front pto shaft vibration question

[lwalsh]

I have a 50in kubota blower that I had mounted to my 2210 and it worked very well. I used an off the shelf weasler 6 series(rectangular) pto shaft to go from the mid pto to the blower mount frame I built. Quick couplers on both ends of the pto shaft and it was about 36" long. I have now transfered this setup to my 2720 and purchased a new pto bar 50" long with 20" of overlap.
As I bring the rpm's up the oscilation of the shaft makes it look like its 2" in diameter not 1" if you know what I mean. This is with no load on the blower. The pto angle is mabey 10 deg. Less than I had on the other tractor.

Are the 3/4 by 7/8 shaft pto's just not heavy enough for this span? What does deere use for a pto shaft?

 

[jd3020u]

I've got a older 59 blower on my 3720. It has a Bondoli & Pavase? triangular shaft size 3 (43.5mm) that came from the 855. I had a new 52" tube put on and have 23" of overlap. (63" overall) I get some vibration once the motor gets to 2-2200 rpm. I'm still trying to narrow things down yet. My driveline guy is recommending a 2" round tube for the high speed needed. I believe thats what the 4310 etc use.

 

[PILOON]

You are describing a wobble in the shaft.
Something is out of balance and you should be actually able to see that with the naked eye.
Bent tubes?
Damaged U-joints?
Bad welds?
Sloppy quick couplers? (loose fitting)

I assume this observation is without the plastic safety tubing on, but if on it could simply be due to the longish plastic and lack of support in center or again not enough overlap of those plastic sleeves.
Shucks on their own, being flimsy plastic, they'd wobble for shure.

Another thought--
Do you have the 2 Ujoints properly oriented? , as I recal they should be out of phase to each other.

 

[aczlan]

Do you have the 2 Ujoints properly oriented? , as I recal they should be out of phase to each other.

The Ujoints MUST be IN PHASE. See: Driveshafts and U-Joints - Tom Sotomayor
The ends of the shaft should match as shown in the diaphragm on the linked website or you WILL have vibration. See: Driveline Basics with Steve Johnson - ORN for an explication of what causes this vibration.

Aaron Z

 

[jd3020u]

Unless welded together wrong his 3/4 by 7/8 shaft can only go together one way, well two but both are right. Tonight I found alot of side to side play in my u-joints, and some run out on one end of my front idler shaft. As a temporary fix to track down the problem I shimmed the u-joint cups on the sloppiest joint and reversed the idler shaft to put the better end on the main driveshaft. I did get some improvement as I went from 2-2200 rpm to 2500. My pto speed is at 2600. Hoping new u-joints all around will do it.

My driveline guy says the higher the rpm the bigger the shaft should be. Length seems to be key also as my shaft appeared to work fine on the 855 at 56" before I had it lengthened to work at 63"

 

[lwalsh]

Thanks for the replies, I think I'm going to call drive-lines.com and see what they want to build me something more rigid. This garden tractor size shafting streched to 50 in is just too weak. ( I think)

 

[defed]

does anyone have a definitive answer on what size shaft is used on 'larger' CUTS? i will need to have one made for my 4300, and want to make it heavy enough the 1st time. i haven't measured the length i need yet, but will be somewhere around 60" overall (not counting overlap).

 

[tommu56]

Thanks for the replies, I think I'm going to call drive-lines.com and see what they want to build me something more rigid. This garden tractor size shafting streched to 50 in is just too weak. ( I think)

Do you have a truck drive line shop near by I think it would be in your best interest to take present shaft to them and let them see it and they can build one that will fit and not vibrate and have them balance it.

Them having it in their hands makes a world of difference.

tom

 

[Craig Clayton]

I had from new a Dodge pickup extended cab with a 2 piece shaft and developed a vibration at 40mph. I sent it to the dealer and they could not find the trouble. It was sent to the Driveline shop and they did not find anything wrong with the shaft. It went to the big Chrysler center and returned perfect, with the same shaft.
Time went on an the U joints needed replaced and my father was a class A mechanic. The vibration was back just like when it was new. All the U joints were aligned as described above. The cure was to undu the U joint at the slip sleeve and ressemble it 180 Degrees. The vibration was gone. I retested it because I became very fast at doing this under the truck and the vibration could be put in or taken out at will. It could not be explained.
Craig Clayton

 

[jd3020u]

According to the Dana/Spicer Driveshaft Installation guide....

With a 3/4 bar you shouldn't be over 30", the driveline shop did say their numbers were conservative. The solid bars get too heavy and at 2100 rpm anything thats not right shows up.

Defed, from the pictures I have collected it looks like the 4300-4310 shafts are 1.75 or 2" If you can match your mount to the factory one you could use the BM19576 shaft @$220 My dealer measured it 52"-to maybe 60" max, I checked over the phone -should have got the diameter:confused2:

If you ever want to use this on a 3720 someday you'll have to move it forward as the grille guards are different. My shaft needs to be 63 1/2" to the end of the couplers. I decided not to put anymore money into my old shaft as the joint cups and couplers were loose. The driveline shop had a 1.75" shaft pre-made for pto pumps on dump trucks etc. It just needs to be shortened and the right outside yokes installed. He could have used 2 inch but only a sloppy 6 spline slip yoke is available for that diameter. I hope to pick it up in a day or two and will post the results...

 

[jd3020u]

Defed if you need an front idle shaft G & G manuf. has 1" 15 spline on both ends and 12" long. Should be about $40, Deere uses two different 9" shafts at $90 and $140. Hydraulic shops might have this also.

If you can mount the shaft towards the mid pto side of the tractor you can reduce your true operating angle. Mine is at 8.6 degrees -just in spec- using the original configuration. This will impact the front shaft of course but it's only 16" long

 

[defed]

i have the front shaft, need the mid shaft. i think my mounting bracket has the shaft connections already offset to the mid pto side. i don't think it is centered on the bracket, but then i can't remember for sure.

i have to price out having a shaft made vs buying on from deere. i thought that deere wanted closer to $400 for the mid shaft, i'll have to check it again.

 

[jd3020u]

The 855 version is $400 some, the 770 version is $275 I think, the 790 version is $375 and the longest, Deere says to 67" if I remember right.

 

[jd3020u]

The results are in... It works. My new shaft is 1 3/4" pipe with QD on one end and a clamp yoke on the other. The yoke has a slip spline built in that has 16 splines and is sealed. The g&g shaft is softer than I would like but the clamp yoke should keep it tight for a long time. Driveshaft was $230 and the 12" shaft was $45. Now to build a quick tach wind break cab

Tim