Topic: Pinion pre load


Ozzy    -- 02-14-2019 @ 1:57 PM
  I am rebuilding the rear end of my 1940 Deluxe and have gone from a 3.78 to a 3.25. New spider gears, cross, diff case and axles, all NOS. All good.

I've been following Vern Tardel's banjo diff book and he says 15ft/lbs preload on the pinion.

Well I've got 75inch/lbs which = 6.25ft/lbs and that seems tight to me. I can still turn the shaft with my hand. Esaier with the torque wrench. though.

Please someone tell me if I'm OK at 6,25.

Thanks






ford38v8    -- 02-14-2019 @ 2:31 PM
  Ozzy, Pinion preload is done with nothing but the banjo, the pinion, and pinion bearings. No axles, no spider, no ring, no housings. The important info is the bearings, which you did not mention. New bearings, offshore bearings, used bearings, all would potentially require different settings.

For a new set of USA bearings, clamp the shaft in a bench vise, with banjo pointed up and free to turn. The correct setting is made when you can spin the banjo hard with both hands, and the banjo complete just one complete turn on the pinion shaft.

Alan


Ozzy    -- 02-14-2019 @ 5:03 PM
  All new Timken USA bearings. The ring gear has been set up with axles ready for assy. Right now I'm working with the pinion and the banjo only.

From what you've said and from what I remember from my past life as a truck mechanic, I believe I've got it set OK.

Please, any tips re setting the back lash and the preload on the carrier bearings ? I've set preloads on other equipment with shims before and then swapped shims side to side to set back lash, but without the pinion in place when setting the pre load.

In the book they're vague enough about the back lash but say nothing about the preload. As this is my first banjo type Ford, any and all help will be greatly appreciated.




ford38v8    -- 02-14-2019 @ 5:32 PM
  Just a couple things you already should know:
Use a flat file to remove any burrs on the mating surfaces.
Reduce trial & error time with a dummy set of split gaskets to determine correct shims.
Do not chase threads on the banjo, as they are tight by design to prevent leakage.
Use thread seal on banjo bolts for final assembly.
Chug a cold one before each trial.

Alan


40 Coupe    -- 02-14-2019 @ 5:48 PM
  Pre load is measured in inch/lbs not foot/lbs. Most likely a typo in the book. I don't have a service manual here to look up the exact spec.


Ozzy    -- 02-14-2019 @ 6:50 PM
  I agree, at 15ft/lbs it' locked up.Gotta be inch/lbs. The 75inch/lbs is tight enough., nearly too tight.

Greg


40 Coupe    -- 02-15-2019 @ 7:32 AM
  go to fordbarn.com and search for the proper spec.
The Ford Spec. calls for 12-17"/#. Ford Spec Dec. 29, 1939 page S-4000.
Take the reading while turning. It may take more torque to start it turning.

This message was edited by 40 Coupe on 2-15-19 @ 7:37 AM


supereal    -- 02-18-2019 @ 1:09 PM
  Many years ago when I was working for a Ford dealer, we set up the pinion bearings by placing the input end of the pinion in a vise before adding other components. We would spin the housing to see if it would turn at least one revolution before stopping. This sounds like a crude way to set the tension, but we didn't have access to the KRW tension scale. We did a lots these jobs without the tools common today. Most of us had never seen a torque wrench. We used a long "T" handled socket wrench extension to tightening cylinder head nuts. With no shop manuals, we learned these procedures from the old timers. Now that I am an "old timer", these tips come in handy at our shop.


Ozzy    -- 02-18-2019 @ 2:21 PM
  I got the pre load set to my satisfaction and I believe most probably to Ford specs. About 25 inch /lbs and feels just right, but I will do the clamp it in the vice and spin test just to confirm though.

Next question, Speedo Driven Gear; from what I can see, the "drive gear" is the same for all Diff Ratios. It's the "driven gear" that changes.

Diff Ratios look to be 4.11, 3.78 and 3.54. I was clever and went for a 3.25 but now I discover that as this looks not to have been a Ford original of the time, there's no Driven Gear for this ratio.

I've been checking with All Ford Parts and they have the gear for all ratios except the 3.25.

Am I out of luck ?


JerryW    -- 02-18-2019 @ 5:14 PM
  This attachment may help you
https://transmissioncenter.net/product-tag/speedometer-gears/


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