K&B questions

[izitbrokeyet?]

Any one know the inside diameter of a K&B 3.5 case and the 7.5? Or the OD of the K&B 3.5 PTO and the OD of a K&B 7.5 pto?........thanks

 

[Tunnelbill]

K&B 3.5

OD 1.028

OH .392

K&B 7.5

OD 1.125

OH .520

K&B 7.5 PRO/ Semi-Pro

OD 1.190

OH .520

 

[Foolwitools]

Whatcha makin, Kev???

I have a couple of 7.5 ob cases you can have to experiment on............

Bob the Fool :blink:

 

[izitbrokeyet?]

hey Bob,

I'm really looking at the PTO. I'm having some problems getting the "rubber to meet the road" on my mod novarossi motor. 1 set of bearings every Quart makes me think I need to look at another option :huh:

any chance you have a 7.5cc pto you will sell me to modify and test for my current mod novarossi powerplant? I really just need a case without the shaft but the whole unit may open up some additional options.

I'm having some severe problems transmitting power through the currently available conversion PTO.

Bill,

You're the man! Thanks again Bro!.....

 

[Slideblues]

Sounds like Kev is makin some major HP, KEWL, Ya not goin fast enough if yer not breakin parts

 

[Foolwitools]

Kev..............

sorry, no 7.5 pto housing at all. Got one for an 11cc, but I don't think thats gonna help...........

Bob theFool :blink:

 

[dave roach]

I know Jim Irwin is at the internats he will be back next week give him a call he mite have what you need. his number is 1-765- 747 4190

 

[izitbrokeyet?]

Thanks Dave....that sounds like a pretty good idea.

 

[Bob Kensill]

The bearings are the same in all three K&B pto plates. Try a better bearing like Boca or get a bearing from Ron Byrd at Racecraft Bearings.

 

[Jerry Wyss]

Sorry about "Barging" in on your topic Kevin,,But what are "W.I.B." bearings? I heard Tim Duggan talking about 'em.

I've been using Boca's Econo kits in my "Tigers" with good success,,but a friend whom I built a tiger for is eating them

pretty fast,,,is "Racecraft " better than Boca?

(I didn't think it would be worth it to start a topic on this,,,sorry again Kevin)

Jerry

 

[Rules]

Those pto assemblies normally last for years with proper care. If the custom ones are eating bearings, then the bearing fit or assembly endplay adjustment might be causing the balls to run tight in the race. You can set them up loose, just right or tight. I usually like a few thou of play in the disk. There is no reason to crush the bearing. You might also check the flexshaft to pto fit. If the shaft is real tight in the broached square hole, you are asking for trouble. The shaft needs to "float", and not transfer undue axial loads to the pto. Make sure the end of the flexshaft is rounded and that all the lays are in place. If the fit is tight, your only fix is to file the pto a tiny smidge to remove any rough spots in the broach. Do not file the flexshaft. This always worked for me, but others might have other ideas. Hope you find a solution, good luck. John in Huntsville

 

[izitbrokeyet?]

Jerry,

The W.I.B. swiss bearings are the brand that Ron Byrd at Racecraft bearings is carrying…they are top shelf for certain.

John,

It appears that the 8mm pto shaft hole was off-center from the bearing holes by .003” When I corrected the centering, I also found that the bearing races were a little on the tight side so I dusted them open too. When doing this I pulled an additional .0005” off of one side of the bearing race and not off the other because they were slightly offcenter too. I ended up milling out a little section for a small rubber o-ring below the top bearing to improve the seal since I opened up the shaft hole by .003” on one side.

Since reworking the PTO, I’ve only put 1 quart through the motor but the PTO is still in great condition.

 

[Rules]

Thats some slick machining Izitbroke, sounds like you have a good technical background and did a good job!!! Are your PTO disks slotted for the crank pin? How was your flexshaft to PTO fit? Adding the O-ring should help the seal, provided the section you milled is adequate. Good machining pays off!!

Have fun, John in Huntsville

 

[izitbrokeyet?]

The PTO disk is slotted on opposite sides for balance, It is a good fit with the crankpin (almost 0 slop). The Flex shaft/pto fit is very good ….I rebuilt that with K&S square tubing and silver solder. Early on, I spun the square drive in the PTO shaft but it’s been acting fine since the rebuild.

Kevin B