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 Post subject: How fast is ok in 4wd?
PostPosted: Wed Dec 28, 2016 8:42 pm 
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Last year I was driving my truck in a soggy field in 4wd and then out on the pavement for 5 miles. On pavement I drove about 45 mph. When I slowed, the truck came to an immediate stop, instead of rolling slowly to a stop. I figured the hubs were screwed up. I put them back in 2wd and they were warm. A few months later, I had the truck in the shop for other work. I told them to look at the hubs. They found some used hubs online and had them shipped over and installed them.

Yesterday I went skiing. I don't usually take my Luv for that but I hadn't put the winter tires on my SUV yet so I decided to take the truck instead. When it got slushy, I pulled over and locked the hubs and transfer case into 4 Hi. I drove about 30 miles to the ski resort, mostly at 35-45 mph. I skied the day and drove back. When I stopped for lunch about 45 miles from the ski hill, the hubs caused the truck to stop quickly again. I had a hard time parking in a spot and had to give the truck gas in 1st to keep rolling. WTH? I thought I just paid to have these hubs replaced! It was 38 degrees out and the hubs were quite cold. Is there some max speed I should stay under while the hubs are locked? Why is there a 4 Hi if I need to keep the speed down?

Maybe I can't take this truck skiing. If so, the 4wd is basically useless because I'm never going to go drive the truck around in 4 Lo intentionally.

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1979 4wd Mikado. G200, Gemini 250 Turbo, Clive Cam, Offenhouser Intake, JE Pistons, maXspeeding Forged Rods, Blow Thru Weber, Trooper 5spd, Intercooled


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PostPosted: Wed Dec 28, 2016 11:08 pm 
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There is no limit to the speed you can go in 4wd.
If the "hubs" you are talking about are the lockout hubs they are not your problem, their only function is to connect & disconnect the front drive axle to the front wheel. There is nothing within the hub that can cause the problem you describe. There is a small bearing around the front axle shaft that turns as the shaft turns, which occurs when the hub is locked or when in 4wd or both. Other than that one bearing & the attached axle shaft everything that turns in 4wd or with the hub locked also turns in 2wd or with the hub unlocked.
If your problem also occurs in 2wd I would first suspect brake drag, probably from a MC or booster not fully releasing. If it positively only occurs in 4wd it's something in the 4wd driveline. If it only presents after extended driving I would look for a bad bearing or a dry differential, but either of these should produce a noticeable noise.
Drive the truck at speed in 4wd with the hubs unlocked, listen for unusual noises, see if the problem recurs (you can do this on dry pavement since the front tires are freewheeling). IF the problem arises feel for overly hot areas among the various front drivetrain parts, from the wheel hubs in to the differential & back to include the transfer case. Report back your findings.

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'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.


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PostPosted: Thu Dec 29, 2016 2:24 pm 
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Ok I'll do that when I drive the truck next.

I think the diff and transfer case are fine. I had the fluid changed 2000 miles ago for both diffs, trans/transfer case, and I had the trans fully rebuilt 30k ago, I assume they would have told me if the transfer case needed work too because they are mated. My shop would have checked wheel bearings when they were in the hubs because they also did a brake hardware kit and rebuilt the steering box on their own (after asking me of course). I don't think they would have messed with a bearing on the axle shafts. It's not brake drag because my shop just did the brakes and it doesn't happen in 2wd.

Thanks for the help!

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PostPosted: Tue Jan 03, 2017 5:19 pm 
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It drives normally with the tcase in 4Hi and the hubs unlocked.

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PostPosted: Fri Jan 06, 2017 12:46 am 
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To eliminate 4x4 bind up or drag....the rear end ratio both front and back must be exactly the same. Also the tire and wheel size must be exactly the same front and rear. Make sure someone has not changed the rear end ratio at some time or other. Stock 79 ratio is 4:10.


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PostPosted: Mon Apr 03, 2017 12:23 pm 
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egg wrote:
To eliminate 4x4 bind up or drag....the rear end ratio both front and back must be exactly the same. Also the tire and wheel size must be exactly the same front and rear. Make sure someone has not changed the rear end ratio at some time or other. Stock 79 ratio is 4:10.


Good point I haven't checked that

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