel-1/

The couple of brake & throttle pedals that I've made from scratch used flanged oilite bronze bushings for their pivots. That let me set both the pin fit and the side to side gap.

Thanks! All kinds of options . I need to get my feeler gauges out and see exactly what I'm dealing with.

I just know it's going to be the monkey and the football getting them up in there in any case .

Todd Z.

 

[nvrstuk]

UHMW.... solves everything. lol

I remember back decades ago b4 my desk job that I was welding hardsurfacing on centrifuge edges. Sand would eat everything up quickly and some rep from some company I contacted showed up and introduced me to UHMW... solved all my issues there and since! lol

Started using it everywhere as it's resistance to abrasion is amazing. Was making "quiet" bumpstops for racers in NV for years... you name it.

Slice a chunk off and make washers of it or buy it already sized since we can buy anything over the Net the past 20 yrs...

Keep us posted!

 

[ntsqd]

We used UHMW-PE for the rub pads under the nose of the Lola T-89/90. Replaced the worn-out Jabroc wear pads with it. My boss was convinced that we'd never need to replace them again. The UHMW-PE was inexpensive but it didn't last even one race where the Jabroc was good for half a season. The Lola OEM parts were astronomically priced, could buy a new set of UHMW-PE for each race for the entire season and not spend as much but we were grinding on that Epoxy/kevlar/glass nose-piece once the UHMW-PE failed and it's replacement cost made buying the Jabroc a no-brainer.

OTOH UHMW-PE makes a spectacularly good bearing for an artificial hip joint. There it does last literally a lifetime.

For polymer pivot bushings & washers I'd start with simple acetal ("Delrin") and move up to something like one of the Turcites or Frelon if that didn't work.

 

[bigmuddy]

I can't imagine Delrin wearing out in this application.

 

[ntsqd]

I wouldn't expect it to, but I've seen it do the unexpected now and then. It does have a higher stiction than does UHMW-PE or Frelon, so there may be grounds for rejection there. Dunno.

 

[jamesroney]

In the never-ending quest to get the rattles and shakes out of the rig, I've noticed that I have a lot more slop in my brake pedal than I think I used to - or at least I notice the noise from it a lot more than I used to on bumpy roads, and some not-so bumpy ones as well. I changed the pedal bushings a month or two ago but that didn't really help much. It's tough to stick one's head up there and see exactly how much play there is, but I'm guessing when I move the pedal around, there's probably 0.030-0.040" of vertical play based on my very poor eye-crometer. There's not a lot of rotation going on, of course but that pivot rod is now almost 58 years old and has been moving around for almost 390K miles now - the brake pedal a few years less.

Curious if any of you can check your rig or a pedal assembly you might have in your shop to see how much slop the brake pedal has on the shaft with good bushings in it? Tight? A fair amount of slop?

TIA,
Todd Z.

I have no idea what we are actually fixing here, but PLEASE do not cram another piece of anything on the shaft. When it comes to bushing material, I always choose the most likely to succeed. UHMW should be fine. PTFE is a maybe. I think the factory used "nylon" but there are lots of Nylons.

If the issue is looseness between the shaft and the pedal support bracket, the bushing will not fix that.
If the issue is radial clearance between the pedal pivot and the shaft, then replace the bushing with something tighter.
If the issue is lateral (axial) clearance between the pedal pivot and the pedal support bracket, I urge you to measure the axial distance, and MAKE a new bushing with a thicker "hat."

You want the bushing to be interference fit in the pedal, and you want the hat to be thick enough to slide up into the pivot. The last thing you want is a loose washer, or shim, or extra piece that needs to be held up, and aligned. Just make one bushing the correct thickness, and it will be MUCH easier to install. There are few things that irk me more than pulling out a shaft under a dash upside down on my head, and having a mysterious bunch of crap fall out. The absolute worst is an annealed 302 stainless wavy washer that is not magnetic, makes a definite "twang" when ejected, and is capable of rolling 20-30 feet after impact with concrete. (can't find it, don't know what it is, don't know where it went, but you heard something go somewhere...)

McMaster has a wide offering of UHMW PE flange sleeve bushings for about $10. Buy one that's got excess material, and machine off the excess. If you know the correct dimensions, I can cut it down for you here for free. Some people prefer Delrin (@bigmuddy) because it's free maching...but if you are only making 1, I'm with @ntsqd and @nvrstuk it's not that big of a deal to keep your tools sharp.

 

[toddz69]

I have no idea what we are actually fixing here,

Some remnant of my sanity, hopefully. I hate that the pedal rattles/shakes on nearly any disturbance in the road surface.

but PLEASE do not cram another piece of anything on the shaft.

Duly noted.

If the issue is looseness between the shaft and the pedal support bracket, the bushing will not fix that.

Correct - I have a little slop there on one side but I don't think it's a big contributor and it would be the hardest to fix.

If the issue is radial clearance between the pedal pivot and the shaft, then replace the bushing with something tighter.

There is slop there - a tighter bushing would be nicer. I did go look at the pedal on my PSD last night and it seems to have similar radial slop but lacks the axial clearance that you note below, which made me think that if I could reduce the axial slop, I could probably "solve" the problem.

If the issue is lateral (axial) clearance between the pedal pivot and the pedal support bracket, I urge you to measure the axial distance, and MAKE a new bushing with a thicker "hat."

There's definitely axial clearance. I don't have the tools or skills to make a new bushing but but a thicker hat would be best.

You want the bushing to be interference fit in the pedal, and you want the hat to be thick enough to slide up into the pivot. The last thing you want is a loose washer, or shim, or extra piece that needs to be held up, and aligned. Just make one bushing the correct thickness, and it will be MUCH easier to install. There are few things that irk me more than pulling out a shaft under a dash upside down on my head, and having a mysterious bunch of crap fall out. The absolute worst is an annealed 302 stainless wavy washer that is not magnetic, makes a definite "twang" when ejected, and is capable of rolling 20-30 feet after impact with concrete. (can't find it, don't know what it is, don't know where it went, but you heard something go somewhere...)

I hear you on all this - I am plagued with the same irks but I sometimes compromise . Shoot - maybe I could even bond/glue a UHMW washer to a bushing - or part of the bushing head since they're split to allow for diameter variations.

McMaster has a wide offering of UHMW PE flange sleeve bushings for about $10. Buy one that's got excess material, and machine off the excess. If you know the correct dimensions, I can cut it down for you here for free. Some people prefer Delrin (@bigmuddy) because it's free maching...but if you are only making 1, I'm with @ntsqd and @nvrstuk it's not that big of a deal to keep your tools sharp.

I may just take you up on that offer.....thank you!

This is just one of 73 projects on the Bronco that need doing...but it's starting to bug me more and more!

Todd Z.

 

[ntsqd]

I was assuming that the slop is purely lateral. In this instance spring loading the assembly laterally is a common method of eliminating or reducing that free motion. Machining the flange to flange width is the Enginerd way of solving the same problem. Either way gets you there.

When I originally proposed the wave springs it was to deal with the radial play at the push-rod pin that results from leaving out the bushing that causes the brake light switch to misbehave. The wave spring wouldn't remove that play, but it would act as a friction damper to keep the parts from banging and clanging. As a bonus, it's down lower where it's easier to see before it sprints for the hinterlands on release.

IMHO the better fix is to leave the bushing in place and change to the GM brake light switch. I did something similar on the Wagon. It originally used a hydraulic pressure brake light switch, which are famous in my experience for leaking. They all leak. If one isn't leaking right now, give it a minute and it will. Dumbest idea ever, and then Ford repeated it with a cruise control switch in the something to '97 trucks. Shakes head.... but I'm digressing.
Anyway, I made a simple bracket for Yeller's suggested GM switch. It has a second set of contacts for the Cruise Control!

UHMW-PE, teflon, and to a lesser degree acetal, are all "low surface energy" polymers. Bonding to them is possible, but rarely easy. Unless you happen to have a plasma gun in the garage....

 

[toddz69]

I was assuming that the slop is purely lateral. In this instance spring loading the assembly laterally is a common method of eliminating or reducing that free motion. Machining the flange to flange width is the Enginerd way of solving the same problem. Either way gets you there.

When I originally proposed the wave springs it was to deal with the radial play at the push-rod pin that results from leaving out the bushing that causes the brake light switch to misbehave. The wave spring wouldn't remove that play, but it would act as a friction damper to keep the parts from banging and clanging. As a bonus, it's down lower where it's easier to see before it sprints for the hinterlands on release.

IMHO the better fix is to leave the bushing in place and change to the GM brake light switch. I did something similar on the Wagon. It originally used a hydraulic pressure brake light switch, which are famous in my experience for leaking. They all leak. If one isn't leaking right now, give it a minute and it will. Dumbest idea ever, and then Ford repeated it with a cruise control switch in the something to '97 trucks. Shakes head.... but I'm digressing.
Anyway, I made a simple bracket for Yeller's suggested GM switch. It has a second set of contacts for the Cruise Control!

UHMW-PE, teflon, and to a lesser degree acetal, are all "low surface energy" polymers. Bonding to them is possible, but rarely easy. Unless you happen to have a plasma gun in the garage....

I still plan to deal with my brake light switch issues with a wavy washer like you originally proposed. That's another thing on the list....

Good note on the bondability of the polymers - no plasma gun in the garage so I may just stick a washer in there as at least a temp fix to see if/how it fixes things and then proceed with a machined solution like @jamesroney suggested.

Todd Z.

 

[bigmuddy]

I have no idea what we are actually fixing here, but PLEASE do not cram another piece of anything on the shaft. When it comes to bushing material, I always choose the most likely to succeed. UHMW should be fine. PTFE is a maybe. I think the factory used "nylon" but there are lots of Nylons.

If the issue is looseness between the shaft and the pedal support bracket, the bushing will not fix that.
If the issue is radial clearance between the pedal pivot and the shaft, then replace the bushing with something tighter.
If the issue is lateral (axial) clearance between the pedal pivot and the pedal support bracket, I urge you to measure the axial distance, and MAKE a new bushing with a thicker "hat."

You want the bushing to be interference fit in the pedal, and you want the hat to be thick enough to slide up into the pivot. The last thing you want is a loose washer, or shim, or extra piece that needs to be held up, and aligned. Just make one bushing the correct thickness, and it will be MUCH easier to install. There are few things that irk me more than pulling out a shaft under a dash upside down on my head, and having a mysterious bunch of crap fall out. The absolute worst is an annealed 302 stainless wavy washer that is not magnetic, makes a definite "twang" when ejected, and is capable of rolling 20-30 feet after impact with concrete. (can't find it, don't know what it is, don't know where it went, but you heard something go somewhere...)

McMaster has a wide offering of UHMW PE flange sleeve bushings for about $10. Buy one that's got excess material, and machine off the excess. If you know the correct dimensions, I can cut it down for you here for free. Some people prefer Delrin (@bigmuddy) because it's free maching...but if you are only making 1, I'm with @ntsqd and @nvrstuk it's not that big of a deal to keep your tools sharp.

No preference on my part, just felt the need to comment that Delrin in my experience is one hard plastic material...

 

[ntsqd]

It doesn't like sustained high static loading, it will cold flow out from under that. Very very slowly.

ETA: IME engineering polymers generally like cutting tool geometry that is closer to being wood cutter than a metal cutter. Not to say that you can't get a good finish with metal cutting geometry because you can and it's not all that hard to do, just that they tend to cut better with sharp, high relief geometry.