Hello everybody , I recently completed my gearbox rebuild with new mainshaft bearing 1st synchro and dog teeth, and flipped diff inn order to use in a bug. It goes in every gear, 1st 2nd 3rd are operate great by hand but in 4th and 5th it makes a kind of gear clunkish sound when turned continuously .Of course I am not a type 4 engine, but I wanted your guys input to know if there is anything wrong
https://www.youtube.com/watch?v=BbX0enNKtB4

You should not have told it that its life was destined for a Bug.....Methinks it is complaining.

Seriously; Dr. Evil, calling Dr. Evil!

No 914 box can be checked on a bench,shit hits the fan when you drive it,are your selectors set up right for those gears ?.

I didn’t mess with the selectors , removed them with the stacks , and installed them along with the stacks

Sounds pretty dry to me. Any gear oil in there?

@Dr_Evil

Delete.

Not sure why I can't get the "@Dr_Evil" notification to work.

It was low, now topped it up, still makes some noise but when some resistance is applied to the flanges it is completely quiet. also when spun faster it is completely silent .

His username has a space in it, so you type the @ and then the username part you have to surround it with quotes.
@Dr Evil

Thank you - looking at it in all his previous posts I thought it was an underscore!

Howdy folks!

As mentioned, shifting on the bench is crap. It really can’t tell you much of anything. The only thing you are really doing when you are shifting from 1,2,3,4,5 is changing the ratios as the gears are always intermeshed. In 4/5 the output just turns faster.

When you flipped the differential, did you swap the bearings and spacers from side to side, at least? Did you check backlash? Too much back lash will be more prevalent in sound as you spin the ring and pinion faster (in 4/5 on the bench). If you simply flipped the diff and installed, start with swapping the bearings and spacers and see if that helps.

I hate to be the barer if further bad news, but if you did not use the jig to reassemble the stack and set the shift rods, it’s gonna shift like crap and have other problems as well as a shortened life (maybe you get lucky?).

Hello, thanks for your answer.
I replaced the diff bearings and moved the spacers from the one side to the other, I checked the backlash and it was 0.15mm
I removed the stacks along with their forks from the intermediate plate because I don't have a jig to set them up properly . I only needed to replace the input shaft bearing and the first gear dog teeth and syncro.
The sound I hear is mostly from the input shaft. Is there a chance that oil hasn't reached its bearings with bench testing or that the new bearing needs some break in ?
When I spin the gearbox from its output flanges I get no noise at all .
Also its turning smooth, no obstructions or changes in resistance It just makes a ticking noise when turning in 4th and 5th without any load. If I touch its flanges when rotating it is better I believe .

Sounds fine then. If you measured backlash (I’ll assume pinion depth was conserved) then you are good to go. Bearings do not need a break in. Oil most definitely not slung completely around the internals with only hand cranking.

Pinion depth was maintained , I didn't even remove the stock paper gaskets for that reason, I removed the intermediate plate very carefully not to break them. I tried moving the gearbox around ( like a bride at the wedding style ) so oil could get everywhere but it didn't help. I hope that it just needs a ride.

They are noisy to turn at first, and in higher gear as the output is moving faster. If you did all the steps right, like you outlined, then should be no issue introduced into the trans.

I think I found my mistake , I think I preloaded the diff bearings to much , I loosened the diff case cover and the rumble disappeared , should I adjust it by removing the thin spacer behind the bearing on the diff or by a paper gasket on the cover?

Did you check the preload on the bearings? The spec is different between SKF and FAG bearings, too. FAG like a lot, SKF a little. The actual numbers escape me. In my experience, changing the bearings does not increase the preload and 99% of the time I have to put thicker spacers on. There is no paper gasket on the mag case 901 used in the 914. If you have a paper gasket, then you have an early aluminum case and that is a single thickness gasket. You cannot add.

The best thing to do is pull the stack, pop out the output shaft gaskets as they will drag and interfere with preload readings, and then fund a correct size shim to put under the output flange to tighten it against the diff and lock the diff spider gears. Then, check preload. It may be fine. Probably is, if not low.

Hello , thanks for your answer , I installed Skf bearings , the thing it that with the diff housing cover it makes a rumble when spinning , when loosening a bit the bolts is
Is quiet . Also checking the preload with the feeler method I have 0.25 instead of 0.15 that I should