Into the world of hydroboosters I go. What a day. I took off the hb and made an extra spacer after I disconnected the brake pedal arm and pulled out another 1/2". So I moved the unit that distance from the firewall. I also went to junkyard and took apart about 4 units and took the rods that connect hb with master, and a larger spring for the return of the b.pedal. Since I took so many rods I played with lengths.

I also bought two 75 chebby k20 4x front calipers for $17 ea. at AZ. I thought the Caddy calipers were big! These things look huge. I'm giving up on the Caddy ebrake calipers. I wanted to solve the problem of my r.rear dragging. I can't wait to try them out. When I have the $ I'll invest in a set of the TSM custom ebrake calipers for this truck. But until then, these chebby cals will lock up a set of 38" tires!!

I thought that while I was back there I'd replace my leaking l axle seal. Heck, since I have a spare set, I'm going to replace them both.

I'm hoping there won't be any more episodes of the self engaging brakes. This morning they were locking so bad I could not drive, and had to change the hb master rod length just to get it home. And since it didn't act up all that way, I knew I had something. It was rod length, and, hopefully, not p/s fluid contamination damage.

To the poster who mentioned that residual valves are only used when the master is lower than the calipers: That is not true. A 2lb residual is commonly used in disc brake systems. With these modern systems, however, it is usually IN the master. ABS brakes, in Orange, CA, installs them in all their systems.

 

I need new soft lines too. The Caddy ones make a 90* turn in the hard section. I need them straight. I may try to straighten.

I can replace from R.Auto for like $5 ea. but then the postage makes them the same price as one of the new ones from AZ. So if I pay $20 more than R.auto, I get them today.

 

Time is money... how much are you worth?

 

I skimmed thru this and your other brake post
https://www.ford-trucks.com/forums/1...d-dog-and.html


First, I’m glad you went ahead and checked your master cyl rod length.

I guess you are referring to me and fordman75 concerning the residual valves.
It’s not common at all to have a residual valve in a 4 wheel disc system. In fact the manufacturers have been going the other way for some time now by using what is commonly known as “quick take up” master cylinders and “low drag” calipers primarily for gas mileage. Here is a link explaining how the piston groove is cut differently so the pad rubs the disc less than a standard caliper.

You had mentioned in your qjet thread that you were after increased mileage.
Using a residual valve would be adding pressure and increasing the brake pad drag, reducing mileage.

I don’t know what master or HB model you used, but most of the HB units will accept a wide variety of different masters with different bore sizes etc and you can just pull out the residual from the rear port if it happens to have one.

Here are some links that explains residual valves and disc systems.

The Brake Man.com - ValveTechI

Typical Brake System Configurations

Brake Article© by Dean Oshiro

You can get the general idea from these links.

 

That's a good possibility there Ted. I do however love the idea of the q-jet on the 300.

 

Well he did take the suggestion of checking the master rod length.

I just hate to see people make some of the mistakes I had to learn by.

 

Q-jets aren't horrible, just a pain. I was referring more to all the gm calipers and hydroboost set up he's running.


Yep been there done that on one of my old F250's.

I wish him the best of luck. He'll eventually figure it out.

 

Push rod length: I got a crash course in them and their length. I went to junkyard and got about 4, and played with them. First off, I had the hb too close to the firewall. I also had to find the correct length for the mstr/hb rod.



I made a new bracket to move the hb further from the fire wall, and make it from the oem v.booster mounts.



You can see the original Astro Van mounting plate that I cut and moded. I left one of the oem bolts to clamp into the vise.





You can see the oem ford attachment for the b.pedal. I had to cut off the A.van one and weld this one on. The length of the shaft is critical, so get it right. Also, pack the hb end of the rod with ice in a rag. There are seals inside the hb that don't like to be heated.





I should also say that during the work I found that the left rear Caddy caliper was not releasing pressure for some reason, and that the right side has a blown out axle seal. I replaced all the seals, and swapped out the ebrake Caddy calipers for 75 chebby ones, that bolted right to my brackets. I now have stud monster brakes.



This is how it ended up looking.

 

Closed until the local mod can deal with this.

 

Lets back this a a little and keep it civil please. Brake systems just like any other system on our vehicles are subject to certain rules and then to personal preference. In other words each builder has to have certain basics to make it work at all, but can also have preference to additional items that they feel enhances the system. Thats it, no one correct or incorrect. I can ask 10 professional shops and 10 backyard builders these questions and I would get at least 5 different answers from each group. That is very evident on this site and is also why you can come here and get help to figure out just about any problem.

I am going to edit and remove a few posts then unlock this thread to see if we can get (and keep) it on the original discussion. Thanks.

 

I want to offer a 'Thank You' to all who contributed/helped with this thread. I know this was the wrong section of the forums to post a brake issue thread, but I have dealt with many of you for years and value your opinion. That is why I posted it here. I hope I did not bother anyone.

Thanks for all the help. The brakes are back to working great. Those Chebby calipers are monsterous. Thanks. k

 

Awesome! How's the Q-Jet working out?

 

It's doing real well. I really like it. I saw an immediate improvement in mpg when I got the brakes to stop dragging. Imagine that. But I also can see an improvement over the Edelbrock 500 I had on it. It idles smoother too. I do need to install a stiffer booster spring. I also have a bit of a minor issue with the throttle spring, but no big deal...just nitpick stuff. I'm sold on the QJ.

 

Glad to hear it. I always wanted to use one a 351w and tweak it. Dad had a '79 suburban with a 454 that he managed to squeeze 15mpg city out of by leaning the carb out, running hotter plugs, and advancing the timing. He said the thing was a rocket ship too.