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1600 Loadstar braking problem


Kawa86
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Hi all,

 

I have a question about our old-timer fire truck.

It is a 1966 1600 loadstar 4X4.

We have been having problems with the braking for a while, late response, difficult to dose, brakes sticking...

My college who was working on reworking the brakes unfortunately passed away unexpectedly last year.

So we where left with a half reworked braking system and not much of information.

 

Every component in the system has been replaced or overhauled.

New master cylinder, booster, pads, brake lines, overhauled brake cylinders.

 

I did some reading in the technical documentation, I’m starting to think that the master cylinder wish is new, is not a good combination with the booster.

In the way that they both don’t have a double check valve.

 

There are no numbers or markings of any kind on the master cylinder, so we don’t know for sure.

But the model looks like a model without double check valve in the documentation.

 

I added picture of the booster and master cylinder.

 

Would it be possible to solve the issue with another master cylinder?

 

IMG-20170702-WA0000.jpg

IMG_7984.jpg

IMG_7988.jpg

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Other issues I have run into over the years are stuck brake cylinders which should not be the case here as you say they are rebuilt but are the brakes in adjustment? You said pads but I am pretty sure they are a shoe type system as I do not recall disk brakes on trucks in the 60's. Anyway adjust each shoe up until it is tight and than back off 5 clicks if new and 3 clicks if used shoes. That is according to IH, personally I usually go about 2 more clicks loose. Rear shoes have 2 adjusters if it has the typical brake system. Front brakes if typical should use a cam adjuster, turn adjuster in direction of normal wheel rotation until wheel locks and than back off until wheel just rotates freely. If you have questions send some pictures of the front and rear backing plates or if the drums are off of the brakes themselves and someone can give you more information. 

You will find the back brakes are very difficult to adjust as the one adjuster is right in line with the spring pack and very little room for an adjuster tool. I will try and remember when I am at the shop today and get the number off the Snap On adjuster that I use, best one I have found for the job.

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I always preadjust the brake bands before I put the drums on the final time it alot easier doing it than after everything is done

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Make sure they are bled good and adjusted first. If you want working brakes you will want the check valve in master cylinder. Without the inside check you cannot pump brakes up easily. Years ago a Chevy pickup had dual brake , clutch master cylinder only difference on side was no check valve for clutch.This is not the valves to hold residual pressure in brake system. The actual check valve in master cylinder.  Make sure the brakes are adjusted good and bled. I would suspect your booster got damaged in the bleeding of brakes. You can bend booster operating rod if air in system and engine running. Start out making sure master cylinder pumps fluid clear, bleed booster than work back to front bleeding brakes. 

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First of all, thx for the answers.

The pushrod is adjusted correctly, we made shure there was play between the rod en the piston.

It are indeed brake shoes offcourse, the adjustment is worked on very hard with several people and inputs so I'm asumming that is not the problem.

The tool would be very handy idd!

We also spend houres on the bleeding the complete system, but we never bled with the engine running.

The check-valve we are talking about is "item L" in picture 1, and I suspect we have a master cylinder like the one in picture 2.
So opening up the master cylinder would be the only way to be shure?

Greetz

Koen

 

 

 

 

1.jpg

2.jpg

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46 minutes ago, Kawa86 said:

So opening up the master cylinder would be the only way to be shure?

On the master cylinder. Remove hollow bolt and insert straight wire. How far does it go in? All the way  to piston or stopped by check valve. That said. I don't think there should be a check valve there. Should be in booster unit.

My experience is to limited to be sure.

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Kawa86 what was the original issue with the brakes on this truck? Was this the issue going into the brake work or is this an issue because of the brake work? Might help us in what advice to give you.

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  There was A Thread on this site Last Fall, I couldn't locate It.

In your Photo you have pictured the Vacuum Brake booster, The front Half is Painted white.

My 1600 load star was leaking under Braking conditions, a Simple test was if we found Brake fluid in our New Vacuum Boster.

We sent our unit to a Rebuilder, Made a Complete Difference!! 

We also thought we Had replaced or Rebuilt everything Possible,....But Brake fluid was Slipping past that Shaft in real world Braking Conditions.

The folks that rebuilt my unit were in Chicago, IL,  I can find there address if you need me to.

My 2 Cents, Jim Droscha

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3 hours ago, Kawa86 said:

First of all, thx for the answers.

The pushrod is adjusted correctly, we made shure there was play between the rod en the piston.

It are indeed brake shoes offcourse, the adjustment is worked on very hard with several people and inputs so I'm asumming that is not the problem.

The tool would be very handy idd!

We also spend houres on the bleeding the complete system, but we never bled with the engine running.

The check-valve we are talking about is "item L" in picture 1, and I suspect we have a master cylinder like the one in picture 2.
So opening up the master cylinder would be the only way to be shure?

Greetz

Koen

 

 

 

 

1.jpg

2.jpg

The check valve L holds the fluid as it is pumped past. It allows fluid to return under slight pressure. It’s goal is to allow you to pump fluid out to fill brakes and if anything is out of adj. it allows you to pump more than one stroke of master cylinder. That check valve is not your problem. You need to make sure everything is bled and adj. first.

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From looking at your pictures the booster is your problem. The chamber on back looks to be good but the black control valve looks old. There is a hole and diaphragm that controls operation of piston and booster. This is what is sticking on yours or working at times not others. This is what causes intermittent and locked up brakes. Make sure everything is bled and adjusted. If the front brakes are out of adj any you loose a lot of pedal and the back or a bugger but you can get them set . I always set them so they drag and three or so clicks back. Use the brakes and reset after they take the shape of the drums.

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I don't know about your truck but I had a 79 1810b Cargostar with a 24ft rollback bed. I had zero brakes on it.Hyd brakes. This so called truck garage replaced drums, shoes,master cylinder and brake booster to no avail. Everytime he said it was done,same thing ,stand on the brakes would not stop.He got all his parts from NAPA. He sent the booster back three times,4k later I got fed up and took truck to REAL truck garage. He called my local IH dealer, gave the best IH partman in the world the line setting ticket.He ordered the booster from Navistar and boom,it was fixed. I talked to parts guy and he told me he told mechanic that failed to fix truck that the  truck took THREE different boosters and you had to get the exact one too work.Well failed mechanic was getting a cut of everything he sold through NAPA so he did what was best for him not me.I never took a thing again to him and won't even speak to him when I see him.He isn't worth my time.But make sure components are the right ones for your truck.It cost me a year of use ,$4000 and a lot of lost business. 

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I think you have the wrong master cylinder. I'm pretty sure you should have MC661.

What are the part numbers and brand of your master cylinder and brake booster?

What size brakes do you have on front and back?

Do you have the line setting ticket?

There was one taped to the driver's kick panel and possibly with the operators manual. If you have it post the brake codes and specifications.

Thx-Ace 

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I have seen the wrong booster business in a old Ford 50 years ago. Stumped what where to have been good mechanics. But the wrong booster worked to put brakes on just would not unlock. Bleed a drop of fluid anywhere in the system it released. One mechanic thought it was fixed because he had cross threaded a steel line that had a very slow drip. The only fix was booster out of junk truck the exact same as original. 

 

But if you don't know what was there anymore maybe you need to go the line setting ticket route. Twenty years ago Loadstar 1700 locked up every time brakes applied. Still had independent auto parts store. Could not decide which of 2 to order, manager ordered both, used the one like the old and all was good. 

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On 2/19/2022 at 4:21 PM, IHC_1470 said:

Kawa86 what was the original issue with the brakes on this truck? Was this the issue going into the brake work or is this an issue because of the brake work? Might help us in what advice to give you.

The origional problems where related to the back axle locking up, but thats probably due to the now empty water reservoir wich makes the back to light.
We were planning on solving this with a regulator to the back axle.

But the braking has always been below average, that is what I hear from the people who used to drive it when it still was in service.

Ofcourse you can't compare it to a modern truck.

I believe my college started to rebuild everything as part of a major overhaul, mostly to replace the old brake lines.

The issues now are:

-after a period of not braking, you somethimes have to "pump up" before you can brake properly again.

  To try and battle this issue we worked hard to be shure the system was properly bled, and the shoes where properly adjusted.

  This made the situation a bit beter but still not reliable enough to be safe.

-when you start pushing the pedal, nothing happens for a long time and then all the sudden you almost lock up the rear axle, so it is very difficult to brake "gently"

-somethimes there seems to be a small ressidual pressure in the system, you only slightly feel it when you lift your foot from the gas, but it is enough to significally heat up   the front brakes. 

  We drilled a hole in the origional "closed" cover of the brake fluid reservoir, attached a hose with a breeder to make shure the reservoir could breed.

  The only problem was that brake fluid is being pushed out of the bypass hole (when you release the pedal) right into the breathing line, causing the brake fluid to spill out.

  

 

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On 2/19/2022 at 5:39 PM, DroschaFamilyDairy said:

  There was A Thread on this site Last Fall, I couldn't locate It.

In your Photo you have pictured the Vacuum Brake booster, The front Half is Painted white.

My 1600 load star was leaking under Braking conditions, a Simple test was if we found Brake fluid in our New Vacuum Boster.

We sent our unit to a Rebuilder, Made a Complete Difference!! 

We also thought we Had replaced or Rebuilt everything Possible,....But Brake fluid was Slipping past that Shaft in real world Braking Conditions.

The folks that rebuilt my unit were in Chicago, IL,  I can find there address if you need me to.

My 2 Cents, Jim Droscha

The booster is indeed a reworked booster, the parts of the origional one are still here, so I am shure it is the same model as the one that was installed before.
It seems that there where isues with the booster in the past as they tried to delete it from the system, wich they say "worked fine".
However this are "stories" from the past, so nobody is really shure how or who did that, and why they installed it again.

I personally don't think you can drive this truck safely without the booster.
 

We tested the function of the booster itself and it seems to work fine, would we see the braking fluid leak out after time if it was leaking internally?

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I will try to look for the line ticket, but I never seen it or heard anyone speaking of it so I won't get my hopes up :)
I'm fairly shure the booster is the right model, we have the old model wich is the same, and I came across the same model on the same truck a few times on the internet.

The only thing that is definitely not origional is the master cylinder, so that is our best guess at the moment.

@acemI looked at the MC661 wich certainly would be an option, but the mounting holes are upside down, so it is not a swap for the origional.

 

@dale560 thx for the video, this will be very handy.
                  the booster seems to do is job though, but I will look into it when I come back.

 

I'm in the Belgian airforce, leaving for MCAS Yuma in two days, I'll be there on exercise for about 3 weeks, I would like to use the opportunity to get my hands on the correct master cylinder, it would save us allot on shipping and taxes.

So if anyone has a tips on where they could help me, thx in advance!

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  • 1 month later...

A little update,

We found the origional check valve from the master cylinder and reinstalled it, bled everything again and did a test drive.

Without the vacuum connected the braking is very hard, but all seems to operate in a normal way.

The moment we connected the vacuum, the brakes just fully apply when you operate the pedal and they stay applied.

You have to stump the pedal a few times to try to release the brakes.

So I guess the problem is in the booster now.

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  • 4 weeks later...
  • 4 weeks later...

So we opened up the hydrovac, it was in very poor condition.

Looks like they used al the parts from the old one, inclusive most of the rubber parts 😕

We are looking for a revision kit or a replacement unit.

I have contacted some company's but no respons so far.

Anyone who knows a good adress?

 

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