Realistic budget of a 2wd -4wd and goodies build

[LCAM-01XA]

Nah, ours does more or less the same thing, well she does cold-start on <10 sec cycle just not as easy. The 15 second glow is our initial for the day after a night's rest and she lights off instantly then. That's what the factory controller did, so that's what we do as well. On a very hot day she will light off easy on 10 seconds even, but anything less than that is reserved for when she's been off for a few hours but engine block still has retained some heat.

 

[Greg5OH]

well frig, i had an annoying bucking at around 55mph before the hanger bearing change. Also a rumble in the driveline upon take off. Changed the bearing, all was fine over the weekend. but sinc eyesterday it has started again. annoying obnoxious bucking at 48-55 mph, and driveline rumble upon initial take off. hanger bearing looks good.
any ideas?

 

[stealth13777]

I would say needing the longer glow is fine. Mine down here in Florida (factory controller) on 88 degree days still glows for a decent amount of time. 10-20sec easy.


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[Greg5OH]

cool sounds good. I also started keeping them on while crnaking, starts faster this wya. I know i shouldnt, but...works fo rthis setup.

now this bucking. I cant quite tell if its the engine bucking, or something in the drivetrain bucking and vibrating. I know the engine doesnt skip a beat when free revving, or in hi rpms in a low geear. Happens in 3rd and 4th, between 35 and 50-55mph.

 

[laserjock]

Driveline vibrations are a pain. Is it more of a vibration or a noise? Rule of thumb when tracking down stuff like this is to remember what speed all the different parts are turning at. The driveline turns at a much higher speed (what ever your gear ratio is) than the tires. If you put it in different gears, do you get the same sensation at the same speed but at a different engine speed? That can help narrow it down to inside or outside of the gear box. Does it do it in both 2 and 4wd? Does it do it both on acceleration and deceleration? I had a truck that the driveshaft was a hair too short on and it would be smooth as silk accellerating and would vibrate like hell decellerating because the diff would twist and shove the slip yoke in far enough to keep it from vibrating. Not saying this is the case but just trying to help you narrow down what part to look at. You could always put it in 4wd and pull the rear shaft and isolate that part of the driveline too. I've done that before.

 

[Greg5OH]

I will have to pull the rear shaft indeed to isolate it. Now I wish i spent the time to mod the hsift rail in the NP205 so i could do front output only lol.
But yes happens at a certain speed, regardless of gear or engine speed. Just sounds almsot like the engine is starting to miss though. Hard to tell since its so damn noisey in the cab

 

[snicklas]

Greg, this may sound funny, but are you noticing this on the same road each time? Reason I ask, on both my Ex and my P71, when I am on the Interstates here in Indiana, at highway speed there is a "harmonic oscillation" that happens. I can't really explain what it is, but I KNOW what I feel. On the asphalt stretches of Interstate, I would swear there was a miss, or maybe had thrown a weight on a wheel or driveshaft. If I am on a stretch of concrete, the "miss" goes away. I took the truck out of state a couple of times here lately, and after crossing the state line the "miss" went away. I took the P71 to my parents house in Illinois, as soon as I hit the ILL state line on I-74 in Danville, the "miss" I was feeling in the car quit. No "miss" the entire time I was in Illinois, on the return trip, hit the state line again on 74 and the "miss" returned........

Could be there is nothing wrong with the truck other than the road. Whit both of mine, you can hear the difference, and feel the difference. The wife was with me, and she noticed the same thing, so I know it wasn't just me. She drove the truck out of state by herself and said it was doing the same thing, as long as she was in Indiana, there was a "miss"........

 

[Greg5OH]

nah this ia all types of different roads. There is one part on my drive home though, i feel it in all cars.
Other than this new vibration, truck runs great

cming home from toronto last weekend,
18.5 mpg,
68 mph
500-600 F pyro flat ground for the most part
190 water temp
1850 rpm
7lbs boost.

 

[LCAM-01XA]

But yes happens at a certain speed, regardless of gear or engine speed. Just sounds almsot like the engine is starting to miss though. Hard to tell since its so damn noisey in the cab

That doesn't make much sense tho - engines tend to miss under certain load conditions only, by shifting gears and varying engine speed you're also varying the load on the engine, so if it "misses" at 2000 in 4th there's a good chance dropping down to 3th and revving her up to past 2500 will get rid of the "miss". Sometimes it works the other way around tho, the bucking is more evident at higher RPMs.You should be able to hold OD at 45 even, so stick her in 5th next time she starts acting up and drop the engine speed and see what happens?

 

[Greg5OH]

like i said, seems speed dependant, not rpm dependant. 3,4,5 all seem to do it at same 35-50 mph speed. it just "sounds" like its missing or bucking. I will pay more attention to throttle input try to feel out where exactly. I dont THINK it does it under WOT, rahter just cruising or light acceleration.

 

[LCAM-01XA]

Well there is a HUGE difference between engine load and fuel consumption in 3rd and those in 5th at the same vehicle speed. So at this point I'm thinking driveline issue, likely driveshaft. When you replaced the carrier bearing, did you check the U-joint next to it? If the bearing was vibrating bad enough it could have taken the U-joint along for the ride.

We had a pesky vibration in our truck once, worst around 45mph regardless of engine speed and gear selection, would come on at around 40 and would be gone by 50-55. New tires didn't fix it, new driveshaft during the 4x4 swap however did.

 

[Greg5OH]

you know, i didnt actually check the longer post hanger U joint. I did look at the one at the tcase, and "appeared" fine. I will do some more investigating on the shaft and u joints themselves.
to check. i put vehicle in gear, and just try to twist the shafts by hand and move them around the U joint ya?

 

[laserjock]

Basically, but it's sometimes really hard to tell a bad joint without taking it apart. Work it up/down left/right and see if you can detect movement that is not (or may be) slack in the ends of the caps. Check the circlips too.

 

[LCAM-01XA]

to check. i put vehicle in gear, and just try to twist the shafts by hand and move them around the U joint ya?

Waste of time! Drop the shafts, move the yoke by hand. With everything still in the truck the weight of the shafts alone is often enough to mask any problems. Even if you know what to look for, a binding u-joint is nearly impossible to diagnose without splitting the shaft - actually I'll go as far as to admit that there's no way in heck I could determine if one is binding with the shaft in place.

In other words, buy your wife something nice - it's a bribe for her to allow you more truck work time

 

[Greg5OH]

lol!
i checked the shaft over reaql quick after work yesterday, tried moving it around, i hear a squeek from pinion area. oh god dont tell me the pinion bearings are going out. upon further investigation.nope! the companion flange at the rear was lose, all 4 bolts backed out, looks like i forgot to loctite them on!!! pulled em out, cleaned, loctite, 80 ftlbs. lets see ho wshe drives todya