Brake pedal stop/bumper adjustment

[dave-68]

Can someone please post a pic of the brake pedal stop/bumper? It doesn't look like I have one. When the brake pedal is disengaged (at rest) it stops on the body of the brake light switch. I'm trying to trouble shoot brake issues by starting with the geometry and adjusting the pedal height to the toe board. I assume the pedal hits the stop but I read on other posts this isn't true. If not what make the pedal stop when at rest and how is the height adjusted?

[dmjlambert]

I put mine back in just now after working on the steering column. My brake pedal arm rests against it.

[dave-68]

Originally Posted by dmjlambert

I put mine back in just now after working on the steering column. My brake pedal arm rests against it.

DJ - thank you. What year is your truck and tranny setup? Mines a ‘68 with original clutch setup (now auto trans). The PO literally welded on a rubber bump stop. Bottom bracket in the pic is the 68 with the weld job. Top bracket is from my 71 that was totaled in a wreck years ago. Didn’t know if they were interchangeable. Trying to clean things up.

[dmjlambert]

Mine is a 1969 CST/10 with TH400 automatic transmission.

[firedemon]

the bottom one looks like its set for the ebrake handle and the top is for 69 and later they should interchange as far as it will bolt in but you will have to use a foot ebrake

[Steeveedee]

The pedal arm is supposed to come back to the stop pad. Any story different from that is incorrect. Why else would it be called a "pedal stop pad"? Make sure that the arm contacts the pad and then adjust the stop light switch.

[tdangle]

Where can you get the rubber stops?

[dave-68]

Originally Posted by firedemon

the bottom one looks like its set for the ebrake handle and the top is for 69 and later they should interchange as far as it will bolt in but you will have to use a foot ebrake

Thank you, i completely forgot about the knee knocker E-brake. It was removed when I got the truck. I scabbed the e-brake and fuse block in that section of the fire wall from a 72 when I did the body work so should be able to use the later bracket.

[dave-68]

Originally Posted by Steeveedee

The pedal arm is supposed to come back to the stop pad. Any story different from that is incorrect. Why else would it be called a "pedal stop pad"? Make sure that the arm contacts the pad and then adjust the stop light switch.

That makes sense to me but how do you then adjust the pedal to toe panel distance if the stop is not adjustable?

[Smitty]

Classic Industries pt #TF300227. Pair for $3.99 + shipping.

[dmjlambert]

Originally Posted by dave-68

That makes sense to me but how do you then adjust the pedal to toe panel distance if the stop is not adjustable?

There is no pedal height adjustment. The only adjustments are the free movement between push rod and master cylinder, and the stop light switch adjustment. Those adjustments are made relative to the bumper stop position.

I see a diagram in the service manual showing what the brake height is, but that is when there is 90 lbs of pressure being applied to the pedal. I think it is a minimum technical spec, but not an an adjustment.

[tdangle]

Originally Posted by dmjlambert

There is no pedal height adjustment. The only adjustments are the free movement between push rod and master cylinder, and the stop light switch adjustment. Those adjustments are made relative to the bumper stop position.

I see a diagram in the service manual showing what the brake height is, but that is when there is 90 lbs of pressure being applied to the pedal. I think it is a minimum technical spec, but not an an adjustment.

On my 70, there is an adjustment that moves the brake pedal height.

[dmjlambert]

Is there a section of the service manual that covers making that adjustment? I don't see it for C-10 in the 1970 service manual. It looks pretty much the same as 1969.

[Steeveedee]

Originally Posted by dmjlambert

Is there a section of the service manual that covers making that adjustment? I don't see it for C-10 in the 1970 service manual. It looks pretty much the same as 1969.

Do you have the manual Hatzie published, that has the title "ST_133_70_Chevrolet_Chassis_Service"? The adjustment is detailed in page 5-9 of that manual.

[dmjlambert]

Originally Posted by Steeveedee

Do you have the manual Hatzie published, that has the title "ST_133_70_Chevrolet_Chassis_Service"? The adjustment is detailed in page 5-9 of that manual.

Yes, that's the manual. On page 5-9 the adjustments are the free movement between push rod and master cylinder, and the stop light switch adjustment. Those adjustments don't affect the bumper stop position. Perhaps we are thinking about 2 different things. I was thinking about the pedal position that it rests at when you are not braking. You and dave-68 are probably thinking about the pedal height when 90 pounds of force are applied to it. Sorry about that confusion.

[dave-68]

I’m talking about the this dim referenced in this pic and post.


https://67-72chevytrucks.com/vboard/...reply&t=811853

I don’t find it in my service manual or assembly manual.

I am actually trouble shooting brake issues and looking at all the geometry starting with the pedal position. I don’t have the adjustment that tdangle talks about. I only have the push rod adjustment. I’m not sure what’s sets the pedal height in the pic.

[Andy4639]

Originally Posted by dave-68

I’m talking about the this dim referenced in this pic and post.
Attachment 2047947

https://67-72chevytrucks.com/vboard/...reply&t=811853

I don’t find it in my service manual or assembly manual.

I am actually trouble shooting brake issues and looking at all the geometry starting with the pedal position. I don’t have the adjustment that tdangle talks about. I only have the push rod adjustment. I’m not sure what’s sets the pedal height in the pic.

I have 3 service manuals and they all say the same thing. 69,71 Chevy and the GMC manual. No mention of the brake pedal resting against the bumper are not. It's not mentioned at all. The only thing mentioned is the 90lbs and the measurements listed there. If the rod going to the booster are manual brakes is going to decide where the brake pedal rests I would think. If you want the pedal high then it would rest on the stops. If you want the pedal lower to the floor then I would think it wouldn't rest on the stop. I would think it's just personal preference. Depending on how long the rod is.

[dmjlambert]

Here's the 1968 service manual, since you have a 68.
http://67-72chevytrucks.com/vboard/s....php?p=5781194

The link you gave is for this tread that we are on now.

Something much like that drawing is in the 68 service manual on page 5-10. The text that goes along with is on page 5-9. Figure 18 is for G-10-20 and Figure 19 is for our trucks (C-10-20).




It is interesting the drawing you posted gives more details about manual and power brake distances.

The drawing seems to vary from year to year a little, and I don't see it in the 1970 manual.

I don't think it's something you adjust, it is an observation you make and if you observe too little clearance between the pedal and the floor you should investigate what's going on with that. That would be measured with 90 lbs applied to the brake, and would be after making the free pedal travel adjustment on the push rod, and after a fresh adjustment on the brakes with drums and other parts that aren't worn.

So, I'm thinking what puts the pedal at that height in the picture is 90 lbs of pressure applied to the brake pedal, assuming a properly adjusted stock system in good repair.

[tdangle]

I adjusted the pedal height using the threaded rod under the dash. I adjusted the pedal height a little higher and I found that I actually had more breaking feel and power. The pedal was adjusted fairly low and was actually passing over the center for the ratio, if that makes sense. Re-adjusted the brake light switch when I was done.

[dave-68]

Thank you guys
Sorry 'bout that try this one:
http://67-72chevytrucks.com/vboard/s...ht=brake+pedal

Andy - just realized the pic came from you. Ha

DM - Thank you for the link to the pdf's. You provided the missing link. Your pic shows the missing 90# reference that Andy's didn't.
What confused me was the post by Andy (no offense Andy) showed the "reserve dim" figure but the wording was for the "free play dim".

You nailed it (I added a little):
Pedal height is not something you adjust using the push rod adjustment (It can but is not its intension). The push rod adjustment is to adjust the "free play" between the push rod and MC. The 90 lbs "reserve dimension" is an observation you make and if you observe too little clearance between the pedal and the floor you should investigate what's going on with that. That would be measured with 90 lbs applied to the brake, and would be after making the free pedal travel adjustment on the push rod, and after a fresh adjustment on the brakes with drums and other parts that aren't worn.

What puts the pedal at that height in the picture is 90 lbs of pressure applied to the brake pedal, assuming a properly adjusted stock system in good repair.

Thank you guys again.

[Steeveedee]

Originally Posted by Andy4639

I have 3 service manuals and they all say the same thing. 69,71 Chevy and the GMC manual. No mention of the brake pedal resting against the bumper are not. It's not mentioned at all. The only thing mentioned is the 90lbs and the measurements listed there. If the rod going to the booster are manual brakes is going to decide where the brake pedal rests I would think. If you want the pedal high then it would rest on the stops. If you want the pedal lower to the floor then I would think it wouldn't rest on the stop. I would think it's just personal preference. Depending on how long the rod is.

Just go look at the page in the '70 manual I posted. You don't have to believe it, but it is still true.

[dmjlambert]

I think there is huge amount of confusion about this subject, because pedal height means different things to different people. Pedal height with foot resting on pedal (the feel), or height with nothing touching the pedal (and then you have to wonder how many people are running around in trucks that don't have a pedal return spring because it's rusted through. Also you have to wonder how many people adjust the push rod to get feel just because their brakes are worn or shoes are adjusted incorrectly. The manual is not clear, and as Andy and others have mentioned they don't mention the pedal arm rests against the rubber stop. Well, if you have a return spring, which you would have had in 1969 when the book was written and long before the spring crumbled into a pile of rust and long before you had 16 previous owners jacking with the system, it would be more obvious it rests against the rubber stop and you wouldn't feel the need to put it in the book. But really it should be in the book. There's other things that should be in the book, such as exactly what are the two different points on the pedal arm that should be used for power booster vs. manual brakes push rod, what is the proper bore size of master cylinder for power brakes vs. manual brakes, etc. Some of the wording in the manual is not good enough. But those guys writing it are people, too.

[Andy4639]

Originally Posted by dmjlambert

I think there is huge amount of confusion about this subject, because pedal height means different things to different people. Pedal height with foot resting on pedal (the feel), or height with nothing touching the pedal (and then you have to wonder how many people are running around in trucks that don't have a pedal return spring because it's rusted through. Also you have to wonder how many people adjust the push rod to get feel just because their brakes are worn or shoes are adjusted incorrectly. The manual is not clear, and as Andy and others have mentioned they don't mention the pedal arm rests against the rubber stop. Well, if you have a return spring, which you would have had in 1969 when the book was written and long before the spring crumbled into a pile of rust and long before you had 16 previous owners jacking with the system, it would be more obvious it rests against the rubber stop and you wouldn't feel the need to put it in the book. But really it should be in the book. There's other things that should be in the book, such as exactly what are the two different points on the pedal arm that should be used for power booster vs. manual brakes push rod, what is the proper bore size of master cylinder for power brakes vs. manual brakes, etc. Some of the wording in the manual is not good enough. But those guys writing it are people, too.

The manuals are not 100% as you stated on all things. Some is good details other lack a lot and same with sections of it also. They can get you in the right direction though most times but the brakes is one section they really lack in.
I have been working on these trucks since 1984 and have never seen two mounting holes in a brake pedal. Everyone talks about them but never show pictures. That being said doesn't mean it's so are not because as you stated someone could have drilled the holes themselves. The manuals I have don't show them but as we know that doesn't mean much either.

Steeveedee,
Just go look at the page in the '70 manual I posted. You don't have to believe it, but it is still true.

I don't need to I don't have a 70 model truck.
I never said I didn't. I just stated facts about what mine said. Sorry you feel like I hurt your feelings.
I go by what my truck manuals say for my year trucks.

[7-D Stepside]

So this bracket is completely missing from my truck (thanks PO). Don't see anywhere in the aftermarket where its available. I don't seem to be having any issues with the brake pedal coming up too high (automatic, so no clutch). But in terms of holding things together under the dash and eliminating squeaks and rattles, it would seem a good idea to get this installed. I can find the column cover plate from LMC and others, but not this bracket.

[7-D Stepside]

Originally Posted by 7-d stepside

so this bracket is completely missing from my truck (thanks po). Don't see anywhere in the aftermarket where its available. I don't seem to be having any issues with the brake pedal coming up too high (automatic, so no clutch). But in terms of holding things together under the dash and eliminating squeaks and rattles, it would seem a good idea to get this installed. I can find the column cover plate from lmc and others, but not this bracket.

Sorry, see photo of the bracket below.