Get rid of the 2 piece ds. Got to a 1 piece. The carrier bearing is just a nuisance.

 

I believe you know several things, at least one of them might be dangerous to talk about publicly.

Also sorta sounds like maybe something isn’t lined up quite right and something is either dragging or trying to be both engaged and disengaged at the same time. Which I guess is what “dragging” sorta means...

Do you have any means of monitoring your gear position (slip) and torque converter clutch status (lockup)? That might shed some light on your transmission issues. The transfer case is a whole ‘nother critter tho. There’s no clutches. It’s either engaged or disengaged and it’s about as simple as it can get. You basically can’t screw it up unless it’s assembled wrong or the tolerances are outta whack.

Hope this helps! Good luck.


Sent from my iPhone using Tapatalk

lol...

That's exactly what the grinding sounds/feels like. The transmission was brand new and the transfer case was certified used as of 200 miles ago and they've both shown the same symptoms as the previously rebuilt transmission(s) and transfer case since their respective installations. While many parts have been replaced/balanced/shimmed, what I can think of that hasn't been replaced/altered includes just the engine and the rearward T-case slip yoke. Could there be any harmonic imbalance between 1750-2000 rpm in the engine that resonates down the pipeline, killing the transmissions and t-cases we've put behind it?

I should also mention that to retain AAMCO's warranty, the transmission must run off the factory tune. The engine still runs off of the EGR delete tune but when AAMCO puts a rebuilt or new transmission back in the truck, they flash the TCM to operate per factory specifications... Could any inconsistency between the engine and transmission tunes be so drastic that "dragging" will continue? Inconsistencies could include- shift points/ louckup points/ line pressure.

As far as vitals monitoring goes, I have an Edge CTS2 which served as the "no line pressure" whistle blower at the beginning of this fiasco. Ever since the TCM has been running off AAMCO's factory tune (2 rebuilds on factory trans and 1 new Jasper), the shift points have been seemingly expedited- Under minimal load, I've seen this truck shift into 6th lockout at 38mph.... which sounds insane as I type it out. Maybe my issue? Maybe between the transmission's erratic shifting and the potentially out-of-balance driveshaft between the T-case and carrier bearing, the transfer case keeps getting mangled by these outside forces. However, this wouldn't explain the deafening (70-85mph / 1750-2000rpm / any load / 5th or 6th gear lockup) cab drone that was still present with the new transmission and transfer case...

Also, could the condition of the rubber in the transmission crossmember mount and the motor mounts (although visually good) cause severe-enough misalignment and be contributing to my issue?

Does the driveshaft between the T-case and carrier bearing need to be clocked in a certain manner? As if it were key'd...

Could the rearward T-case slip yoke be damaged or driveshaft be inserted improperly? I've heard that slip yoke is pretty stout and is unlikely to be my issue.

 

I believe you know several things, at least one of them might be dangerous to talk about publicly.

Also sorta sounds like maybe something isn’t lined up quite right and something is either dragging or trying to be both engaged and disengaged at the same time. Which I guess is what “dragging” sorta means...

Do you have any means of monitoring your gear position (slip) and torque converter clutch status (lockup)? That might shed some light on your transmission issues. The transfer case is a whole ‘nother critter tho. There’s no clutches. It’s either engaged or disengaged and it’s about as simple as it can get. You basically can’t screw it up unless it’s assembled wrong or the tolerances are outta whack.

Hope this helps! Good luck.


Sent from my iPhone using Tapatalk

 

Here's my random thoughts -

-Cab drone from 70-85? Drivetrain related or 5" exhaust related? If the latter, put a 30" FTE resonator on the truck and then you'll hear non exhaust noise in cabin only
-Trans tuning/etc I would recommend DRD's tuning (have no idea what Aamco is flashing) or get Revmax to troubleshoot your transmission -
-One piece driveshaft? But shouldn't be necessary the truck should run well regardless

Depending on how many hp the tune is, and what factory gears are on the DRW (3.73?), with the tires it could be straining - 35's are decently tall on a DRW and thats a lot of mass to move

 

Here's my random thoughts -

-Cab drone from 70-85? Drivetrain related or 5" exhaust related? If the latter, put a 30" FTE resonator on the truck and then you'll hear non exhaust noise in cabin only
-Trans tuning/etc I would recommend DRD's tuning (have no idea what Aamco is flashing) or get Revmax to troubleshoot your transmission -
-One piece driveshaft? But shouldn't be necessary the truck should run well regardless

Depending on how many hp the tune is, and what factory gears are on the DRW (3.73?), with the tires it could be straining - 35's are decently tall on a DRW and thats a lot of mass to move

Hmm.. I'll have to look into Revmax and DRD. My tune is on a 5 position switch up and I leave it on the lowest setting at all times. Also, the noise exists in all 5 tunes.

As far as drivetrain strain, tires, and exhaust drone- A few weeks after I got the truck, I put the 6 brand new Toyo's on (They're actually just smaller than 35"- its a metric size that I cant remember). After the tires, the truck drove soooo smooth. The old ones were chopped a little bit. About 2 months later is when I took it to AAMCO for the first time- they rebuild the trans and 100 miles later, I get the pulsating cab drone/floorboard grinding noise/feeling which has been consistent ever since. They replaced the transmission and transfer case- went on a test drive and no change in noise. They shimmed the carrier bearing and the pulsating factor went away but it was still droning/grinding/vibrating.

All in all- the only thing that has helped thus far is them shimming the carrier bearing about 1&1/8".

 

1.125? That is a lot!

 

That's what I thought but the both rear driveshafts are in line with each other now. However, I'm not sure if that's how they're supposed to be...
Does anyone know the proper method for shimming/checking alignment these 2 piece shafts?

 

A driveshaft should never be perfectly in line with the u-joints. At static is should be about a 3 degree pinion angle minimum. That allows the u-joint to actually be a joint. If they’re perfectly aligned, it sorta defeats the purpose. I think these trucks had a 2-piece shaft simply because it was too expensive to properly triangulate and balance a single driveshaft that long. Might’ve had something to do with suspension geometry as well; the carrier bearing should be roughly in line with the front perches for the leaf packs.

Definitely check your exhaust to see if they moved or tweaked something. A 5” is a snug fit, and I know there were a few spots I had to “spit on it” with a 20oz percussive convincing tool to make it fit without rubbing. Usually hear about it contacting the firewall/floorboard junction area in the downpipe. Exhaust pipe contacting the body ANYWHERE will cause an AWFUL drone.

I’m almost wondering if they didn’t clock the transfer case wrong. There’s only six bolts and I have no idea how they’d screw up. Maybe look at a stock truck and compare to yours and see if the adapter is different (ie prior owner had a lift on the truck and used a clocking adapter)...

Again, hope this helps. I know we’re just spitballing here, but hopefully one of them is the money-splat and you can stop playing “make it rain” in your local aamco like a 70s Vegas strip club.


Sent from my iPhone using Tapatalk

 

A driveshaft should never be perfectly in line with the u-joints. At static is should be about a 3 degree pinion angle minimum. That allows the u-joint to actually be a joint. If they’re perfectly aligned, it sorta defeats the purpose. I think these trucks had a 2-piece shaft simply because it was too expensive to properly triangulate and balance a single driveshaft that long. Might’ve had something to do with suspension geometry as well; the carrier bearing should be roughly in line with the front perches for the leaf packs.

Definitely check your exhaust to see if they moved or tweaked something. A 5” is a snug fit, and I know there were a few spots I had to “spit on it” with a 20oz percussive convincing tool to make it fit without rubbing. Usually hear about it contacting the firewall/floorboard junction area in the downpipe. Exhaust pipe contacting the body ANYWHERE will cause an AWFUL drone.

I’m almost wondering if they didn’t clock the transfer case wrong. There’s only six bolts and I have no idea how they’d screw up. Maybe look at a stock truck and compare to yours and see if the adapter is different (ie prior owner had a lift on the truck and used a clocking adapter)...

Again, hope this helps. I know we’re just spitballing here, but hopefully one of them is the money-splat and you can stop playing “make it rain” in your local aamco like a 70s Vegas strip club.


Sent from my iPhone using Tapatalk

Aamco did mention an adapter on the transfer case that was there from a previous lift and that they took it out. I'll crawl under there and compare to pics of a stock setup just to make sure everything is straight.

As for the exhaust, Aamco took the truck to an exhaust shop to check over everything. they replaced some rubber hangers and gave it a clean bill of health. I even crawled under there and couldn't find any contact points- but yes, it was a pretty tight fit getting that 5" from the turbo to under the truck. I suppose that maybe under load and between 1750-2000 rpm, the engine could, in theory, be torqued over a little bit- narrowing the gap between the exhaust and the firewall area.

For the driveshaft, I'll be sure to find some factory specs or proper carrier bearing shimming procedure before anything.

Thanks for the reply!

 

My initial 5" downpipe install was too close to the body but the horrible (and really obvious) rattle occurred immediately when I put it in gear. Can't remember if it was D or R. You can loosen the V-band clamp and the next band clamp downstream and rotate it a little bit it that's the case but I don't think that's your problem.

I have a 1 piece shaft but from what I just googled it looks like the 2 piece shafts use 3 regular u-joints (as in NOT a double cardan like the front shaft). There are several ways to properly set up that configuration and any competent driveline shop should know what to do but you should check it yourself as any excess vibration there is a big problem. I've found that the first thing to get killed tends to be the t-case, starting from a leak at the seal but all my driveline angle experience is with old Toyotas. My gut feeling is that your problem originates with driveline angles and you're shaking your t-case to bits. I'm not sure how that is affecting transmissions, though.

Roger Brown did an incredible write-up on driveline angles here: https://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

 

My initial 5" downpipe install was too close to the body but the horrible (and really obvious) rattle occurred immediately when I put it in gear. Can't remember if it was D or R. You can loosen the V-band clamp and the next band clamp downstream and rotate it a little bit it that's the case but I don't think that's your problem.

I have a 1 piece shaft but from what I just googled it looks like the 2 piece shafts use 3 regular u-joints (as in NOT a double cardan like the front shaft). There are several ways to properly set up that configuration and any competent driveline shop should know what to do but you should check it yourself as any excess vibration there is a big problem. I've found that the first thing to get killed tends to be the t-case, starting from a leak at the seal but all my driveline angle experience is with old Toyotas. My gut feeling is that your problem originates with driveline angles and you're shaking your t-case to bits. I'm not sure how that is affecting transmissions, though.

Roger Brown did an incredible write-up on driveline angles here: https://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

Looks like I've got some homework to do haha. Your thoughts are consistent with my suspicions: driveline angles. I'll read up on that and make sure everything has the correct angles considering the lift. I'd like to do a 1 piece shaft but there's so many opinions out there on whether or not it will work at that length for this truck. Is your 1 piece shaft aluminum or steel? @H3LZSN1P3R 's post has me thinking...

 

What happens when you remove the front shaft? I had a past truck with a 4” lift front and rear. The rear drive shaft was a big issue. No amount of time spent shimming fixed it for me. I ended up fixing my vibrations with a one piece shaft. The rear shaft is probably not the source of all your issues but if you decide to go one piece look at driveline specialists in San Antonio Texas. They ship nation wide and have a great product. Its where i will be getting the one piece for my truck. A one piece gets rid of the launch vibration these trucks have under load or heavy throttle. Every single two piece truck i have ever had wobbled in the carrier when taking off heavy or spirited.
My last truck shook so bad with the lift and improper carrier angle that i ripped out two carrier bearings within a couple thousand miles or so.
And, i had no idea anyone even went to double A MCO honk. Advertising works i guess. And as far as a Jasper is concerned i hear they are hacks. Big time slap in back togetherers. On their motor rebuilds short cuts are the name of the game. Like just mix and matching pistons that look good and slapping an engine back together. I could only imagine what they would do to a 68rfe. I always figured they were the go to guys to get a truck going just enough to trade it in. When i hear Jaspers i cringe down inside then catch my breath and RUN. I would have used either Randys or Red Horse for that 68rfe repair and kept the trans tuning that matches your trucks tuning.
Anyway, i am interested in if removing the front shaft helps any.

 

Have you tried putting the truck up on blocks and seeing if you can find it. Process of elimination—. Pull rear shaft and run in FWD and get to speed/ rpm, see if problem persists. Try in rear wheel drive alone without front wheels turning. Also this will eliminate any tire noises. You can also get someone else to hit the go pedal and you can put an eye on your driveline to visually check for any erratic pulsing/ vibrations?????

I know it’s not the best idea to get tire speeds up to 75-80 on blocks/rack but after that many tranny builds......... ????

 

What does that rear lift consist of? Hopefully not tapered blocks. If so you'd have a helluva time getting the U-joint angles correct.

And while I'm not a fan of multiple driveshafts, when even I managed to set up a 3-piece shaft so the angles are correct and it doesn't vibrate, it's obviously fully doable.

Oh, and the shafts are phased correctly, right?

 

The rear lift is up 2" and yes it has tapered blocks. If they need to be removed, I will do so, gladly. And yes the rear shafts are phased correctly

 

UPDATE-

I went down to Aamco on Saturday to inspect the transfer case while they had it open. They told me nothing was wrong with the tail bushing but I, for one, had not been smoking crack that morning. See pics. I'm wondering if this could be a large part of my issue. It would explain the small runout I felt on the shaft coming out of the t-case and the returning "SERV 4WD" light on the dash.

Apparently there are none of these in stock anywhere as they were discontinued years ago. Might have to have a machine shop mill one out for me. If anyone wants to take a jab at finding the part, the part number is 68161330AA. It's a BW4446 t-case. I'm placing a $20 Paypal bounty on the in-stock location of this part as I'm sure someone on here has access to strings I haven't yet pulled.

Borg Warner used to sell the bushing by itself, then they sold it already pressed into a new rear t-case housing (PART #: 68161327AB), then they discontinued both parts. Note: the tail bushing for the bw4446 used on the 4500 and 5500 is about 1/2" shallower than the 3500 one- it has the correct inside and outside diameters though but still can't be used.