Not really sure that I understand the question, alwaysworking.. the scenario in which i hear the noise loudest/most clearly is in 4th gear, just letting the truck slow down from about 35mph to 25mph or so. Its not constant.. it pulsates, and sounds like a grinding.

I was on the phone with my uncle this morning, who is an automotive powertrain engineer - he has worked for Dana and now works for American Axle and has been on the design team for several well-known vehicles. Anyways, he thinks it could be a drivetrain vibration at a certain harmonic frequency with the engine at a specific RPM. But I could swear it sounds like a grind...I'd really like to have someone familiar with these trucks listen to it, hence my other thread.

My uncle also said to put heavier oil in it than 5w-30. He says that engine oil has cleaners and other additives that are not good for gearboxes. "Heavier is better.. the gears love it" he says. Keeps oil in bearings better and whatnot.. I know this has been a longstanding debate, and you (always working) from your sig run the heavier stuff.

 

i run whats be tried and true for years in semi's, but with gear oil they shift a little harder when cold but when the oil warms up it fine.

at that speed it has to be in my opinion backlash, try driving in the next gear lower at the same speed and see how that feels.

 

27mph in 4th is ridiculously low RPM, unless you have 5.13 gears. If you are still in 4th at 25mph, you are just a hair above idle, and could be contributing to the noise you hear, grind or growl it may be.

In my last 4.10 truck, i never shifted into 4th at less than 35mph' with 3.54s, I stay in 3rd til at least 40; I've gone 45 in 3rd for a long stretch if I know I'll be slowing down in the next 1/2mi (city driving).

Without driving it, it's hard to say for sure, but it sounds to me like you are getting normal noises associated with the cyclic vibrations of the engine, combined with a transmission that doesnt like low RPMs. Try driving it at higher RPM for a while. It will sound like it's really screaming if you aint used to it, but see if the noise changes.

What did you set the preload on the mainshaft? I set mine to .004-.006. The book calls for .006-008, but I have been told by some experts that a hair loose is better than ANY too tight. You basically want to take up the slack so there is no up-and-down movement in the mainshaft. I set up my mainshaft, take it out. Set up countershaft, resinstall mainshaft, and I'm done.

Daniel

 

Daniel,
I set it to .006. All this worry could be for naught, which I hope it is. I am just a relatively conservative driver, and seeing as how this is my first diesel, I have no basis for comparison.

Yeah, I would usually shift out too early I guess, because the engine would seem so dang loud. 4" straight piped exhaust from the PO doesn't help that either!

Ah the teething pains associated with moving to a new engine technology

 

you got it figured out now, right.
does it have a govenor spring in it yet?

 

Do a search for oil and the getrag. In essence, you want to run 1.0 to 1.5 quarts more than the oil fill level. Basic reasoning that there are parts in the getrag that do not get lubricated well at the standard level. Running a heavier lube prevents it gettting into some of the tight tolerance places in the transmission - so you do want to run a good 5-30w synthetic motor oil in the transmission.

I understand your uncle's viewpoint. I initially thought 5-30w?, but I am since convinced. The two best things I did for noise was to overfill the tranny and then not lug the motor.

 

That right there is GOOD ADVISE!

3200GSK will let you wind the Engine up a bit higher before you shift so you won't lug as much durring normal driving.

BTW it growls more in 4th because that's direct drive and there isn't any real load on the gears so they rattle around more.

 

Well the PO said the pump was rebuilt by craigville diesel, here in Indiana, and there's a sticker there on the pump to confirm it. I don't know if the governor spring has been done yet, honestly. Truck has no tach yet.. hoping to change that soon.

Here are some facts.. maybe we can figure it out together

someone (alwaysworking I think) said that with his 3200 gsk he could go to 50mph in 3rd. Well, I did a test today and I can go 45-47mph in 3rd, and I have 4.10 gears. The truck has factory sized tires on it, so speedo is accurate. We could do some math to figure out rpms i suppose, but I don't know all the numbers, like the circumference of the tire, or 3rd gear ratio.

 

I really think you have an issue with the input shaft bushing or lack therof. You might be running without anything in there but a disintegrated bushing, however the fact that you said your input shaft looked ok with no wear or scoring would contradict my theory. You really need to get the flywheel bored out and have the ball bearing installed whenever trans rebuilds are done.

 

Like they say, its always faster the second time.. I might soon take the trans out again and install throwout bearing, and get the bushing done.. Here I have some pics of stuff while it was apart.


The input shaft is poking its head out from behind the case.



Can you see if there's a bushing in there?




Let me know what you see.. I don't really know what I'm looking for.

EDIT: I guess you cant link to photos hosted somewhere else.. here are the photos http://picasaweb.google.com/avewilson/Getrag

 

well
I don't see it in the pics, the only thing I saw was a small view of a fairly good looking input shaft... but I can't know for sure. did you remove your clutch with the install?? you have to remove it and expose the bare flywheel. In the center of the flywheel is a hole, that the tip of the input shaft rides in, that is where the bushing should be... you wouldn't have seen it if you didn't pull the clutch off.

 

You should pull it out and overfill with 5w30, setup preload etc, machine out the flywheel to accept the larger bearing, get a new clutch assy off ebay for 400 bucks that includes a throwout bearing. Actually dude I have a throwout bearing you can have but it might have been thrownout!! I bought one in addition to a new clutch for my conversion because I didn't know one was included with the clutch. so the other I am not using. they are cheap anyway.. oh well. I would go the whole route. the flywheel must come off anyway to get resurfaced with teh new clutch. and while you're in that far you might as well replace the rear main seal for the crankshaft as well. and no, I'm not kidding.

 

I have posted a lot of info about getrags in the past. It might behoove you to do a search in my posts. I pasted a lot of info from "mysteryman" aka Terry Elder from TDR who was the lead chrysler engineer that originally put and tested the cummins in our trucks back in the 80's. He's a Getrag guru.

 

Here's something I should have mentioned: the clutch is only about 10,000 miles old, because the previous owner swapped in the Getrag and replaced the clutch. The clutching action feels good and solid, no vibrations or funny noises, and throwout bearing isn't squeaking or anything. (I know what a bad clutch/uneven flywheel feels like - my dad's toyota MR2 turbo has had one for 15k miles... lol)

I will call the PO and ask him if he replaced the input shaft bushing when he was in there. Based off the input shaft condition, and the relative newness of the clutch, I am deducing that all is well in bushingland.. but you can never be sure.

I did shim to appropriate specs 6-8 thousanths when I put it back together. Also, I did read alot of the stuff you copied over and posted from that Getrag Guru when I was first trying to diagnose this before I replaced all the bearings. Guess I should have posted then so you could've admonished me to check out the bushing. I was just a reader then.. lol

Also, on a more positive note.. the more I read from everyone here, and all the around-town driving I did yesterday, I am thinking that I was just in too high of a gear at too low of a speed causing the gears to clatter.

I have overfilled bu 1 qt, but I am going to drain that out as a break-in oil for the new bearings and then re over fill by 1.5 or so.. ie just buy the 5qt jug at wally world and dump it all in.

Thanks a ton for all the responses guys.. I am loving this forum, the people here are actually interested in helping, not just saying something to say something. \\

Avery

 

NOPE!! this isn't the youtube comments section! We love these trucks and want to keep them alive.