Busted Frames

[Carl La Fong]

I noticed while on the other board that one member, Aldo, had his frame break. Frame breakage, especially at the neck, has been a problem with a number of bikes. It was felt, by those who don't know any better, that this problem was limited to the early bikes and was eliminated when BH went to the investment cast neck. It has always been my contention that the neck, either cast or built up, had no bearing on these failures as the breaks have never (as far as I know) occurred at the neck itself. Blame has been laid at the feet of the upper motor mounts. This is an absurd premise. The upper mounts, on my bike, looked like screen door hardware. They weren't capable of holding the frame of a half ton motorcycle and keep it from breaking anymore than if they were made of paper mache. If you look at the breaks in Aldo's frame, you can clearly see that it snapped at the welds in the heat affected zone. This is a result of poor welding practice possibly coupled with inadequate material thickness and poor overall engineering. What is odd is, the early bikes, with the built up necks, also break in the same area. This causes me to believe that the breakage is due to poor design and thin walled tube.

While I was building my bike, I was communicating with Big John and Bill Alexander, both of whom offed a lot of valuable advise. For those that don't know, Big John has a Ranger conversion and rides it like he stole it. Bill is a retired NASA engineer. Both are old time BH guys. Bill has three of them. As I was nearing the end of my build, I got an email from John. His frame broke a few inches below the neck, just like Aldos. The solution was to sleeve the down tubes internally and weld it back up. Bill had already told me that if you set up a dial indicator about halfway down the tube and bounce the front end up and down, you would be amazed at the movement. As the neck is stressed, it tends to cause the tubes to bow forward slightly. There is no triangulation at the neck. If you look at almost any tubular frame, they all have an upper tube that runs back to the seat post and a lower tube that also runs back to the post. this creates a triangle and transfers a lot of the load back, towards the rear. The front down tubes are, mostly, in tension.

All of this concerned me so, while the bike was in a million pieces, I grabbed the Sawzall and lopped my neck off. I went to the metal supply a bought a piece of DOM tubing that was as close to the ID of my frame as I could find. The wall thickness of the tube is 1/4 inch. Pretty stout stuff. I had to turn it down a tad to get a nice slip fit. The slugs were made to fit as far as possible into the frame, so they go from the neck all the way to the bend that wraps under the engine. The frame was drilled with a 1/2 bit above and below the cut and the slugs were plug welded in place as well as being welded at the cuts that I made when I severed the neck. So far, so good.

I don't want to scare anyone, but these frame do fail. Given the number of known failures compared to the total number of BHs built, If the same stats were applied to a known and potentially fatal flaw in Ford F-150s it would be on the evening news. I do cringe when I see people put raked front end on our bikes and think of the additional stresses that it puts on a proven weak area. A break, like Aldo's, at 120 MPH wouldn't be very Kewel

[hogv8]

The first thing I thought of when I saw Eldo's pictures of the broken frame was , wow , no matter what caused the frame to break in that area just think if he had a set of raked trees , he would have been sliding down the road on the lower frame . I agree that there was probably stress put on the frame by improper spacing of the top motor mounts .

I like La Fongs idea for fixing the problem area and I think we should all be conscious of possible breaks in our frames and carefully inspect them periodically .

[Carl La Fong]

I was aware of frame failures below the neck before I bought my bike. I'm surprised that the know it alls, over there, haven't commented on them. I don't get it. It has happened way more than twice. When I was shopping, I was advised to look for a later bike with the cast neck because they didn't break like the early ones. Well, that is hogwash, now.
If it is the upper mounts being out of adjustment or busted, as mine were, that's what separates your ass from the pavement, then I would be extra scared seeing as how flimsy they are. I redid my mounts and feel that they are as strong as they can be. I am confident that my neck ain't goin' nowhere.
Another reason I don't post on that site is that any ideas, modifications or techniques have to be filtered through the Grand Poohbah before they can be given the stamp of approval. Even something as simple as using Nylock nuts on the fan mount mod rather than the Mickey Mouse double nut method that is required by His Highest. God help you if you think BH should add a drain petcock.
Heresy, burn him, he's a witch!!!!

[Imzz4]

Carl, When I saw you mentioned Bill, I wanted to totally agree that he is a good man who is full of knowledge and experience. I spoke with him several times and ask his opinions. He convinced me to stuff the downtubes of my new trike frame with 1 1/4" tubing even after I went up on the 1 1/2" wall thickness to .125. I welded very beefy "bungs" with 1/2-13 internal threads to accommodate cylinder head motor mounts also. Those stock ones are terrible.
Sounds like you have yours pretty squared away now!
jeff

[hogv8]

Jeff , I'm in the process of sleeving my front frame tubes from as high up into the neck as I can go all the way down to the crash bars . I'm using 1 1/2 " ID , 1/8" wall chrome moly that will be split in half to enclose the original frame tubes and they will be welded to the frame top and bottom and the seems welded from top to bottom with the sleeve splits also being welded to the frame . I am fabricating new motor mounts and frame clamps very similar to Carl la Fongs set up and yours with 1 3/4" clamps around the sleeved frame . I think this will do the trick .

[Imzz4]

Jack that will stiffen it up a good bit. Years ago, I called the factory about the early stile frames cracking, since my 98 was all new to me and I was quite worried. They sent me two specially cut frame gusset pairs similar to how you are describing your tubing addition. They supplied them at no charge . Perhaps they still have these ?? Anyone might want to call them and see what the story is especially if your taking your machine apart this winter.
There was also the issue of no triangulation on the rear frame . One man had his break and it drove the seat forward and knocked the cap off the distributor after he hit a bump or a pothole.. He was lucky !
On some frames, I welded gussets. On mine I made SS 1/2" rods connecting the rear passenger peg bolts to the upper shock bolts.
The new owner of my 408 has piece of mind regarding those issues.
I sold it a month ago . Last I heard from his wife he was a "happy man".

[hogv8]

Jeff , I'll post some pictures of the project when I get it finished . Deer and the woods are calling to me this time of year but I'll getter done .

[hogv8]

Jeff , I guess I don't understand how you connected you passenger foot peg bolts to your upper shock mounts with 1/2" SS rod instead of welding gussets . I understand how it could be done but just can't picture it or how it works . Could you please explain and if possible post a photo ?

Thanks , Jack

[hogv8]

Jeff and anyone else interested I had my wife post some pictures of my frame and motor mount mods on the other V8 site but wasn't sure how to post the same thing over here . So if you would like to see the picture please check them out on the V8bikeriders.com site

Thanks , Jack

[V8Bikers]

Jack, here is how to post pics,
- once you hit the reply button, page down until you find the "Browse" button.
- That will open up the files on your computer.
- Navigate to the folder where your photos are.
- Click on the photo then hit "open" on the bottom of the page the photos are on
- Click "add the file" next to the Browse button.
- A window will come up breifly sayting "The upload is now in progress"
- Once that window closes, hit the submit button as you normally would for a regular post and the pic will be shown.

Let me know if you have any questions.

Thanks,
Bill

[Carl La Fong]

that's exactly how I did mine, 'cept yours is prettier

[V-MAN]

Jeff and anyone else interested I had my wife post some pictures of my frame and motor mount mods on the other V8 site but wasn't sure how to post the same thing over here . So if you would like to see the picture please check them out on the V8bikeriders.com site

Thanks , Jack

Jack -

I moved the pics here for you, hope that is OK.

That is a great job, looks very clean and I can't see you ever having an issue with breaking.

Don

Here is Jack's explaination of pictures and the pictures themselves:

[b]Picture's #1 and #2 show the chrome Moly , 1 1/2" ID x 1 3/4" OD split sleeves I fabricated to go around the the frame tubes and gussets that I had previously had welded in . The split line of the sleeves were ground down before welding so they could be both welded to each other and to the frame itself and both ends. .
Picture #3 shows the finished product including the new motor mounts . I used the original frame clamps which I bored out to 1 3/4" .
Picture #4 another view of the motor mounts .
Picture #5 and 6 show a close up of the right and left motor mount clamps .[/b]

Picture #5 and 6 show a close up of the right and left motor mount clamps

[hogv8]

Thanks Don , I agree that I can't see where mine should ever have a problem with breakage in this area . It was also a good opportunity to detail a few other things out and do some maintenance on the forks , fork bearings , radiator , new alternator and water pump while it's easy to get to . Putting it back together this week .

Jack

[Ric]

Im interested in the differences in the Big Block frame. It appears quite different than any of the pics I've seen. I can tell I have a cast neck, but the down tubes seem to have a cast expansion from what seems like 1 1/4" to 1 1/2" to the drop legs. Is this the weak point in a big block frame? I've certainly amplified the potential problem by having a Kewl Metal front end installed if this is going to haunt me down the road. So far all the frame breakages were on SB's what's the word on past issues with BB's?

[SQ4MN]

Jack, I'm always impressed by your work. Sanitary and well thought out. I am still living on the ragged edge with my Boss Hoss frame. So far no cracks but I inspect it often and just HOPE for the best. I stand by my opinion that the material is wrong and to thin to start with. The factory in my opinion should get rid of chrome moly and go with the proper grade of cold rolled with a thicker wall. If a bike is modified like yours or LaFongs it will never break. When and if mine cracks I'll copy your set up. I worry more about my trike as the stresses on the front end are much greater. It seems to me that most of the bikes and trikes go thru life without problems and its just the luck of the draw. In any case its a bad design as no motorcycle or trike frame should ever break under normal use.

[Imzz4]

Jack, I seem to have those pics on another drive. I'll post them then. jeff