Frame crack on MCI - suggestions on how to pick a good welder?

daveola · April 20, 2011, 04:51:08 PM

When I took my 102A3 in to get it looked over, I was sad to discover two cracks that I want to take care of:

1) The base for one of the rear drive airbags has a crack through it from its transit days (it had been welded at least once, probably twice before I got it, and it's cracked again).

2) The engine cradle has a crack up near the top. Here's a video (9M) that shows the area of the crack (presuming your computer can handle Casio's movie format), but it's not enough light to actually see the crack:

http://davepics.com/tmp/cimg5545.mov

Eventually I want to tow a trailer, but regardless, I need to get these fixed. The engine cradle crack seems like it would be difficult to get to, I'm tempted to just cut a hole in the bus floor so it can be welded. I have a bunch of experience welding, but I know that this is out of my league, so I want to find a welder who can fix something like this, probably certified.

My mechanic here in the Bay Area says that they are having a hard time getting enough hours out of the welder they use to do work on their fleet, so evidently it's not easy to find good welders out here (though I'll happily listen to any suggestions on that).

I read the fantastic thread at:
http://www.busconversions.com/bbs/index.php?topic=16871.0

(I'll send the reminder to HighTechRedneck that he wants to move that to the Tech Archives...) and some people talk about the necessity of pulling the engine out. I'd really rather not do that for obvious reasons, it seems to me I should be able to just put some support under the cradle and have a welder weld some plates on the joint to strengthen it, am I wrong in this assumption?

And since I'd like to pull a trailer some day, would now be a good time to stiffen the cradle, and any suggestions on good ways to do that? I'm not sure where I would add any beams in, since I doubt that the floor above the engine can hold much extra weight.

Tenor · April 20, 2011, 07:04:29 PM

Living in Michigan is not going to help you find a welder, however, I can tell you what my shop did. I have a MCI 7, so the whole cradle thing is pretty much the same. I had the inside of my cradle plated from rear end to rear axle in 1/4 inch plate. The shop made templates first, then made cutouts with a plasma cutter to go around water lines and cradle clamps. And they even painted it! They had the bus up on blocks (under the wheels) so they could get to everything. I spent $1200 for the whole job. I just spent several hours cleaning up the inside first. Best money (along with spray foam!) I've spent! Good luck!

Glenn

Charley Davidson · April 20, 2011, 11:07:35 PM

The first way we can help you pick a welder is tell us "Specifically" where you are. My biggest pet peeve on here when people ask for help or need something but we have no clue where they are.

Chaz · April 21, 2011, 05:47:10 AM

If it has cracked before, "sumting wong".

Somebody here may know of the "issue" why it's cracking. Be sure you get a good idea why before fixing it. Then, make sure you "at least" have it "Fish plated" if not totally plated (like Tenor). The welder will know. If he doesn't, keep on movin.
Chaz

TomC · April 21, 2011, 07:05:45 AM

When AMGeneral brought out the 10240A it had numerous cracking problems because they switched from a T drive to a V drive (since most all transits in the 70's were V drive). The offset weight of the engine/transmission at the very end of the bus caused the engine cradle to crack. On my 10240B model, you can see on the cradle where they used reinforcing plates welded on mostly at joints and corners. Hence-no more cracking.
Welding reinforcing plates will probably solve the problem-but you need someone who knows what they are doing from an engineering stand point so the plates are effective. Good Luck, TomC

artvonne · April 21, 2011, 07:33:18 AM

Quote from: TomC on April 21, 2011, 07:05:45 AM

Welding reinforcing plates will probably solve the problem-but you need someone who knows what they are doing from an engineering stand point so the plates are effective. Good Luck, TomC

This is exactly what I was thinking as I read along. There are some darn good welders out there in the world, but very few have any real engineering degree.

Have you considered contacting MCI and see if someone there has some technical knowledge to offer on how best to solve the problem?

chev49 · April 21, 2011, 07:50:56 AM

You don't need an engineering degree to properly fix a heavy frame or an engine cradle. Does helpeth greatly to have your welders n plasma cutter... n grinder which is a welders best friend...

artvonne · April 21, 2011, 08:21:40 AM

Quote from: chev49 on April 21, 2011, 07:50:56 AM
You don't need an engineering degree to properly fix a heavy frame or an engine cradle. Does helpeth greatly to have your welders n plasma cutter... n grinder which is a welders best friend...

Fixing is not the same as design. Buses have a long history of cracking cradles and structural failure of the back end, thats a mighty big motor these dudes are carrying. Im not saying Rusties Welding cant make it work with enough welding and heavy plating, what im saying is that an engineer could possibly solve the cracking with only a simple brace or gusset in the right spot.

MCI built it, there had to be some technical reason they built a tube steel truss back there rather than using a box steel frame. A box would have been much simpler and cheaper to build, and more ridgid.

Tenor · April 21, 2011, 08:54:46 AM

Oops! Thanks Tom for pointing out the V Drive vs T drive!

Glenn

eddiepotts · April 21, 2011, 09:35:01 AM

Make sure you find a welder that understands electrolysis. With the engine in and welding next to it your roller bearings will arc and get small pits in them. A few RPMs later you will start having mechanical failures. It will all determine on how he grounds the bus. Don't let him ground to the front bumper then start welding in the back. It will light up the whole bus and ark everything from the wheel bearings to the TV antenna. This is not something you will see but pay for later.

artvonne · April 21, 2011, 10:11:28 AM

Quote from: eddiepotts on April 21, 2011, 09:35:01 AM
Make sure you find a welder that understands electrolysis. This is not something you will see but pay for later.

Never heard of it, just googled it, fascinating.

daveola · April 21, 2011, 11:10:17 AM

Quote from: Charley Davidson on April 20, 2011, 11:07:35 PM
The first way we can help you pick a welder is tell us "Specifically" where you are. My biggest pet peeve on here when people ask for help or need something but we have no clue where they are.

Sorry - I should have been more clear that "Bay Area" means San Francisco. It's a common SF-centric mistake we make out here, as if we have the only Bay.

Quote from: Chaz on April 21, 2011, 05:47:10 AM
Be sure you get a good idea why before fixing it...

I got the impression (from reading the boards) that cracking of the engine cradle is not uncommon for age. But now I'm not sure, is there some way to figure out what happened here? I like the idea of calling MCI,

Quote from: artvonne on April 21, 2011, 08:21:40 AM
MCI built it, there had to be some technical reason they built a tube steel truss back there rather than using a box steel frame.

The part of the cradle that is cracked is box not tube, at least on my bus - though I know it's hard to see on my poorly lit video.

Pete359EX · April 21, 2011, 12:02:59 PM

Call Peterson Tractor, The local Caterpillar Dealer, ask for the service dept., and see if anybody there does welding on the side. Or maybe they could recommend somebody. Cat always treated me right, at least in Florida.
Fred

Tom Y · April 21, 2011, 05:33:49 PM

I had cracks on my MCI also where the engine cradle was welded on. I remave it and put a plate on and made a new cradle. So far so good. Tom Y

Chopper Scott · April 21, 2011, 06:56:12 PM

I guess I don't understand the electrolysis part previously mentioned. Any welder that knows the basics will ground as close to his work as possible. I've been in the welding/repair business for 35+ years and repairing a cracked bus frame is not rocket science. Just common knowledge. The hard part is preperation and actually being able to comfortably get to the area in question as it is with any welding repair. You may actually want to find a welding repair business in an agricultural area. Guys like us have pretty much seen it all.