Power brake booster angle

[douce48]

Looking for insight into why my power brake booster/master cylinder
(1972 GMC K2500) is angled down so much?

Is it possible the mounting bracket is backwards?

Thanks for any replies.
Bill

[Steeveedee]

In pic #3, it looks just like my truck's angle.

[douce48]

It's so close to the alternator. It just seems so odd to be on such an angle.

> I'm curious if this is GM's design for a reason??

I want to replace it eventually with a new power brake booster and I'm assuming I can put one in that is of "lower profile".

[Getter-Done]

Here is another thread about the subject.


https://67-72chevytrucks.com/vboard/...cylinder+level

Hope this helps.

[douce48]

Thank you Getter-done...

Well found this on Hot-Rod website which talks about the angle.
Weird, it states the booster in those years are pointing 17 degrees "up".

Now I'm going to do more research since this seems to be one of those "what is really the design" from GM at that time AND does it matter that its angled either up or down?

I'd rather level and not so much bracket.

[douce48]

Found this on "Trifive" website...

"One reason to mount the booster at an angle is to get more clearance to the valve cover for a bigger booster, and that's important if you need it.

Another reason to mount the booster at an angle is so that you can angle the booster push rod downward, so that you can re-drill the push rod clevis hole in the brake pedal 1" downward to change the pedal ratio so that it suits a larger master cylinder. This keeps the push rod perpendicular to the booster which is good. A larger master cylinder increases the effort you need to apply to the pedal (it reduces the boost). It also reduces the pedal travel you need to apply the brakes fully. Reducing the pedal ratio and using the larger master cylinder is what the factory did with most power brake systems, so this is the "feel" you are used to with most later model cars and trucks with power brakes.

So..., if you want to mount the booster flat, you'll need to lower it on the firewall to keep that reduced pedal ratio - by 1". This in turn will cause your booster to valve cover clearance to be reduced even more. You possibly can go back to the stock height at the firewall by going to a smaller booster, keeping stock pedal ratio, and going to a smaller bore master cylinder - this evens out the boost vs. pedal ratio effects, but at the expense of quite a bit more pedal travel. And this will also help your valve cover to booster clearance. Bottom line, you're walking a tightrope between clearance, boost, and pedal travel."

> The angle, seems to be related to the "booster push rod orientation". I have no valve cover clearance issues, rather the whole unit almost touching the alternator.

[douce48]

Some more insight...

https://www.trifive.com/threads/boos...or-what.94155/

[Getter-Done]

Originally Posted by douce48

It's so close to the alternator. It just seems so odd to be on such an angle.

> I'm curious if this is GM's design for a reason??

I want to replace it eventually with a new power brake booster and I'm assuming I can put one in that is of "lower profile".

With this research done.

I have A Question.

Your Alternator is close.

Something may have changed over the Years?

Is it adjusted to the max of the bracket Slot?

Are you Sure the Belt and the Brackets are Original to the setup?

I am not trying to be the Know It all.
Just trying to see if I can put some light on the situation.

I have seen in the past where there was fan belts used /Just to make it Home