1987 Suzuki Quadrunner 300 Knocks When Down Shifting

[Lafytafy]

When ever i down shift from any gear, it makes a singular loud click or knock and I don't know what it could be. Anybody have any idea

[Gwbarm]

I think the first thing I would look at are loose or worn shift linkages, they can be adjusted, the manual tells you exactly how much play you need, im not sure on your model.

[Lafytafy]

18 hours ago, Gwbarm said:

I think the first thing I would look at are loose or worn shift linkages, they can be adjusted, the manual tells you exactly how much play you need, im not sure on your model.

How and where do I adjust them?

[Mech]

Do you blip the throttle as you downshift ? 

[Gwbarm]

You might try what Mech suggested, but the adjustment is on the linkage attached to the foot shifter. the manual tell you the exact freeplay it needs. 

[Lafytafy]

13 hours ago, Mech said:

Do you blip the throttle as you downshift ? 

no i shift it like normal and i dont abuse the heck out of it either

[Mech]

Well the noise you are hearing may be the gears inside the gearbox banging together because the two gears are spinning at different revs.

If you blip the throttle just enough to bring the engine gear up to the revs it's going to need to be at to engage the new lower gear you are changing down to, It may stop that noise.

I think you need to try that and see if it lessens the noise. The noise could be in a diff, or an axle, or the gearbox. If we eliminate the gearbox gears clashing it would be a good first step to diagnosing the noise..

The exact procedure if you are slowing down is you let the throttle off till the speed gets low enough to shift down a gear, then give the throttle a small  blip to raise the revs just at the instant you are moving the shift lever down, then let the throttle off to continue slowing down. If you are shifting down to tackle a hill then you have the throttle open as you approach the hill, then just as you are about to move the shift lever, but before you move it, you let the throttle off slightly to take the load off the gears you are in so they can slide apart easily, then just as you move the shift lever you give the throttle a blip so it raises the engine revs enough that it will be at the revs it should be for then new lower gear you are selecting. All these small throttlings on and off are done in milliseconds and it's critical they are timed right, and that the amount of throttle is just enough..  It's worth practicing though because in makes the bike last longer, increases your traction control and so riding skills and abilities.

Bikes and quads are not like modern cars or trucks or even tractors. They use really simple old gears and need user input to get the best out of them.

[Lafytafy]

16 hours ago, Mech said:

Well the noise you are hearing may be the gears inside the gearbox banging together because the two gears are spinning at different revs.

If you blip the throttle just enough to bring the engine gear up to the revs it's going to need to be at to engage the new lower gear you are changing down to, It may stop that noise.

I think you need to try that and see if it lessens the noise. The noise could be in a diff, or an axle, or the gearbox. If we eliminate the gearbox gears clashing it would be a good first step to diagnosing the noise..

The exact procedure if you are slowing down is you let the throttle off till the speed gets low enough to shift down a gear, then give the throttle a small  blip to raise the revs just at the instant you are moving the shift lever down, then let the throttle off to continue slowing down. If you are shifting down to tackle a hill then you have the throttle open as you approach the hill, then just as you are about to move the shift lever, but before you move it, you let the throttle off slightly to take the load off the gears you are in so they can slide apart easily, then just as you move the shift lever you give the throttle a blip so it raises the engine revs enough that it will be at the revs it should be for then new lower gear you are selecting. All these small throttlings on and off are done in milliseconds and it's critical they are timed right, and that the amount of throttle is just enough..  It's worth practicing though because in makes the bike last longer, increases your traction control and so riding skills and abilities.

Bikes and quads are not like modern cars or trucks or even tractors. They use really simple old gears and need user input to get the best out of them.

It can't be the gears because it sounds like a shifter linkage or something is slapping the right side casing. I know it is something to do with something hitting the casing though but can someone help me out with figuring out what is hitting the case? Thanks!

[Gwbarm]

There is a snap ring that holds the gearshift shaft in the correct position to keep it from moving, on the outside of the case, you might check to make sure it is still there and the shaft is not moving out of position. 

[Lafytafy]

Near the front sprocket?

[Gwbarm]

The shaft the the foot shifter attaches to coming out of the engine, there is a seal in the engine case right next to the seal is a snap ring that holds the shaft in place. If its there that's good sometimes they pop off, just something to check.

[Mech]

Ok that second explanation about the noise is much more helpful.  Does it make the noise if the engine isn't running ?

Forums are great if you get someone that has had the exact symptom before, or if there is some common problem with a model, but other than that we have to try and figure the problem by doing tests and noting the results and then following through a flow chart to isolate the thing, and hopefully the only thing, that could be causing it.

There is a shift lever operated clutch linkage over in the right side case. If you take the bung out to check the clutch adjustment you might see something looking too close to the cover, and while you are there you could check the clutch adjustment.

You should check the circlip Gw is suggesting too. 

You could try videoing down by the right case and talking us through exactly what stage of moving the lever you at as the noise happens..  If I was there and could hear and see it I could probably make an educated guess about what was happening, but from this distance we really are dependent on you taking careful note of the small details and reporting everything you notice to us.. Does the shift lever move smoothly and freely, does it have end float, does the noise happen every single downshift, is there any similar noises upshifting, at what stage of the lever travel does the noise occur, can you feel anything tapping on the right case if you rest your fingers on it ?
 

[Lafytafy]

Is there any other sort of adjustment i can do without taking the engine out? Thanks!

[Gwbarm]

I would say taking the engine out is what happens as a last resort, after you figure out what's making the noise. Its hard to diagnose where the noise is coming from with the engine out. You say the noise is coming from the right side , that's the clutch side, you might try adjusting the clutch as Mech suggested, or post a video of the noise its making, maybe we can help diagnose what's causing the noise.

[wiktoriatopajew]

are you sortet it out? if no i can help you i have service manual for this jsut send me pm thanks

[Mech]

Yes I agree with Gw.. Don't pull it out or anything apart till you are sure as you can be what it it causing it, and what you are going to do to fix it..

I think that right side cover can be taken off in place.. The manual will say.

Have you tried resting your fingers on the case as the noise happens to see if you can confirm it is something tapping the case ?

If you get the service manual it will have diagrams of what is in there, or online parts places have very good diagrams.

[Lafytafy]

I found the problem!! The shift linkage was worn out and it was traveling to far and slapping the case. Thanks for the help ya'll. 

[Gwbarm]

Thats good you found that , now aren't you glad you didn't pull the engine out.

[Mech]

Well done..  Glad you got it figured..