Inherited Brake trouble, need your help.

[DustinU]

Since buying my Blazer I have lived with this issue and the only solution has resulted in a decreased turning radius which is really annoying me and obviously not correct (Longer bump stops on spindles).

Here is a post from the previous owner when he was trying to figure it out:
"Here is the problem. The brakes work fine when I am driving around straight and 90 degree turns. If I turn the wheel completely to one side I immediately lose all breaking ability. Not just a power assist... the pedal will go all the way to the floor and the truck keeps moving. I am guessing the power steering is somehow taking/steeling vacuum pressure out of the booster when i do that? Anyone have any idea what my problem could be?
I can pump the brakes to get them activated a little bit... and after a while it will fill back up. Is it just a bad booster that wont hold pressure unless it is constantly getting vacuum? Throw some ideas at me. "


Any ideas? Of the responses I read the most likely is the master cylinder and prop valve are incorrect... I think they are still the drum setup that were not changed during the disc conversion.

Any help would be appreciated, Thanks!

[notsolo]

This article might help...calls for 18 in vacuum pressure to upgrade brakes..Are you still running separate belt for PS..can you disconnect belt and test for same symptoms..Good Luck... http://www.classicperform.com/TechBo...keTroubleshoot

[bk2life]

Lol…

Your caliper is being hit by the tire when on full lock. It is quite common with small wheels. When you turn full lock the tire pushes the caliper which causes the fluid to be pushed back to the master cylinder. Then you have to pump your pedal to push the caliper back out, then you have perfect brakes.
Bigger wheels, or find out what the caliper is hitting.
Used to be very common in the 15” wheel days. But since everything is usually 18s and bigger most don’t have the problem.

[DustinU]

Originally Posted by bk2life

Lol…

Your caliper is being hit by the tire when on full lock. It is quite common with small wheels. When you turn full lock the tire pushes the caliper which causes the fluid to be pushed back to the master cylinder. Then you have to pump your pedal to push the caliper back out, then you have perfect brakes.
Bigger wheels, or find out what the caliper is hitting.
Used to be very common in the 15” wheel days. But since everything is usually 18s and bigger most don’t have the problem.

This seems like the most likely cause from what I have seen on the truck and what I have checked, THANK YOU! I will look into it tonight.

I see your from Phoenix, do you know this truck by chance?

I will update with progress, I can even throw on some 18" wheels to see if it goes away.

I will also check the vacuum pressure at "full turn"... there is no cam, heads etc to rob the vacuum but worth a look...thanks!

[truckster]

I would look into what bk2life says. As far as power steering affecting braking, they're two different and independent systems. The power steering is hydraulic, powered by the power steering pump. The brake booster, unless you've converted to hydroboost, is powered by manifold vacuum. Unless your PS pump is killing the engine at full lock (in which case you have other problems), it's not going to affect the brake booster.

[cleszkie]

If this is a 69 blazer, it would have drum brakes up front. So the calper/rim contact theory would go out the window. I would check the flexible lines between the frame and backing plate for damage, or just replace them all together in case there was internal delamination of the rubber hose causing fluid flow issues.

[jaros44sr]

I agree with cleszkie, easiest place to look would be a pinched hose at full lock, or adeteriated rubber hose

[truckster]

Originally Posted by cleszkie

If this is a 69 blazer, it would have drum brakes up front. So the calper/rim contact theory would go out the window. I would check the flexible lines between the frame and backing plate for damage, or just replace them all together in case there was internal delamination of the rubber hose causing fluid flow issues.

He mentions a disk conversion, so I assume he's talking about the front being converted to disks. Still, I agree with you that a pinched/collapsed hose is a good place to start.

By the way, every time I see your avatar I'm a little bit jealous.

[DustinU]

The PO did do a front disc brake conversion and was up front about this issue when I bought it. The hoses appear new, no cracks, pinching and are long to accommodate the lift. I am heading to my brothers tonight to throw his 18" wheels on to see if it is my 15" wheels causing the problems (I hope not as I like my 15's lol)...I will let you know what I find out.

Thanks again for all the help.

[DustinU]

So, we put on my Brothers 17" wheels with less back spacing.. problem is still there.

While we were looking at it again, my brother noticed the banjo fitting on the caliper was wrong and hitting the caliper... which led to really looking at the calipers which we think they may be wrong. I am going to look into it a little more, but it looks like I will just throw in his front axle since he is in the middle of a 2wd conversion and his axle happens to be on my driveway.
FYI- While testing it, the brakes only go soft/flat on hard left turns...not right.

[bk2life]

Originally Posted by DustinU

I see your from Phoenix, do you know this truck by chance?

from phx, currently sittin in afghan..

did the truck come from phx? any pics? i can ask my buddies back home..

[DustinU]

Originally Posted by bk2life

from phx, currently sittin in afghan..

did the truck come from phx? any pics? i can ask my buddies back home..

Yes it did come from Phx, I flew there and drove her home. I have a build thread on it with a bunch of pics in the build/projects sections, haven't done too much to it ther last come months except driving it . The PO was on AZK5... good guy named Jim.

Take care of your self over there.

Thanks again for your help.

[floyd]

Your steering stops arent adusted correctly, at full lock the caliper is contacting the axle "C" this is pushing all the fluid back into the master cyl.

My rock buggy had the same problem...

[DustinU]

Originally Posted by floyd

Your steering stops arent adusted correctly, at full lock the caliper is contacting the axle "C" this is pushing all the fluid back into the master cyl.


My rock buggy had the same problem...

You are correct, they are hitting the "C", but I think I also may have the wrong calipers and/or spindles due to the lack of turning radius. Pass side I removed the stop completely (no issues) and the Drivers side has the stop on (pictured, brakes fail with out it (caliper hitting)).
Other than the Banjo fitting on the brake line being wrong, anything stand out to you guys as being wrong with the spindles or calipers causing the steering issues???

[DustinU]

If you want/need any other pics... I would be happy to post them. Thanks for the help guys!

[floyd]

After looking at your recent pics I think the caliper bracket it installed one set of holes up..... The caliper should be mounted further down the rotor meaning it would almost be horizontally on the same plane as the axle tube...

Heres a random caliper mount image I found online(everything i have has a dana 60 so I couldnt just go out in the yard and look)



I think yours is clocked up one set of holes,this makes your caliper closer to hitting and you losing all your turning radius.

To fix it, I think all you need to do is remove the caliper,rotor and mount-then reinstall the mount one set of holes down so the caliper is closer to the ground and almost centered on the rotor when viewed from the side.

a side shot picture with the wheel removed should have your caliper looking like this....



The pics of your calipers dont look correct either...you may go down to a local auto parts store and have the pull a reman one out and take it and compare to yours....those big blocks on the back of yours arent how I remember any of my dana 44 calipers....

[DustinU]

Originally Posted by floyd

After looking at your recent pics I think the caliper bracket it installed one set of holes up..... The caliper should be mounted further down the rotor meaning it would almost be horizontally on the same plane as the axle tube...

Heres a random caliper mount image I found online(everything i have has a dana 60 so I couldnt just go out in the yard and look)


I think yours is clocked up one set of holes,this makes your caliper closer to hitting and you losing all your turning radius.

To fix it, I think all you need to do is remove the caliper,rotor and mount-then reinstall the mount one set of holes down so the caliper is closer to the ground and almost centered on the rotor when viewed from the side.

a side shot picture with the wheel removed should have your caliper looking like this....

The pics of your calipers dont look correct either...you may go down to a local auto parts store and have the pull a reman one out and take it and compare to yours....those big blocks on the back of yours arent how I remember any of my dana 44 calipers....

Thank you Floyd, this post makes perfect sense, I will look at moving them down a notch tomorrow. I will be checking the brakes and calipers at the same time.
I will update with results. Thanks again!

[bk2life]

after seein that picture, that looks like a very viable option

[DustinU]

Floyd you nailed it! Rotated the caliper down to the three o'clock position, had to grind away some of the knuckle for clearance and longer brake lines, but I can TURN!!!! lol!!

Thanks again for all your help everyone!!!