Vibration at 80 mph

[johnbell]

Gathered the magnets, laser pointers and other implements and tore it down. The red lock tite on the drive shaft bolts was my first problem. Got em finally, then the magnet would not rest on the differential flange, I took the flange off, found the nut to be loose, trued the flange with a big file, got the laser mounted. It pointed about 1 1/2 inches ABOVE the tranny's output shaft. I pulled the four bolts on the ron tyler mount and wedged the front of the differential down to where the laser lined up with the tranny's center. this turned out to be 7/8 of an inch. I just spaced the poly mount down on the Ron Tyler which lowered the front of the diffy the required amount. Eureka! the vibration is gone. There is a new one at about 90, but its' more of a noise than a shake. I think this is gonna turn out to be something in contact with something else. Anyway, thanks for the advice and let me tell you all, ol' John Bell is one happy camper!

[NewZed]

I think that laser is used to help set the pinion shaft parallel with the transmission output shaft. You may have got lucky and your pinion shaft and output shaft are on the same center line, or you might be able to get better results with a little more adjusting.

 

If you can put the laser on the center of the transmission output shaft and it points back at the center of the pinion shaft, then they're on the same center. Otherwise, you want to adjust until you get the same offset pointing backward as frontward. Point the laser backward and measure offset from the pinion shaft center to the laser line, move the laser to the back and point it forward and measure offset from the output shaft center to the laser line. Adjust until the offsets are the same, both up and down and side to side. That will give equal and offsetting movement of the front and back u-joints, nullifying the vibrations.

 

That's my understanding.

[johnbell]

my bet is that you are correct in alignening both,, My problems were: one of the cat toy lasers was so misaligned with the body of the laser that it was not usable, nor returnable after modification. My suggestion is for anybody doing this is to mount the laser in a drill press or a lathe chuck and see how far it is off to start with. these guys are cat toys, not precision. anyway, i ended up with one usable laser. after having to true the diffy flange, etc. I was about tired of fooling with this, laying on my old back. I managed to get the laser to scribe a perfect circle around the output shaft of the T-5 transmission. I figgered that was close enough..proved to be true. You know a 7/8 inch difference in alignment in a 30 inch shaft is a lot. I know, I know, we want a 2 degree difference on each end and no lateral difference. But tell that to a jeep guy, he'll laugh. they run a lot of pitch and get away with no vibration..the trick is..one plane only..up..down. Or. side to side. but not both..I cannot tell you how many boat drive shafts that I have lined up. I just forgot what was important and what was not. Let's not make a bigger deal out of this than what it is. I believe this, from reading all of the post that are applicable, You don't know what you got till you check it!! All of these hybrids are different!! I had to lower my diff, one other guy had to raise his, and raise the tranny too! I could not raise my tranny without the harmonic balance r getting into the front cross member. But, I do not have the 3/8 spacers between the body and the cross member. I betcha that is prolly why JCL put them in, Drive shaft alignment. Anyway, I'm well on my way to having this fixed and again, I appreciate all the input!!

[johnbell]

By the way, I have not seen how you install the laser on the transmission end..Had I though I needed to I could have worked it out, but the initial instructions are wanting on this! Suggestions??