Who has experience with PowrLok in the front axle? - please help

Dear fellows,

who has experience with a PowrLok in the front axle (flat-shaped and/or dish-shaped clutch packs).

My background so far:
I have PowrLoks on both axles on my M38 A1. I recently tested it off road with good result on the rear Dana 44 but not satisfying on the Dana 25 (not enough equal traction on both wheels).

So I made the torque wrench test on both axles (as the manual recommends):
- amount for the rear is well above 100 ft/lbs
- amount for the front is 35 ft/lbs

Thus the difference is quite big and since the clutch packs are new. I assume the following reason for this: I heard that there are two types of clutch packs. I seem to have the more aggressive dish-shaped type on the rear Dana 44 and the flat-shaped smoother type on the front Dana 25. Can you agree to this or do you see another explanation?

Handling on road with my smooth PowrLok in the front is convenient - no erratic behaviour when cornering or on sloped roads.

Is the dish-shaped, more aggressive, clutch pack an alternative or will it make handling on road (especially when slippery) unconvenient?

I appreciate your advice!

Best

Philipp

 

are you using locking hubs up front ?

 

You can add a extra washer to the pac to make them a little more aggressive

 

You need some slipping in the front, otherwise you can't turn.

 

:iagree: Especially on a D25 front axle. Not just about the turning part, you could also be more likely to break something if your running larger tires.

 

Phillip E-mailed me directly with this question and I replied to him via E-mail but I should clarify something about the Powerlock clutch packs here. The Powerlock clutch packs rely on the dished disc (also called a belleville spring) to incorporate the preload to the clutch packs. Without at least one on each side of the pinion gears (spider gears), there is not the correct pre-load, hence the lack of performance he is experiencing. Some clutch packs have two belleville springs on each side, some only one. Obviously the packs with two springs on each side will be more aggressive. Unfortunately I've seen some replacement clutch packs not come with new belleville springs and I feel this is ridiculous as it's usually the belleville spring that gets chewed up or worn out first. Sounds like Phillip needs to install the belleville springs to his front Powerlock to make it perform like it's supposed to. You can "tune" the performance of the clutch packs by changing the pre-load of the packs, but it isn't simply a matter of adding more clutches as there isn't enough room. You have to remove a clutch disc and replace it with one that will add more preload to the packs but still be able to bolt the case halves together solidly. The way most people add preload is to remove a clutch disc of a certain thickness and replace it with a belleville spring of the same thickness. This will add extra preload without making the pack too thick.
My FSM says minimum of 45lbs. of torque for breakaway or the pre-load isn't set up correctly. Phillip's post shows 35 lbs., that isn't enough for proper operation. I looked last night as I happen to be putting together a 27 powerlock at home. Nickmil

Double checked the preload and should be 40 lbs\ft torque, not 45 as stated above. Nickmil

 

A Dana 25 PowrLoc should have five discs on ea. side of the spyder gears. The thinnest shim is near the outside, then the bellville shim cupped towards the center, then two smaller diameter, thick shims side by side and then the last thick large shim next to the spyder gear. It will slip fine for turns but then 80% lock up when it senses tire slippage. You definitely need the bellville shim to make it work right. The shim or clutch pack is different for each Dana axle, but I think they all have five discs per side.