Hello all,
During my floor removal and replacement, I found a few members that are broken. There are 4 total, 2 on each side. 3 I can weld in place but the other I will have to jack the frame up to line it back up before welding.
My question is, has anyone else seen this before? Should I just weld them back and forget it or look for an underlying issue?
I will attach 5 photos. A zoomed out image and the 4 breaks .
All information is appreciated
Here is the other 2 images. One of which is the worst to weld
Although I havent any direct knowledge of your model bus and i can't tell if its a welded box beam configuration, without understanding the root cause of the breaks, I would doubt welding would fix it for long. I would consider doublers attached over a wider area where possible.
Pattern appears to be weak structure points and/ or too much torque applied to the frame. It looks like what i would imagine to be the bus driven a bit with deflated air bags or some other version of improper suspension or motor dampening... Just thinking out loud....
On a side break as there you could in my opinion fabricate an addition plate to weld on and bolster the break. A similar design like a widened octagon. Or a elongated diamond shape is quite common.
Good day
Floyd
MCI have been cracking since the beginning of time.
Keep your perspective, howmany miles to get like that, vs how many miles you are going to put on...
Weld 'em up and add a bit of strengthening where you don't like your welding.
Pay attention to the body panels outside,they tell a story in their ripples, bends and tears.
Happy coaching!
Buswarrior
With the design on buses using stainless and steel since stainless has no flexibility it finds the weakest point to crack from flexing, most of the time it is the stainless steel that cracks on MCI's and Prevost , gusset and welded it all you can do
Yes, stainless steel has been a blessing and a curse to the bus industry.
The horrible rust issues have been replaced with massive frame cracking, with the stainless being much stiffer, it cracks instead of bending, and stainless welding repairs are not as simple as old steel.
Theindustry is trying out an "in the middle" steel that is rust resitant, but more flexible, I have not heard how this latest fad is working out...
The busnut will be entering the stainless era now, and having to add stainless welding to the skill set.
Happy coching!
Buswarrior
So this isn't regular steel in these areas but stainless steel?
It can be both just use a magnet if it sticks it is metal if not it is stainless that is the way I tell on the painted metals,on later models I know that area is stainless never been there on a 102A
Where in the chassis that that section? front, middle, rear, part of the bulkhead that the engine hangs from? If it's stainless you should try to TIG weld it with a flux or gas shield inside the tube, or you get oxides forming inside the weld that lead to cracks (again). Try to reverse-engineer why the cracks happened, so you can get your plan to fix it right.
I doubt any stainless in frame for a 1986.
Too soon.
The hapless Flyers, 1990 vintage, werethe buses thattaught the political administrators about the word "rust", then the marketers taught them the word "stainless" with no other important info... and into the spec it went, and manufacturers either built with it, or lost the contracts...
Happy coaching!
Buswarrior
These cracks are in the rear where the return vent starts right over the rear wheels. It's the frame that crosses over the middle of the 2 tires from side to side. It's pretty severe and probably irreversible at this point. I placed a jack underneath between the tires as far as I can get and no results as far as moving it. Right now I plan to weld everything together as is and add some strengthening plates to hopefully prevent any more breakage. I can't tell what the culprit is
Dill a 1/8" hole at the end of any crack that you can before any repair. This will help in preventing the crack from migrating further. Drill, weld, plate, prime, stir, enjoy!
When repairing make gussets in a diamond shape with rounded corners or if you use a L shape round the welding surface on each end, never do a plate or gusset with straight welds it will just crack again and use T1 steel to make your gussets then it will last.
Sam Caylor the MCI guru won't repair those cracks I have saw him scrap some nice buses just for cracks
Post weld update.
Well I can say it's hard to do a good job at welding when you haven't done it since sophomore year in high school ~11 years, but trail and error leads the way. Here are my after pictures. I placed a single diamond gusset over the 2 minor cracks. For the other cracks I welded the cracks and welded a set of corner gussets turned different ways in each weld. I didn't bother with the lower portion of the member as I believe the extent of the break is at it's max. The weld will look better once I either fix or replace my angle grinder. As for now, ites grind and prime then forward towards the front with frame prep for new plywood.
Final 2, the major ones
Why your at it check the radius Rod that acts like a sway bar over the rear axle to make sure it is still hooked up and not broken or bent or missing the rubber bushing as well as your other radius rods back there. If you have a hitch check out how it is hooked up that it is not loose or attached to engine rails or pulling on frame. Check engine mounts that they are not cracked also. Just sayin. :)
I wonder how much rust is on the inside of those tubes. The way the metal appears pulled around screw holes, it is either fairly thin metal or has rust thinning the metal.
Dave, I believe all of that would be seen under the bus. From the inside there is a few pieces of metal preventing me from seeing anything near the axles
Yep under the bus in back after blocking it up and look up or over a pit
That will be a later day for sure. My goal for the next week while I have it off is to have the new floor in and ready for layout design
The frame on my 89 96A3 was cracked in two of the same spots.
The steel in that area is surprisingly thin.
I just beveled it and welded on the driver?s side, on the curb side, I ended up cutting out the area and welding in a patch.
The steel was surprisingly difficult to weld, I ended up stitch welding it with many small welds.
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.peterbylt.com%2Fmci96a3%2Fframecracks.jpg&hash=533951e5d82fe61236003417575061ecfbbbc94f)
(https://busconversionmagazine.com/forum/proxy.php?request=http%3A%2F%2Fwww.peterbylt.com%2Fmci96a3%2Fframecracks1.jpg&hash=152796a2391209c2f35cd6c59936d15a8bf5a860)
Peter
Peter,
That I agree with you on. My first weld wanted to eat right through the metal which was frustrating. For such a member to go fromone side to the other you would think that it would be solid as a rock. This bean for me also has rust on both sides at the wheel wells as well. It's a huge C-channel. What is more odd is that it sits just above the main frame where the rear wheels connect. I would imagine that they had a design change shortly after a few years of making this. So for the rust in the wheel wells, I think I'm going to apply a molded stainless cover that will cover everything from the under side as there's nothing to keep the water from coming in from the underside while inside the body. Anybody know of a good paste/sealant that is strong to cover over screw heads that would work well in the wheel well?
While my experience is in an MC5, I replaced all my wheel well "covers". In my bus, the front and back wheel well cover plates were aluminum riveted to stainless frame. Due to galvanic corrosion of disimilar metals, they corroded through but the stainless frame was in perfect condition, The corroded aluminum let in the road water which soaked up in floor boards leading to replacement of all the floor panels. What I did was to replace the aluminum sheet with stainless sheet riveted to the original stainless framing. I sealed it with a 3M marine epoxy (5000 I thought) anyway, rivet them, no screws. Use stainless, good flexable sealant and be done with it.
Astro,
You were close. It's called 3M marine adhesive sealant 5200. Available at lost in a caulking gun tube. I'll add that to my list of places to go this morning once again
I've used Silaprene Adhesive Sealant before putting my stepvan back together. It seems to hold up well with the body panels I installed. Just throwing it in the mix in case another alternative is needed. I got it from Mill Supply.
You need to check the engine frame rails on your 102a real close that is a major problem area on a 102A,there is one on the MCI F/B page the guy is parting out because it was going to cost to much to repair
Quote from: Dave5Cs on July 01, 2018, 12:40:03 PM
Why your at it check the radius Rod that acts like a sway bar over the rear axle to make sure it is still hooked up and not broken or bent or missing the rubber bushing as well as your other radius rods back there. If you have a hitch check out how it is hooked up that it is not loose or attached to engine rails or pulling on frame. Check engine mounts that they are not cracked also. Just sayin. :)
From above :)
I read that Dave I just wanted to tell him again so he didn't just focus on the one area,lot of times people get real deep into a A only to find out it has some major problems that is what happen to guy on F/B
I didn't think stainless steel would cause galvanic corrosion with aluminum. Probably from salt.
Quote from: luvrbus on July 02, 2018, 08:37:13 AM
I read that Dave I just wanted to tell him again so he didn't just focus on the one area,lot of times people get real deep into a A only to find out it has some major problems that is what happen to guy on F/B
Clifford just makin sure I was not on your ignore list and still on the Buddy list,LOL :)
Low grade stainless is magnetic. Car mfgr. use this for exhaust systems. It'll rust some, but not like regular steel.
Quote from: chessie4905 on July 04, 2018, 03:38:57 PM
Low grade stainless is magnetic. Car mfgr. use this for exhaust systems. It'll rust some, but not like regular steel.
The tubing on buses are made from 303 stainless
Here's some info on 303.
http://www.pennstainless.com/stainless-grades/300-series-stainless-steel/303-stainless-steel/
Quote from: chessie4905 on July 03, 2018, 07:06:30 AM
I didn't think stainless steel would cause galvanic corrosion with aluminum. Probably from salt.
Surprisingly, it does: https://www.engineersedge.com/galvanic_capatability.htm I have plenty of stainless bolts and washers next to 6061 and 6063, and they're showing some slight galvanic oxidation where they meet. Am I worried about it? Nope, it's not a boat in sea water. I'll just live with it.
John