Z1OwnersClub GB

Is there any difference between a 1973 Z1 frame and a Z1a frame?

Thanks

I think if my memory serves me, is there were differences in the frame gusset area, the older frames were prone to cracking here that spread to the down tubes.

Identical on Z1, Z1a and Z1b as far as I know. Only difference being the frame number..

Z1streetfighter71 wrote:I think if my memory serves me, is there were differences in the frame gusset area, the older frames were prone to cracking here that spread to the down tubes.

Pretty sure the extra bracing didn't arrive 'til the A4. I thought Z1/A/B frames were the same??.

On the black gusset there are holes this was the later 73 and 74, the yellow gusset has no holes and this is one of my 75' and i think and im open to be corrected the early 73 gusset was straight.

You may well be correct but I do know there was extra bracing on the last A4. (my old 900).....

The Z900 and Z1000 both had thicker walled tubes and extra support on the gusset but like i said i think i remember reading about the early 73 (some call it the 72) that had a slightly different gusset to the later 73/74. Anyone out there with an early bike? Sorry nerding out a bit...

The oil cooler holes mentioned in the previous post were removed circa frame number 65000.
There was also another slot shaped hole added to the central brace (can be seen in the yellow frame pic). This started to appear circa Jan 1974

z2.john wrote:The oil cooler holes mentioned in the previous post were removed circa frame number 65000.
There was also another slot shaped hole added to the central brace (can be seen in the yellow frame pic). This started to appear circa Jan 1974

Thanks for that John, the only pic of an early 73 frame gusset is this one but i think the builder removed the oil cooler holes in the repair he did, maybe thats what i read and just picked it up as a straight gusset.

The oil cooler holes were on there from day 1