brake drum screws

[kevbo]

ok, just running thru some of the post and saw one on the three screws that hold the drum on. as of right now all drums are off but i did not mark the holes for the retaining bolts. how big of a problem am i up against?

[scottsmyth]

By the way, where can you get replacement bolt?

[amphi]

I did the same thing before reading about the marking and indexing. Many others have as well.

Mine went back on in random positions. I don't notice a major problem but the truck doesn't see the road much either.

I'm sure others will post up with some more definitive information for you.

This subject comes up a lot and has had much discussion.

IMHO -- this subject is a good candidate for a sticky post or at least some post tagging.

[Warthog]

By the way, where can you get replacement bolt?

ABLinn on ebay has them is stock. Look him up and send him a message.

[sermis]

My hubs are also in random position on the truck. No problems. I went to a local nut / bolt supplier and picked up some counter sunk allen screws. They had them in stock and they work good and are easy to get back out. Use anti seize on them.

[brute4c]

My 34 manual, in Chapter 21 says:

21-11. Assemble Hub and Drum
Refer to figures 21-1 and 21-2.
a. If the wheel studs were removed, or if a new hub is to be installed, install new riveted type studs, matching the flat surface of the head with the shoulder on the hub. Press new studs into place with an arbor press.
b. If the flange studs were removed, install flange studs in the hub and tighten.
c. If the bearing cups were removed, install new cups in the hub, using an arbor press. Make certain that the cups are bottomed in the hub counterbores.

Note. Bearing cups are already installed in a new hub.

d. Install the brake drum.
e. Lubricate the inner bearing cone with grease using a roller bearing lubricator or kneading the grease into the bearing rollers with the fingers. Position the cone in the inner bearing cup.
f. Apply a thin film of grease to the oil seal lip and position the seal in the hub with the lip of the seal next to the inner bearing cone. Fit the replacer over the seal and drive the seal into position.
g. Install hub and drum.
h. Install the wheel and tire.
i. Adjust wheel bearings. Refer to paragraphs 21-5 and 21-7.
j. Install front wheel drive flange or rear axle drive shaft.

21-12. Brake Drum Service
See paragraph 21-13.

21-13. Brake Drums
The brake drums are separate from the wheel hubs. To remove a brake drum, first remove the wheel, 3 flat head screws holding the drum to the hub, and then slide the brake drum off the wheel hub.

Note. Mark the location of the three flathead screws so that the drum assembly may be installed to its original position on the hub.

The problem from not indexing seems to be that the self activating brakes can come on by themselves if the drum is not kept idexed to the hub at the lowest runout position.
This had been noticed during flat towing by several people...after going some distance, the hubs were found to be hot to very hot...or worse, in mycase, the fronts came on so hard on the highway that the M715 drug the tow vehicle to a stop and the front brakes were on fire with the backing plates glowing red hot all over.

During driving people havent reported this...possible due to the use of the brake pedal over and over during driving which moves the shoes around a bit each time.

The least run out position will also allow the shoes to contact the drums more evenly giving better braking and better drum and shoe life. Also it has been reported that brake adjustments are harder to get right if the drums are no ndexed properly.

[sermis]

There is nothing there that addresses new hubs needing anything other than installed. I think the screws index the brake drum to the hub to keep it centered on the hub. Kind of like lug nuts. If you don't put the screws in the brake drum could be off centered from the hub and thus cause the problem.

[brute4c]

The last line says:

Note. Mark the location of the three flathead screws so that the drum assembly may be installed to its original position on the hub.

If one were just to put the drums on so that the lug nuts were the only attachment for the drum, like most vehicles, it would be noted that the drum has no side to side motion...yet, without indexing, several have noticed problems albeit it has always shown up during flat towing...Why then and no other time? No clue except for the use of the brakes from time to time when driving.

[rboltz]

The last line says:

Note. Mark the location of the three flathead screws so that the drum assembly may be installed to its original position on the hub.

I did not do this when the brakes were rebuilt last year. I had no problems until this week when the new dual master went in. A test drive had the vehicle pulling RIGHT when braking but with an obvious high point. In other words, you could tell it was pulling at only one point in the rotation as the steering wheel would jerk. Jacked it up today and sure enough, there is a high point rubbing when turning the tire by hand. Pulled the drum and turned it one screw hole and it seems to be OK now. I have not driven it but the high point went away when turning the tire.

[chrisnwmsu]

I did the same thing. Just put it back on and try turning the drum. If it rubs in an area try it again.

I had on that was wrong. Took it back apart and turned it one and seems to be working now.

When it was wrong I would just barely push in on the brake and the tire would lock up.