That plastic pedal box bearing...

Rupunzell

Rupunzell

Bernice Loui
often neglected, often worn (most are very worn these days), cause of creeks-squeaks, sticking pedals and more..

Time came to deal with this problem which means making one out of SAE 660 bearing bronze.
exxe%2520pedal%2520box%2520bearing%2520dim.jpg


OD= 0.9465"

ID= 0.5520" (The Mahr digital bore gauge is set with a calibrated setting ring of 0.50000", with the digital read out added on to the setting ref)

Bearing clearance should be 0.002"

OAL= 4.894"

The slot is 0.110" wide, 0.100" deep, far end of the slot from the bearing edge is 0.280"


There are two stock plastic bearings on the lower right hand corner of this image. These are worn, grooved and very tired..

To get the SAE 660 bronze bearing to work properly, the stock clutch pedal shaft must be cleaned, and smoothed with 220 grit silicone carbide paper and worked up to 400 grit silicone paper and eventually a fine scotch bite pad. Same applies to the brake pedal bore.

exxe%2520clutch%2520pedal%2520shaft%252C%25200.550%2520inch%2520dia.jpg



New bearing with pedals:
exxe%2520bearing%2520with%2520pedals.jpg




Bernice
 
Very Nice, Bernice

Great improvement! Too bad they don't make an oilite bushing that size.
Thanks for sharing.
 
I dont suppose...

You'd offer up a few of these? The RaceX is in serious need of something like his as the clutch pedal sticks like crazy. I have to hit it with lubricant every now and again during an autoX, and even then, it'll stick and I have to lift it with my toe.
 
Not sure if I'm going to get into production of this bushing.

The basic information to make this is here. It could be best for those who are interested to use that as a starting point.

What often cures the problem with sticking and annoying noises from the pedals is rust/corrosion between the pedal bushing-shaft and plastic bearing. Taking it apart, giving all the parts a really good cleaning and proper lubricant often resolves the problem. Another item that is a problem, the slot on the end tends to get worn out of shape when the pedals are sticking-stuck. This causes the plastic bearing to rotate in bad ways. The plastic bearing can be flipped 180 degrees and a new slot cut for the triangle retaining plate. This will extend the life of this plastic bearing and give the brake pedal a newer surface to roll on.



Bernice
 
Plastic bushing.

On the early 5 speeds what I saw way back then was that the external clearance was too tight. When the car was in a warm climate the plastic bushing would swell and jam the brake pedal down off of the stop. This allowed the brakes to drag a bit and over heat the rotors and fluid. I turned the plastic bushing down and all has been fine since.

I like the bronze bushing replacement, nice work.

TonyK.

Grimsby Ontario Canada.
 
Very nice.

Excellent work as usual Bernice. However, this issue is another tick mark in the column favoring an aftermarket pedal cluster for me....
 
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In the PBS x1/9 race prep book there is a drawing for a brake master conversion that uses two generic GIrling mastery cylinders in a sheet metal box with bias bar all mounted inside the front bonnet.

This could be another alternate to installing one of the many aftermarket pedal assemblies on the market today. What is nice about that PBS set up, both brake master cylinders are easy to get at which means ease of changing master cylinders as needed and the bias bar allows easy adjustment of front -vs- rear brake bias. With the addition of a control cable to the bias bar allows brake bias adjustments from the driver's seat.

Making a version of the PBS unit has been on the back of my mind for a while. As designed, the PBS conversion is welded in place. It should be do-able with a properly backing plate reinforced bolt/nut/washer joint in place of welding.

Still do not like welding as a jointing process due to all the things that can go so very wrong. Works good when done properly, more often than not, welding is used like hot glue with mixed results. It remains one of the most difficult methods of jointing to do properly.


Bernice


mblommel said:
However, this issue is another tick mark in the column favoring an aftermarket pedal cluster for me....
Click to expand...
 
too true....

Luckily for me I went to school for GTAW (TIG) welding and have a setup for such in my garage....:)

I have the PBS drawings, but was thinking of using one of the aftermarket assemblies that would put the master cylinders in the frunk for easy access the way PBS did.
 
Great work Bernice, nice attention to detail and great design :)

mblommel said:
Luckily for me I went to school for GTAW (TIG) welding and have a setup for such in my garage....:)

I have the PBS drawings, but was thinking of using one of the aftermarket assemblies that would put the master cylinders in the frunk for easy access the way PBS did.
Click to expand...

I've been contemplating a pedal box from summit for some time but always chicken out ($$$).

Forward mount master cylinders would be in the way of storing the targa top in the front, which is why I assume fiat did it the way they did. For a race car obviously that doesn't matter and a simple reinforced plate with an aftermarket cylinder and tie-rod connector bar could suffice. After just changing the MC I'm in favor of getting that stuff out of there.
 
HI Bernice,

I'm having the sicking brake pedal problem and found this thread. Did you make additional bushings by any chance? If so, I'd love to buy one from you! My brake lights are sticking on, and in this UK winter, I'm not looking forward to dealing with this by just cleaning the plastic one as I fear it's a short term solution!

Kind regards,

Mickey
 
No extras made. There is enough information in this post to have one made locally which IMO, is the better solution.

Find a good local engineering shop with proper machine tools and provide them with this information and they should quite capable of producing one as needed.


Bernice
 
Rupunzell said:
No extras made. There is enough information in this post to have one made locally which IMO, is the better solution.

Find a good local engineering shop with proper machine tools and provide them with this information and they should quite capable of producing one as needed.


Bernice
Click to expand...

Indeed! Thanks fir the detailed info. I think I'll gave one made for when I overhaul my clutch and brake masters - I'd rather just so this once )hopefully)
 
Bernice (@Rupunzell), or any other materials experts here... Would acetal (aka Delrin) work as a replacement material for the original plastic pedal box bearing? The other option is to use C932 (SAE 660) bronze as you did but I do have the acetal on hand and might be a like-for-like replacement. Sure seems that the industry uses it for that very purpose.

Thanks in advance for any input from you all.
 
darwoodious said:
Would acetal (aka Delrin) work as a replacement material for the original plastic pedal box bearing?
Click to expand...
I am certainly no materials expert, so this is only an opinion. I think acetal would work great for that. I considered doing the same but my old bushing was still in good condition so I opted to reuse it for now (if it needs to be replaced in the future I would use acetal). As you noted it has been successfully used for lots of other similar applications. And it would be an improvement over the original plastic bush. Plus it would be easier to work with than bronze when making the part - at least for most of us that do not work at a machine shop. ;) You might want to include a means to lubricate it occasionally, to prevent 'squeaks'.
 
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