Kennedy - Got A Driveline Question For You!

[Billy14]

John,

After reading your recent posts regarding drive shaft & pinion angles, it's obvious your quite knowledgeable in this area. My question is back to the driveline clunk with the single shaft.

After a little grease from the dealer, no clunk & smooth as silk but it will come back after a month or so. The grease has got to be blending with the tranny fluid which I find disturbing although no problems to date.

I have driven several trucks identical to mine that were produced with the single shaft & no clunk. Do you, or anyone else out there know if the pinion-driveshaft angle on a single shaft is setup different than a factory produced split shaft? The split shaft comes off the carrier bearing at a greater angle than the single shaft directly out of the transfer case.

Mine is a split shaft replacement & I have noticed that a few others that had the mod now have the clunk like myself. If the pinion-driveshaft angle is different for the two shafts, could this be causing the clunk? On my truck without using a bubble protractor the driveshaft appears to be ALMOST parallel with the pinion plane. When the pinion climbs it will certainly break over the centerline of the drive shaft.

My guess so far is dull tooling. I tight spline is going to bind more than a loose one cut with a new broach (if the slip yoke is made by broaching).

Thanks,

Billy

[ 05-10-2002: Message edited by: Billy14 ]</p>

[Colorado Kid]

Billy,

John is enroute to BC (or already there) for the Rendezvous, so I don't think he'll be able to address you question for a week or so. I wish I knew what to tell you about your problem, but you seem to have better educated guesses about it than I would.

[Billy14]

Colorado Kid,

Thanks for the info, will try again at a later date.

Billy

[mark45678]

billy I would try to regrease the shaft,1st to see how much was in there and second to clean out the metal pumice thats in there befor reinstalling the shaft. you only need grease on the spines and not a lot,just enough to fill the spines from the valey to the top all the way around.

[TimofCharlotte]

FWIW, I had a 1989 C1500 that had that same driveline clunk due to play and movement in the slipyoke. Back when I first got the truck, the dealer took it apart and regreased several times and problem went away for a month or so, then came back. I was assured that the problem did not cause any damage.
I did notice that if I had a load in the bed or was pulling something, the clunk was not there or was not noticeable.
145,000 miles later, I finally sold the truck to my brother, and the clunk is still there, but no other problems related.
I'd keep pressing the dealer, but after a certain point, you have to hope that any rough edges just get wore down.
I suppose if you wanted, you could ask them (or do it yourself) to clean the splines of grease first, take some 200-400 grit emory paper to the edges of the splines to knock off any light burrs, and then clean/regrease/reassemble.
Any thoughts from the more knowledgeable on this as a worthwhile effort?

[Billy14]

Mark45678 & Timof Charlotte,

Thanks for the input guys. I cleaned the slip yoke bone dry with spray brake cleaner, then blew it dry with compressed air. Slick as a whistle. Spread a golf ball size glob of the grease (supplied by my dealer) with a wooden tongue depresser evenly over the spline ridges & valleys. Like I said before. Smooth as silk & even improved the ride over rough roads. If the drive line can't flex it's going to throw you around because the suspension can't do what it's supposed to do. Everything is pushing & pulling against itself. BINDING. Thrust loads being applied to bearings that were not designed to handle this kind of lateral loading & pounding.

The problem is after about 2,000 miles or a month or so, the clunk comes back. The grease must be getting flushed out by the tranny fluid. As stated before, this to me is a red flag waving in the breeze. Maybe the grease mixing with the tranny fluid won't hurt anything but this is a WARRANTY question I can't answer. At least my dealer gave me the special grease & TOLD me what to do.

Thanks again,

Billy

[stevem]

Billy14.

The grease will not mix with the trans fluid if your truck is a 4x4. If it is a 4x4 the driveshaft connects to the transfer case(does not conect to the expensive Alli trans) No need to worry about a little grease in the transfer case fluid.

Dont worry be happy, Steve

www.picturetrail.com/stevem

[ 05-12-2002: Message edited by: stevem ]</p>

[Billy14]

stevem,

You know, this is getting better by the minute. I do a a 4x4 & asked the dealer Service Manager this very same question. His reply was the transfer case used the same lubricant as the Allison itself. Flowed between the two. I thought this was a little odd but figured he should know.

If your right, think it might be time for a grease zerk in the slip yoke!

Billy

[Ironhead]

I Dont claim to know anything about these tranmissions or transfer case, but just an observation from what you been saying.
If the grease on the yoke can intermingle with the trans fluid (like you been saying). Then why cant it do the opposite? It seems if the grease could get into the trans, then the trans fluid would also be able to get to the splines and keep them lubed without any added grease. I would guess they either dont inter mingle OR its a drivline angle/ ujoint problem. If they DO intermingle, I would think you wouldn't want to be squirting grease in there.
Like I said I dont know a whole lot about this and I probably shouldnt even be commenting. Good luck on solving it.

[SoMnDMAX]

The transmission and the transfer case DO NOT share fluid supplies. They use the same TYPE of fluid.

There is not supposed to be any swapping of fluid between the two!!!!!

Billy 14, with a service manager that doesn't know that the Allison and the transfer case use seperate fluid supplies, I'd be finding a different dealer. JMHO.

[mark45678]

do you think synthetic ATF is worth a try in the tcase? I am sure it has better lube results.and a comment about the allison and T case shareing lub, I dont think so all the gm truck I have had a part had seals on the T case input side.the tcase input is lubed by the trans fluid but thats are far as the trans lube goes. I am not 100% sure but I think the T case only holds about 4 qts and it does have a drain plug.give this a try and let us know if this helps!

[ 05-12-2002: Message edited by: mark45678 ] smile.gif

[ 05-12-2002: Message edited by: mark45678 ]</p>

[Billy14]

I THINK YOU GUYS ARE RIGHT!

I've never known the two to swap the same fluid either. Made me wonder though since the Allison isn't your everyday tranny.

When I pulled the slip yoke out to lube it I noticed the fluid inside was red. This is what made me think the dealer was on cue but SoMnDMAX is probably correct.

This being the case, a synthetic lube in the transfer case might do the trick with better lube properties.

Think I'll browse through my owners manual & see if it specifies a different lube & capacity for the transfer case. So far I haven't been able to find any worthwhile information in the manual or the DMAX supplement regarding the Allison.

Billy

[ 05-12-2002: Message edited by: Billy14 ]</p>

[SoMnDMAX]

The New Process transfer cases used in the 2500 HD and 3500's, regardless of manual shift or push button shifting require a Dexron III spec fluid. Our trucks DO NOT require the Auto Trac II fluid. The owner's manual (and some dealers/SM's) are somewhat confusing- some will interpret the manual incorrectly.

The only trucks that require the Auto Trac II fluid are the 8600 GVWR 2500's (2500 LD), the 1500's, and the 1500 HD, only when equipped with the Auto Trac transfer case.

Presently, I am using Castrol Syntec Dexron in my T-case, and I will soon switch it over to Transynd when I install the deep transmission pan.