Trooper rear suspension change

[Guest Lenny]

I recently posted some details on my rear suspension changes. I've got to admit, it felt really good and I was excited. However Flatbed who knows a lot more about suspension then I do advised me that my setup though feeling good to me had some problems as to how I approached the geometry. One thing he said was that I would blow a shock with my setup. While I hate to let him be right (DARN) but my next trip out ended up with a blown shock. While I look for fox shocks, I'm going to convert my stock shocks to rebuildable. I have a machine shop in my garage so this shouldn't be to complicated. When I zero in on my new seal part numbers, I post them here along with how I made the change over. It should be a better quality shock when I'm done.

Lenny

[flatbed]

lenny, the 2.0 sleeve that goes between the two springs should fit the stock shock, 5" and 10" would do wonders in the back, Try to use a spring compresser with the stock shocks, or make sure you use oil on the threads, I had one of mine siez up when taking the springs off. When you get the shocks apart you might be able to build a new piston to acept good seals. Make sure the shaft has a good nut holding the piston on. You got the right idea, might be able to sell a kit to others, a exchange program.

[Guest Lenny]

I have had my threads seize also to a point where I was forced to cut the stock adjuster off. This obviously creates a lot of damage to the threads. There is a fix that works real well. First use a thread file or a three sided file to clean up the threads the best you can then use one o the good adjuster nuts and get some 240 grit grinding compound (comes mixed with oil in a can) and spread it on the threads. Now take a good nut and run it on the threads by turning it back and forth maybe 45 degrees at a time as you slowly screwing it farther on the shaft. When you get to a tight spot, don't force it, instead just keep turning it back and forth while proceeding only as it allows you to. Do this until the nut runs smoothly over the damaged spots. I also added synthetic oil to the mix to help prevent sticking. This hones the threads to fit the adjuster nut without honing the nut itself enough to matter. When your done, make sure you use a solvent to wash all remains of gringing compound from the nut and shocks threads. After, add lubercation, I prefer oil over greese as it doesn't hold contaminates as well. You'll find now that the threads actually look real good where the damage was and the nut runs properly on it. I always blow the threads off with an air hose before any adjusting. A spring compressor should also always be used to remove spring pressure before any adjusting. Their available on Ebay for about $20-$30.

I've added a picture of the cut open shock. From left to right you have the rubber bumper then some scrap peices of the cut end of the shock body then there is the wiper seal which alos provides saling between the gland and body tube, then there is the gland which fixes at the bottom of the tube where it's cut off. This gland holds the main shaft seal that keeps oil from getting out of the shock or blowing. Once it blows, the wiper seal isn't enough to stop as it will just push away. At the left end of the rod is the valve assembly. This is a series of thin flat disk that get larger is dia. as they stack.

Lenny

[Kinarfi]

Lenny, Take a look at these photos I took of my shock when I took it apart, I probably didn't do as good a job as you, but I got lots of photos. If I have any parts that you need, let me know, I figure a cap can be made to thread onto the body that holds the seal, thereby making it rebuildable.

[flatbed]

Lenny, if you use a limit strap you can get rid of the spring which will give the shock more travel. Measure the thickness of the shims on the valving. To me it felt like the compresion was to stiff and the rebound was to soft.The shims should be different thickness stacked like a pirymid, is there enough shims to where you can move them around. I am sure you can figure out which way the oil flows. The end with the hime should come off. I use alum halfs with a hole in it, use the press to aplpy force on the shaft. Use map gas to release the lock tight to take the end off. Also you might be able to get rid of some material on the shaft bushing end. Can you put a snap ring on the inside of the shock body to hold the shock together, maybe weld a machined piece on the end of the body so you don't make it longer. That body is already to long for the stroke of the shock, try to keep it short.

[Guest Lenny]

Flatbed, thats a good idea, I'll take a look at it when I get it back. Right now it is at a hydraulic shop. There is a older guy there that has worked with hydralic cylinders for 30 some years. Needless to say, you feel like your in school when you talk with him. Anyway, he wanted me to leave the parts so he could go through his catalogs to find the best seal combination. He knows exactly what I want to do. There is a stack of pyrmiding washers on both sides of the bypass block. the stacks looked the same on both sides. I'll check it when it's back and let you know if I find anything that looks unexpected.

Lenny

[Guest Lenny]

Lenny, if you use a limit strap you can get rid of the spring which will give the shock more travel. Measure the thickness of the shims on the valving. To me it felt like the compresion was to stiff and the rebound was to soft.The shims should be different thickness stacked like a pirymid, is there enough shims to where you can move them around. I am sure you can figure out which way the oil flows. The end with the hime should come off. I use alum halfs with a hole in it, use the press to aplpy force on the shaft. Use map gas to release the lock tight to take the end off. Also you might be able to get rid of some material on the shaft bushing end. Can you put a snap ring on the inside of the shock body to hold the shock together, maybe weld a machined piece on the end of the body so you don't make it longer. That body is already to long for the stroke of the shock, try to keep it short.

Well flatbed, I have my shock parts back. I need a little advise if you would share your knowledge. There is a pyrmid stack of shims which are as follows:

1-.021" thick x .770" dia.

2-.019" x .917

3-.015" x 1.066

4-.015" x 1.303

5-.011" x 1.381

6-.017" x 1.586

I can see that the oil is allowed to flow through the center block up against the largest washer side of the stack. As washers are added, the flow is more restricted (dampened). The washer stacks are idenical on both sides of the center block. How and what washers would you sugest be moved from the compression dampeninbg stack to the extension dampening stack and where in the stack should it go.

You also said something about removing, I assume, the main rod from the heim. I'm not sure why you wanted me to do this. Also what is Map Gas, I never heard of it and where do I get it? I do plan on removing the spring and adding limit straps as you sugested. I also will be weldng a band on the very end of the cylinder to reinforce where I will be cutting an internal groove to receive a snap ring.

I now have all my seals. The new rod seal is specifically designed to seal a hydraulic rod. It is rated to hold 5000# working pressure. The stock shock only has an O-ring for this purpose. As I laid everything out it seemed that the rod could be about 3" to 4" longer. ( see picture at http://good-times.webshots.com/photo/29162...104282158irnRUN ) This would increase the stroke by 3" to 4". I would then make a remote reservoir for the nitrogen ( in my case argon). So my next question is, is there any reason I don't want to do this? And if I do, could I go to a 6061-t2 aluminum shaft or would this be to soft or not strong enough. Otherwise could I use something in the 7000 aircraft aluminum series? That not being acceptable, should I just get a peice of ground and polished stainless steel shaft? I really don't know the maximum pressure put on this shaft otherwise I could just run the engineering numbers to select the shaft material. But these numbers don't tell me about rather it wants to be hard or not. It just gives me the working column strength of the shaft.

Anyway, I'm up to my normal self. Everybody says there is something wrong with me. I start out to do a fairly simple project and by the time I'm done, I've turned it into a major production. Maybe the doctor can give me something to make my mind go dormant for a while so I could relax. I live in a retirement neighborhood and they all think I'm nuts.

Lenny

[flatbed]

lenny, you need the extra 3" for the area to fill with oil when the shock is all the way in, the rod is taking up area that has oil in it when it is extended. since you are going to work with the shim stack that you have, i think i would take #5 out of the compresion side and double stack 5 on the rebound side. I think the rear springs are overpowering the shocks, and you proved it when you moved the shock mout. It gave the arm more leverage against the spring. I asume you are moving the shock back close to stock.

[Kinarfi]

Lenny, you say you got seals, did you get one for the bottom that looks like this? If so, I have some ideas, again, about a rebuild kit.

Jeff

[Guest Lenny]

Lenny, you say you got seals, did you get one for the bottom that looks like this? If so, I have some ideas, again, about a rebuild kit.

Jeff

The seal in your picture is the wiper seal which in this case also serves as the gland seal, The back side has circular ridges which seal against the bottom of the gland. Inside the gland is the main rod seal which on joyners shock is only an O-ring. I didn't blow out the o-ring in mine, I just blew oil past it which in turn blew out the wiper seal taking the gland seal with it and thus all the oil was lost. The seals I have gotten are different. I plan to use an o-ring to seal between the gland and the shock tube. I will cut a grove for the O-ring on the middle step on the OD of the gland. I then will modify the bottom of the gland to receive a wiper seal which is only about 1-1/4" in dia. The internal groove in the gland which receives the rod O-ring seal will be remachined to receive a good quality retangular cross section seal. The gland also has 4 holes in it that provide oil pressure to the back side of the original Wiper/gland seal (the one in your picture). These are required for their seal design. I won't need these so they will be welded shut. This modified gland with it's new seals will slide into the tube at a position pretty much where it was originally. To hold it into the tube I will cut a snap ring grove in the inside end of the tube to receive, you guessed it, a snap ring. I'm not comfortable with the amount I will have to thin the tube wall where the snap ring groove will be so I will be welding a reinforcing ring about 3/4" long to the end of the tube to reinforce the thined area. To rebuild, just pop out the snap ring and slide out the guts. The finished shock should be much more reliable then the stock one. If you have any ideas, let me know. I got side tracked putting a windshield on for the colder weather but tomorrow i'm going to be back on the shocks. I'll do pics when available.

Lenny

[Kinarfi]

Terrific, thanks for the info, I'll be checking mine tomorrow to get familiar with what you told me.

Thanks again,

Jeff

[flatbed]

Lenny, there may be something that keeps the rod bushing and seal holder from sliding into the tube to far, i do not know if the tube has that in it since i have not seen one of these shocks apart. You will need something to keep it out at the end besides the preasure that is in the shock. There are a couple of ways of doing it, i am sure you can figure it out. You talk about alum for the shock shaft, I dont think it would wear very good, plus it would ding pretty easy. You need a hard steel with crome or stainless.

[Guest Lenny]

Flatbed There is a step about 1/2" inside the tube end that prevents the seal gland from moving any farther into the cylinder. Thus the gland will be trapped between the step and the snap ring I'll be adding. I ended up making new glands for the seals. The original glands were centered metal and thus not weldable.