brakes

[dondiesel444]

well I installed the new slack ajusters on my Mack, manuals, and the truck stops SOOOO much better. but now that I can actually adjust the rear brakes, I can see they are REALLY wore down. so tomorrow I'm gonna pull the brakes apart and replace the shoes.

I've never done brakes on a big truck before, my Int'l had new brakes when I bought it. so are there any tips?
thanks

 

[Duke]

Don,

That's great, at least you've got the problem resolved.

Any tips? YEAH, be careful you don't hurt your back with them damn tires! and make sure you check all the lugnuts TWICE after replacing the rims.

 

[PackRat]

A few simple suggestions that make things a lot less painful, now and later.

1. Check the camshaft bushings, while you have the shoes off. They can be a real shoe travel robber.

2. Don't forget the lil springs on the opposite end of the shoes. It'll only take once, pulling the wheels and drums back off, and it'll be burned into your memory until you die.

3. Do the swap while the parts store is still open. If you don't have a seal on hand, Murphy's law says you will have one leaking.

4. Put a lil spray lube on the studs, before you put the wheels back on. The lug torque will be more accurate, and they won't be rusted up next time.

 

[Pacific]

Whoa don't start tearing things apart untill you get the parts you will probably want to replace the drums too. If I remember correctly Mack uses there own brake shoes and drums.

When you have a single axle you don't want to skimp on the brakes so replace everything you will want to order oil seals too.

The hardest part is getting the wheels and hub off you take them off all in one. You get a piece of sheet metal and grease it up so you jack the truck up just enough so the wheels spin and slip the sheet metal under the wheels. You have to make sure the sheet metal is atleast 3' wide and 4' long.

So you take the the axle shafts out you will take the 8 nuts off then take a hammer and smack the face of the axle shaft. You may have tapered wedges that slip over the studs you have to pull them out then slide the shaft out.

Now you get to the axle nuts you should have the proper socket to take the nuts off then slip the wheels and hub off the spindle make sure you don't bang the threads on the axle housing.

When you get the wheels off you will see the upper and lower shoes and 4 return springs holding them. Check your S-cams for wear also check to see if the bushings are tight.

If you don't feel confedent doing the job yourself take it to a shop or have someone that knows how to do it with you.

 

[dondiesel444]

my Dad has done dozens of brake jobs before. I'd feel more comfortable takin it to a shop, but my Dad says it's no big deal, he's gonna help me do the work.

thanks for the tips guys!

 

[Pacific]

If your dad has experience doing it do it yourself it will probably save you 500 dollars or so and it will be a good learning experience. All you need is a warm place to work I imagine its still cold out in the east.

The biggest problem people have with air brakes is the over grease the S cam tube and then it gets onto the brake shoes and they wonder why the brakes don't work.

When I do truck greasing for the contractors its usually 1 pump if it feels like there is alot of pressure its done by feel for me.

If you really wanted a premo brake job you take the shoes and your drums to get the shoes arch'ed it pretty much eliminates break in period.

I would like to say it again I can't stress it enough check those brake drums they must be measured if they are well in spec so they have tons of meat left reuse them. If they are close to wear limit turf them its not worth risking your life with thin drums. They heat up fast and they will turn into a egg if you apply the maxis with hot drums. They also expand so much that harder you apply the brakes more they expand and the truck doesn't stop.

With a single axle you back brakes do 80% of the stopping plus they are you emergency brakes. I don't know what kind of engine retarder your Mack has but if it has one that should never be turned off.

The Mack probably has a heavier tare weight compared to the Cornbinder you had.

Anyhow in this area the DOT is very strict when it comes to brakes if you get stopped and you have a out of adjusted slack theres it used to be 100 per wheel. If they check your brakes are out of spec the truck is condemned on the spot untill its fixed and re-inspected. The truck is either towed or police escorted to where ever the truck needs to go get repaired.

How do you like the Mack compared to the International ?

How is the turning radius on the Mack I know the tandems with a 230wb need a football field to turn

You don't see to many R model singles Mack used to make quite a few old B Model singles a local guy used to run a B Model hiab truck.

 

[dondiesel444]

well we got everything apart. we couldn't break the lug nuts loose (damn budd wheels) so we removed the drums and wheels together, then I brought the drums/wheels to the truck shop and they had a tough time taking the lug nuts off with their 1"drive HD impact gun!! anyways I got new shoes and hardware, but I have to wait for new drums and seals. they will be here this afternoon, so I should get everything back together tmorrow I hope.

 

[dondiesel444]

Pacific,
I wish I had a warm place to work, but I don't have access to a garage that a truck the size of my Mack will fit in

I Mack is a LOT heavier empty than the Int'l I had, and the dump box on the Mack is even a little smaller I love the power of the Mack 300 hp it's awsome I don't even have to downshift climbing hills loaded I'd have to downshift 2-3 gears with the Int'l. the turning radius is surprisingly good, I'm amazed, I though it would be worse then the IH but I think it's actually better. I was never impressed with the turning radius of the IH.

you are right there aren't many single axle R models around period, mostly tandems and tri-axles.

 

[Pacific]

I know what you mean about budd wheels your truck probably has stud pilot wheels which are not as bad as hub pilot wheels which are torqued on super tight.

You will have to heat each nut to loosen them up and keep at it with a 1" drive impact.

Its one of the reasons why I don't like budd wheels is the damn lug nuts are

Dayton wheels are not pretty but atleast they are easy to work with.

Good Luck with the brake work I bet the truck will stop really good now.

 

[dondiesel444]

next project it a Jake Brake!!

 

[dondiesel444]

well, the brake job is done!! it wasn't too bad except everything is so damn heavy, I'm prety sore from moving hubs and tires around. the truck actually stops now! I was actually scared to drive it before, it's such a big difference now, I don't think I even relized how bad and dangerous it actually was before. I wound up replacing: the brake shoes, both drums, hardware (springs), axle seals, and all lug nuts. the brakes have a break in period I guess, then they should work even better right?

 

[Duke]

Oh yeah, they'll only get better.

 

[Pacific]

The brakes will take abit to break in you just have to be carefull not to overheat them right away.

As for JAKE brake I don't know what kind of retarder you can put on a Mack. A Telma brake works good its expensive but if you did put that on your brakes would last forever. One of the local disposal companies has a single axle garbage truck usually grosses 34,000lbs has a telma the trucks brakes rarely needed.

A engine retarder sounds better especially with a straight pipe

 

[dondiesel444]

you can put an actual Jake Brake on a Mack which is two-stage, or a Dynatard which is Macks own version of the Jake, but it's only single stage. I'm looking for an actual Jake.

 

[abbamover]

I feel for ya , all that hardware is a backbreaker especially the hub assemblies.
Real awkward getting them onto the spindles without damaging the new oil seals by yourself.
I do all the repairs on our med and heavys and to get those wheels off you need a good 1 inch drive air wrench of at least 1100 ft lbs or better torque.
Don't forget a good big a$$ compressor and 1 inch hose out to the air wrench.
Hope you have the big a$$ torque wrench to do up the Budds right ?
I think you gotta lean on them with 550 ft lbs, at least on mine I do !!!
When you have the right tools everything goes more smoothly.

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