70's Ford Truck: Turn existing brake drum or buy a new brake drum?


#1

One of the rear brake drums must be out of kilter, as when I adjust the brakes – you know by turning that star wheel gadget – the car’s wheel turns freely without contacting the brake shoes in one part of the arc but stiffly and almost to being locked up 180 degrees away. Only one of the drums is like this, on the others shoes hit the pads pretty much all at once. So I’m taking a neighborhood walk one day and there’s a new auto shop just opened up and the have no customers. So I stop in and introduce myself, ask them if I bring my brake drum to them will the turn it for me? The mechanic there , he’s a young guy but seems pretty knowledgeable , he tells me he doesn’t have a turning machine, but even if he did he’d recommend I simply purchase a new brake drum.

What do you guys here think? Find a place who will turn the existing drum (original to the truck) provided it is within dimensional specs, or fu-git-a-bout-it and just buy a new brake drum at the auto parts store? I did a little research and I think I can buy one for around $50.


#2

I would think a thorough inspection of the system and analyzing the problem is the first step, Don’t start throwing parts at a problem without proper diagnosis.


#3

I’d check the axle bearing, just to be sure. And I’d take the drums to an experienced shop and see if one is out of round, and if they can turn it in round. Each drum has the max. ID stamped on it somewhere.

How old are the shoes? Once you turn it you’ll be better off with new ones. How are the wheel cylinders?


#4

by setting up on a lathe will tell right away if its out of round/warped. Depending on how much will have to be cut to true it will depend on if its still going to be in spec. Depending on what shop charges to cut it, you might be half way to a brand new one anyhow


#5

The neighborhood mechanic told me the cost to set it up on the lathe and turn it would usually be more than just buying a new one, so that’s why he recommends to skip the lathe idea entirely, and to just to buy a new one. I was sort of surprised when he said this. I’d though that turning on the lathe would usually be considerably less expensive than a new one. But the economies may have changed what with all the outsourcing of auto parts manufacture. So I was wondering if other people have come across this?


#6

@GeorgeSanJose

Assuming your drums are decent quality, and have enough material left, I’d rather cut them versus buying new, cheap chinese drums

New, cheap chinese drums might be less costly than machining your existing drums, but I’d be wary of the quality

FWIW . . . if you physically hand the drums to a guy in the machine shop and ask him to machine it, I can’t imagine they’ll charge you an arm and a leg. Certainly cheaper than bringing them the whole truck and have them do the complete brake job

" . . . the cost to set it up on the lathe and turn it . . ."

It doesn’t take very long to set up the lathe


#7

I’d recommend turning the existing drum if there is enough “meat” left. I say this because I have been disappointed with the quality of new replacement drums. I’ve bought 2 new drums and had to turn them on a lathe to get them true.

If someone walked in and handed me a drum to resurface on my brake lathe I’d charge him $20.


#8

Call the parts store and get a price. The shop mechanic may be correct. I had the rotots on an old '77 Honda turned, and the jerk turned a warp into them. Spent $20 for two bad turns only to find out Pep Boys had Raybestos rotors in stock for $20 apiece. That was back in the '90s, but check it anyways.


#9

@BustedKnuckles - I had the same thing happen to a set of discs, the parts shop butchered the first one, then the guy had the whatever to say ‘the metal is soft, see, doesn’t it feel soft?’ His manager gave me a new disc free, so I just bought one more, total was about the same for turning 2.


#10

I never have anything turned or faced anymore. I just buy a new one but never the cheapest ones they have. You get what you pay for. Why throw good money after something that is half used up when you can have a brand new one for not much more money. I hate going back and fixing something again because they did a lousy job or the thing is so thin it warps in 3 months anyway…


#11

New Quality drums will not be cheap, assuming you can even get good ones for that truck anymore. I have found its hard to get a Good quality, made in usa replacement part for some old cars even at higher price points.

Be careful turning the drums. Some people running the machine take to big of bites to quickly and turn the drums farther than needed. Just turn enough to clean them up and break the glaze on the surface, and take small amounts on each pass as not to get the metal too hot.

I swore I remember my old mechanic who relined my brake shoes used to make the shoes thicker to make up for drums turned beyond specs, but almost no one will reline brake shoes anymore. Brakes are the most important element of your car, no shortcuts. Also while your in there flush the brake fluid and of course clean everything up and get everything moving freely.

I suggest you lay the shoes inside your drums and make a decision based on how much contact area there is. If it’s 80-90% or more, it might not be worth it to get new drums, If it’s less than that you probably should get new ones.

If you have new shoes and new drums there is a good chance the fit will be good. If you have new shoes and worn drums there is a good chance the fit will be bad. Thats why they used to re-arc brake shoes to fit the drum. But those days are mostly gone.

I used to bring my mechanic a case of beer and he would reline and re-arc the rear shoes on my camaro, this was back over 20 years ago which around here was actually closer to the 1950’s than it is today. Discs are much less forgiving than drums, if you machine a disc too thin it will warp, drums are hardy because they have more contact area and will tolerate being machined a bit above spec. I would think a old drum machined a tad over spec would still be better than a new Chinese drum.


#12

Thanks for the great comments everybody …


#13

I suspect the drums on George’s truck are pretty big. As such, new quality drums will be fairly pricey. Therefore, it’s probably worth it to cut them, provided there’s enough material

If the guy manning the lathe is even halfway competent, a machined drum works just as well as a new drum, for less money


#14

Look in something like www.rockauto.com for drums and see what they have. If you read everything you can figure out what’s made in the USA. Don’t forget to add in shipping.


#15

Funny, @wentwest, I was just checking there - $30-$40 each or so, with me guessing the year and engine.


#16

I had a 72 for 19 years, and helped other car owners and others have helped me and honestly have never heard of this kind of a problem with a brake drum. I would be looking at operation of brake components first. (second warning)


#17

So, @texases, what engine and year? I guessed 76 F-100 with the smallest V-8.


#18

I went with 1974 and the 302


#19

Since various other aspects have been covered, I’ll throw this out and it’s something I’ve seen several times.
If the truck has steel wheels it’s possible for the face of the wheel rim (where it mates against the drum) to become distorted for whatever reason. When the lugs are tightened the drum may distort due to the wheel rather than the wheel conforming to the drum.

You might consider loosening the wheel lugs to see if that tight spot disappears. If it does, retighten the lugs and note if the tight spot returns.

After that, maybe measurement of the drum diameter and inspection of the shoes would be in order.

As to the truck itself, my guess is 1973 with a 360. :slight_smile: