1965 C10 LWB Project Build Thread

[SCOTI]

Originally Posted by JohnIL

I want to start this installment by thanking Scoti for his advice on an alternate procedure for manually bleeding brakes. His process is much more controlled and methodical than the way I've always done it. After three rounds of bleeding Scoti's way, I don't think I'm chasing air bubbles anymore. In fact, I didn't see any air bubbles at all. Now, I'm pretty sure I have a different challenge.

After bleeding again, the pedal was still soft. The brakes stop the truck, but the pedal feel was awful. I've felt air in the lines before (on other vehicles) and this felt different. It felt like maybe I wasn't getting enough brake pedal travel, like the pedal was hitting the floor before the master cylinder was maxed out. After thinking about the geometry of the booster and master cylinder, I lengthened the brake rod by adjusting it out one full turn. This improved the pedal feel. It's still softer than I would expect, but I finally got resistance at the end of the pedal stroke. So, I adjusted the rod out two more full turns and the pedal is starting to feel normal-ish.

All of this begs the question, how do you properly adjust the brake rod length?

With the old manual drum setup, I just took all the slack out of the pedal and adjusted the rod so there was 1/8" of free play before the brakes started to engage. I tried to do the same thing with the new power setup, but that appears to be way to loose. With the cushioned resistance of the brake booster, it's very difficult to tell when the brakes begin to engage. Is there a magic formula or should I just keep lengthening the rod until the brakes drag?

As always, I appreciate any wisdom you guys can share.

Manual & power brakes use different leverage on most vehicles. When I swapped to vacuum/power assisted brakes from Hydraboost on my Squarebody dually, it required a different ratio.

When I swapped to disc brakes on my drum brake trucks, I kept them manual so it was just as you did (remove the slack @ the pedal).

[JohnIL]

Originally Posted by SCOTI

Manual & power brakes use different leverage on most vehicles. When I swapped to vacuum/power assisted brakes from Hydraboost on my Squarebody dually, it required a different ratio.

When I swapped to disc brakes on my drum brake trucks, I kept them manual so it was just as you did (remove the slack @ the pedal).

I actually had that same thought. If I can't figure out how to firm up the pedal, I would almost rather go back to manual brakes. The pedal actually feels pretty good without the engine running (no vacuum assist). I've worked with factory power disc/drum setups on lots of other cars and I've never felt a brake pedal this spongy before. I've also never done a manual to power conversion before, so this all new territory for me.

I did some extracurricular reading last night. My booster and master were part of a CPP kit. According to CPP's online documentation, they should already be "mated" to each other. But, there's always a chance that the booster actuator rod needs to be adjusted. That would explain the soft pedal. I have a booster rod measuring tool ordered from the Amazonians. When it arrives next week, I'll verify that the booster and master are playing nice with each other. Then, theoretically, I should be able to adjust the brake pedal rod, more or less like a manual setup. Take out the slack and adjust to 1/8" -1/4" headspace.

Keep the advice coming. I'll take all the help I can get!

Thanks.
John

[JohnIL]

I figured out why the driver side spring is out of alignment. The upper spring pockets aren't symmetrical. Take a look at my thread in the Suspension section for pictures and details. I know what the problem is, but I don't what to do about it.

https://67-72chevytrucks.com/vboard/...d.php?t=855327

Thanks for any advice you can give.

John

[JohnIL]

I found a solution, at least partially.

I tried swapping the passenger side spring to the driver side. No good. The interference actually got worse. So, I tried something completely different.

By trial and error, I discovered that purposely mis-aligning the spring by rotating it 90 degrees eliminates the interference with the spring pocket. I took the truck for a short drive and everything seems good. No noise, no interference. BUT, I suspect the spring will eventually rotate and the interference problem will come back.

Does anyone have any suggestions on how to keep the spring where it is, rotated 90 degrees away from the alignment "dimple" in the lower spring pocket?

[SCOTI]

Originally Posted by JohnIL

I found a solution, at least partially.

I tried swapping the passenger side spring to the driver side. No good. The interference actually got worse. So, I tried something completely different.

By trial and error, I discovered that purposely mis-aligning the spring by rotating it 90 degrees eliminates the interference with the spring pocket. I took the truck for a short drive and everything seems good. No noise, no interference. BUT, I suspect the spring will eventually rotate and the interference problem will come back.

Does anyone have any suggestions on how to keep the spring where it is, rotated 90 degrees away from the alignment "dimple" in the lower spring pocket?

Drill a hole where you need the coil to 'stop'. Put a 'nut & bolt' through the hole as your stop.

[JohnIL]

Originally Posted by SCOTI

Drill a hole where you need the coil to 'stop'. Put a 'nut & bolt' through the hole as your stop.

Perfect solution! Simple and effective.

I have a few other things to investigate from my thread in the Suspension section. If I stick with the current springs, I'll definitely use your suggestion. As always, Scoti, thank you for your help.

By the way, do you have any advice on a good brand of 2" lowering springs? The previous owner added CPP springs and I'm losing confidence in them. Considering how inexpensive new springs are, I'm considering trying a different brand to see if the results are any better.

Thanks.
John

[JohnIL]

If you've been following along my with my disc brake and power brake conversion, you probably know that I also replaced the ball joints and bushings, and moved my lower control arms forward to add caster adjustment. With all of the minor challenges I've run into, the caster modification kind of got lost in the noise. I want to take a minute to write down my initial impressions of the caster mod.

While testing the brakes and the front springs, I've driven the truck 10ish miles. That's not much distance to form an opinion, but I'm pretty happy with the additional caster already. I went for a short drive yesterday on a blacktop road with a strong quartering wind. Before the modification, the truck would have wandered all over the road because of the zero caster alignment. Now, the truck tracks straight, with only minor steering wheel input. The drivability is MUCH better.

After I get all the brake and spring silliness sorted out, I will schedule an appointment at the alignment shop. I've changed a lot of items in the front suspension and I'm sure it needs some adjustment. I will post my caster numbers back here along with more "feels like" data after the alignment.

[SCOTI]

Originally Posted by JohnIL

Perfect solution! Simple and effective.

I have a few other things to investigate from my thread in the Suspension section. If I stick with the current springs, I'll definitely use your suggestion. As always, Scoti, thank you for your help.

By the way, do you have any advice on a good brand of 2" lowering springs? The previous owner added CPP springs and I'm losing confidence in them. Considering how inexpensive new springs are, I'm considering trying a different brand to see if the results are any better.

Thanks.
John

I've always stuck with OE springs & cut a coil off for my '2" drop' needs. My stuff has always been pieced together so I used the coils the truck/s came with as that gave me the best dimensions to start & use as the base of my measurement expectations. It goes back to the question 'what do they base their drop dimension off of' since the OE spring vs a new stock replacement spring yield different dimensions more often than not.

If they were coils that came via kit, they would've been from Belltech as that's the only manufacturers kit I've used on C10's for others.

[SCOTI]

Originally Posted by JohnIL

If you've been following along my with my disc brake and power brake conversion, you probably know that I also replaced the ball joints and bushings, and moved my lower control arms forward to add caster adjustment. With all of the minor challenges I've run into, the caster modification kind of got lost in the noise. I want to take a minute to write down my initial impressions of the caster mod.

While testing the brakes and the front springs, I've driven the truck 10ish miles. That's not much distance to form an opinion, but I'm pretty happy with the additional caster already. I went for a short drive yesterday on a blacktop road with a strong quartering wind. Before the modification, the truck would have wandered all over the road because of the zero caster alignment. Now, the truck tracks straight, with only minor steering wheel input. The drivability is MUCH better.

After I get all the brake and spring silliness sorted out, I will schedule an appointment at the alignment shop. I've changed a lot of items in the front suspension and I'm sure it needs some adjustment. I will post my caster numbers back here along with more "feels like" data after the alignment.

Dial in the alignment & you'll REALLY appreciate your efforts:

*NEG .5° Camber
*POS 4-5° Caster (as aggressive as possible w/that Camber target)
*1/16 - 1/8" total TOE in

[JohnIL]

I really hate that this is Part 7 of the brake conversion. It REALLY shouldn't have been this hard. In any case, I think I can finally call this project done.

Front Spring Clearance Issue
Following Scoti's advice, I drilled a hole through the bottom of the driver side lower spring cup and installed a 3/8" grade 8 bolt to act as a stop to keep the spring in place, turned 90 degrees from the factory position. This rotates the spring away from the front edge of the upper spring cup. The truck sits level and rides great. Best of all, there's no more spring noise.

Brake Pedal Feel Issue
After scratching my head for a couple of weeks, I called the Speedway Motors tech line for advice on fixing the spongy brake pedal. After I described the work I've done and how the pedal feels, the tech line guy (I think his name was Jim) said, "I'll bet your rear brake shoes need to be adjusted out further." It turns out he was right. I thought I already had the new brake shoes tight, but there was still room for improvement. I adjusted the shoes out until there was drag on the drums. That took a lot of the play out of the brake pedal.

I took the truck for a 20ish mile drive with lots of opportunities to test the brakes. The brakes worked well and nothing got hot. I'll call that a win.

Combination Valve Weirdness
While trying to solve the spongy pedal mystery, one of the many possible causes I investigated was the combination valve. I thought maybe the shuttle had tripped and was cutting off brake pressure to the rear brakes. The rear brakes are working, so it sure seems like the combination valve is OK. BUT, the brake warning light circuit in the combination valve is grounded, as though the shuttle is tripped. I'm not sure what's going on.
Maybe I got a defective valve? These valves are cheap, so I've ordered a new one, just in case this one gives me any trouble in the future.

What's next?
Now that the truck is drivable again, it needs an alignment to get all the new front suspension bits coordinated with each other. I hope to get an appointment at the alignment shop in the next week or so. After that, the C10 goes into winter hibernation. The expanded use antique license plates go dormant for the months of December, January, and February. Really, that's for the best, considering the amount of road salt we see during the cold months. I'll be back soon with alignment specs. I'm eager to see how much caster I'll end up with.