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Author Topic: MC9 drive axle plates  (Read 1604 times)
solodon
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« on: June 23, 2013, 08:16:06 PM »

Hi, I'm new to this BBS stuff so please bear with me.  Working on a MC9 with leaking bags.  The bags were on the side with plates.  I don't know how old these parts are.  I'm going to put 4 new bags on.  I've not been able to get any idea how much plates cost and am considering making my own, buying the bolts, 4 new bags (what's the difference between a bellows and an assembly other than $70?) and getting it back on the road. I'm also thinking about using a spot of weld on the bolt heads to keep them from turning as I tighten the nuts.  When I'm taking the nuts off the head needs to be held in place with a metal plate and vise grips or the bolt spins after the nut is loosened.  The nuts seem to be some sort of a locking nut which is what causes the problem.  If the nuts weren't locking nuts one could hold the bolt head in place with their fingers.  BTW I do have access to machinery and materials for making the plates myself.  Any input from other members, pro or con would be appreciated.
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Don
1979 MC9
8V71,Automatic.
Indianapolis, IN
Just getting started. Bags are in, interior metal out ready to insulate and cover, then do the floor
Dave5Cs
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1979 MCI MC5Cs 6V-71 644MT Allison, Roseville, CA




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« Reply #1 on: June 23, 2013, 08:41:05 PM »

Best way is cut the nuts or bolts which ever is easiest for you. When you get the new ones from Luke in NJ or Mohawk  have them assembled. Because the Bellows is just the rubber bladder and the assembly is just that. The bolts need to be new with new nuts and then you don't have to try to put the new rings on them either or plates.

Dave5Cs
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"PATHFINDER"(Bus)
Toed 1998 Jeep TJ
Debo
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« Reply #2 on: June 24, 2013, 03:29:55 AM »

I replaced the rear bags on my '81 MC-9 using plates and bag assemblies I got from Luke Bonagura at US Coach in New Jersey. (check the archives here and get more info on him - great guy.) The difference between the bellows and assembly is that the assembly has the rings, bolts, washers, nuts, etc. The bellows is just the rubber part. As I recall, the plates weren't that expensive. If you make your own, make sure the thickness is close to the after-market ones so the bolts will fit. Also - order a couple of extra bolts, nuts, etc. Especially the longer ones that you'll need for the plates.

I didn't have much trouble getting the nuts off, although there were a couple of "spinners" that I had to cut off. If you do the spot weld, make sure you file them down flush with the rings so they don't chafe the bags. Also, if you spot-weld the bolts it's going to set their position and eliminate any wiggle room installing the bolts. Something to think about.

Once you get the proper orientation with the bolts in the rings, mine didn't spin while tightening them - just while loosening them. I'm thinking the weld may create more problems than it solves. One last thing - the bolt head is offset, so they fit in the rings flush only one way. Make sure you have them oriented correctly before tightening or the bolt head will stand proud of the ring and chafe the bag.
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1981 MCI MC9
Detroit 8V-71N
Spicer 4-Speed Manual
Outer Banks, NC (Nags Head)
wg4t50
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« Reply #3 on: June 24, 2013, 03:47:23 AM »

Would forget welding, the correct nuts & bolts seem to work fine, get longer ones if use the plate.
One of the best things I did was install the plates on the rear, not only cured leaks, but gave lil more stability L-R leaning wise.
Its just a minor issue with the bags, by the time they need replaced again, you will be somewhere else most likely.
Dave M
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MCI7 20+ Yrs
Foretravel w/ISM500
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Central Virginia
bevans6
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1980 MCI MC-5C




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« Reply #4 on: June 24, 2013, 04:11:44 AM »

My concern whenever I see someone putting plates on bags is that they have really inspected the structural stability of the air beam.  It goes without saying that if there are plates in the picture the beam is almost certainly corroded to the extent of leaking - so the question is has it corroded to the extent of no longer supporting the bus weight adequately?

If you have plates on one side you have a pattern to follow for the other side, if you can fabricate them why not?  Tacking the nut heads to the ring to let you get the nuts off would be fine for me, as long as you realize that in doing so you probably ruin the ring - so just buy the assembly with the ring and the special formed-head bolts and nuts.  I would definitely NOT weld the bolt heads on re-assembly, there is no need as the heads hold the bolts in place just fine. The nuts on mine were corroded on, not so much a self-locking nut issue.

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
Tatamagouche, Nova Scotia
Sam 4106
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« Reply #5 on: June 24, 2013, 05:44:18 AM »

Our MC8 had block off plates on the front and drive axle's air bags when we got it. Six of eight were leaking. I found that the cast aluminum plates against the steel original plates were corroded enough to have cracked the aluminum where the horizontal hole is to let air into the bag. The front plates, also cast aluminum, I got from Luke. Two on the rear I made from 3/8" rolled aluminum plate. I sawed out the circles with my band saw, leaving a flat spot to weld a 3/4" square by 1" long aluminum bar for drilling and tapping the hole for the air line fitting. I used an old plate as a template to drill the bolt holes.The other two on the rear I made from 3/8" steel plate cut with my torch and circle cutting attachment. If I were making more I would use steel to eliminate the corrosion between the aluminum and steel. I did put a thin layer of urethane caulk between the block off plates and the original plates to reduce corrosion. Clean the corrosion off the original steel plates before installing any new plates. I was able to reuse all of the bolts by spraying penetrant on the threads overnight and cleaning the threads with a wire brush in a Dremel tool before I tried to remove them. Then I used a thread chaser to clean the threads before reinstalling them.

Good luck, Sam
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1976 MCI-8TA with 8V92 DDEC II and Allison HT740
solodon
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« Reply #6 on: June 26, 2013, 04:22:17 PM »

Thanks for all the responses.  I've decided to make 4 steel plates, buying the needed bolts for the installation.  I'm also buying just bags as I've already taken one apart and it's not that big a deal.  Not worth $70 to me for the bolts, rings and preassembly of the bellows to the rings. Should I use any kind of sealant between the bag and the surface it is being bolted to?

Again thanks, Don



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Don
1979 MC9
8V71,Automatic.
Indianapolis, IN
Just getting started. Bags are in, interior metal out ready to insulate and cover, then do the floor
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