DIY monoshock repair

In detail: do-it-yourself repair of a monoshock from a real master for the site my.housecope.com.

We continue to get acquainted with the next instructions for repairing shock absorbers. What is a monoshock? This is an inverted shock absorber (with the stem at the bottom). There is oil at the bottom of the shock absorber and high pressure gas at the top of the shock. The gas in the shock absorber not only acts as a gas spring, but also prevents the shock absorber from failing with a sharp rebound and compression (a large bump or deep ditch). This shock absorber design allows them to be installed on heavy motor vehicles.

So, we are repairing the monoshock.

We start repairing the shock absorber by removing the spring. We take the most common grips. We put them on the spring from both sides and clamp them in turn until the spring is compressed and the washer that fixes it looses. Be careful when unsprung the monoshock using the available means. On these shocks, the spring is much thicker than on the backpack-type shock absorbers, and it has much more energy when it is released.

Image - DIY monoshock repair

Image - DIY monoshock repair

In our workshop, shock absorbers are sprung on special equipment

After we have removed the spring, set it aside. It will be useful to us only for the final assembly.

In our workshop, when repairing a shock absorber, we use a pneumatic vise for a soft grip so as not to damage the body.

Then we wash, wipe and blow through the case, after that we can begin to disassemble the shock absorber.

Image - DIY monoshock repair

Image - DIY monoshock repair Image - DIY monoshock repair

In our workshop we use a special stand for drilling and filling the shock absorber with nitrogen.

Video (click to play).

We retreat from the end of the body 17 mm and mark this place with either a marker or a core. After you have marked the future hole, take a drill with a diameter of 4 mm, and as straight as possible, holding the drill at an angle of 90 degrees, drill the hole.

Gas should come out. If oil comes out with gas, then the pneumatic piston is at bottom dead center. This, of course, is not very good, but fixable. There are several solutions to this problem:

1. You are trying to gently pull out the piston through the drilled hole with a thin screwdriver.

2. You drill another hole at the mount of the silent block and push the piston out with either a thin screwdriver or a jet of air. Naturally, then this hole will need to be welded.

In both cases, it will be necessary to replace the piston O-ring and caprolon guide.

If you have a damaged piston in the shock absorber and you need to make it, you can always contact our company for help.

If you drilled a hole and the piston is higher, do not forget to insert a small rivet there or use the available tools. This will be the simplest stop for the piston to keep it from dropping to bottom dead center. You can even wrap this place with paper tape, this will keep the stopper in place and prevent it from falling out of the hole.

We continue to disassemble the shock absorber. After we have released the gas, you can unscrew the lug from the shock absorber rod (if this is provided for by the design). Do not unscrew the lug until you have released the gas from the shock absorber! Take care of your forehead. Then we lift the top cover and upset the sleeve with the oil seal to remove the retaining ring.

Image - DIY monoshock repair

Image - DIY monoshock repair

The retaining ring is removed. We take out the shock absorber rod, pour the remaining oil into a previously prepared container. Wash, blow and wipe. It is recommended to wipe the shock absorber parts either with a paper towel or with a cloth that does not give lint and does not crumble into fine threads.

We take the shock absorber rod and disassemble it.We unscrew the nut on the rod and remove the bypass piston with a plastic clamp. This will save you time during assembly and nothing to lose during repairs. And it is very convenient to blow the piston after washing. If the thread in front of the nut is rolled, use a file, or a grinder, or a sharpener, but remember to wrap the bypass piston with paper tape before removing the thread. This will save the piston from excess dirt and possible mechanical damage.

Next, we disassemble the cover in which the oil seal is located. We take out the rubber bump stop, take out the washer and take out the cuff.

We wash the sleeve and blow it with compressed air. The assembly takes place in the reverse order. We insert a new cuff, then a metal washer and fix it with a rubber bump stop. The shock absorber can now be assembled.

We put on a bump stop, if it is not there, then we go to a car shop and buy a Zhiguli silent block. It should fit almost perfectly on the shaft. If there is an opportunity to overpay a little, buy a polyurethane (yellow) silent block, it will serve you much longer than a regular rubber silent block made of non-oil-resistant rubber. Trim it if necessary.

Then we put on the assembled sleeve with an oil seal on the rod, put on the bypass piston and tighten the nut. Do not forget to roll up the thread. Clamp the nut in a vice and screw on the eyelet. In this position, it is convenient to tighten, because both threads work for tightening.

If the shock absorber rod has mechanical damage or corrosion, our specialists can make a new rod for you.

If you cannot find a cuff, oil seal, bump stop or shaft guide, you can always contact our company.

Naturally, after we have drilled the shock absorber body and released the gas, we will need to refuel it, without it the shock absorber simply will not work. What are we doing…

We go to the nearest tire service and purchase various fittings and nipples there. All this will not cost much, so I recommend taking each type one at a time. After we drove a couple of shinomancers in the area, we have.

Now we are guided by the situation. If the place where the shock absorber is located allows you to put a long fitting, put a long one. If the space allows you to install only a short one, then, accordingly, install a short fitting.

We take the injection fitting, apply it to the shock absorber hole, fix it with a clamp and go to a good welder to weld this fitting. Do not forget to remove the piston from the shock absorber and unscrew the nipple from the fitting before welding. Remember to check the weld seam for leaks after welding.

Image - DIY monoshock repair

Image - DIY monoshock repairImage - DIY monoshock repairImage - DIY monoshock repair

We put the shock absorber housing vertically, the piston that divides the shock absorber into two chambers, insert it into the shock absorber housing and rest against a thin screwdriver or awl, which we previously threaded into the nipple. Place an empty container underneath to drain excess oil before filling the shock absorber with oil. Otherwise, all the oil will be on the floor. Fill the shock absorber with oil and carefully insert the assembled rod. When the rod rests against the separating piston, it will be necessary to remove the excess oil in the shock absorber housing. This can be done with a regular syringe, which is sold at any pharmacy. After that, you can insert the bushing with the gland and fix it with the retaining ring. We take out our screwdriver or awl from the fitting and screw the nipple into it. In this case, the shaft is in the extended position.

After assembling the shock absorber, the rod must not be pressed into the shock absorber housing. ... Otherwise, you will have to disassemble the shock absorber and get the separating piston from bottom dead center

Then you take the assembled shock absorber and go to the nearest fire department or to the scuba divers. You need to pump 22-26 atm into the shock absorber. The amount of pressure depends on how much you weigh, what you are carrying with you, and who you are riding with. We usually pump 22 atm into monoshock absorbers.

In our workshop for the injection of high pressure nitrogen, we use a special booth

Image - DIY monoshock repair

Image - DIY monoshock repairImage - DIY monoshock repairImage - DIY monoshock repairImage - DIY monoshock repairImage - DIY monoshock repair

After filling the shock absorber with air, the piston rod must come out of the body under pressure. After that, we will be able to determine if it is assembled correctly or not. If there are smudges and oil stains on the shock absorber rod, then you will have to repeat the assembly and disassembly again, because something is not assembled correctly and is leaking oil somewhere. If the shock absorber rod is dry and there are no leaks, then you have repaired the shock absorber. Install it on your motor vehicle and use it.

  • You want to fill the shock absorber with nitrogen;
  • You want to repair the shock absorber or diagnose an already repaired shock absorber;
  • You want to purchase a spare part for a shock absorber from us or you need to make it according to your sketch or drawing (we send spare parts to the regions by mail or courier service).

We draw your attention to the fact that in our company all repaired shock absorbers are checked at a two-speed test bench, which allows us to give a 12-month warranty for the repaired unit.

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magneticman 18 Feb 2014

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magneticman 20 Feb 2014

Repair of gas-filled shock absorbers
A source :
Author: Nazar Gazzz
Repair of gas shock absorbers using the example of the Kawasaki Zephyr 750.
Initial data:

There is a pair of leaking shock absorbers from a 1991 Kawasaki Zephyr 750. Add. defect - the absence of rubber bumpers on the rods. On the body of the shock absorber there is an inscription stating that the shock absorbers are not repairable, and it is generally not worthwhile to climb into them, because they may explode.

The first thing you need to know for someone who is going to independently repair motorcycle shock absorbers is their device. We will try to study the basic scheme and fix the main breakdowns with the help of this article.

So, the shock absorber consists of a working cylinder with a lower eyelet and a welded bottom, a rod with a piston and its guide, and a separating piston. In the working cavity there is a shock absorber fluid, in the second cavity there is technical nitrogen under high pressure. The principle of operation of this unit: when the suspension is compressed, the piston goes down, as a result of which part of the liquid flows from the cavity under the piston through the valve into the cavity above the piston. The valve is a throttle channel, which is closed by a plate compressed by a spring.

Image - DIY monoshock repair

Shock absorber problems don't have to be accompanied by oil on the stem. Let's take a look at some of the signs, in the presence of which it is worth repairing motorcycle shock absorbers. If on uneven sections of the road while driving you began to feel the "punching" of the fork, then you should already be on your guard. You should also look into this part of the motorcycle if it has become less stable than before, or the fork has become much "softer". Another signal for concern will be the phenomenon when, while driving, you begin to hear an incomprehensible noise or knock from the shock absorbers.Image - DIY monoshock repair

Using a damaged motorcycle can be unsafe and there is no need to postpone repairing the shock absorbers. After all, they have a heavy load during braking, and especially during emergency! The reasons for the breakdown of motorcycle shock absorbers can be different. For example, the most common of them are: irregular oil changes, improper repairs, breakage as a result of impacts against obstacles, mechanical damage to the stem (scratches, rust, stone fragments), damage to the shock absorber spring.

Image - DIY monoshock repair

To begin troubleshooting, you need to place the motorcycle on an elevated position, such as the centerstand. If you do not have one, you can use a special holding device or any improvised items, since this is not a multi-ton car. Install the motorcycle so that the wheel you need is hanging out. Use a counterweight if necessary.Image - DIY monoshock repair