Diff pinion bearing pre load

[Sirjames]

Diff pinion pre load.
In the jag book they say between 8-12 inch pound.
In the Dana 44 instruction sheet they say 20-40 inch pound.
Does anyone know why there’s such a difference?

I’m assembling a jag diff. After crushing the crushable sleeve with lip seal in place I got to 30 inch pound.
Anyone experienced this already?
Thanks
James

[mgcjag]

Hi James...do you mean you have crushed the spacer with 30ftlb or you now have 30tflb preload?......read right through this post there is some good detail...also lots ofbinfo if you search.... pinion preload.... viewtopic.php?f=3&t=4847&hilit=Pinion+preload .Steve

[Sirjames]

Hi Steve, thanks for this. But that’s for the hubs which need end float.
The diff pinion needs pre load or drag. And the unit is inch pound, not foot pound.
I don’t know the torque applied to the pinion nut as I just kept on tightening until I started to get pre load or drag. I just wonder if 30inch pound was too much

[angelw]

James Wrote:

In the jag book they say between 8-12 inch pound.
In the Dana 44 instruction sheet they say 20-40 inch pound.
Does anyone know why there’s such a difference?

Hello James,
Its not only the Dana Diff, but also the Salisbury Differential used on later cars. Its called evolution. Over time, it was determined that the increase in pre-load was better.

I know the retired production manager of Timken Bearings Australia from the period of their hay day and have gleaned a lot of information regarding differential set up. Taper Roller bearing prefer to in pre-load than haveing end float and under load (driving), some of the pre-load of the pinion bearings is diminished. If the pre-load was at the very bottom end of the scale, then its possible to have actual end float under load, resulting in a slight shift in the engagement of the Pinion and Crown Wheel, culminating in noise.

Regards,

Bill

[mgcjag]

Hi James..in the post i linked to i was refering to post number 21 where Bill (who just replied to you) discusses diff pinion preload.....yes my typo ft/lb for in/lb....Steve

[angelw]

James Wrote:

I don’t know the torque applied to the pinion nut as I just kept on tightening until I started to get pre load or drag. I just wonder if 30inch pound was too much

Hello James,
In the S3 Manual, its states 120 - 140lb/ft torque, but make no mention of the pre-load on the bearings; perhaps an oversight. It also states that if 140lb/ft torque is exceeded, a new crushable must be used. This is balderdash. The most important measurement is the bearing pre-load (measured as the torque required to rotate the Pinion Shaft in the absence of the Crown Wheel).

I've not experienced any pinion assembly, using the crushable spacer, where the correct pre-laod has been achieved at less than, or equal to 140lb/ft torque. The component that will be most affected by the torque is the Threaded Journal and the torque for that size thread and pinion shaft material is well over 200lb/ft. Having said that, I dislike the crushable spacer, and use solid spacers. My procedure is as follows:

1. Assemble the Pinion Shaft System using a Master, Solid Spacer that is of a length that will ensure measurable End Float.

2. After completing step 1. and torquing the system to 140lb/ft torque, I measure the End Float.

3. Based on the result of 2. I select a spacer (I have many in 0.025mm (0.001") increments) the End Float amount, plus 0.05mm (0.002"), less than the length of the Master Spacer. This normally gets me within the Torque tolerance range.

Regards,

Bill