R80 ST or G/S Frame inspection

[carockwell]

My R80 ST suffered a low side accident and I am trying to determine if the frame is bent. Can somebody with an R80 ST or G/S inspect their bike and tell me if the lower edge of the two gussets welded to the steering head are perfectly flat? This is easy to check by placing a small ruler on the lower edge of the gusset and seeing if there is a gap between the gusset and the ruler. Thanks for your help!

[tkpinsc]

My R80 ST suffered a low side accident and I am trying to determine if the frame is bent. Can somebody with an R80 ST or G/S inspect their bike and tell me if the lower edge of the two gussets welded to the steering head are perfectly flat? This is easy to check by placing a small ruler on the lower edge of the gusset and seeing if there is a gap between the gusset and the ruler. Thanks for your help!

My ST is not handy to check at the moment, but I think the gusset plates on both sides of the headstocks of all airheads should be flat. This is one of the first visual checks when looking at a bike for purchase. A quick look at both sides of yours should answer the question, they should be identical. I can probably look at mine Monday night for you if no one else steps forward sooner.

[carockwell]

I know the R 5, 6, &7 bikes are flat, I am not sure about the later monoshock bikes. The bow in my gussets appears very symmetrical on each side. Just my luck, a symmetrical hit! Whoo Hoo! :D

[mark1305]

The gussets on my 83 ST where the down tubes attach to the steering tube are flat.

Those are some sturdy gussets on mine (build date 10/82). I can't imagine them getting bowed in a crash without bending the forks. Strange things happen though.

[carockwell]

From other posts on different boards I have found that a few R80 ST and R80 GS have the bowed gussets, which makes sense to me looking at how the factory would need to close the weld gaps. I guess I'll just fix the fork and see what I get. Thanks for the help. I will repost my results when I am done.

[tkpinsc]

From other posts on different boards I have found that a few R80 ST and R80 GS have the bowed gussets, which makes sense to me looking at how the factory would need to close the weld gaps. I guess I'll just fix the fork and see what I get. Thanks for the help. I will repost my results when I am done.

I meant to add this to my earlier post.

I would inspect the forks, triple tree for any bending, and the rest of the frame for any cracking in the paint etc. If I didn't find anything else visually wrong I'd ride it and not worry about it if it handled as well as before. Lots of airheads are on the road that are not quite straight.

After I offered to inspect mine I remembered I had the gussets replaced on mine when the frame was straightened by the frameman so it would not indicate what the factory did when new. I bought it as a salvage knowing the frame was tweaked.

[vanzen]

if the steering stem plates are not PERFECTLY FLAT ...

your frame is BENT – or rather, the steering stem is no longer positioned as designed by the factory relative to the frame.

No type247 frame (that I know of) was designed with "bowed gussets".
I recently finished building a frame based on an R80GS salvage / donor. The frame was perfectly straight at the beginning of the build and the plates were perfectly flat – till they were removed and replaced by tubing.

Do have the frame checked for straightness by a reputable concern (such as 'Frameman') – the situation is potentially dangerous, and the expense is 'cheap insurance' to quarantee your safety.

[carockwell]

Vanzen;

I don't know right now. I will know when the bike's fork is replaced. If the wheelbase is perfect, then the frame can't be bent in that direction, ie shorter wheelbase.

[vanzen]

Vanzen;

I don't know right now. I will know when the bike's fork is replaced. If the wheelbase is perfect, then the frame can't be bent in that direction, ie shorter wheelbase.

your scenario only tests for movement straight back.
a very slight 'tweak' to the left or right at the steering neck results in a considerable (lateral) change in geometry at the front tire's contact patch,
... and yet the wheelbase might remain the same.

quoting Tony Foale from his book Motorcycle Handling and Chassis Design, the Art and Science:
"It is especially important to maintain the alignment between the center planes of the wheels and the steering axis, otherwise directional stability will suffer and the tendency for wobble type instabilities may be increased."

in addition to your wheelbase measurement
do a wheels alignment proceedure to see if the bike is still "on track"

again, if the plates aren't perfectly flat – the frame IS bent.

if you can risk riding a "bent bike" – well, it is your butt, and your choice.