Author Topic: My 84 K10 could use better brakes..What should be done?  (Read 2944 times)

Offline 84Silverado4x4

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My 84 K10 could use better brakes..What should be done?
« on: April 03, 2020, 10:23:24 PM »
I have an 84 chevy k10 SCSB that could use better braking.  I'v been using it as a daily driver for the last 6 years or so and have made a lot of changes and a few have made things a little better but still not what I think they should be.
Here is what I have:

84 K10 Born a 305 with power disc in front.  I assume the booster and master are correct for what it came with factory.
Truck has a 4" lift and extended braided front brake lines have been added.
Front and rear axles are off an earlier truck.  73-76  I think.  Front is a Dana44 with stock disc and I have replaced the pads and rotors and bled them.
The rear is a 12 bolt with new drum hardware.  It seems adjusted good but I know I have to apply pretty good pedal to get the rears to do much.

Lastly  The truck is equipped with a 5.3 vortec I installed from a 2006 chevy pickup and it is all stock and should provide plenty of vacuum.  Wheels are MT Classic III's 16x10 with some cooper A/T 35" tires.

Do I have a bad combo in there or is there something a should change to improve things?
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt

Offline VileZambonie

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #1 on: April 04, 2020, 04:59:17 AM »
What needs to be better specifically? ASSuming you've checked everything thoroughly at each wheel, have you checked the brake booster? When the booster stops lending a hand the pedal will require much greater effort.
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Offline 84Silverado4x4

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #2 on: April 04, 2020, 09:13:22 AM »
It's a little hard to determine exactly.  There is decent power from the booster and the truck does have brakes but it just seems weak.  Like even when you press really hard they don't really want to lock up and the front just kinda groans.  They work ok for average stops but not good in a panic situation or if I have any additional weight on the truck like towing a trailer it just wants to push through.  The rear drums seem like they are adjusted properly and any tighter it would drag but I have to be using about 95 % of my pedal range to get them to do anything.  If I am on ice and I go from park to drive I have to really stand on the brakes to keep the rears from wanting to spin.  It seems like my fronts are weak and they are doing 95% while the drums are doing 5%.  I didn't know if maybe my 1984 booster, master, and proportioning valve are not properly matched for my 1973 axle brakes?
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt

Offline VileZambonie

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #3 on: April 05, 2020, 08:32:14 PM »
I would advise you go through the whole system with a fine toothed comb. Recheck everything and if you can't stop on ice, master/booster is in order.
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              `()_);-;()_)--o--)_)

Offline JohnnyPopper

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #4 on: April 06, 2020, 03:20:05 PM »
I don't think the proportioning valve is miss matched, but I would suspect it is NOT proportioning correctly. Is it connected to the indicator light?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline 84Silverado4x4

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #5 on: April 06, 2020, 09:52:35 PM »
I have Dakota digital VHX gauges in the truck and I do not have any of those brake indicators hooked up.
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt

Offline ehjorten

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #6 on: April 07, 2020, 09:08:51 AM »
One of these makes diagnosing braking issues much easier!
https://leedbrakes.com/p-33765-leed-brakes-brake-pressure-gauge-kits.html
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline 84Silverado4x4

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #7 on: April 07, 2020, 10:24:33 PM »
I think I have one at the shop.  what should front and rear pressure read?  Also if I decided to throw some new calipers on the front is there another option that would perform better? Like JB6/JD6 - 11" - 2-15/16" piston diameter caliper VS. JB7/JD7 - 13" - 3-5/32" piston diameter caliper?  I know I could always look towards an aftermarket company for brakes but I can't imagine I can't get decent brakes from OE parts but if I'm buying new anyway maybe there is something better to put on?
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt

Offline ehjorten

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #8 on: April 08, 2020, 08:56:10 AM »
You should be able to stomp on the pedal and get at least 800 psi.  Under severe braking you would want to have maybe as much as 1,200 psi.  But really, what you are looking for is an imbalance, that would point to a circuit that isn't building pressure.  Then you need to systematically troubleshoot to find what components or components are causing the issue.
-Erik-
1991 V3500 - Gen V TBI 454, 4L80E, NP205, 14 bolt FF, D60, 8" Lift on 35s
1977 K20 Silverado - 350, THM350, NP203, 14 bolt FF, D44, Stock Lift on 31s
1969 Chevelle Malibu Sport Coupe - EFI350, THM350
1968 Chevrolet Step-side Pickup - 300HP L6

Offline JohnnyPopper

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #9 on: April 08, 2020, 10:23:18 PM »
Test the proportioning valve's electrical state:

Use a volt omh meter and test continuity between that connection tang and the chassis. If there is continuity, the valve needs adjusting if you posses the knowledge and ability, replacement if you don't.

Throwing new parts on the ends of the circuits is the last thing to do.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline roundhouse

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My 84 K10 could use better brakes..What should be done?
« Reply #10 on: April 11, 2020, 10:20:14 PM »
Have you replaced the drums with high quality not made in China drums ?
New high quality shoes ?
    Do the parking brakes work good ?

Replaced the calipers with high quality new, not rebuilt ones ?
New quality  pads ?

The master cylinder with a quality new not rebuilt one ?

Most of the pedal feel comes from the rear drums , while most of the actual stopping power comes from the front brakes.
If the rear brakes are not adjusted properly your pedal will drop a long way before it does anything

And lastly you may have to add in a aftermarket adjustable proportioning valve

We had to install one on ours
The factory prop valve just would not work right .

I adjust the rear brakes by turning the drum and using a brake spoon or screwdriver to click the star wheel two clicks  at a time until you can hear the shoes scrape the drum

Then if everything is working properly they will self adjust when you back up and apply the parking brake

You don’t really need them to lock up on pavement


But you can test them on dirt to see which wheels are locking up first , showing you which wheels are not providing enough brakes.

Also bleed them using a vacuum bleeder or a power bleeder that forces the fluid through the lines

If you have a tiny air bubble anywhere in the system is will take away a lot of braking power
« Last Edit: April 11, 2020, 10:49:28 PM by roundhouse »

Offline 84Silverado4x4

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #11 on: April 11, 2020, 11:32:39 PM »
Test the proportioning valve's electrical state:

Use a volt omh meter and test continuity between that connection tang and the chassis. If there is continuity, the valve needs adjusting if you posses the knowledge and ability, replacement if you don't.

Throwing new parts on the ends of the circuits is the last thing to do.

I had time to test for continuity and there was none.
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt

Offline 84Silverado4x4

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #12 on: April 11, 2020, 11:52:43 PM »
Test the proportioning valve's electrical state:

Use a volt omh meter and test continuity between that connection tang and the chassis. If there is continuity, the valve needs adjusting if you posses the knowledge and ability, replacement if you don't.

Throwing new parts on the ends of the circuits is the last thing to do.


I had time to test for continuity and there was none.

Have you replaced the drums with high quality not made in China drums ?
New high quality shoes ?
    Do the parking brakes work good ?

Replaced the calipers with high quality new, not rebuilt ones ?
New quality  pads ?

The master cylinder with a quality new not rebuilt one ?

Most of the pedal feel comes from the rear drums , while most of the actual stopping power comes from the front brakes.
If the rear brakes are not adjusted properly your pedal will drop a long way before it does anything

And lastly you may have to add in a aftermarket adjustable proportioning valve

We had to install one on ours
The factory prop valve just would not work right .

I adjust the rear brakes by turning the drum and using a brake spoon or screwdriver to click the star wheel two clicks  at a time until you can hear the shoes scrape the drum

Then if everything is working properly they will self adjust when you back up and apply the parking brake

You don’t really need them to lock up on pavement


But you can test them on dirt to see which wheels are locking up first , showing you which wheels are not providing enough brakes.

Also bleed them using a vacuum bleeder or a power bleeder that forces the fluid through the lines

If you have a tiny air bubble anywhere in the system is will take away a lot of braking power

The rear drums are set up with high quality parts and have been bled as well as adjusted.  The truck was missing the parking brake cables when I purchased it and with an auto I have never taken the time to install new.

I should also state that I restore classic cars for a living and install brakes on a lot of vehicles so I'm fairly familiar with most aspects. 

The pedal feel is actually pretty normal in my opinion.  The booster is working like it has good vacuum and with a stock modern 5.3 Vortec engine I have no reason to believe there is a problem there.

I have bled the fronts and replaced rotors and pads.  The truck is lifted and has extended braided brake lines.

The brakes feel good enough to drive it as I do daily but I don't think the rears are doing their part even though they are adjusted properly and the front could be improved.  I changed to a lighter wheel and tire combo recently and shaved over 22 lbs per wheel and tire off and it definitely helped but not as much as I'd like.
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt

Offline JohnnyPopper

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #13 on: April 12, 2020, 08:22:56 PM »
Ok, now you have my attention: What type of classics do you restore?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline 84Silverado4x4

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Re: My 84 K10 could use better brakes..What should be done?
« Reply #14 on: April 13, 2020, 07:35:45 AM »
The name of our shop is Muscle Car Creations and we specialize in 60's and 70' muscle but we will restore just about anything.  I try to stick to American Made stuff.  Almost every vehicle we do gets a brake job and we are starting with all new parts usually using one of the big name companies.  The bulk of them get 4 wheel disc and the high horsepower stuff will get Hydroboost and most systems use and adjustable proportioning valve.
84 Silverado Reg Cab Shortbox 4x4
4" lift with 35's
5.3 vortec, 4l60e, np208, dana44, GM 12 bolt