I am working on a DBD which has a broken frame cross tube, the one that crosses the frame behind the battery tray. It had been repaired with a tube splint that went around the tube and was fastened with U-bolts.
I vaguely recall being told many years ago that it was common for the frame to crack in that spot, and it was one of those things that was better not to reweld, as it was a focal point for vibration, and would just break again.
My '59 Gold Star Clubman race bike broke that frame tube twice and when I went to repair it the first time I had seen previous repair. So, yes, it is a weak point in the frame. Someone replied to this inquiry previously that that particular tube had a thinner wall then the rest of the frame. I can't recall that I noticed that on repair, that was back in the late '80's. My frame had a platform welded onto this tube to support the center mount oil tank and it may have structurally reinforced it as I didn't have another issue with it in 6 or 7 more years of racing.
cheers and happy 4 of July The 1960 Gold Star I have now had been build a clubman but was raced for years and I have nice photo of it upside in mid air with my good buddy Hugh from 6st nyc still on it. but to get to my point the bike came with a center oil tank mount that was cut off to weld the cracked frame tube it was welded to. but has not re cracked with years of hard racing. from what I have read 1960 Gold Stars came with the center mount for the center oil tank even if it was sold in clubman trim. just my two cents and it's a good day to have a few to the founding fathers . hunter
from what I have read 1960 Gold Stars came with the center mount for the center oil tank even if it was sold in clubman trim. hunter
I'm pretty sure the tray was available as an accessory and was added to some Clubmans for a center mount oit tank for road racing. I've never read or heard that it came that way from the factory before. Do you remember where you read this?
The CB32 I mentioned above was run without the head steady. Several other bikes through my shed over the years have not had broken crossmember, but all used head stay arrangements! Varieties of engine balance factors were run, so the variable were many..
No generalisation is wholly true, not even this one. Oliver Wendell Holmes
Jerry, When I bought the frame, it was already cracked....
After all the war stories I've heard over the years, I always try to ride with head steadies in place. These bikes vibrate, and hopefully, the factory did try to make parts live as long as possible, I hope..... We're left with what remains of their efforts I guess...
The factory has been gone for 45 years now?
Re: Broken frame cross tube on DBD GS
#701399 07/11/171:03 am07/11/171:03 am
"Me Two" .... Many years ago when racing at the El Cajon, CA TT, I had a similar experience with the cross tube having a 'spiral break'. Having discovered this shortly before a race there was no time for a nice fix. I took the bike to a welding shop in SD and the gent arc welded the crack and then fit a split piece of 'water pipe' over the tube. The bodge is OK to this day as my road 'special'. As I remember the break was prolly caused by loose motor mounts and BTW shortly thereafter all of engine and tranny mounts were replaced with AC grade bolts with lock nuts. As a rule I rode with the upper engine mount most of the time as I do now.
I've found the aircraft bolts available in 1/16" 'AN" shank increments from Aircraft Spruce the home built supplier to be a good economical supplier and have used them on a couple of GS builds. But I have freshly cad plated OEM bolts/nuts in the cupboard for fitting to the 'Lookee See Me' Goldie I'll be building up next. heh