Power brake booster install problem

[Underton]

I recently purchased a new vacuum brake booster to replace my old one that had a leak and wasn't working as well. I started to install it and noticed the brake master cylinder didn't fit up to the new booster. The new output shaft is way too long for the original master cylinder that was using. I'm wondering if I am doing something wrong on the install or if I just have the wrong part or something.

Here's a photo album to show the issue I'm having.

http://imgur.com/a/60k7a


After doing some research I think this is the master cylinder I have,

http://www.speedwaymotors.com/Power-Manual-Master-Cylinder-1-1-8-Inch-Bore,36760.html

 

[bronconut73]

That shaft is usually adjustable. But your original one looks a little odd. Doesn't seem like it could reach far enough into the mc.....but I am probably wrong.

 

[Underton]

The shaft does adjust but only to make itself longer, the old brake booster fit up perfectly with the mc

 

[thegreatjustino]

Your MC is not stock. It has just a small dimple in the piston which is why your original booster had such a short rod. The booster you have now is for a stock MC which would have had a much deeper hole in the piston for the rod, which is why the rod on your new booster is so long.

You need to get the correct booster to go with your MC or get the correct MC to work with your booster. The MC is most likely a GM unit, so you'd need a GM booster to go with it.

 

[DirtDonk]

Part of the reason we sell a master cylinder like this: http://www.wildhorses4x4.com/product/Hydroboost_Master_Cylinder
Notice the little bullet-shaped thingy in the pic? That's a spacer to slip into the back of the piston to fit the very common short rod boosters. If you leave it out, the piston is the standard deep well of a manual brake setup, or EB booster setup like you have now.

Your old one was very likely just an aftermarket swap. What year is your rig?

Paul

 

[Underton]

Part of the reason we sell a master cylinder like this: http://www.wildhorses4x4.com/product/Hydroboost_Master_Cylinder
Notice the little bullet-shaped thingy in the pic? That's a spacer to slip into the back of the piston to fit the very common short rod boosters. If you leave it out, the piston is the standard deep well of a manual brake setup, or EB booster setup like you have now.

Your old one was very likely just an aftermarket swap. What year is your rig?

Paul

It's a 1970, and I talked to the previous owner and he said the entire aftermarket brake was from James Duff. So I'm not sure what it's compatible with. The booster I bought from Tom's. Would your stock mc work with Tom's booster?

 

[DirtDonk]

It might. Seems like it would, but no sense taking a chance. I can measure one for you tomorrow if you like.
Keep a dial-caliper at the front counter because some kind of "does this fit that" question comes up about every day! ;D

Can't hurt to double-check.

Paul

 

[Underton]

Are you guys going to be open tomorrow?

 

[DirtDonk]

Yes indeed. If you have the day off, stop on by if you can.
Then you can look at the masters yourself. Not to mention a "few" other Bronco things!

Paul

 

[DirtDonk]

Okee dokee. Looks like I didn't get all the info I'd hoped. But it should be enough to get you started.

The stock replacement booster I looked at had approx. 1.8" of rod extension past the mounting surface just as it came out of the box. Didn't try to adjust it to minimum or maximum because I just didn't have the time. If you measure yours to compare, that should give you some point of reference.

If it's close to that, a stock replacement master should work for you.

Paul