[JD H355]

So I purchased a new shock for my project, an '85 FZ750N, a Hyperpro Emulsion. The top of the shock doesn't fit into the frame slot, too large a diameter. I emailed the company I bought the shock from and the company that made it. I was wondering if anyone here has any sort of advice?

I need a rear shock for the bike as the one that came with it is pretty well shot. Unfortunately, an OEM replacement setup in about $850-900 thanks to discontinued parts. The Hyperpro setup cost me $650 already so the less expensive the solution, the better!

Thanks!

Here's a link to the build thread for the bike:
http://www.customfighters.com/forums/showthread.php?t=81545

 

[VTCB750]

Is there a top and bottom to the shock. Can you mount it the other way? Take some good pics of the mounts so we can see what you are working with

 

[JD H355]

There is a top and bottom to the shock, however the bushings are totally different sizes and the bottom is even larger in diameter. The issue is that the top bushing mount has too large a diameter to fit into the slot in the frame. If the diameter was about 1/8" less, it would probably fit right in. However I'd prefer not to file/grind down a $650 shock if possible.

Here's the pictures I have of the shock, I'll get some more tomorrow to post up, including the frame slot.

The new shock:

The old shock:

Side by side:




Notice the size difference in the tops of the shocks. The bottom will bolt fine, but the clearance in the frame slot is too small. I'll get pictures of the frame tomorrow and post.

 

[Jackstand Johnny]

Let's see a picture or two of the upper shock mount. Thats gonna help us out a lot. Theres a couple options off the top of my head you can do:

A. remove material equally from each side of the inside of the top shock mount OR
B. Cut off the upper shock mount entirely and fab a new one thats wider.

Is your shock mount bolted on or welded? This is why it would really help to see some pics of it. Dont go getting rid of that nice new shock yet. Im sure we can all figure something out.

 

[JD H355]

Unfortunately had to put the old shock back in the bike so one of the cars could come back into the garage. I did get a few pictures that might help though.

These two show how the shock sits in the slot.

The next two are the sides of the mount. As you can see, it's welded into place. Not sure how much I could grind and I'd prefer to keep the frame intact as it was just powdercoated in the spring.

Until I can get another day to move things outside the garage (snow/rain prevents that, sadly) I can't get the bike back up and the old shock pulled.

 

[Guest]

if i have this right from the pics, the top of the new shock is narrow enough to fit the frame its just the bushing in it that is too wide right?

if thats the case you can either make a new bush or grind the the existing new bush to fit, pretty simple really

 

[sebwiers]

One better aftemarket shocks, those bushings (or even the whole top end) can usually be swapped out, allowing use of one shock body on various style bikes (and keeping inventory costs down). I'd expect the shock dealer / mnfr can help you figure out the parts you need. I'd go that route before cutting anything. Did they never respond, or are you just impatient and looking for a DIY solution?

And yeah, if its just a matter of the bushing being over-wide, chucking it in a lathe and making it a bit thinner seems a logical solution.

 

[JD H355]

The issue isn't the actual bushing. The top support the bushing sits in (the darker grey portion) is too thick on the shock. As the frame slot has a 90 degree angles box, it won't allow the shock to fit in far enough to allow a bolt to go through both sides of the frame mount and the bushing. I'd rather not grind down the mount for the bushing for the sake of structural stability.


I have been trying to contact the shock manufacturer since Saturday. I managed to get a brief response today via their facebook page where they told me to send an email to someone at their company. The email address they sent me was not valid, though, and I have yet to hear back from them. The company I bought the shock from told me to keep them updated on what Hyperpro has to say. I'm hoping for a solution that'll allow the use of this shock.


I did have one idea that I'll throw out here, If I were to fabricate a bracket that bolts on to the frame with a new space fro the shock, it may allow me to use it. I'm only concerned about the geometry. Any thoughts?

 

[F'dup]

Does the shock fit in there "upside down" or the other way that you were trying to mount it in there?

 

[Guest]

So from the centre of the bush to the top of the shock is to tall to fit in the mount IE there is too much material above the bushing to allow the hole to line up?

New bush with an offset hole maybe ?

 

[JD H355]

Shock will not fit upside down due to bolt and bushing sizes as well as the bushing mount on that end being larger in diameter than the top mount.

The bushing itself is not the issue, the top of the shock where the bushing mounts is too large in diameter. If you look at the picture of the shock, you can see that the bushing sits in a welded on mounting hole. That is what is causing the issue as it keeps the bushing from lining up in the frame. A different sized bushing won't solve the issue as the centerline will still be too large.

 

[sebwiers]

Ugh, I've got a bicycle that's the same way (bought frame for wife, had a couple shocks, the one that SHOULD fit is to boxy because they changed the design- same model, different shape). If the actual part that hold the bush is to fat / close to the shock body to fit / rotate in the upper shock mount.... yeah, I got nothing.

 

[F'dup]

So what do you have for a part number on that shock?

You think they could have sent a genesis frame style?

 

[JD H355]

After finally hearing from Hyperpro, I think they may have sent a Genesis shock as they already asked of the bike was a Genesis. The only "part number" is "PA7028" on the label on the box...though the label says it should be for a 1985 FZ750. Hoping they have a solution for me, if not I may have to see if I can get a bracket made up for it.

 

[JD H355]

Well besides returning the shock, Hyperpro has no solution. According to them, the shock should fit and that is their smallest top piece they make. They also say they had a Dutch dealer pull up the specifications and it will fit for their bike. Not sure if I have a one-off frame or what could be going on there.

Only other thought would be to fabricate a new shock mount that bolts into the frame. Though as I sourced another shock, I'll most likely just return it and purchase one that actually fits correctly.

 

[a_morti]

I just saw this thread after posting in te other one.

The nitron of the type I had on my cbr is likely to have the same problem but I would still drop them a line with a clear detailed description of your problem and see if they can help.

Otherwise since hagon shocks are steel bodied, they use less material where you need clearance and so will probably work.

 

[JD H355]

I'll give them a shout and see if they have any advice or if they could build something to fit.