Need Getrag Help - 3rd gear. 3rd time!

[DMcLeod]

Gonna pull the trans for the 4th time. I noticed a few other 5spd topics on here lately, so hoping someone knowledgeable on the Getrag can advise me.

Couple years ago, a front countershaft bearing blew up on me at highway speed.

#1. I pulled trans, took to local trans shop for rebuild with new bearings, seals, syncros. Otherwise looks to be in good shape.

Installed trans, but within a few months 3rd brake not working, and began slipping out of 4th. Oil was silver.

#2. Pulled trans, shop warrantied parts and went through it again.
Installed trans but no change - worked the same as when I took it to shop.

#3. Pulled trans, shop found deep groove wore into 3rd/4th shift fork. Replaced necessary top cover parts.

Installed trans, within the year, 3rd brake not working, began slipping out of 4th, then could not shift into 4th.

Parked truck last summer.

I don't know transmissions, but have read the getrag manual a couple of times. Seems something is wearing out that 3rd/4th fork. Anyone know if a rebuilt top-cover will fix this? Or what is wrong deeper in the case? Sure could use some expertise here. Seems not too many 'good' repair options around these parts. I'm going to pull the transmission soon and have another go at it.

By "brake" I mean; when you pause just before slipping into gear, the gears mesh......well after a while when I went for 3rd it would want to just go right in with no resistance and grind. That seemed to be the 1st thing that went wrong, then after driving a bit more 4th gear would start gradually wearing out; meaning lever would begin to pop up (would not stay completely down into position where it should be); this would get worse and worse until it began to pop out of gear altogether once in a while, and then eventually would not stay in 4th at all. (On the positive side, I've got transmission removal down to an hour!.....and I did refresh the pilot bushing and release bearing. Clutch looks good.)

 

[Simplysmn]

Are you keeping the rpm's up when driving ?

 

[NIsaacs]

I would say your bearing preload on your input shaft/main shaft is too loose. Either from original repair setup or they are bad. The pocket bearing controls 3rd/4th. The bearing is on the front of the main shaft with the race built in to the end of the input shaft. All three bearings are tapered and adjust together, if one is loose they are all loose. When you pull the transmission grab the input shaft and see if you can move it side to side. A properly set up transmission should not have any side movement. There is a fine line between too tight and too loose. Tight bearings will fail quickly.

Nick

 

[RVTRKN]

I remember something about resting your hand on the stick, that was causing wear. I don't remember what trans it was, but that might be a clue to the fork wear.

 

[DMcLeod]

I'm aware of RPM, and never rest hand on stick. I've heard over and over about bearing preload on these, and how critical that is. 3 bearings, huh? The shop replaced all bearings, you'd think the preload would have been at least close. I can understand missing the shift fork wear groove the first time (well...an experienced mechanic should not!) but to have that wear out in the same fashion again so soon??? Thanks.....keep it coming.

 

[MMeier]

Might be time to consider a nv4500 swap ? Just my .02

 

[Philip]

1st question to ask any shop about working on a 1st gen. Do you have a factory service manual?

The shop you used I don't think has one. 3 times and the same problems points that way.

Just looking at the pic. 1st gear syncro looks like its trashed, 5th syncro is junk. Those syncro should have some space between the ring and the engagement teeth. If you notice those gears I mentioned do not. Like mentioned. Bearing preloads not right. Jumping out of 4th gear most likely means syncro shot and maybe the engagement teeth on 4 th gear bad now. Once meshed into gear the only thing to pop it out would be the engagement teeth have worn.

 

[Philip]

Let me correct yesterdays post. I stated 5th gear in that post. I meant to say 4th gear. Its popping out of gear. You can bet the front bearing and input shaft is gone.

 

[DMcLeod]

Ya, the pics were taken before working on it, so we found the junk syncros. After replacing all bearings and syncros is whan I began having troubles with 4th. Shop said quality of parts available for Getrag isnt great. I fail to see how syncros wont last more than a few months. Shop warrantied the parts (syncros) and replaced them, but 4th gear troubles showed up again immediately. If 4th synco is junk after a few months, why? What in there can eat up 4th synco in short order?

 

[NIsaacs]

The pocket bearing controls 3rd/4th. The bearing is on the front of the main shaft with the race built in to the end of the input shaft.

Nick

Fourth is the only gear that locks the two shafts together. The shifting collar slides forward and engages the input shaft right at the joint of the input/main shaft. There is a pocket bearing right there. If it is bad or loose the two shafts can wobble, right at the joint and kick it out fourth gear. The shift collar and or the teeth on the input shaft may be worn or damaged also.

Nick

 

[DMcLeod]

I never did solve the getrag mystery. Didn't want to tackle it on my own (glad for the comments provided tho- maybe someday I'll tear it apart), and couldn't find anyone locally I could trust to repair it correctly. Finally installed a new nv4500 just last weekend - glad to be rolling again. AA conversion kit as expected except for the following.
1. Had to grind a corner off the supplied transfer case shifter bracket to clear the transmission case casting - no big deal.
2. Using the linkage parts provided, the new transfer case linkage is approx. 3/4" longer than old - had to fiddle with adjusting to proper length for shifting.
3. Slight difference in overall length required me to hammer a dent in my 4" exhaust for front driveshaft clearance.
4. AA trans mount is terrible! Flimsy 10ga 3" square tube. I built one from thicker material. The trans sits too far back - I had to elongate the holes in the cushion mount at least 1/2" to bolt it together, and because it sits too far back it torques the mount. I'm not happy with it and will end up moving the crossmember back to properly support things.

 

[RWherley]

Just some thing to watch for, if your 4500 has the factory aluminum tail housing keep a eye on it, they were not intended to hold the weight of our iron 205 transfer cases and i have seen some where the aluminum mounting flang cracks and starts to break off. there are all steel tail housings out there now that take the weight and stress much better

 

[DMcLeod]

Thanks for the heads up. Fortunately I bought one with the cast iron adapter. The 205 IS a beast! I did renew the 205 input double seal too.