Recently, when Ed H was visiting, he talked about all the fun he had changing the rubber bumpers that mount between the airbags. Another thing that I just never looked at. Well, guess what, mine are shot too. I can appreciate all the fun one could have removing the remains of the old ones, but was thinking if there could be an easier way. For example, could I just get some super industrial glue and put appropriate rubber pads or bumpers in place? Particularly on the front, it does not look like there are forces that would be working to dislodge them. If there are any alternative ways of dealing with this, I'd sure like to know. Thanks
Well I bought the bumpers from MCI and can't use them....Got 6 of them at 40 or some such $......Every time I put a pipe wrench on the remains of one it broke off at the threads...sooooo,...... I shelved that idea for now until I can figure out how to r&r the darn things (angle drill maybe ? sure would be a PITA) if you find out how , let us know......thanks........................s..............
Yes a angle drill will work. I had to redrill 2 out of 4. Tom Y
I could not get a good look at what remains there. What is the diameter of the bolt that would have to be drilled out?
Lin, i think it is 3/8 or maybe 7/16. I used different sized drill bits as i worked my way up. Might even be 1/2 but i know it is no larger than that. For everybody else, i used a lot of PB Blaster for 3-5 days before trying a wrench on them and it may have helped on one of them. They were rusted from the outer edge all of the way in and nothing could get to the bolt threads on the other 3. I cut notches and used a cold chisel and a hammer trying to get them to turn. I used a dremel and cut the plate around the head of the bolt and removed it so i could use PB again and get more wrench on them, i tried heat, i tried cussing a lot, i still broke off 2 or 3 of them. Had to buy a 90 degree air drill and even with the bus aired up as far as i could go, ( i can adjust each corner on its own) i still had to cut off my drill bits to be able to get the drill in. The first one i drilled out enough to get an ez out in and broke it off. >:( And i couldn't get it out so i had to drill that out too! Not the first time i have done that, but what a pain!!! The first one was the easiest (shoulda known) and took about 4 hours from getting everything out,..... jacks,blocks, tools, wheels off and back on etc, to putting everything away. The next one took me the better part of 3 days from start to finish. The other two took a day or two each. When i ordered the frame bumpers from Luke he just laughed and said "oh boy". I didn't even bother to ask what he meant by that as i had a feeling that i already knew it was going to be one of those types of projects. I think that the 4 bumpers with shipping to Yuma was just less than $60. Good thing about it is i should never have to do it again, i think that they had never been changed before. Lin, your idea of gluing something on the plate might work.
Hey Lin, i just sent you a personal message here. ;D
Thanks Ed, I got the PM. Maybe I will go take a look at what he has. As far as the glue idea goes, if I can get some adequate rubber, I would try it. At the worst, it will fall off. There are some pretty amazing adhesives around these days. The only thing is to get the right one. I would think that the main stress would be if the bottom of the rubber spreads a bit as the weight comes down on it, so the glue would have to remain somewhat flexible.
I guess older GM bumpers are easier to replace because they have nuts on the bumper studs.
These studs usually snap when trying to remove the nuts but that just makes it easy to lift out the bumper.
Gus--That could be of interest. I wonder if the GM bumpers could be adapted to fit an MCI. At least the material would be tough enough
I could use some help with finding the right materials. Today I rolled the front of the bus up on ramps and had a good look at what was there. Basically, almost all of the bumpers are gone, but there were 1/4 inch thick chunks still stuck to the metal base. I chiseled those off and realized that the metal disk base was part of the rubber bumper assembly. This, of course, means that that the rubber was just glued on to begin with. Hence, it would seem that there is no reason that new rubber could not simple be glued to the existing disk. We all know that that is not going anywhere. It would be relatively easy, when compared with removing the disk, to clean its surface. Really, there is just rust and dust--no grease.
So does anyone have a suggestion about where to get blocks of good, strong rubber? I think that 4" -5" wide pieces that are 2"-3" thick would work fine. I assume that the adhesives available now should be as good as those in 1965. Any suggestions there too? I suppose as a last resort, I could buy replacement bumpers and cut the rubber off, but that does seem wasteful.
One layer of glue 5 layers of glue, if the glue works for one layer you should be able to build up a bumper with a couple of layers of whatever you can find. Contact cement if applied properly should do it, the first layer to fail would be the metal to rubber, and that one shouldn't as long as you clean the metal with acetone or sim. . The bump stops are hardly a stressed member, just a place for the bus to sit down slowly on when you're parked and it airs down. I could be wrong on this but I'm pretty sure buses don't go over bumps and bottom out on the suspension, certainly I've never been in one that did.
I have to assume you're talking about the rubber bumpers between the air beam and the frame? (MCI)
Mine are collapsed but I couldn't imagine they'd be threaded into the lower frame.
Heck! I'd saw the stud off and use one of the great epoxies available now and replace them. Comments?
NCbob
That's what the plan is now. The rubber mound on the original is glued to a steel disk with a stud in the middle. The bolt head only protrudes about 3/8 inch on top. The stud is basically rust welded into the frame. Therefore, people have fought them, broken them and had to drill them out to put the new one in. Aside from having to drill within a very restricted space. You almost certainly must remove the tires to get to it. I have not studied the back ones yet, but on the front using the glue approach would allow you to drive the bus up on ramps, block the airbags in some way in case of the catastrophic failure, sand/grind the surface and slap the new rubber in place. So far, I have not found the rubber. The worst case scenario is just to buy the whole piece (I think are about $6./each) cut the rubber off and use it. I was thinking that the Sika product that they use to glue siding on semis and rv's may be a good adhesive to use. Does anyone know what that product is called?
By the way, I am not so concerned with bottoming out as the extra stress on the airbags when collapsed. The rubber bumpers would hold the frame up a couple of inches. Although I am sure the factory part will last longer, I am willing to settle for 10-20 years of service on this.
When these are made, the steel part is in the mould when the rubber part is poured so the rubber and steel are made in one piece. The rubber isn't glued on to the steel after. At least, that's how similar bits that I have used are made. What I don't understand is why you don't just cut the old one off with a torch and be done with it. If you can get a wrench on it, you can usually get a torch on it.
Just my thoughts, I haven't actually changed mine at this point.
Brian
Sika-Flex? ;)
Yeah Van, but which number. They have a huge catalog of products for all sorts of purposes.
I suspect that a surface glue or adhesive will not last. :(
The process of bonding rubber to metal just isn't that simple in a high performance application like this one.
When the bus sits on these rubber bumpers, the rubber spreads out - this leads to shearing at the bonded joint.
A quick search yielded this site that went into some detail about bonding rubber to metal.
http://www.azom.com/details.asp?ArticleID=917 (http://www.azom.com/details.asp?ArticleID=917)
As for getting the rusty bolt out, I have found that heating the offending bolt red hot & immediately turning it (reheat as necessary) works sometimes - I have been known to use a welder to heat & add mass to the bolt. Gave something more for the vice-grips to hold on to too. ;D
Holding an air chisel on it to vibrate it as you turn it sometimes helps too - but often this is impractical. :(
Lin, I would be concerned that your driveshaft may be sitting on the rear axle without the stops in place. Mine was, but I also had some cradle issues. May be worth your time to drill out the rear onesand do it right. Goodluck Tom
Tom, Thanks for the heads up. I just checked and the rear ones are gone too. Looks like they have not been there is many years. I will have to wait for the air bags to deflate to check the drive shaft issue.