Another brake drum adjusting question (1 Viewer)

[Fallon 40]

I have done a complete rebuild on my FJ40 4/71 four wheel drum brakes.
New OEM master cylinder, all new steel braided lines except the right rear hose I cannot get off yet.
Rebuilt seven wheel cylinders had to buy one after market from MAF.
All new shoes and turned all drums. Bench bleed the MC then bleed all the lines. I have a good hard pedal. Adjusted each cylinder until wheel would not turn then backed off a few clicks.
I’m getting a hard pull to the left, almost a u-turn! Scary and not safe at any speed.
I have readjusted each cylinder several times with the same results. I pulled each drum off and checked each cylinder to make sure the pistons were moving and there were no leaks. If I back off the adjustment so there is no drag then my pedal goes down ½ to ¾ and the pull does not seem to be so severe. I tried backing off the adjustment on the left front and rear keeping the right side a little tighter but that did not seem to change anything.
I’m pretty much at a loss as what to do next. I’d really like to get the drums to work like they should.
Thanks for any insight as to what I should check or triple check.
Ken

 

[PabloCruise]

Good question!

I do not know the answer, but would love to hear what the experts says...

 

[amaurer]

I have a very similar problem, only mine will stop straight for ~15 stops after I readjust and then the problem comes back!

As I understand it this is just part of the fun with drums... gotta keep at it.

 

[lostmarbles]

Hi Fallon40

My vehicle (drums all round) stops in a straight line. So having drum brakes doesn't mean you've got to accept driving a "dangerous vehicle".

All I can suggest is that you recheck work that has already been done. Check that all pistons move freely and that all springs etc are installed correctly.

Another idea - Perhaps you could swap your front drums and see if it makes it pull to the other side. (Perhaps whoever turned your drums turned one or more of them off-centre?)

Such a VIOLENT pull means that it must surely be a problem with the FRONT.

Sorry. Not much help. - But keep a clear head and work methodically and you should be able to suss out what's causing your problems.

 

[JB740i]

Have you tried to get off the right rear brake line already? Could it have gotten pinched and made it ineffective and so it pulls hard left?

 

[Fallon 40]

Another idea - Perhaps you could swap your front drums and see if it makes it pull to the other side. (Perhaps whoever turned your drums turned one or more of them off-centre?)

Such a VIOLENT pull means that it must surely be a problem with the FRONT.


[/quote]
As I was laying in bed last night thinking about this I thought I should swap the drums! I will bleed the lines again as well.
I will try this as soon as I get home from work.

I was thinking the rear hose might be expanding to. I just can not get it off and I do not know how to double flare the hard brake line.
The hose seems to be ok, I thought if it was expanding my pedal would be soft.
Since I do have a good firm pedal I'm guessing the hose is ok.
Thanks

 

[Fallon 40]

Have you tried to get off the right rear brake line already? Could it have gotten pinched and made it ineffective and so it pulls hard left?

I just tried to turn the fitting and since I could not move it I have left it alone. I will have to have the hard line cut and re double flare the end by someone other than myself.
Thanks for the reply.
Ken

 

[igotta40]

Are you using PB Blaster and a flare nut wrench to get the fitting loose? That should do it. If not, go to the vise grips and plan on replacing the fitting. Better to spend a little more than planned and be sure it's done all the way.

If it gets to the point of going mad, the methodical approach is the only way to stay sane. If all else fails, try removing brake lines one by one and blow compressed air through them. You may have one blocked with rust. If they are original, well, 1971 was a looooong time ago.

One thing is for sure. When it left the showroom it stopped straight. It can be made to stop straight again. It's only mechanical....

 

[lostmarbles]

.....I was thinking the rear hose might be expanding to.........

And this has made me think of something else:

Most of the braided stainless lines I have seen have a much smaller bore (internal diameter) than ordinary brake hoses. Perhaps this could mean that your old hose (larger bore?) is able to supply your RH rear wheel cylinders with fluid ahead of the others?

Left-Right balance is vital with brakes of course. (You should never have any left-right mismatch/imbalance.)

Just a thought.

 

[amaurer]

Rebuilt seven wheel cylinders had to buy one after market from MAF.

I've heard you shouldn't do this, that is, replacing just one. Since you rebuilt all the others you might be OK, but something to think about.

Also make sure the one you replaced has the same bore size as the others; there are a few different sizes available. The size is cast into the body of the cylinder.

 

[lostmarbles]

I've heard you shouldn't do this, that is, replacing just one. Since you rebuilt all the others you might be OK, but something to think about.

Also make sure the one you replaced has the same bore size as the others; there are a few different sizes available. The size is cast into the body of the cylinder.

x 2

Best to do exactly the same things to each side.

 

[malcb]

The size is cast into the body of the cylinder.

Even a small difference in bore size will cause a huge unbalance in braking effect. Size is in inches.

 

[Pin_Head]

Did you just do the brake job?

It is likely a friction difference L to R.
Possibilities:
Shoes not arced properly to drum on one side.
Drum on one side has a bad surface.
Shoes on one side contaminated.
Shoes on one side installed wrong.

Adjustment isn't going to make it pull much because they won't develop pressure until the shoes on both sides make contact.

 

[GarnerFJ40]

Your right axle seal isn't leaking fluid onto your right drum, causing it to slip is it? (Was happening to mine...)

 

[1969 FJ40]

Thinking out loud here...
Were all drums turned to the same diameter? Is one drum been turned past maxiumum allowable diameter? A previous post had a good point on the arc of the shoe not matching the drum arc and diameter could play a role with this.

 

[albee]

Make sure both shoes touch the drum at the same time when adjusting.

I stop and pump the brakes often, when I am backing the adjusters off a few clicks. You can really feel how much contact the each shoe is making to the drum, when you turn the wheel.

Having the two wheel cylinders wheel working together, seems to be just as important as the left and right wheels working together. It is easy to get one wheel cylinder cranked down a little more then the other. This is how I stoped my truck from pulling to the side.

good luck

 

[Fallon 40]

I swapped out the front left drum with the front right drum and adjusted the shoes last night. At speeds below 20 mph it was much better but at higher speeds it was still a death march. Not sure if changing the drums or just readjusting made the difference.

With all the reply's I have plenty of things to check tonight.
I will take some pics and post with the drums off.
Thanks
Ken

 

[Coolerman]

One more thing to consider: Did you get all the cylinders onto the correct side of the truck? They are clearly labled L and R. See Pic...

 

[Fallon 40]

One more thing to consider: Did you get all the cylinders onto the correct side of the truck? They are clearly labled L and R. See Pic...

I'm 99% sure I put the cylinders back on the way they came off but I will double check that they were on correct to start with.I labeled each one and only did one side at a time.
In my FSM the pic has both springs behind the shoes and that is how I removed them. I beleive there is only a few months between our cruisers coolerman, why would your pic show one in front and one behind the shoes?
btw, I read your write up many times before I did my brake rebuild.
Could not have attempted it without it.
Thanks
Ken

 

[71FJ40]

One more thing to consider: Did you get all the cylinders onto the correct side of the truck? They are clearly labled L and R. See Pic...

Also note the cylinders in the pics are clearly labeled 1 1/4 - this is the bore diameter.
If you used aftermarket cylinders, make sure the bore diameter is the same, otherwise you will get unevenly applied pressure = pull to one side.