Stephen- need advice- T-case/Doubler vibration at no-load situation

[FWP]

Seems to be most pronounced at 40 MPH or above, you can really tell at 55-75 MPH. Push on the gas, no problem, de-accel, no problem. Have the motor running the same rpm as the driveline, it makes a heck of a racket. What the hell is going on? It's in the transfer case setup- nowhere else. Need some help here before it drives me nuts, and I drop the case pieces to find out......

 

[Stephen]

The last guy I heard this from went with a CV jointed rear driveshaft and fixed the problem so that might be something to consider.

Loose output yoke nut(s)? Oil levels OK?

Vibration at low power levels but high speed would indicate a condition that depends on the gear thrust keeping a bearing tight or something like that, maybe a bad needle bearing in the output shaft?

Any idea on whether it's in the 203 or 205? Have you tried it with one case in low?

Lots of stuff to look at here but maybe this will help.

 

[HarryH3]

I had a brand new F-150 once that would do that. Turned out to be too much slop in the slip joint on the rear driveshaft. Ford replaced the shaft under warranty and the vibration was gone. /forums/images/graemlins/cool.gif

 

[FWP]

Thanks guys. I just finished narrowing it down to the 205, rear output area. I need to remove the rear driveshaft next, just to make sure (even though the driveshaft is less than than a week old - different story)

Does the master rebuild kit for the 205 come with thrust washers? and the shims for the idler?

 

[Leadfoot]

The master rebuild kits come with the shims for the idler, but the thrust washers are to be re-used. Inspect them for signs of wear and replace if needed (Usually can be purchased from a GM dealer). Worn gears "can" happen in a 205, but the chances of them becoming excessively worn is minimal unless it was run on low fluid, overheated, and took the temper out of the gears. Those gears are pretty hard (rockwell hardness). You should also be able to "see" any excessive wear. Usually the wear occurs on the engagement teeth, clutch ring, and shift forks. The noise could also be a sloppy bearing. When under accel or decel there is a "load" placed upon the bearing, and under steady speed, the "load" is taken off, allowing the bearing to "wobble" and/or vibrate. Also (as has been discussed here before), a sloppy shifter will make a heck of a racket when the case is not under a load (just something to keep in mind). Now this is just a guess without seeing the case. If you plan to keep it, get the rebuild kit and go through it. Also alot an extra $200 (just in case), as your shift forks, collars, engagement teeth, thrust washers MAY need replacing and they do not come with the rebuild kit (just bearings, seals, and shims).