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Hello everyone,
I have a slow Snapper quantum xrm 6.5 hp (10 years old), I can't seem to figure out the cause.
Perhaps some of you can shed some light on the subject and help me figure this out.
I've spent many week ends on this challenging project.
I'm no expert but I believe this is a great mower, It has run great since day one and still performs very well except for the speed problem. This issue started several months ago.
Here are the details.

Behavior:
The lawn mower moves too slow even at the highest gear selection. (6 positions)
I use to have to run behind it at that gear selection.
(Yes, I did that on a few occasions)
Basically, it moves as if it was set on the 3nd gear position when it was operating normally.

Troubleshooting steps:
1 Replace driven disc spring-Yes
2 Replace driven disc-Yes
3 Replace all belts-Yes
4 Replace clutch cable upper spring-Yes

Other failed attempts:
I glued some 60 grid sand paper on a stick and applied it on the drive disc with the mower running. I did that to give the drive disc some texture for better grip.
I also tried to select a lower gear just to position driven disc on another surface area. It still ran slower that it should have.

Thats all I can think of right at the moment.
Hope to get some tips soon.
Thanks,
Michele

When you engage the drive does the drive wheel slow down or stop spinning? There are two different springs in this system. One applies tension to the idler pulley for the v-belt on the drive plate. The other applies pressure between the drive disk and drive plate. If either one of these are worn or missing it can allow the belts to slip and not spin as fast. Lastly, I did not see where you replaced or adjusted the serpentine belt. This belt actually transfers the power from the drive plate and disk to the differential. This also has another spring in it that can actually be adjusted as well. I would not recommend using sand paper on the drive plate again. It is designed to be very smooth. Any texture in it will cause premature wear on the drive disk.

Your engine rpms are OK?

jtk said:

When you engage the drive does the drive wheel slow down or stop spinning? There are two different springs in this system. One applies tension to the idler pulley for the v-belt on the drive plate. The other applies pressure between the drive disk and drive plate. If either one of these are worn or missing it can allow the belts to slip and not spin as fast. Lastly, I did not see where you replaced or adjusted the serpentine belt. This belt actually transfers the power from the drive plate and disk to the differential. This also has another spring in it that can actually be adjusted as well. I would not recommend using sand paper on the drive plate again. It is designed to be very smooth. Any texture in it will cause premature wear on the drive disk.

Click to expand...

Hi JTK,
thanks for the reply.
No the drive wheel does not slows down at all I don't think. I'll have to confirm.
I'm clear about the 2 springs.
As far as the serpentine ("V") belt, I don't remember an adjustment, only the drive spring.

I'm including some pics to highlight what was replace and/or adjusted.

Thanks,
Michele

Fish said:

Your engine rpms are OK?

Click to expand...

Hi Fish,
Thanks for the reply.

Yes the RPM's are fine.
I even tried to produce slip in the drive system by lowering the mower's rear wheels on concrete with the drive engaged.
No go either.

Thx.
Michele

Take a small flat tipped screwdriver and dig a little into the v of the pulley/disc, I have seen layers of cooked/dried grass
bake in there and that could change your pulley/speed setup.

Have you checked the yoke. If it has groves worn in it it will affect the driven disk's engagement.

If you stand your mower on end you can run your finger along the inside of the yoke and if it is bumpy it needs to be replaced.

I attached a pic from one of the manuals I hope it helps. It is labeled the lift yoke in the first diagram. It is under the driven disk in figure 4.6.

First, I agree with "Fish" about grass build up in the "v-groove" of the drive plate. This happens all the time and will actually change how fast the drive plate spins. It sounds like you cannot get the wheels to slip even on concrete. This indicates that all the belts and pulleys are working like they should. If you could get the wheels to stop by engaging the drive and just holding onto the handles it would tell you either the belts are worn or a spring is off or not adjusted right. Since this is not the case now look at where the drive wheel contacts the drive plate. In "high" the wheel should be on the outermost edge of the drive plate. If not, you can adjust this by sliding the plate that attaches the arm to you selector rod. This plate is held on with one 5/16" bolt. Loosen the bolt and then slide it closer to the drive assy (this will then pull the drive wheel further out).

I'm with jtk. I don't think the drive disc is going far enough to the outside of the drive plate?

My bad, I just realized the mower in question is a push mower not a RER. :ashamed::ashamed::ashamed:

Fish said:

Take a small flat tipped screwdriver and dig a little into the v of the pulley/disc, I have seen layers of cooked/dried grass
bake in there and that could change your pulley/speed setup.

Click to expand...

Ok,
I carefully looked in that area and found absolutely no obstructions. In fact it was cleaner than I had expected.
I'm not sure what to do next.

Thanks,
Michele.

jtk said:

First, I agree with "Fish" about grass build up in the "v-groove" of the drive plate. This happens all the time and will actually change how fast the drive plate spins. It sounds like you cannot get the wheels to slip even on concrete. This indicates that all the belts and pulleys are working like they should. If you could get the wheels to stop by engaging the drive and just holding onto the handles it would tell you either the belts are worn or a spring is off or not adjusted right. Since this is not the case now look at where the drive wheel contacts the drive plate. In "high" the wheel should be on the outermost edge of the drive plate. If not, you can adjust this by sliding the plate that attaches the arm to you selector rod. This plate is held on with one 5/16" bolt. Loosen the bolt and then slide it closer to the drive assy (this will then pull the drive wheel further out).

Click to expand...

As suggested, I took a closer look at where the disc meet the plate. To me it's exactly where it's been all alone.
I'm including a couple pics so you can see.

Could one of those plastic pulleys in the drive mechanism (V belt) be worn out?

Thanks,
Michele

Tommyboyxd said:

My bad, I just realized the mower in question is a push mower not a RER. :ashamed::ashamed::ashamed:

Click to expand...

Thanks the same.

Michele

Michele3918 said:

Ok,
I carefully looked in that area and found absolutely no obstructions. In fact it was cleaner than I had expected.
I'm not sure what to do next.

Thanks,
Michele.

Click to expand...

you looked at the bottom of the plate where the belt rides? No build up under the belt?

How about the other belt, the ribbed one? Is it in good shape and not slipping?

Can you send another picture a little closer of tge side view and then again of the drive plate assy? I dont see the idler pully in your pics. There is another spring that places tension between the idler pulley and the belt that goes from the crankshaft and the drive plate. This spring is identical to the one used to place tension on the drive wheel. If it is missing this coukd be the issue.

jtk said:

Can you send another picture a little closer of tge side view and then again of the drive plate assy? I dont see the idler pully in your pics. There is another spring that places tension between the idler pulley and the belt that goes from the crankshaft and the drive plate. This spring is identical to the one used to place tension on the drive wheel. If it is missing this coukd be the issue.

Click to expand...

I have a snapper of that vintage and they do not have an idler pulley for the v belt.

I have the exact same problem with a 1o year old 21" Snapper Ninja mower. Were you ever able to solve the problem? I don't want to invest in a new driven disc, belts, etc. if replacing those didn't help for you.

RobCS said:

I have the exact same problem with a 1o year old 21" Snapper Ninja mower. Were you ever able to solve the problem? I don't want to invest in a new driven disc, belts, etc. if replacing those didn't help for you.

Click to expand...

Sorry to say, no I have not figured out the problem. Have you?
I've lived with it but one of these days I will examine everything again.

4 years later reply...:smile:

Thx.
M.