DEUCE:Metal 'clacking' sound in 5th gear high/low only??? Any ideas what it might be?

[NCAR15MAN]

I recently bought a 1972 M35A2, and I drove it a month or so ago and had a metal 'clacking' sound when I was driving along in 5th gear low and high. It didnt seem to do it in any of the other gears. I am not super mechanically enclined...so any ideas of what to look at would be much appreciated.

Thanks,
Newbie

 

[poppop]

It sounds like you may have a chipped gear tooth on the fifth speed gear. If you can't feel any kind of bump when you hear the clack it may not be to bad and may not cause any more damage. The best thing to do is pull the tranny cover and inspect the gears. You can rotate the shafts and inspect each gear.

 

[gringeltaube]

As Poppop said; probably some missing teeth, on one- or even both gears for 5th speed. (2nd pair, counting from F to R)

See this other thread... http://www.steelsoldiers.com/showthread.php?73023-Noisey-5th-gear-teeth-rubbing


G.

 

[shannondeese]

Another thing it could be. The input bearing could be going out. I had a metal grinding and clanking noise in my Deuce in 5th gear only, and it was the input bearing broken. Good Luck.

 

[glcaines]

That sounds like the sound mine had in 5th gear when I retrieved it from Fort Indiantown Gap. A few weeks after a horribly long drive back to Georgia, the transmission started shelling teeth from 5th gear. I got a takeout to replace it. Mine made the most noice in 5th gear when I let up on the accelerator. Hard acceleration caused it to quieten down. Don't wait until it quits on you. I got lucky when mine quit close to home.

 

[iwantmud]

MIne is making a noise in 5th also. It only does it when you on the throttle, as soon as you let off there is no noise. I just noticed it when i put a muffler on and ran the exhaust out the back.

 

[glcaines]

When everything is copacetic, there should not be any noise coming from the transmission other than normal gear whine. A deuce is so loud that any transmission noise you can hear is not good news.

 

[m715mike]

Well, I guess it's time for me to look in the transmission.

I got my M35A2 out for a short drive yesterday. Once on the main road, I started going up through the gears. Everything was fine until I hit 5th gear. At first, I heard the "metal 'clacking' sound" mentioned above. The clacking continued and next it sounded like small pebbles were flying up from my tires hitting directly below the cab. That was followed by a horrible grinding noise. I slowed down and dropped back into 4th gear. The noise and grinding stopped. I continued in 4th gear and got home without any other issues. While the truck made a lot of noise (and the grinding increased my pucker factor), the truck shifted and ran well even in 5th gear. The noise/grinding did not impact performance. Granted, I did not leave it in 5th gear for long.


Wahoo... My truck got a fresh engine earlier this year. I guess now it's begging for a transmission!!!

 

[gringeltaube]

Sorry to hear - Sounds like another 5th-gear lost the fight...
Keep us posted with what you found.

 

[glcaines]

When my A2 transmission gave out, the gears were so trashed I didn't even consider rebuilding it. I got a takeout and swapped the transmission. I went ahead and replaced the clutch at the same time. I'm still running on the used transmission. Good luck.

 

[m715mike]

I made a deal on a takeout transmission this afternoon and should pick it up this weekend. It may be a while before I'm able to swap the takeout transmission into my truck. I'm also thinking about a new clutch.

 

[Jeepsinker]

Mike, your engine came with a brand new clutch and throw out bearing.

 

[m715mike]

Sorry to hear - Sounds like another 5th-gear lost the fight...
Keep us posted with what you found.

It's taken me a couple of months, but things are finally in motion. I should have a new transmission in my truck next week. I'll keep you posted on the progress in this thread >>>


http://www.steelsoldiers.com/showth...-Jeepsinker)&p=1929558&viewfull=1#post1929558

 

[plym49]

What causes fifth gears to buy the farm?

 

[frank8003]

4 ton in back, slammin into 5 and poppin clutch?
or was it the operator incorrectly operating?

 

[rustystud]

What causes fifth gears to buy the farm?

Basically abuse. Remember when the 3053 is in 5th gear it is "not" spinning but is engaged to the main shaft by the synchro. So that is not the cause.
The main shaft is spinning faster then the input gear so the roller bearings in the input gear are working just like they are when in any other gear except in 1:1 like 4th gear in the 3053 and 5th gear in the 3052. So that is normal. The bushing the 5th gear rides on only has one "key" to engage the mainshaft. If it doesn't get enough lube between the gear and bushing it can snap or twist on the shaft but that is not in action when the truck is in 5th gear as the 4-5 synchro is engaging it to the mainshaft. That really just leaves operator error. These Spicer transmission are not to be shifted "fast" like car or even modern truck transmissions. When you are taught to drive them in the military they teach you to "double clutch" these units. They are slow but steady drivers. The clutch "dogs" on the fifth gear are also smaller then say the second or third gears by about half. So anyone shifting "fast and furious" will cause damage to them. Also you should never "lug" these trucks in 5th gear. If the RPM is going down then downshift. Don't wait until your forced to shift or kill the engine. That puts tremendous strain on the gears when you do this. You can feel this when you push-in the clutch and pull the shifter out. It almost will not come out of gear. You should at any time be able to pull the transmission out of gear without using the clutch. Try and keep your truck above the "sweet spot" when driving. You will know this spot when you feel the engine seems to really want to pull for you. Every engine has it's own "sweet spot" . Mine is around 1800 RPM . Yes I do run my engine to 2400 rpm when on the freeway, but I never lug it down below 1800 rpm unless I'm coming to a stop. I would recommend everyone check out the military TM on driving motor vehicles. (I don't remember the number just now, I'll try and look it up later). This would help a lot for the life of your transmissions and transfer-cases.

 

[plym49]

Basically abuse. Remember when the 3053 is in 5th gear it is "not" spinning but is engaged to the main shaft by the synchro. So that is not the cause.
The main shaft is spinning faster then the input gear so the roller bearings in the input gear are working just like they are when in any other gear except in 1:1 like 4th gear in the 3053 and 5th gear in the 3052. So that is normal. The bushing the 5th gear rides on only has one "key" to engage the mainshaft. If it doesn't get enough lube between the gear and bushing it can snap or twist on the shaft but that is not in action when the truck is in 5th gear as the 4-5 synchro is engaging it to the mainshaft. That really just leaves operator error. These Spicer transmission are not to be shifted "fast" like car or even modern truck transmissions. When you are taught to drive them in the military they teach you to "double clutch" these units. They are slow but steady drivers. The clutch "dogs" on the fifth gear are also smaller then say the second or third gears by about half. So anyone shifting "fast and furious" will cause damage to them. Also you should never "lug" these trucks in 5th gear. If the RPM is going down then downshift. Don't wait until your forced to shift or kill the engine. That puts tremendous strain on the gears when you do this. You can feel this when you push-in the clutch and pull the shifter out. It almost will not come out of gear. You should at any time be able to pull the transmission out of gear without using the clutch. Try and keep your truck above the "sweet spot" when driving. You will know this spot when you feel the engine seems to really want to pull for you. Every engine has it's own "sweet spot" . Mine is around 1800 RPM . Yes I do run my engine to 2400 rpm when on the freeway, but I never lug it down below 1800 rpm unless I'm coming to a stop. I would recommend everyone check out the military TM on driving motor vehicles. (I don't remember the number just now, I'll try and look it up later). This would help a lot for the life of your transmissions and transfer-cases.

Thank you. That is incredibly useful advice. I love explanations like that on the care and feeding of these monsters, arguably one of the best motor vehicles ever created despite their flaws or, better, idiosyncrasies.

 

[Aussie Bloke]

G'day everyone,....

When you are taught to drive them in the military they teach you to "double clutch" these units.

Funny, but that is just what I do.

I have found it very easy to change slow and using the double clutching method.


I can drive the work trucks all day as I do with 'racing changes' but the way these feel they just work smoother with the 'slower is smoother, smoother is faster' method.

You should at any time be able to pull the transmission out of gear without using the clutch.

As long as there is little to no load on it yes, any torsional load will make it hard to pull out of gear, I find that if you back off the throttle a little to unload the torsion and match the input and output shafts it makes it very easy to change.



Aussie.

 

[m715mike]

The transmission issues in my truck happened shortly after an engine swap. Could a new, fresh engine been a contributing factor?

 

[rustystud]

The transmission issues in my truck happened shortly after an engine swap. Could a new, fresh engine been a contributing factor?

If your transmission had previously been abused and you acquired it and then repowered it then yes the extra torque could have caused the last remaining clutch dogs to let loose . You never know what the last owner did or did "not" do like change the oil on a regular basis.