New gear break-in (1 Viewer)

[Cruiserdrew]

I just got Precision Gear 4.88's installed at a local diff shop, and with the help of another lister installed the diffs in my 80 yesterday. I'm curious about break-in. I drove about 5 miles of slow streets, then stopped for a brew with 2 other members of the list. Then home. Then I did 10 miles, including a 1 mile segment of freeway. Today I did 20 miles of medium speed (40mph) with a few lights. Diffs feel warm, not hot after each run. The gears seem to run as quiet as stock, and I was listening hard.

My problem is that I'm driving this truck to Cruise Moab (2500 mile high speed round trip) so I want to make sure the gears are broken in prior to the trip. I will be lucky to accumulate 500 miles prior to that, especially avoiding long freeway cruises. Any tips for making sure the diffs are well broken-in prior to my blast across Nevada and Utah? I do plan to change the lube just prior to leaving for Moab. I'm not super worried about this, but if 3 weeks of extra care will make a long term difference, I'm willing to do it. Thanks.

 

[lagwagon]

My wife will put 500 in town miles on it for you this week Oh, easy miles, never mind.

 

[landtank]

Check Randy's ring and pinion site. they have a detailed writeup on break in. I followed their recomendation and haven't had any issues.

 

[T Y L E R]

....Andrew , what did the parts cost in total ? Gears and all the necessary bits .. exclude labour .

Thanx ,

Tyler

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[Cruiserdrew]

I have misplaced the receipt, but the front set is $184, the rear set is $220, and the install kits with new bearings, seal, shim etc were $125 each roughly. I'm very happy with the quality of the Precision Gears. The diff guy I used said they set up really well. He also said the original bearings looked like new(at 86k miles) and could have been reused. The original ring and pinions are in like new condition. I credit that to a steady diet of Mobil 1 and later Chevron Delo Gear and yearly changes. I drove all over town today at 0-50 mph but still am under 100 miles on the gear set. I almost need to spend a whole day in city traffic-stop light to stoplight which seems perfect for new gear break in. I may let Jeff's(Lagwagon) wife have the truck to break in the gears!

One side note: After airlocker install last year, I had a bit of a "clunk" that the 80's are famous for. With the new gears, the clunk is completely gone. Could R&P backlash be the real reason for the clunk? On the bench, I did see that the gears have minimal backlash. Something like .006.

 

[lagwagon]

I bet the clunk went away because when you removed the front driveshaft you pushed in the slip yoke and lubed it well. Are you running Slee's driveshaft?

 

[drexx]

29Mar2004 (UTC -8)

Why 4.88's Andy? I thought you got 33" tyres? Or have you secretly upgraded? But even with 35"s, I'd go only with 4.56 as they bring me closer to stock speedo readings than 4.88.

 

[robbie]

Hello Andy: We usually drive the regeared trucks under 55 for 20 minutes and then allow the gears to cool for about 2 hours. All is golden after this. We do reccommend that you change the gear lube after 500 miles to the lube you will be running later. I really would not miss this 500 mile change. As for 20 minutes it to allow the gears to heat up then cool down hardening the teeth and meshing the pattern in.
As for the clunk this might be more pointing to the back lash in the spiders then the ring and pinion. with air lockers all the internals are replaced. later robbie