| Author | Message | ||
| FAST FRED (4.245.191.131) Rating: N/A |
A buddy with out good internet access is doing a MCI-9 with raised roof and Series 60 power. He is undecided if rivets or goop would be best at holding on sidewalls. He realizes the roof Must be riveted. MCI is claimed to be "semi Monocoque" maybe just the roof , or maybe it all. Any sugestions from the group? Stickaflex has dozens of goops , which is "correct" for this application? FAST FRED | ||
| TWO DOGS (4.227.119.7) Rating: N/A |
don't really understand the question | ||
| Marc Bourget (209.142.38.81) Rating: N/A |
Dear FF, The structure in a MCI similar to Semi Monocoque is the riveted shear plate on the inside of the cabin structure below the windows. This is not a technically correct use of the term "Semi-Monocoque", however. Craig "Gumpydog" Shepherd witnessed a sag of about 1/4" in the middle of the span along the roof and 1/8" along the floor (read his site!) when he was raising his roof. Some converters, (weedface, for one) have claimed to experience none. Sikkaflex 252, mentionied in the Bus Converter's Bible, is identified as the "Good Stuff" but my copy is dated and current data or website should be checked . What I do recall from the MAK convention just after this stuff came to converters' attention is that proper application requires maintaining a minumum adhesive thickness, which may have been as much as .060 (this is contained in the Sikkaflex literature, so read the *$^$&*% instructions! LOL!!) Maintaining this dimension requires spacer beads if you want to achieve the advertised performance. The stuff is urethane based and I believe that it has been observed to "creep" over time. Question, what is he reskinning with, aluminum, and, if so, why? Onward and Upward Marc Bourget | ||
| TWO DOGS (4.227.119.7) Rating: N/A |
I'd definitly use rivits wheather I used sic-face or not.. | ||
| Gary McFarland (Gearheadgary) (68.79.120.182)
Rating: N/A |
Rivets and goop, 3M 5200 (Howdja Guess) Gary | ||
| FAST FRED (4.245.191.46) Rating: N/A |
"Question, what is he reskinning with, aluminum, and, if so, why?" nope he got tired of the endless rust from the MCI frames (must have been old Eagle stuff) and rebuilt the frame in SS. Will be using SS as surface too. My sugestion was for rivets with minumal 5200 as just edge seal , worrying about crevace corosion if everything SS was sealed too air tight. His plans are to head WAY south so constant tropical moisture ect should do as much damage as boating. FAST FRED | ||
| TWO DOGS (63.156.216.34) Rating: N/A |
easy on the Eagle comments....my bus will outrun your bus................  | ||
| Bob (Bobb) (216.232.250.26)
Rating: N/A |
Recommendation from Sikaflex is either 221 or 252 for this type of application. Rivet the edges and bond the field. A minimum 3mm bead of adhesive is required. | ||
| TWO DOGS (63.156.216.34) Rating: N/A |
I'd rivet the hell out everything I could get a rivet in to...and...I still prefer home depos PL adheasive....can but 10 of them for what one sic-a-flex...& it has a GOOD shelf life...sic,does not | ||
| Sojourner (68.60.169.142)
Rating: N/A |
About Sikaflex adhesive to rivet. Fast Fred all-ready known most of this but may help someone else. I am not associated with Sikaflex but want share my homework. My Sojourner MCI-8 is in process to install fiberglass skin to an lengthen and widen new frame with roof re-curve to MCI-9 spec. All MCI-5,7,8,9 (10, 12 and D’s not sure) are rivet depended for monocoque construction. All Eagles, “H” Prevost and “E” MCI are trusses design vertically wall construction. All brand bus’s roof is monocoque using sheet-metal with rivets unless diagonal brace or trusses design to accept fiberglass skin. However if one-piece fiber-glass roof skin contain build in diagonal fiber-glass tubing (beam), then it can substitute some metal roof’s framing. Monocoque means……A metal structure, such as an aircraft, in which the skin absorbs all or most of the stresses to which the body is subjected. Trusses means…. A rigid framework, as of wooden beams or metal bars, designed to support a structure, such as a roof. Only and I repeat ONLY buses that contain trusses can use Sikaflex 252 as adhesive to fasten (as well flooring and roofing) skin to frame HOWEVER need to use rivet around outer perimeter of skin. Sikaflex 252 does added structural rigidity of the vehicle however will not substitute build-in trusses buses. Sikaflex 252 is only an adhesive with tough-elasticity to move side-way or pull away from frame to a point. Thicker the bead such as 1/8 to 3/16 inch spacer to maintain gap is best for 1 ½ inch wide framing, the greater shear strength and good elongation bonding (300%) before it break. Another word, the thicker the more elastic stress distance before it break however to keep panel in control, use recommend spacer for most practical purpose. Such as bus’s sheet metal roof over lap side wall’s skin as well joints are lap with leading overlap trailing skin. Sika Transportation Buses….. http://www.sikaindustry.com/ind/ipd-transoem/ipd-transoem-bus.htm Product…. http://www.sikaindustry.com/ipd-transoem-body Data……. http://www.sika.com.au/home/cmi/sikainside/sika_transport/intro/products/pdfdatasheets/SIKAFLEX252.pdf About comparing 252 to any other brands, there none better for this practical purpose in vehicle transportation to bond panel onto frame. Be sure to follow instruction. There are others that will hold strong bonding but limit elongation. Body paneling… http://www.sika.com.au/home/cmi/sikainside/sika_transport/intro/application/indexb.htm And application…. http://www.sika.com.au/home/cmi/sikainside/sika_transport/intro/application/indexappbody.htm Roof bonding…. http://www.sika.com.au/home/cmi/sikainside/sika_transport/intro/application/indexb.htm Good example of re-building a MCI-9 Monocoque side-wall into trusses in Craig’s bus…… http://www.gumpydog.com/bus/MC9_WIP/Structural/Reframing_The_Sides/reframing_the_sides.htm For those rivet sheet-metal to over lap onto fiberglass panel is use care not to over tighten or later you will have crack in fiberglass. Sikaflex 252 is good to apply before riveting. Sojourn for Christ, Jerry | ||
| Jim Ashworth (Jimnh) (172.202.31.165)
Rating: N/A |
To answer FF's question: He should use what MCI used, T-6 .060 aluminum siding or equivalent, and rivet using bucked hardened rivets as MCI used. This, along with the interior skin riveted on with mandrel retaining rivets will duplicate the original design. Sikaflex doesn't come into the picture as being necessary. Those using Sikaflex for other reasons, here is simplified info: Sikaflex 221 tensile strength=200-300 psi Sikaflex 252 tensile strength=450-550 psi Sikafled 255FC tensile strength= 650-750 psi Most of the other specs are similar between products, the only difference is with 255FC having a shorter "tack" time. Surface preparation is critical to obtain these strength ratings. Use the cleaners and primers as directed for best results. Sika's website is difficult to navigate. Be patient and try everything. I have yet to find the application data sheets. Jim | ||
| Gary McFarland (Gearheadgary) (68.79.120.182)
Rating: N/A |
FF -- Crevice Corrosion in a non submurged application? Come on.... Two Dogs, the PL adhesive gets brittle, quick. Polyurethanes never do. Also, the working time for polyrethane is REAL long.... Cost? well you can actually buy about 3.5 tubes of Liquid Nails ($2.99) to one tube of 5200 ($10.50). For general construction on Automotive/Bus Applications I always reach for the 5200, only because they have it at any Home Depot. I would however, "Order In" Sika for more specific applications, like laying ceramic tile in a shower in a Yacht/Bus. Gary | ||
| FAST FRED (4.245.221.217) Rating: N/A |
"FF -- Crevice Corrosion in a non submurged application? Come on...." The ONLY requirement for crevice corrosion, as far as I know, is an absence of O2 and some moisture. Seems like gooped to a frame rail would qualify, thats why I',m wondering. FAST FRED | ||
| Gary McFarland (Gearheadgary) (209.128.79.46)
Rating: N/A |
I worked with lots of different kinds of metals, SS included, and I never ran across Crevice Corrosion until I started messing about (Working on) boats. Stainless Keelbolts were my first experience. Crevice Corrosion is an electrolytic process, so if you have enough electrolyte to cause crevice corrosion, I think that issue is low on the overall priority list. I think "why is my bus submerged in saltwater?" would be a bigger question. But Seriously, Crevice corrosion is a concern when the part is exposed to trapped electrolyte for an extended period of time. Now, there is a question I didn't mention before, but I will now. I love working with stainless, in terms of welding, grinding, shaping finishing, you can create things of beauty. However, you can't form it, it's brittle, and as far I know, unless you're building a lettuce picking machine, you shouldn't do structural with it. What do you think? Does SS framework really seem like a good Idea? I think good ol' mild steel with Epoxy primer is the deal. Gary | ||
| Jim Ashworth (Jimnh) (172.129.108.120)
Rating: N/A |
Stainless is fine if the design does not permit movement or bending. Stainless work hardens very easily whether by cutting or bending. Eliminate the situation that causes it and SS is a fine structural material. Its just not as forgiving as mild steel. With that you can be somewhat sloppy and it won't come back to bite you. Jim | ||
| Gary McFarland (Gearheadgary) (209.128.79.46)
Rating: N/A |
I've a lot of stainless come to me cracking just beyond the weld, from various sources, various welders. With all the great coating products there are out there, I'm not sure why anyone would go to the trouble and expense of SS. gary | ||
| Doug Dickinson (Dougd470) (65.161.188.11)
Rating: N/A |
The 83 MC9s that NJ TRANSIT bought and used for 20 years, are all stainless structural members below the floor. It lasted well and continues to work just fine. Stainless comes in all kinds of "flavors", but does tend to be brittle. It all depends on the specific metal you are talking about, and it's application, as to what is OK for a structural element in a coach. Later Eagles at NJT had the Corten or "Core 10" self rusting metal in the frames. I don'tm recall if MCI went to that in the "special" MC9s that NJT bought in the late 80s. Doug St Louis MC9 | ||
| FAST FRED (4.245.185.48) Rating: N/A |
Seems to increase service life the MCI E series has lots and lots of SS. They just stuck on some gussets at the corners to get rid of cracked weld syndrome. Seems to work , there still getting about $300K a coach. FAST FRED | ||
| Derek (Derek_L) (172.168.164.208)
Rating: N/A |
Isn't the Prevost H-Series all-stainless? | ||
| Jim-Bob (12.46.52.74) Rating: N/A |
Isn't all mild steel "self rusting? Especially that used in Eagles? Easy now, I own one too! | ||
| Niles (4.4.119.26) Rating: N/A |
Yes the H-series are all SS frames - absolutely no signs of any structural problems in mine - Niles | ||
| FAST FRED (4.245.212.52) Rating: N/A |
"Isn't all mild steel "self rusting? Especially that used in Eagles?" Self rusting doen NOT imply any special property . Corten steel rusts a bit more slowly. On boats the steel is expected to leave at .004 per year. Not much wall thickness on the Eagle Super Rustalot fraiming , so those .004 (or MORE!)add up to reframe time rather rapidly. FAST FRED |