Author Topic: Rear shock installation assistance (Read 19972 times)

HCorn · « **on:** February 24, 2012, 12:16:07 PM »

I recently installed a Progressive 465 rear shock. While I've been happy with the performance, I recently had a disconcerting situation that I think may be from the shock. While taking off from a stoplight, I felt and heard sort of a shudder/mild thuds while in first and second gear. Not really sure how better I can explain it, other than it was clearly coming from the back of the bike (driveshaft, rear wheel, maybe tranny). I had felt this before more subtly, but this was enough that I pulled over to inspect the bike, especially since I recently replaced the rear tire. This was on a rougher bit of asphalt and didn't happen again.

I believe this is being caused by the rear shock. The eyelets on the Progressive shock are like Heim joints, allowing for the shock to rotate a bit - maybe 20 degrees. I can rotate it with my hand very easily, but didn't think much about it since I assumed it is just to allow for some movement in other directions. Although I don't recall my Works shock having this sort of rotational movement. But I think this play is causing the shock to rotate and hit the frame (repeatedly) in certain situations. See the pics below.

Here is the top mounting point showing the range of movement:

The second picture shows the contact that I think is causing the shudder/thumping.

Here is the bottom mounting for reference:

Let me know if you think this could be my problem or if I did something wrong on the installation. I'm sure I could easily add a rubber washer to minimize the movement, it seems like this should be pretty straight forward. Thanks for the help.

johnny · « **Reply #1 on:** February 24, 2012, 01:53:29 PM »

greetings hcorn...

about this photo... my works performance shock... the bolt passes through a split bushing... it centers the bolt in the shock hole and the nut tightens against the washer that tightens against the bushing... the shock floats on the bushing...

you gotts a bushing in there...

j o

HCorn · « **Reply #2 on:** February 24, 2012, 02:02:03 PM »

The split bushing is in there (that black rubber O Ring is on the outside half of it). It appears to be fitting properly - I can't move the shock side to side. I worried the bushing was too wide, i.e. the two halves compressing against each other, but not the shock. But if that were the case, I would expect to see some side to side movement. The movement you're seeing in the pictures is the rotational movement of the Heim joint, not the shock on the split bushing.

johnny · « **Reply #3 on:** February 24, 2012, 02:10:53 PM »

yawl...

photos be deceiving... yourn looks as if the washer tightens against the shock instead of the bushing...

unless you gotts a puddle of 75-90 under that thing i just donts know bro...

j o

HCorn · « **Reply #4 on:** February 24, 2012, 02:25:10 PM »

Well I appreciate the help nonetheless. I sent an e-mail to Progressive, maybe they'll have some insight.

The flip side is that it may very well have nothing to do with the shock and it is the tranny or final drive. I had the splines (all) lubed recently and was told they look good (bike only has 21K). I think I'm more concerned it may be the tranny, but it seems to coincide with the road surface.

DRxBMW · « **Reply #5 on:** February 24, 2012, 04:22:14 PM »

Quote from: HCorn on February 24, 2012, 02:25:10 PM

Well I appreciate the help nonetheless. I sent an e-mail to Progressive, maybe they'll have some insight.

The flip side is that it may very well have nothing to do with the shock and it is the tranny or final drive. I had the splines (all) lubed recently and was told they look good (bike only has 21K). I think I'm more concerned it may be the tranny, but it seems to coincide with the road surface.

I installed a Progressive 420 rear shock on Pete's K 75 in 2008.

FWIW, same issue with the bottom bushing NOT fitting correctly. (loose) Similar noises to what you are describing.

Progressive is a lame company to work with. Problem was still unresolved after several attempts to make them aware of the situation.

We ended up going with a Works shock the next year.

Be me, I would try an Ohlin bushing as a substitute. Or have a machine shop fabricate the right size bushing.

google "rod end bushing"

Go here:
http://performanceshock.com/shock-parts-oil/rod-end-shock-reducer-bushings

HCorn · « **Reply #6 on:** February 24, 2012, 04:52:09 PM »

The bushing definitely fits well (diameter) inside the shock eyelet and onto the stud. There's no play. My only doubt with respect to the bushing would be if the shoulder of it are too far apart. But since I can't move the shock itself side to side on the stud, it seems like it is ok.

However, the bushing has an O-ring that sits against the shoulder and I'm not totally sure why. It would make sense that it is there to limit/cushion the eyelet as it rotates on the Heim joint. From what I can tell, the O-ring never makes contact, so the only limit on the eyelet's movement is the limit of the Heim joint or my frame, which is essentially at the same point in the rotation.

johnny · « **Reply #7 on:** February 24, 2012, 05:09:30 PM »

i gotts another idea...

hcorn just likes to say heim joint...

say it... heim joint...

j o

HCorn · « **Reply #8 on:** February 24, 2012, 05:24:12 PM »

And the sad thing is I'm not even sure it's the right term!

But it looks and acts like one of these thingies:

Hymen Joint? No, that's not it either.

HCorn · « **Reply #9 on:** February 25, 2012, 07:18:01 PM »

So I took the shock off today to get a better look at things. Everything looks OK.

What I did learn from my inspection is that the range of motion is limited by the O-ring, not by the heim joint (I said it again :neener:). So I'm hoping to install a thicker O-Ring to limit how much play the shock has. I bought a whole variety so hopefully one of them works. If not, plan B will be two large rubber washers at the upper mount.

DRxBMW · « **Reply #10 on:** February 25, 2012, 08:28:07 PM »

Quote from: HCorn on February 25, 2012, 07:18:01 PM

So I took the shock off today to get a better look at things. Everything looks OK.

What I did learn from my inspection is that the range of motion is limited by the O-ring, not by the heim joint (I said it again :neener:). So I'm hoping to install a thicker O-Ring to limit how much play the shock has. I bought a whole variety so hopefully one of them works. If not, plan B will be two large rubber washers at the upper mount.

Confused, under the impression the bottom mount bushing was rotating. (twisting)

Explain how plan B would help ?

HCorn · « **Reply #11 on:** February 25, 2012, 08:52:49 PM »

The whole shock twists. I don't think the two eyelets twist independently, at least not without a lot of force. Limiting the movement of either end (ideally both) should solve the problem. However, the washers wouldn't really work at the bottom as there isn't anything for the washers to sit flush against. At the top, the washers would sit flush against the frame which is also where the eyelet contacts it.

If you look in this picture:

You can just barely make out the shoulder of the bushing (Dark black next to the lighter O-Ring). As the eyelet twists, the shoulder squeezes that O-ring against the eyelet limiting the movement. Ideally, an O-ring with the same ID, but slightly larger OD would be the way to go. For reference, the two piece bushing looks sort of like this (with the O-Ring on the inside of the shoulder):

DRxBMW · « **Reply #12 on:** February 26, 2012, 08:39:26 AM »

Quote from: HCorn on February 25, 2012, 08:52:49 PM

The whole shock twists. I don't think the two eyelets twist independently, at least not without a lot of force. Limiting the movement of either end (ideally both) should solve the problem. However, the washers wouldn't really work at the bottom as there isn't anything for the washers to sit flush against. At the top, the washers would sit flush against the frame which is also where the eyelet contacts it.

OK, securing the top eyelet will help.

Did Progressive ever get back to you ?

Obliviously, there is a fitment problem with the BMW shock stud on the lower mount.

HCorn · « **Reply #13 on:** February 26, 2012, 03:59:55 PM »

Unfortunately, none of the O-rings I purchased are the right size. And my washer idea did little to nothing to minimize the movement.

Progressive hasn't gotten back to me, but I'll give them a couple days since I e-mailed them on Friday.

I'm going to look a bit more for other O-rings since I think that is the root of the problem (aside from not having a perfect fit from the beginning).

HCorn · « **Reply #14 on:** February 28, 2012, 08:18:47 PM »

I received about 12,000 O-rings courtesy of McMaster Carr. The good news is that the shipment had the right size O-Rings. I installed them and it is accomplishing the goal of minimizing the how much the shock can twist (while still allowing a little play).

Now the question is whether this will be the solution to the actual problem of the bike having that shudder or just a Red Herring I've been chasing.

HCorn · « **Reply #15 on:** March 02, 2012, 01:56:48 PM »

I took the K out for about 20 miles over varied roads. I didn't encounter the same issue during the ride. However, the initial problem was intermittent, so I'm not ready to say it's solved. But I'll keep riding and hopefully nothing will explode.

billday · « **Reply #16 on:** March 02, 2012, 07:32:28 PM »

I just bought an old Progressive 465 that's new in the box (never installed, with instructions).

There is an extra sheet with the instructions headed "BMW K75/100 465 Series Single Shock Supplement."

It says "Shouldered sleeves with O-rings should already be installed in the shock eye. If not insert sleeves with O-rings in the top eye."

My unit has these items installed top and bottom, held in with zip-ties. Yours looks to be missing them.

HCorn · « **Reply #17 on:** March 02, 2012, 08:14:42 PM »

I didn't have that supplement. I bought mine from an online retailer, not directly from Progressive. But it does have the shouldered bushings and O-rings. IIRC, they were zip tied in place, too.

On yours, you'll notice that, although the bushings are snug, you can manipulate the joint quite a bit. That manipulation is only limited by the shoulder of the bushing squeezing the O-ring against the eyelet. If and when you install yours, I wonder if that play will result in contact between the eyelet and frame, or maybe there's enough variance in the tolerances between bikes. On mine, it barely contacted the frame at the extremes if you twisted the shock. Maybe on another bike it wouldn't contact.

My solution was essentially to just put a fatter O-ring (1/8" vs. 3/32") on the bushings.

If you find you need to do the same thing, PM me your address and I'll send you some of the bigger O-rings. I have about 11,996 left. :biggrin:

I am curious why your instructions say to install them in the top eye (rather than both top and bottom). Mine had them for both. :hmm:

lukeman · « **Reply #18 on:** March 13, 2012, 03:52:07 PM »

Hey HCorn,

I just bought a used 465 and recently installed it onto my bike. I ran into the same issue of the shock rotating with little resistance. I thought that this couldn't be normal as I really didn't enjoy the thought of the shock wiggling around on me while riding. I'm glad that someone else had the same issue so recently! :yes

I believe that my shock didn't have either of the O-Rings one either side which would be problematic if I understand the dynamics of these. I'll hit you up a PM seeing if you could send me some of those 19k o-rings you have.

HCorn · « **Reply #19 on:** March 13, 2012, 08:37:53 PM »

I replied to your PM and will send out those O-rings.

Upon more riding, however, I don't think the shock was the underlying problem. The problem is 2nd gear and I'm going to post a separate thread about that.

lukeman · « **Reply #20 on:** March 14, 2012, 09:56:08 AM »

Oddly enough I just did a transmission swap because my 2nd gear popped out of gear under acceleration...

conybeare · « **Reply #21 on:** March 14, 2012, 04:35:46 PM »

I think I'm a little late to help HCorn, but thought I would add that I asked a BMW tech at Chicago Motorworks about this exact thing - the shock rotating. He said it was normal, and just a function of that type of joint.

HCorn · « **Reply #22 on:** March 14, 2012, 06:45:12 PM »

Quote from: conybeare on March 14, 2012, 04:35:46 PM

I think I'm a little late to help HCorn, but thought I would add that I asked a BMW tech at Chicago Motorworks about this exact thing - the shock rotating. He said it was normal, and just a function of that type of joint.

It is clearly designed to rotate. But I'm just not sure it is supposed to rotate quite so much. Since it wasn't the source of my issue, the stock O-rings may have been fine. But I don't think I am going to swap back to them. Thanks for the info - I'm sure it will come up for others.

DRxBMW · « **Reply #23 on:** March 14, 2012, 08:20:21 PM »

Quote from: conybeare on March 14, 2012, 04:35:46 PM

I think I'm a little late to help HCorn, but thought I would add that I asked a BMW tech at Chicago Motorworks about this exact thing - the shock rotating. He said it was normal, and just a function of that type of joint.

Ask the tech WHY the Ohlin or the OEM does NOT rotate then ?

Sounds like bullshit to me.

lukeman · « **Reply #24 on:** March 15, 2012, 01:04:20 PM »

Well it think its more about what advantage does this type of pivoting of the shock have? Perhaps someone with more understanding of the physics of a shock could enlighten us.

News:

Author Topic: Rear shock installation assistance (Read 19972 times)