Rebuilt gearbox noise when spun by hand

[pnikas]

Hello everybody, I have just finished building my gearbox, flipped to go in a beetle, I was trying the gears, spinning it in each one of them, it is relatively quiet in R !23, but on 4th and 5th it has a kind of clunkish sound, then again I am not an engine, but I wanted to have your guys input to be on the safe side of things .
https://www.youtube.com/watch?v=BbX0enNKtB4

[jess p]

Is there smooth engagement of the selector when you select 4 and 5th.

[pnikas]

Originally Posted by jess p

Is there smooth engagement of the selector when you select 4 and 5th.

Yes, very smooth , I had somebody apply minimal restisrace to the output flanges and I spun it . No noise at all

[jess p]

Is there any play in the output shaft forward and backward. It sounds that it’s the ring gear rubbing on the side of the case.

[pnikas]

Originally Posted by jess p

Is there any play in the output shaft forward and backward. It sounds that it’s the ring gear rubbing on the side of the case.

No play at all
Could it?

[jess p]

As you are facing the transaxle and turning the drive shaft it looks like you are turning it counterclockwise, I see the output shafts spinning away. Did you have it in reverse? Instead of 4/5 as you suggested.

[pnikas]

Originally Posted by jess p

As you are facing the transaxle and turning the drive shaft it looks like you are turning it counterclockwise, I see the output shafts spinning away. Did you have it in reverse? Instead of 4/5 as you suggested.

It’s flipped to go in a beetle . It does that sound when no resistance at the flanges , could it be that oil hasn’t gone everywhere yet ?

[jess p]

In a factory issued 914 transaxle if you face the bellhousing and turn the driveshaft clockwise, the output shafts will turn into the forward direction, provided you are in 1-5 th. You have switched the ring gear thus everything is in reverse. It can be a little tricky putting in the 1/reverse slider and if not installed correctly can make the noises you are experiencing, particularly as it engages the the small reverse idler gear.

[jess p]

Gear oil will help quiet everything down but I’m concerned about that noise.

[pnikas]

Originally Posted by jess p

In a factory issued 914 transaxle if you face the bellhousing and turn the driveshaft clockwise, the output shafts will turn into the forward direction, provided you are in 1-5 th. You have switched the ring gear thus everything is in reverse. It can be a little tricky putting in the 1/reverse slider and if not installed correctly can make the noises you are experiencing, particularly as it engages the the small reverse idler gear.

How can the slider be installed wrong ? That could be a step to finding the problem . The idler was a pain to install . I stacked it on the intermediate plate and then put carefully the tail section on top

[jess p]

If you don’t have the spacers in correctly, the small bearing,etc. Ok, here is what you can do. The transaxle I believe requires at least 3 quarts 90w hypoid gear oil. Fill it, stand it on its end for a short while, lie it on each side for a while, plug the breather tube and stand it on the drive output shaft end. Then spin it in each gear, reverse included. You really can’t spin it by hand enough to thoroughly saturate all the bearings etc. see if the noise persists.

[pnikas]

Originally Posted by jess p

Gear oil will help quiet everything down but I’m concerned about that noise.

https://youtu.be/-M2BLzHnO_4
Here is a vid in neutral
And here is a vid in 5th again

https://youtu.be/11l7ptmJips

Admittedly it has gone a bit quieter now that I topped it up with oil (had about 1 litter less in the first video ) but it still does a slight rumble when no restisrance is applied at the flanges

[jess p]

How much torque did you apply to the output flange bolts?

[jess p]

Make sure everything is saturated with gear oil as I mentioned in my 8:41 post by turning it and standing it on each end. That gear oil is very thick and takes awhile to work into all the bearings. Just turning it by hand won’t be enough.

[pnikas]

the output flanges are torqued to 35nm.
I did a bit of dancing with it to get oil everywhere, it did help but didn't completely eliminate the noise. what is your guess ?

[jess p]

You torqued the drive and pinion nuts to the required specs? I’m assuming you removed the drive and pinion shafts from the intermediate plate. Did you replace the drive shaft bearing in the intermediate plate. I’m just wanting to get a feel for how far you went on the build. The pinion bearing in the trans housing is a large bearing and needs oil to quiet down. Additionally, the drive bearing in the intermediate plate as well as the detent components can get lubed well before starting by standing the trans on the tail end. If you replaced either the drive or pinion bearings in the intermediate plate did you press the inner races on. The carrier bearings need a lot of oil to quiet down and that is achieved by lying the trans on both sides to get oil in there. Finally, if you still have noise upon turning the trans over you could by some processes of elimination first remove the output shafts and the side carrier cover and turn the drive shaft to see if noise persists. You could do this with the front of the trans elevated to about 45 degrees so all the gear oil would be in the tail end and you wouldn’t lose it or make too much of a mess. When you set up the shift rods going through the intermediate plate did you use the jig for the 914?

[jess p]

When I torque the drive and pinion nuts to their respective shafts I took an old clutch disc and welded rebar to the disc so I could lock the drive shaft after I had the assembly in the housing. What did you use?

[pnikas]

Originally Posted by jess p

You torqued the drive and pinion nuts to the required specs? I’m assuming you removed the drive and pinion shafts from the intermediate plate. Did you replace the drive shaft bearing in the intermediate plate. I’m just wanting to get a feel for how far you went on the build. The pinion bearing in the trans housing is a large bearing and needs oil to quiet down. Additionally, the drive bearing in the intermediate plate as well as the detent components can get lubed well before starting by standing the trans on the tail end. If you replaced either the drive or pinion bearings in the intermediate plate did you press the inner races on. The carrier bearings need a lot of oil to quiet down and that is achieved by lying the trans on both sides to get oil in there. Finally, if you still have noise upon turning the trans over you could by some processes of elimination first remove the output shafts and the side carrier cover and turn the drive shaft to see if noise persists. You could do this with the front of the trans elevated to about 45 degrees so all the gear oil would be in the tail end and you wouldn’t lose it or make too much of a mess. When you set up the shift rods going through the intermediate plate did you use the jig for the 914?

I removed both pinion shaft and input shaft from the intermediate plate along with their forks so I don't alter their adjustment( rather hard when putting together but didn't have a jig) I installed the bals and peanut in the correct way like you told me on another post. Thankfully the races came of both shafts relatively easy, the pinion bearing was very good, the input bearing was destroyed, I checked all the bals in the pinion bearing and dind have any pitting, nor did the races show any wear. I installed the new input shaft bearing on the intermediate plate, the race on the input shaft, I put it back together along with the forks , placed the races from the other side, put first gear and reverse and torqued down both nuts. I oiled the rear bearings a bit, but completely forgot about oiling the carrier bearings on the other hand , the ones next to the diff, I honestly completely forgot about oiling them up.

[pnikas]

Originally Posted by jess p

When I torque the drive and pinion nuts to their respective shafts I took an old clutch disc and welded rebar to the disc so I could lock the drive shaft after I had the assembly in the housing. What did you use?

Thats exactly what I used. except not welded. just 2 holes in the disc and bolts.

[jess p]

The cage on the drive shaft in the intermediate plate of my trans was broken in 3 places. I replaced both bearings. I placed the intermediate plate in the oven After removing the steel retaining cover to remove the outer races. Heated the plate up again to drop in the new outer races. Now as I read you left the shift forks on both shafts with their respective shift rods while you tended to the bearing issues. That sounds very difficult to do, that’s why I had the jig. OK, as I mentioned you had some playing around to do when switching the ring gear and the small spacer. I’ll go back and watch again all three YouTube videos and try to hear the noise. But as you mentioned the noise is most noticeable previously when you had it in 4/5 gear.