Aftermarket rear Shock Modification

Merlin III

New member
This Winter I researched aftermarket rear shocks with adjustments that the stock shock doesn't have. Here are some pictures.
The first photo shows the easily usable damping adjustment and the rear wheel height adjustment: Suspension 1.jpgThe second and third photo depicts the external fluid reservoir which also has an adjustment for high and low speed compressionSuspension 2.jpgSuspension 3.jpgSuspension4.jpgThe last picture shows the easily adjustable pre-load adjuster suspension5.jpg
Out of the box the ride is greatly improved. Getting the best settings possible for our comfort zone is an art and I just recently took the bike out of Winter storage and haven't had the time to experiment.
 

Steven

Member
Thanks Merlin. I actually spoke to the fellow who installed this on your bike. I really appreciate that you brought your bike in and let them perform surgery on it. Now we have an option other than stock.

I can't speak for everyone, but the suspension is totally inadequate for heavy riders. Sure we can beef up the preload/sag of the oem shock , but that doesn't help much when the roads get rough. Hmmmm, I feel like I'm preaching to the choir here.

In any case, I ordered the same shock, but if it corrects what's wrong with the CTX's suspension, it's well worth the cost. The CTX does so much other stuff right that it's worth the investment.
 

Mister Hand

New member
After Market Rear Shocks

The main complaint I have about this otherwise amazing bike is the rear shocks and how jarring the ride is... even after I have adjusted the stock shock to its softest setting. My partner rarely consents to ride on the thing 'cause she says it hurts her back when we hit large bumps and is very unpleasant over the smaller ones.

So... if two of you on this forum have installed this aftermarket shock.... how is it? And from what I have said, do you think it would be appropriate for me? I weigh about 160 and with my partner and gear we weigh just over 300 pounds.

I really want something that I can easily adjust preload and rebound and not go through the torture I experienced while adjusting the current stock shock.

Many Thanks,
Tony
 

Merlin III

New member
The main complaint I have about this otherwise amazing bike is the rear shocks and how jarring the ride is... even after I have adjusted the stock shock to its softest setting. My partner rarely consents to ride on the thing 'cause she says it hurts her back when we hit large bumps and is very unpleasant over the smaller ones.

So... if two of you on this forum have installed this aftermarket shock.... how is it? And from what I have said, do you think it would be appropriate for me? I weigh about 160 and with my partner and gear we weigh just over 300 pounds.

I really want something that I can easily adjust preload and rebound and not go through the torture I experienced while adjusting the current stock shock.

Many Thanks,
Tony

Tony, I weigh 170. I played with the pre-load adjustment on the stock shock every which way I could. It didn't help no matter which way I adjusted it. As you intimated, the shock isn't made to be adjusted so either you attempt to adjust it for one or two persons and just leave it there. The VP of the Yankee Beemer MC club has a CTX700. I met him and his wife at a camp out and their complaints were the same as your wife's. It was their first 2 up and she was saying "never again".

The Penski shock has relatively easy adjustment for preload. I have seen shocks that were easier, but the Penski is much, much easier to adjust than the CTX stock. What you do is set your preload for one up and mark it. Do the same for two up. The damping adjustment is very easy to adjust. I am still experimenting and trying to find the best setting. It is a trial and error process. I haven't even looked at the high and low speed compression adjustment yet.

One of the biggies is ordering the right spring for your weight range. I rode today and thought about the quality of the ride with the new shock. I put the quality of the ride, at this point in my experimentation, on a par with my wife's Dodge Grand Caravan.

The only gripe I have is the quality of the instruction manual. I think it was written for someone more knowledgeable than your typical bike owner. In the best of all worlds, I would take it back to Boston Computrak and have them actually work with me on tuning the shock. Tuning a shock IMO is an art and the more knowledgeable one is the faster the process will go. Boston Computrak will sell the same shock with less adjustments for less money. You can get one with pre-
load and damping for around 700 dollars.
 

Steven

Member
The main complaint I have about this otherwise amazing bike is the rear shocks and how jarring the ride is... even after I have adjusted the stock shock to its softest setting. My partner rarely consents to ride on the thing 'cause she says it hurts her back when we hit large bumps and is very unpleasant over the smaller ones.

So... if two of you on this forum have installed this aftermarket shock.... how is it? And from what I have said, do you think it would be appropriate for me? I weigh about 160 and with my partner and gear we weigh just over 300 pounds.

I really want something that I can easily adjust preload and rebound and not go through the torture I experienced while adjusting the current stock shock.

Many Thanks,
Tony

Mine hasn't come yet, perhaps next week. I'll update when I can get it installed. As for the oem shock, I'm not a light guy (at least not yet, working on that too), I have added shims to increase the preload and that has helped, but I still bottom out once in a while. Where the oem fails mostly is when encountering sharp bumps or pot holes, it feels like the bike is going to break. The oem (shimmed) does just fine on small bumps, but on some larger (but more rounded) bumps I can feel the shock really pumping up a down using all of it's travel.

As for adjusting the oem shock, it' such a PITA that it's easier for me to remove it from the bike, which I have. The Penske shock comes with a little bar for adjusting the preload and the preload aduster has round holes for inserting the bar. At this point, it seems that would be much easier to use compared to a spanner wrench or a punch and hammer that some people use.

I'll let you know...

It all works out well, I'm going to go with the cartridge emulators too for the front forks. While the forks don't effect ride quality as much as the rear shock it should help some and make the bike a little safer. Nothing is worse than being beat up during a long ride.
 
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Steven

Member
Just FYI, the shock will go out in the mail tomorrow, I'm excited. If all goes well, the fork cartridge emulator is next.
 
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BigO1987

New member
Placed my order this week for new shock.

Just FYI, the shock will go out in the mail tomorrow, I'm excited. If all goes well, the fork cartridge emulator is next.

I went with a different shock, the Penske 8975. I spoke to Peter from computrack and decided to go with the more simple shock. It is already on their website. I should get mine in two to three weeks. The front forks will follow after the rear shock. The racetech emulators and maybe new springs...not sure about springs yet...will be on mod list.

If these mods improve the ride and handling by 20%, then it will be well worth the expense!!! I plan on keeping my CTX for some time, as it meets all of my needs for my motorcycle adventures.
 

ofdave

Member
@BigO1987
keep us posted on the shock, always good to have more choices
and let us know what's involved in installing the emulators
 

Steven

Member
I've read a lot about the emulators and it's all good. As for the springs, you need to check your front end sag. At my weight just sitting on the bike, I only had an inch of travel left on my forks. I had added preload and that helped. If you don't have the right sag, you should seriously consider new springs.

Yesterday, with the stock suspension, I was doing 85mph on a slightly non smooth road, it was not fun. It was windy but that wasn't the problem, the suspension was just too soft and I felt like I was on the edge of loosing control. I have high hopes for these suspension changes, we'll see...
 

Steven

Member
Just FYI, the new shock is coming today.. Now it's a matter of getting the ambition to swap it out.
 

Steven

Member
Preliminary report...

Last night I installed the shock, it's getting easier every time. The first thing I notice was that the Penske was shorter by about an inch. It has an adjustment to make it longer by about 1/2 inch, so I extended it out that 1/2 inch. Being shorter changes the rake of the front end and slows the steering which is very noticeable. That may be a good thing as it makes it more stable. It also lowers the bike a bit and reduces the clearance between the tire and the fender, but that may not be an issue. I can't really notice that the bike is a little lower. It also looks like the new shock has more travel (Peter from RaceTech said it would). The only other thing was that it's also a little wider then the oem. It does look like a quality piece. After looking at the manual, I come to realize that this shock is very adjustable in about every way. It's a very impressive piece of engineering.

I did take it for a ride, but I'm going to hold off on my review of that until I get the sag set, at the moment I don't think there is any sag. I may also have gotten too strong of a spring, but we'll see. With the oem, when I would take the bike off the center stand, the bike would bounce a little, with the Penske it didn't compress at all. Like I said, I need to adjust the sag, before I continue or risk putting my foot in my mouth.
 

Merlin III

New member
Preliminary report...

Last night I installed the shock, it's getting easier every time. The first thing I notice was that the Penske was shorter by about an inch. It has an adjustment to make it longer by about 1/2 inch, so I extended it out that 1/2 inch. Being shorter changes the rake of the front end and slows the steering which is very noticeable. That may be a good thing as it makes it more stable. It also lowers the bike a bit and reduces the clearance between the tire and the fender, but that may not be an issue. I can't really notice that the bike is a little lower. It also looks like the new shock has more travel (Peter from RaceTech said it would). The only other thing was that it's also a little wider then the oem. It does look like a quality piece. After looking at the manual, I come to realize that this shock is very adjustable in about every way. It's a very impressive piece of engineering.

I did take it for a ride, but I'm going to hold off on my review of that until I get the sag set, at the moment I don't think there is any sag. I may also have gotten too strong of a spring, but we'll see. With the oem, when I would take the bike off the center stand, the bike would bounce a little, with the Penske it didn't compress at all. Like I said, I need to adjust the sag, before I continue or risk putting my foot in my mouth.

Yes, I forget the number Peter told me, but it was a substantial amount. You got yours from RaceTech? The Spring was most likely engineered for your weight by Penske, mine was. It takes time playing with the adjustments, at least for me it did. I am still playing with the damping. :) I have a rally coming up in a week and hope to put more time in on it.
 

Steven

Member
BTW, I just spoke with Peter and he said they will work with me till it's right, assuming there's any problem. I also mentioned the difference in shock length and he said that the Penske and the oem should be the same. He said that there was a special order requiring a shorter shock and that perhaps Penske made this one under those specs. He's looking into it.
 

BigO1987

New member
BTW, I just spoke with Peter and he said they will work with me till it's right, assuming there's any problem. I also mentioned the difference in shock length and he said that the Penske and the oem should be the same. He said that there was a special order requiring a shorter shock and that perhaps Penske made this one under those specs. He's looking into it.

Interesting. I may call them tomorrow to make sure my order does not have this potential issue. This is not an inexpensive project for sure.

Looking forward to your updates.
 

Steven

Member
First, concerning the shock length... After looking at it in the light the rear sits pretty low now, so shock length is very important. Yesterday I began adjusting all the settings.

Preload/Sag - I guess it was pretty tight because the bike had almost no give/sag, which made me think the spring was too strong. After adjusting it one turn, it was much better. I was rather surprised that one turn was the difference between feeling like it wouldn't move at all to being more compliant. I went two turns just to give it some play while I was adjusting the other parameters . With the way the shock is constructed, it was very easy to change the preload with the supplied tool.

I found that the compression setting made the most difference to smooth out the bumps. I did the rebound first. Both setting are easy to do, and can be done without taking the bike apart.

As for the ride, it does help a great deal, but I'm still having trouble with it handling sharp hard bumps. On the other hand, I took the bike on a section of road that was moderately rough and when I got to the end I thought to myself... Did I miss all the bumps? Yes, this is actually true. So, so far so good.

I can't help feeling that with the rear setting so low now that it has some effect on the ride. I'm sure there is some extra weight being put on the rear due to leaning rearwards.

One last thing...

I'm new to adjusting suspension and so I don't know what I'm doing. Sometimes it seems counter intuitive. For instance, if I hit a bump and it feels hard, the first thing I think is to reduce compression, but the proper thing to do (often) is to increase compression. On the other hand, if compression is already set too high it will feel hard on that bump, so reducing compression is what is needed. Can you see where I'm going with this?

I guess you have to see in your mind what's happening between the tire and the road. Anyway I won't bore you folks any further, you probably know all this stuff.
 
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Merlin III

New member
Thanks Steve. You are inspiring me to get off my ass and fine tune my suspension. I adjusted mine so that I had (from memory) 35MM of sag. That was sort of arbitrary IMO. From there I adjusted the damping starting from the middle setting 2 clicks at a time to a point where I thought it was fairly good. I haven't touched the high and low compression. Fortunately, I can go for a two hour ride and see Peter for expert advice. When I picked up my bike (he installed it because it was a prototype), he was going to do the complete setup with me, but when it came to it we both decided it was just too damn cold. Have you adjusted the high and low suspension yet? Also, I don't know what you mean by sitting low (suspension)?

Just a couple of things I have learned:
1. All adjustments should be done with the suspension warmed up. That equates to a 1/2 hour ride first.
2. I found that putting the bike on the center stand (although not necessary) made it easier to adjust the pre-load.
 

Steven

Member
I don't know what you mean by sitting low (suspension)?

The Penske shock was about an inch shorter than the oem so that when I installed it the tire sits further up into the fender (the bike is squatting down so to speak). An inch on the shock is a great deal more on the wheel. I didn't actually measure the difference but it looks to be about an inch difference on the shock. The tire looks like it sits in the wheel well about two inches too far. Here's some pictures... The one without the plastic is with the Penske shock. They are at different angle, so you'll have to use your imagination a bit.

Now I don't know what you mean about hi low suspension... I should read the manual. I should also note that the reservoir hose leans up against the bike frame. I put some duck tape on it for now, but will devise a more permanent solution later.
 

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Merlin III

New member
Here are my specs:
8983 shock
1400 spring rate
152 free length
142 set length
10 preload

I didn't notice any difference in ride height with my shock, but then again I didn't check for a difference either. Maybe you can check your specs against mine and compare to what the guy from the other site posted on his original shock mod.
 

Merlin III

New member
I turned my damping knob counterclockwise a few more notches and went for a long ride. Part of the ride was over an Interstate highway bridge abutment that has quite a change in elevation at one of the expansion joints. The shock handled it pretty well.

That was the same expansion joint that I wrote about last year in the other forum that apparently bottomed me out and caused me a back injury that took me nearly 6 months to recover from.
 
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