Z1OwnersClub GB

what are the differences between a z1000a1/a4 and a z1000j swingarm

i know the bearings are different but are there any other things different eg; chainguard mounts, distance from bearings to axle?

I have a GPz b1 swing arm if you want pics etc

Mfp, Not sure about the "J" swing arm, however, the Z1000 A1 & Z900 A4 are the same dimensions, with the exception of two eyelets on RHS of the arm to support the hydraulic line for the rear disk on the A1. The stay-bar mount is also different.
Many Z900 owners convert to the Z1000 rear end, to have a rear disk brake. You simply have to mount the rear master cylinder on frame.
RegardZ.

I'm pretty sure the J arm is a different dimension at the pivot mount

The 1000J arm is 235mm at the pivot point.
I think it also has larger tubing than the earlier Z1000 arm.

the reason i'm asking is when i came to replace the bearings they seem to be z1000j type, my bike originally was a z1r d3. the chain guard didn't fit right but i thought it might have been a bad copy. it had also but cut to clear the rear shocks just wondering if the bottom shock mounts are closer together on a j model

MFP, standard shocks do not usually interfere with the chain guard. I think you will find they are aftermarket shocks, that have the spring protruding down further than the originals. I have seen many chain-guards cut away to cater for these possibly better shocks.
RegardZ.

Further to the dimension check of swing arms, I found this in a previous post, relating to Z1 series/ Z900 and Z1000.

Now, width of the swing-arm bare is 220 mm.
When you add the bearing flanges you have 226 mm.
Then, allowing for grease caps you have 228 +- 1mm.
RegardZ

just measured my swingarm; the bearing tube is 235mm so it looks like its a j arm.
the internal measurement of the shock mounts is 240mm. can anyone measure a early z1000 to compare.
thanks

The J arm is 235mm at the pivot point but I don't know the distance of the shock mounts, a Z1000 A1/2 is 228mm at the pivot point and the shock mounts are 250mm measured from the outside edge of the inner mounting lugs and 293mm measured from the inside face of the outer lugs.

thanks everyone for your help