Complete rear assembly from a 90 to my 84?

[Canadianlocost]

So I am well into the disease of modification. 2 months into my ownership of this 841100, and I now have a bent shifter fork, I found my rear suspension linkage has a TON of slop, my rear tire is done, and the front end swap that was done by the PO is an inch and a half short of original in length. So... I bought a bastardized "streetfighter" bike that would not run. It has a brand new rear tire, and nice clean suspension, low miles on the motor, and original front end.
My question is, if I do the whole assembly, is the rear suspension a direct bolt in? I have been googling and hunting here, and have not found a direct answer. The 1200 is now a pile of parts, and I will do the engine swap tomorrow, and I am hoping someone can tell me about the swingarm swap before I start.

Thanks in advance!

[aviationfred]

The quick answer to your question is.... You need to find out what year the 1200 is. Does the 1200 have dog bones, is so, the swap you are looking for is not an easy swap. If the 1200 has the same scissor type lower shock linkage as your 1100, than it should be an easy direct swap. Here is a photo example of a late model 1200 with dog bones.

Fred 

[Canadianlocost]

The new one is a 90, and I have the complete bike. My plan is to use the engine, swing arm assembly, and forks. My parts bike was clean, low miles, but the victim of a wild imagination!

[Canadianlocost]

the linkage I have...

[balky1]

the linkage I have...

Compare the upper mounts of the shocks. I think there lies one of problems. And is the way that shock linkage connects to the frame similar to that of 1100? Or does it connect to the frame at all?

[Pat Conlon]

Yes, the '90 swing arm and linkage will work on your '84. Use the shock off the '90 to get you going. The '84 shock will be too long besides the '90 relay arm shock mount needs a clevis style attachment. Plan on a shock upgrade in the near future. The oem shocks on the FJ leave a lot to be desired.
Plan on some custom dogbones (easy to make) to get the rear height where you want it.

[Canadianlocost]

Yes, the '90 swing arm and linkage will work on your '84. Use the shock off the '90 to get you going. The '84 shock will be too long besides the '90 relay arm shock mount needs a clevis style attachment. Plan on a shock upgrade in the near future. The oem shocks on the FJ leave a lot to be desired.
Plan on some custom dogbones (easy to make) to get the rear height where you want it.

Pat (et al), you said plan on some custom dogbones to get ride height... I think I misunderstood initially, and have been scratching my head. I bolted it all up with the complete 90 assembly, and it is REALLY tall like, the centre stand does not touch the ground, and the shock is touching the swing arm! I am pretty sure the shock with the parts bike is stock, but it looks like it is longer than the one I took out. MAybe the one that came with my 84 was super bagged out? The bike was way short before...

[Pat Conlon]

So you used the '90 shock, correct? It should be shorter than the oem '84/85 shock.

With the bike on the center stand, disconnect the dog bones, place a piece of 3/4" plywood under the back tire. Now measure for the new bones, understanding that they will be longer than your existing oem '90 bones.
If the back end is still too tall for your tastes repeat the process with a thicker piece of lumber under the back tire.

When you make the bones be sure to clamp both pieces of the strap steel together to drill the holes. That way the holes will be accurate between each bone.
Any deviation on the measurement of the holes on your dog bones will unevenly load the needle bearings in the swing arm and relay arm, resulting in premature bearing failure.

Hope this helps.

Pat

[Canadianlocost]

Yes sir, I saw the post with the advice to another wayward soul... I have the extra barrier right this moment that the front end is off the bike too for front tire replacement. Must exercise a bit of patience. I am using the 90 shock... for now at least. This is turning into a really expensive undertaking, and I need to pace myself now.

Thanks for the help Pat. I LOVE the look of your bike! I am looking forward to having mine similar.

[Firehawk068]

Wasn't Mark (Monkey) going through this exact process, trying to swap a "Dog-bone" style suspension on to an earlier non-dog bone frame?
I believe I recall him running into an issue with the upper shock mount being too low in the frame for the length of the shock, or something to that effect? 

[Canadianlocost]

I read someone was trying to change some parts, not all parts. I sat and stared (wonderfully relaxing for me!!) for quite a while, and I am sure Pat is right. A little longer dog bones, and I will be ready to go. I have the 90 frame, and I did not look at them both stripped and side by side, but id the mounting points are different at all, it is not much.

[FJmonkey]

Wasn't Mark (Monkey) going through this exact process, trying to swap a "Dog-bone" style suspension on to an earlier non-dog bone frame?
I believe I recall him running into an issue with the upper shock mount being too low in the frame for the length of the shock, or something to that effect? 

Here is my unfinished effort. http://www.fjowners.com/index.php?topic=12878.0

[Canadianlocost]

The dog bones were only 1/2 an inch longer... The centre stand does touch them though. What to do about that will be a later question.