Hello I just finished my swap and got to take it for the first test run. Everything is fine except for a little vibration at highway speeds the u joints are new so I dont think its that, the axle is centered, but I think I may have pointed my pinion to high. I measured the factory axle before I removed it and it was at 5.5 degrees so thats what installed the new axle at. I'm running the factory carbon driveshaft in a 91 jeep yj with a 2.5L. is it to high, should I lower it, or any suggestions? Thanks
8.8 swap question??
- Thread starter oooyah69
- Start date
Bounty__Hunter
Super Moderator
It's a good chance the pinion angle is wrong, it should be parallel with the transfer case output, meaning the ujoint angles should be exactly opposite each other in order to cancel vibrations.
Take a pic of your rear pinion angle and driveshaft.
Take a pic of your rear pinion angle and driveshaft.
Bounty__Hunter
Super Moderator
It looks like the pinion is slightly too high. It should be lower than the driveshaft about the same amount that it is higher (than parallel) now. With this type of driveshaft, your pinion angle should be parallel or slightly down from parallel with the transfer case output.
Is there a transfer case drop or motor mount lift on this jeep? The rear output of the transfer case looks unusually low.
Is there a transfer case drop or motor mount lift on this jeep? The rear output of the transfer case looks unusually low.
Bounty__Hunter
Super Moderator
Are those stock springs or lift springs?
You have plenty of spline engagement on the rear driveshaft slipyoke, I would remove the transfer case drop first and see if the vibe goes away. From the pics it looks like this may solve your angle problem.
It will be a lot easier than changing pinion angle.
You have plenty of spline engagement on the rear driveshaft slipyoke, I would remove the transfer case drop first and see if the vibe goes away. From the pics it looks like this may solve your angle problem.
It will be a lot easier than changing pinion angle.
Bounty__Hunter
Super Moderator
Remove the transfer case drop, that's the best route at this point. It will be less work, improve ground clearance, improve appearance, and restore shifter height inside the jeep.
Take two more similar pics once you remove the drop, and let us know how it drives.
Take two more similar pics once you remove the drop, and let us know how it drives.
Bounty__Hunter
Super Moderator
Difficult to tell from the angle the pics were taken, but it looks like the pinion could stand to come down just a little, maybe a degree or two.
If you have a magnetic angle finder, the face of the pinion flange should be at the same angle as the back side of the transfer case, or with the pinion just slightly down from the same angle.
If you have a magnetic angle finder, the face of the pinion flange should be at the same angle as the back side of the transfer case, or with the pinion just slightly down from the same angle.
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