Hard Clutch Engagement Problem

A peak underneath would definitely help. I'm curious if there are any added idler pulleys, and what type of belt he's using. I've seen 5/8" belts on 1/2" pulleys and they act like that... no slipping, just grabbing.

AcreFarm wrote:

A peak underneath would definitely help. I'm curious if there are any added idler pulleys, and what type of belt he's using. I've seen 5/8" belts on 1/2" pulleys and they act like that... no slipping, just grabbing.

he did say he bought a new belt, Ive yet to have a new belt, so I was thinking the new belt may just need some wearing out? but, still it shouldnt grap that hard. Im sure someone has had this happen before..

He is going to get a video of the underneath

I saw that video earlier today. If he is using a Kevlar belt then I am betting it is the change i belt angle going into the clutch. His clutch setup is similar to mine using a similar Tranny. I have to be careful as hell if in 4th gear or higher or i will jump the front off the ground. Just the same way he is. My planned solution was to put a tensioner idler pully on the clutch side to re aline the belt to come into the clutch the way it originally did

Maine Mud Mower wrote:

I saw that video earlier today. If he is using a Kevlar belt then I am betting it is the change i belt angle going into the clutch. His clutch setup is similar to mine using a similar Tranny. I have to be careful as hell if in 4th gear or higher or i will jump the front off the ground. Just the same way he is. My planned solution was to put a tensioner idler pully on the clutch side to re aline the belt to come into the clutch the way it originally did

That may have something to do it with, as well as the different belt material.

I'd also be looking at whether or not the belt and pulleys all have the correct profile.

I know this thread is from January, but I am completely new to modifying lawn tractors and I have the same problem. What was the solution to this? I have a '95 murray with a 12.5 HP briggs and a peerless 206 transaxle. I left the rear pulley stock and just modified the front pulley stack to sit upside down. I measured and got the correct length belt, but I cannot let the clutch off slow enough to keep it front grabbing. At first I thought the belt just needed broken in, but It's been nearly a month and I cannot keep the front wheels from jumping off the ground when I let off the clutch no matter what gear I'm in. I'm afraid I'm going to sheer a pulley keyway or even worse, throw a tooth in the transaxle.  Assistance would be appreciated.

FINALLY! a properly revived thread!

my bolens will act like that when the belt is extremely worn and about to let go, because there is so much rubber showing. You said yours is a brand new one so thats out the window, kind of.

check all the pullies for rust or debris. it might help to take some very fine emry cloth or sand paper and brush up all the metal pullies.
check to make sure ALL the pullies are in line, examine the belt for more wear on one side compared to the other.
make sure all the idlers are free of resistance, and the tranny as well. put it in neutral and see if it takes alot of effort to turn the input pully.
id also advise picking up another belt, just to be sure its not that

It sounds like the belt keepers are to close to the pulleys, and/or if you have a adjuster for pulleys, is try to back it out for maximum slack you can get.

I hadn't even thought about the belt keepers. I just flipped the keepers over in their brackets when I flipped the pulley over. This places them where they were located when the large end of the pulley operated the mowing deck. If I engaged the deck too slowly the belt would slip before the blades got up to speed so I can't see how this would be the problem, however, I'm open to any suggestions. Is there a rule of thumb on how close the keepers should be located?

W546 wrote:

I hadn't even thought about the belt keepers. I just flipped the keepers over in their brackets when I flipped the pulley over. This places them where they were located when the large end of the pulley operated the mowing deck. If I engaged the deck too slowly the belt would slip before the blades got up to speed so I can't see how this would be the problem, however, I'm open to any suggestions. Is there a rule of thumb on how close the keepers should be located?

Im not sure about every one else, but to a point where you cant just yank the belt out with your hand. So, a little closer then 1/2". Like 3/8" i guess. Does it have the stock clutch spring on? And my offroading mower has a all custom belt system (front/rear pulleys and clutch system) and it jumps in the higher gears, like 4th and 5th, even easing onto it. having a gas petal is one of my top suggested mods, that way you can take off from a idle, and the just gas it, way better way of controlling it. I think that yours jumps because the pulleys are much bigger so the belt gets much more traction. Like i think your running somewhere around a 5" front pulley and 8" rear? Lots of surface for the belt to yank, and seat into the pulley groove, if that makes seance. Smaller pulleys grip, but allow more slipping when you ease onto it. Ive seen people on youtube do 7"-7" pulleys, and it really doesnt allow to much middle ground in clutching, either, slip all the time, or the belt seats and you go flying.

That makes sense. I checked and at least eyeballing it everything appears lined up so I don't think it's an issue with the belt being pulled at an odd angle. The pulleys appear smooth and clean. My keepers are right around where you suggest and aren't too tight. When the clutch is in there is decent slack on the belt. I do have the stock spring on the clutch, but I don't see how a lighter spring will help because I am controlling the amount of force on the belt when easing out on the clutch. I have even tried to make it slip and take 5+ seconds to just barely ease off the clutch and it still grabs instantly and pops the front wheels off the ground.

I hadn't thought about the fact that a larger pulley will have more "traction." The stock pulley was around 3" or so and now it's more like 5" I haven't run the numbers, but that is probably something like twice the surface area touching the belt so it would obviously grab twice as hard as stock. I do have better luck when I let the mower idle and start up and then give it some gas after moving forward, but that's not really a good solution either because it is still grabbing like crazy and nearly kills the engine and makes the engine shoot out a cloud of black smoke. (Governor shoots wide open and runs crazy rich for a second or two) I have been watching youtube for this for the last month and see a lot of people supposedly running 5" - 6" pulleys in the front and similar or larger in the back and they seem to get pretty reasonable take-offs without nearly flipping it over. I guess my option right now is to try another belt. The belt I have I got off fleabay so quality is questionable. Perhaps the gripping surface angle is wrong and the belt is actually binding in the pulley or maybe the material used has too much grip? Who knows. I'll try a different one and see what happens. It will be a week or two until I get one. Thanks for the ideas everyone and I'll report back once I try a new belt.

I know this dosent help but my Kevlar belt jumps like that the first few times I let the clutch out but after that the belt gets warm and its nice and smooth engagment

just write the length belt you need, go to tractor supply and get a blue "huskee" belt. its made by Pix, and its kevlar so its good stuff. i would try starting with a 5/8 thickness and if thats too much, try a 1/2 inch thickness

willis923 wrote:

just write the length belt you need, go to tractor supply and get a blue "huskee" belt. its made by Pix, and its kevlar so its good stuff. i would try starting with a 5/8 thickness and if thats too much, try a 1/2 inch thickness

Id actually suggest trying a 1/2 before 5/8", stock mowers usually have 1/2" and when you clutch, there is more space in the "V" of the pulley for the belt to move out of the groove, and for more clutching/unseating from the pulley

Ok... I checked last night and the belt I got on ebay was sold as a 1/2", but it is actually a 5/8" It actually appears to be decent quality and isn't just one of those cheap "rubber" ones. I am thinking that a combination of additional pulley surface area combined with the larger 5/8" belt just has too much grip. Unfortunately, I don't have a tractor supply near me so I'm kind of stuck with ordering online or going to a big box store. I'm not sure what to do because if I order one online I risk getting the wrong belt again, but they don't sell the belts by length at a big box store. I wonder if an auto parts store would have belts sold by length other than those rubber ones... I'll check around.

W546 wrote:

Ok... I checked last night and the belt I got on ebay was sold as a 1/2", but it is actually a 5/8" It actually appears to be decent quality and isn't just one of those cheap "rubber" ones. I am thinking that a combination of additional pulley surface area combined with the larger 5/8" belt just has too much grip. Unfortunately, I don't have a tractor supply near me so I'm kind of stuck with ordering online or going to a big box store. I'm not sure what to do because if I order one online I risk getting the wrong belt again, but they don't sell the belts by length at a big box store. I wonder if an auto parts store would have belts sold by length other than those rubber ones... I'll check around.

Yea, I really think the 5/8" is your problem then. I've got a 5/8" before and it just didnt act the same (for the worse) try amazon. I'm quite surprised you got the wrong belt. I wouldn't really think it would happen again.

Edit: I remember that 5/8 belts are longer then 1/2". Like, a 78" belt can actually be 81", or something. It's like a 2"-3" difference between them because the 5/8" belt seats farther out in the pulleys, making it longer.

i know Northern tool sells blue kevlar belts, Pix brand too. very cheaply priced as well. auto parts stores should have lawn and garden belts as well

Ok... so I got it all sorted out and it's running like it should now. I bought a 1/2" belt, but it was about 2" too long due to it being 1/2" and not 5/8". (I didn't see the post about the differences in lengths until after I placed my order online) So I order another 1/2" belt (2" shorter this time) and put it on. Viola! Now the mower runs like a dream. No more mandatory wheelies and I'm sleeping better at night now that my neck isn't being jerked back every time I try to start off.

I was concerned that I would get excessive belt slippage when pulling hard, but the belt doesn't seem to slip at all once fully engaged. At one point this weekend I even loaded up a small utility trailer three deep with 16" blocks to move them up a pretty steep hill and it didn't miss a beat. (I'm absolutely amazed at the pulling power of these mowers even when pulley swapped!)  Thanks for all the tips and ideas guys. Hopefully someone down the road will read this and avoid some of my headaches...