Brake pedal travel - not spongy brakes (1 Viewer)

[lettereleven]

Thank you in advance for the insight!

Here is my problem: brake pedal travel is really long on the first, and only first, depression of pedal. The second and subsequent presses, brake are amazing.

Backstory: I took it to the shop and the front rotors machined and new front pads were installed. Also replaced front brake lines with new rubber ones. As part of installation the 2-person bleed technique was done.

I had the problem as noted above and took it back. I thought it was air in the lines. They did the vacuum bleed method and definitely got all the air out. But I still have the problem.

Thoughts: Im definitely not a mechanic but my thought is perhaps there is too much space between the new pad and rotor. If it was really an air issue, the spongy brakes would be more consistently spongy, not just on the first pedal push.

If you've got any additional thoughts, I would sincerely value them!

Edit - there is no ABS.

 

[Delancy]

No, you're not a mechanic.... The pad literally rides on the rotor, engaging pedal merely squeezes harder.

There's air in the ABS solenoid, which takes an SST to engage.

Edited: or, you can try to engage on a gravel/slick road, in hopes it'll pump the air out.

 

[nukegoat]

Loose spindle nuts - the rotor wobbles around since the hub is loose and creates too much clearance between pad and rotor. Pressing the pedals clamps the rotor into alignment and subsequent braking is fine.

 

[lettereleven]

@Delancy , yup, you nailed it. I think its good that at least I know im not any good.

Should add that there is no ABS on the truck. Will edit the original post.

 

[nukegoat]

Did you check spindle nuts?

 

[lettereleven]

I didnt check the spindle nuts - they were checked and torqued by the mechanic last week. I would check them myself, but that would involve removing the 54mm nuts. Every time I do that I seem to screw up the bearing preload, even though I have the FSM and the right tools.

I've never had a vacuum brake bleed done before. I wonder if there is still air in the lines in the rear brakes (he didnt bleed those, only the front where the lines were changed).

Jamie

 

[ajax1]

You could gravity bleed the brakes by yourself and see if there was air, I would check wheel bearing nuts also, and since calipers were off would hurt to check torque on those too

 

[Dragos80]

Usually better brake pedal feel (shorter travel after subsequent pumps) is the result of air in the lines and/or ABS (depending on if you have ABS or not).
If the rotor or pads are worn out the pedal travel would not be affected as the cylinder does not fully retract and then travel a longer distance to close the gap between the pads and the rotor again.

 

[flintknapper]

LSPV is hard to get air out of, have no other suggestions for you.

 

[lettereleven]

OK - I will give it a few days and then go back to the shop and get the lines bled again (assuming it doesnt resolve itself by magic).

Thanks all very much for the insight. Very much appreciated.

 

[Ken C]

They should bleed all the lines in order.

 

[larry butler]

Don't worry about all that preload stuff, jack up, and pull back and forth on the top of each tire to check for bearing play/slop. If it jiggles, fight those stupid cone washers and tighten the spindle nuts until no slop.

 

[baselfish]

I would concur about the bearing preload - especially on the rear bearings....

how the lock screws are positioned - you only have a really 2 spots to lock the bearing down (I believe @ 2 oclock and 7 oclock)
in general - I believe most folks lightly wrench tighten the bearings in to set the pre load and then back it off a 1/32 or 1/16 -
to set the lock screws - although the final position might seem a bit flimsy - again you have little choice as tightening the bearing to
the next locking point would be not possible....

Bf