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Aligning the Driveshaft

Aligning the driveshaft is a very important part of keeping your XR4TI running without vibrations. The guibo is a torsional dampener. It is not a U-Joint. It is meant to run in a straight line. That is why you align the driveshaft. The whole driveline should have zero degrees runout. In other words, the shaft between the trans and the rear should be a perfectly straight line. You will need a dial indicator to read the runout of the driveshaft. If the driveshaft is not running perfectly straight you will also be tearing the rear transmission seal to pieces and possibly damaging the rear pinion.

Important Note: If the Center Support Bearing is old, replace it now. If the bearing is sagged too much you will not be able to align the driveshaft until it is replaced because you will not be able to go up enough to get a straight line with the driveshaft.

The rear differential is bolted to the unibody through the rear differential mount. The engine is bolted to the unibody through the motor mounts. Since both of these parts are rubber they will eventually sag and go out of alignment. The guibo is right in the middle of all of this movement. If those parts are not aligned correctly it will cause vibrations. If the alignment is way off the guibo will fail quickly. If it is not aligned correctly it will vibrate. The guibo can not absorb any deflection. If you try to make it flex you will see how hard it is to move. It is meant to run in a straight line. Also there is a bearing inside the circle of the Guibo to help keep it running in a straight line. This bearing takes a beating if the guibo is bad.

The Center Support Bearing is right next to the guibo and it should be in good condition.

The Rear pinion is part of the driveline angle. If it is not correct it will add some vibration to your car.

Put the car up off the ground so that you can get under it. You need to support the rear end by the control arms so that the car thinks it is on the ground. Try to make the car level when you do this.

Place the jack stands under the rear control arms.

This is the dial indicator with a standard attachment and a mirror attached to a bent hacksaw blade so that you can read the dial indicator when you rotate the driveshaft while checking for runout.

This is a hose clamp around the driveshaft right behind the guibo. This will hold the dial indicator in place.

Put the indicator tip on one of the three bolts that are connected to the transmission output shaft. Then set the dial indicator to zero after turning the driveshaft so that the dial indicator is at the bottom. The picture looks weird but you are actually looking straight up at the floor of the car

Next turn the driveshaft 180 degrees. Use one of the rear tires to turn the driveshaft so that the indicator is at the top and use the mirror to read it. Don't turn the driveshaft with your hand! Check the dial indicator. If it doesn't read zero then you will have to add or remove spacers between the center support bearing and the floor of the car. Add or remove the same amount of spacers from both sides of the center support bearing.

This is where you add or remove spacers. The spacer goes between the center support bearing and the floor of the car.

This is the center support bearing with the exhaust hanger bracket removed from it.

These are pictures of the spacers. The first picture is one that I was measuring to use on the car. The second picture is the stock spacer that comes from the factory. You will probably have to add different thickness spacers to get zero runout because the motor mounts compress and this lowers the engine and trans which affects the alignment of the trans and rear differential. I used washers. You can use anything you want as a spacer.

After you get the dial indicator to read zero for up and down runout you can then check the side to side runout. It must be done in this order. Turn the driveshaft to one side and set the dial indicator to zero. Then turn the driveshaft 180 degrees and check the dial. If it doesn't read zero then loosen the bolts and move the center support bearing to one side or the other until it does.

Move the center support bearing to get to zero runout.