Hello All,

I just replaced my vacuum booster and I have gone from super hard brakes to super soft brakes. Not sure if its just the transition, but it almost feels like I have too much travel before I get pressure. Plus when I do get pressure its seems very soft, but I do stop. When I come to a full stop I can apply more pressure and there is still more travel before it reaches the floor. I believe It's my fault, I put the shim from the old on the new thinking that it was needed. I've also found information about adjusting the push rod in the booster, which I didn't do. Just looking for some advice on how I should remedy my issue.

Thanks

 

Did you open the hydraulic system at all to make the swap, or just unbolt the master cyl and set it aside?
There should be a rod you can adjust behind the master cyl. Sounds like it is adjusted too short.

 

I got lucky and didn't need to open the brake lines to move the master cylinder out of the way. I even checked the pedal to see if there was air in the lines. They don't gain any pressure when I pump them, so I don't think they have air in them.

Do you or anyone know what the length needed to be or how many turns I needed to let out the push rod or is it more like trial and error?

Thanks

 

not trying to be a smart a$$, but did you go back and read it?
sometimes we miss the simple things.

 

Good point. Could very well be the issue.

 

In my original post, I didn't explain very well. When checking a manual on my vehicle is stated that the booster shouldn't need adjustment and that it would have already been adjusted by the manufacturer, hence why I didn't adjust it. I can see that now that you can't always trust everything you read.

 

Ive never had to adjust one in all my years unless mix matching parts.

 

Excellent observation.

 

You've been lucky or accept sub-standard pedal travel.

 

Really even working automotive for a living most of the time low pedals cause rears are not adjusting them selves anymore .

 

That is technically correct, the booster doesn't need adjustment as a periodic maintenance thing. If you buy the master cylinder and booster as a complete unit it shouldn't need adjustment either. But replacing just one or the other you may have to tweak it a bit.
You could measure the length of the old rod and set the new one to match, else it's trial and error.

 

Correct. But radi is right on here. Replacing just one, with the manufacturing/differences nowadays, you can have a mismatch. Heck, even with a new or reman assembly, there's no guarantee Wunhung Lo didn't screw up.

I fixed 2 F-350s and a coupla XJs by adjusting the booster rod. Check it out some time. Easy to do. Wonder why the OP's instructions advised adjusting?

 

True the pride and quality of aftermarket parts aint there no more for sure.

 

Wunhung insists that quality is job #1 and his feelings are hurt.

 

going by that name, more than his feelings are hurt.
I remember his book "Ruptured Chinaman"

sorry