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Author Topic: Need brake repair advice. Parts, DIY or shop  (Read 694 times)
Gordie Allen
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« on: July 19, 2013, 03:57:47 PM »

GM 4104:
I set out to replace stripped lugs on the RF wheel.  I've got new lugs and outer nuts.  Couldn't get brake drum separated from hub.  The flat head machine screws did not respond to penetrating oil, heat, or other means of persuasion.  I'm considering drilling and easy-out next.  So anyway, I pulled the entire hub.  Good news was new bearings, and seals and fresh grease!  Bad news was I couldn't break loose a single nut with 3/4" impact (and heat again).  MORE bad news - the brake shoes have not touched the drum in a very long time.  The shoes are worn down to 1/8" from rivets.  The brake cam rotates when brakes are applied, and shoes move freely.  So, the ambient heat was so bad (96 with 100% humidity) that I just put it all back together.  I've got 8 good lugs.  I chose not to pull the LF or rears for comparison, but assume they all need attention.
QUESTIONS:
1.  Can these drums be turned?
2.  Can you still get new drums?  I haven't called Luke yet regarding parts availability.
3.  Is there a good shop within 50 miles of Kalamazoo (one without a cranky owner and does good work).
4.  Should I just man-up and do the work myself? (I CAN get the lugs out one way or the other, but a good shop could do in a day what will take me a week.)  
« Last Edit: July 19, 2013, 04:02:02 PM by Gordie Allen » Logged

Augusta, MI
1956 4104
DD 671
Jon
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« Reply #1 on: July 19, 2013, 04:26:40 PM »

I am assuming the drum is secured to the hub with 5 flat head screws of a diameter of the head of about 5/8 to 3/4"

I have no clue why those screws are there because when the wheel is applied the drum isn't going anywhere. But on my first Prevost I drove a lot in the winter in the snow belt and the salt and corrosion "welded" the screws in place. I thought of drilling them out but before I did that I machined a chisel so it had a blunt end the exact size of the screwdriver slot in the screws. The fit was as tight as I could get it. I then put a socket on the impact wrench and used the 1/2" impact wrench with light applications of the trigger to encourage the screws to break loose. Every one did although I had to regrind the end of the chisel to keep the fit on the screws as tight as possible.

Good luck.

As far as turning the drums there must be specs for the maximum allowable diameter.

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Jon

Current coach 2006 Prevost, Liberty conversion
Knoxville, TN
Gordie Allen
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« Reply #2 on: July 19, 2013, 04:36:22 PM »

Jon,
Yeah they did that on cars with drums too.  I guess just to keep it in place when you take the wheel off.  I took a 3/4" Grade 8 bolt and cut off the threads, then ground a blade on the end to fit the screw slot tight, like you said.  Kept it cool so as not to lose hardness.  It didn't budge any of the screws.  If I do the work myself, I think I'll just drill them out and clean up with a tap.  They don't have to have all that much holding power.  Like you said, once the wheel's on, it's not going anywhere.
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Augusta, MI
1956 4104
DD 671
bevans6
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« Reply #3 on: July 19, 2013, 04:50:08 PM »

I can recommend two routes to getting the brake drum screws out, having just removed 9 of them.  One is drill off the heads, pull the drum, pull the hubs, drill out the rest of the screws, chase the threads, buy new screws.  That's what I did.  A faster route, requiring a little more skill, recommended by Clifford, is to use a torch to flame-gouge off the heads of the screws (the heads will blow away and the cast iron drums won't be touched) and then use heat and vice-grips to remove the remaining bits of screw.  The second hub I pulled the whole thing and drilled the screws out on the drill press with the hub still attached.  It's heavy...

If you don't have the tools to remove the lugs and replace them, you need a shop to do the heavy lifting.  Mostly good shops just go directly to the amount of violence and impact that we kind of work up to.  Drums are available, you just need to measure them to see if you need new ones.  They aren't the same as truck drums so you may need to wait a few days for them.  These days buying new is about as cheap as having old ones turned.  New shoes ditto.  You sound like your entire system needs a look-see - cams, bearings, etc to see why the shoes aren't seeing the drums.  It sounds like you haven't done a brake inspection in a long time - what does your brake pushrod extension look like?  Are the slack adjusters working and adjusted?

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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1978 Lola T440 Formula Ford
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Gordie Allen
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« Reply #4 on: July 19, 2013, 05:06:35 PM »

Brian,
You're right.  I've spent the last year and a half gutting and rebuilding interior, wiring and mechanicals.  Engine and suspension are in great shape, but brakes need a thorough going over.  I'd  rather take it to a good shop and have it all done right.  Ed, do you have any shop recommendations?  She drives good and stops well, so willing to travel to find a good shop.  There are a couple guys on the forum in my area (I think Scotts and Stevensville, if I recall from a previous post), hoping they read this and have some recommendations.
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Augusta, MI
1956 4104
DD 671
bevans6
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« Reply #5 on: July 19, 2013, 05:13:49 PM »

If it was me, I would do a through investigation of the brakes before I took it to a shop, just because brakes are easy - big, heavy, obnoxious, but easy.  Get the drums off and you can see all.  You can see the S-cams, judge the bearing wear on the S-cams, look at the slack adjusters, and get a feel for what is needed.  Changing things is easy, about the only things that are hard is setting up automatic slack adjusters - I would use a shop for that - and possibly changing S-cam bushings if required.  New shoes should be over the counter, and a tape measure is accurate enough to do a check on the drums ID.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
gumpy
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« Reply #6 on: July 19, 2013, 05:31:05 PM »

Removing the retaining screws:

Heat with torch until it starts to show some color (red).
Spray with WD-40 (makes a lot of smoke).
Take the corner of a small cold chisel or a center punch and place in from the edge about 1/4 of the way.
Use hammer to persuade the screw to turn.
Replace screws with new ones and use anti seize compound on the threads.

There are some photos of the chisel/punch method on this page:  http://www.gumpydog.com/Bus/MC9_WIP/Mechanical/Steer_Axle/steer_axle.htm
and more details on this page: http://www.gumpydog.com/Bus/MC9_WIP/Mechanical/Tag_Axle/tag_axle.htm
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Craig Shepard
Located in Minnesquito

http://bus.gumpydog.com - "Some Assembly Required"
trucktramp
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« Reply #7 on: July 19, 2013, 05:39:31 PM »

Lindsey Dedicated Services in Kalamazoo would probably do it for you.  They have done some work on my bus.  It's a trucking company with a shop that does outside work.  Give Becky a call and tell her I sent you.  The shop rates are decent.  You may have trouble getting parts locally.  Cargo, Fleet Supply, RTE all carry truck and trailer parts.  I've always had to order what I needed.  If you need 2 stroke Detroit work, I'm told there is a guy at Luke's Driveshaft on Gembrit that still works on them but I've never used him.  Chad at Lindsey may know someone if he can't work on Detroits.  Hope this helps.
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Dennis Watson
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Scotts, Michigan
1966 MCI MC5A
8V71
Spicer 4 Speed Manual
Dave5Cs
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« Reply #8 on: July 19, 2013, 07:43:36 PM »

I use a torch to heat up and use my impact driver that you hit with a hammer. Out they come

Dave5Cs
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bevans6
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« Reply #9 on: July 20, 2013, 02:51:38 AM »

Oh ye optimists...  Grin  When those screws come out with nothing but a little heat, some penetrating lube, a driver or punch and a hammer that's a sign that they weren't really stuck!  I did my fronts a month or two ago, and one came out.  I broke my impact driver bit off, I had the screw heads cherry red, I hammered with a punch until the screw slots disappeared and one came out.  There was more I could have done (I've been known to Mig weld a nut on to the flat screw head) but the drill came out and the screw-heads and the drum came off about a half hour later.  The part that really irritates me is that it was a pro truck shop that put them in too tight and with zero lube or anti-seize on them and they just rusted solid.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
chessie4905
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« Reply #10 on: July 20, 2013, 03:12:59 AM »

  Those screws are supposed to be brass. Personally, I wouldn't screw with turning down the drums. Get new ones, as they aren't that costly, while still available. Then you don't have to get oversize shoes and rollers. Do it right this time and you'll never have to do it again.The brake camshafts will probably have severe wear at the bearing area. If Luke can't get new ones, you can have a machine shop weld up the worn area and turn it to factory new specs. Coach uses manual slack adjusters, Don't think they make an automatic that'll fit. Might as well add maxi brakes to rear while you are at it, unless someone already did. Fortunately the 04's have enough clearance for them to fit, unlike the newer GM models.
  You need to check the front end for kingpin wear while you are at it. If it turns out that they are bad also, you'd best start there, and find a good shop for the work.
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GMC h8h 649#028
Pennsylvania-central
ArtGill
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« Reply #11 on: July 21, 2013, 04:20:15 PM »

I did my brakes a year a go and my coach is newer, but my truck parts store was able to match the drums and other parts by measurements.  She had to measure the drums to find the right ones.  The only difference was my old drums had some slots in them for additional cooling.  Find you a good parts person that will take the time. 

Art
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Art & Cheryll Gill
Morehead City, NC
1989 Eagle Model 20 NJT, 6v92ta
chessie4905
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« Reply #12 on: July 21, 2013, 05:02:30 PM »

One difference with GM models is that they use a 14" or so drums. They are still available though.
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GMC h8h 649#028
Pennsylvania-central
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