8.8 vs 9.75 diff driveshaft height differences?

[Sugarkryptonite]

Hi guys

Say there are two trucks side by side, both are crew cab 6.5’ bed with the 2 piece driveshaft with carrier bearing, both trucks COMPLETELY STOCK.

Now say one truck has an 8.8 diff and the other a 9.75” diff.

Are the center driveshafts different?

Reason I ask is I was looking at them online, and some specify 8.8” or 9.75”, but not both. Now I know the lengths are the same and u joints are the same, but are the CARRIER BEARING HEIGHTS the same?

That is to say, is it possible the pinion output on the 8.8” diff is higher up in the truck vs the 9.75”? I put a driveshaft in one of these trucks that specified 8.8", the truck was a 9.75” diff and we needed to shim the carrier bearing to get rid of a take off vibration. Is it actually a height difference from the factory or was it just crappy quality control with the driveshaft we got?

Sponsored

 

[Porpoise Hork]

There are multiple things that can cause this vibration with a two piece shaft design. My 2020 Ranger in fact all the early NA spec 5th gen Rangers had this issue because Ford added lift blocks to the existing design and did not account for this in the drive line an it created the same issue. The prop shaft manufacturer tried to fix it with balancing and peppered the absolute shit out of the lower drive shaft as a result. Then Ford released a TSB to install wedges on the rear axle mounts to change the pinion angle in relation to the shaft. That failed. The Tacoma has the same issue when an aftermarket lift is installed and the fix is for them was to shim the center bearing which did work well. On the Ranger it was a hit/miss solution as it worked for some but not others. If you put about 300+ pounds in the bed causing it to squat the vibration went away confirming that it was due to Ford's genius engineers not knowing what cause/effect is. The only 100% fix for the Ranger was an aftermarket single piece shaft that cost between $4-900 depending on where you went to get it.

The main things that can cause this take off vibration are Incorrect drive shaft phasing, incorrect or poor shaft balance, differences in position angle of the u-joint mount at the pinion between the 8.8 and 9.75", incorrect suspension lift that alters the shaft angle to be out of spec, or Incorrect parts and/or defective u-joints.

The only way to confirm if the shafts are the same or even phased the same is to place them next to each other and compare how the U-joints are clocked. https://managedmobile.com/driveshaft-phasing-importance/ From there the next step would be to have the shaft balance checked. This can be done both on and off the truck at your local drive shaft company. They can also verify that none of the u-joints have failed. If the phasing is correct and the shaft is balanced correctly then the next step is to alter the geometry of the shaft angle by shimming the center bearing which may require longer bolts or adding/removing lift blocks to the rear end. If all else fails have a custom one piece shaft made or use the correct two piece shaft from a 9.75" setup.

 

[Sugarkryptonite]

There are multiple things that can cause this vibration with a two piece shaft design. My 2020 Ranger in fact all the early NA spec 5th gen Rangers had this issue because Ford added lift blocks to the existing design and did not account for this in the drive line an it created the same issue. The prop shaft manufacturer tried to fix it with balancing and peppered the absolute shit out of the lower drive shaft as a result. Then Ford released a TSB to install wedges on the rear axle mounts to change the pinion angle in relation to the shaft. That failed. The Tacoma has the same issue when an aftermarket lift is installed and the fix is for them was to shim the center bearing which did work well. On the Ranger it was a hit/miss solution as it worked for some but not others. If you put about 300+ pounds in the bed causing it to squat the vibration went away. The only 100% fix for the Ranger was an aftermarket single piece shaft.

The main things that can cause this take off vibration are Incorrect drive shaft phasing, incorrect or poor shaft balance, differences in position angle of the u-joint mount at the pinion between the 8.8 and 9.75", incorrect suspension lift that alters the shaft angle to be out of spec, or Incorrect and/or defective u-joints.

The only way to confirm if the shafts are the same or even phased the same is to place them next to each other and compare how the U-joints are clocked. https://managedmobile.com/driveshaft-phasing-importance/ From there the next step would be to have the shaft balance checked. This can be done both on and off the truck at your local drive shaft company. They can also verify that none of the u-joints have failed. If the phasing is correct and the shaft is balanced correctly then the next step is to alter the geometry of the shaft angle by shimming the center bearing which may require longer bolts or adding/removing lift blocks to the rear end. If all else fails have a custom one piece shaft made or use the two piece from a 9.75" setup.

Thanks but all that has been done already. If you read my post you will see the vibration was solved.

Don’t mean to be rude, but I’m just looking for a simple yes/no to the question whether the heights are the same or not.

 

[Porpoise Hork]

Well if it didn't vibrate when you had the shaft from a 8.8" but did with a 9.75" (or vise versa) then yes, they are different.

Sponsored