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3A, 3B, DJ Technical Knowledge Base => "Original"-- Technical Questions, Answers, Observations => Topic started by: JohnR on June 28, 2014, 07:35:05 AM

Title: Pinion preload 27 in/lbs
Post by: JohnR on June 28, 2014, 07:35:05 AM: Hi,
Finally getting around to buttoning up my Dana 25, and have run into a few snags.ï¿½ I had to purchase a used ring and pinion since my original was shot due to water damage.ï¿½ The original pinion had a squared shoulder for the preload shims to ride on, the replacement requires a spacer.ï¿½ The shims in the front end kit, however, are diametrically too small on the OD to contact much of the spacer.ï¿½ They also came in only .010 and .015.ï¿½ I did use them in conjunction with my original shims to fid the proper stack, and hence my dilemma.ï¿½ A .003 change will take me from about 7-10 in/lbs to 27 in/lbs. I stuck with the 27, since my manual specs 15-25.ï¿½ I guess I am used to worn out diffs that spin like a roulette wheel, because 27 in/lbs seems tight.ï¿½ I can spin it with two fingers, but there is certainly some resistance.ï¿½ With the seal and carrier installed, my total resistance is 37 in/lbs.ï¿½ All bearings are new, and I am looking for some opinions on the pinion preload.ï¿½ Run it, or come up with a different solution?
Thanks,
John
Title: Re: Pinion preload 27 in/lbs
Post by: Carls_jeep on June 28, 2014, 01:57:00 PM: my guess is you have the wrong ring gear and pinion. They should exactly match your old ring gear and pinion in every way, except wear.
Title: Re: Pinion preload 27 in/lbs
Post by: JohnR on June 28, 2014, 05:13:42 PM: The original gear set was made by Salisbury, the replacement by Spicer.ï¿½ I got it from Herm.ï¿½ The spacer is shown in some Dana 25 diagrams and not in others.ï¿½ I found one at Willys Jeep Parts in AZ.ï¿½ That appears to be the only difference between the two.
Title: Re: Pinion preload 27 in/lbs
Post by: Carls_jeep on June 28, 2014, 09:00:58 PM: I'd say run it. It will loosen up as it sets in. Actually taper bearings can be set loose or tight according the the use. Some truck wheel bearings have no preload and others are preloaded. It depends on the engineer/designer.

When you think about all the pinions out there with light preload you start to wonder if it really makes a difference.
Title: Re: Pinion preload 27 in/lbs
Post by: Birddog7 on June 28, 2014, 09:51:00 PM: JohnR, I am in the process of rebuilding my 25 too. I will let you know what my resistence is. Did you have a oil slinger behind your pinion before the bearing. I seen a oil slinger in one of my manuals but can not find it right now. I see Walcks sells one for a 25 but it will not fit into any pumpkin I ever seen. Also did you find a felt seal for your yoke?
Title: Re: Pinion preload 27 in/lbs
Post by: JohnR on June 29, 2014, 08:00:32 AM: Thanks for the replies.ï¿½ Yes, I did have an oil slinger right behind the pinion.ï¿½ $25 seems a bit steep for a glorified washer.ï¿½ Maybe try Willys Jeep Parts in AZ.ï¿½ I ordered felt seals for my yokes, but I don't believe that there was one on my front diff.ï¿½ The dust shield is way too small for one.
John