Whining 915 Trani

[Uwon]

My trani has a momentary low rpm rattle if I lug the motor in any gear which turns into a whine at higher speeds and very high pitch at cruising. Whine not gear dependent. Shifts like butter. Can’t say that the whine is getting worse- may have always been there. Swepco oil to middle plug on driver’s side.

Trani was refurbished a couple of years ago by a knowledgeable strictly Porsche indi shop more as a perceived precaution as it already had 400k+ km (250k+ miles) and more than 10 DE track seasons.
Work done:
(1) replaced synchros and dog teeth for gears 1,2,3 and sliders for 1-2 and 3-4 with all OEM parts
(2) one surprise was the retaining bolt for the shifter detents pulled from the case so Yarko had to drill and timesert the case
(3) replaced the 5 needle bearing cages under each gear that fell apart when gears removed - replaced with OEM new.

I don’t know much about transmissions but maybe it’s time for me to venture directly into the matter.
Any thoughts and suggestions would be welcomed.
TIA
Cheers,
Johan

[kevingross]

Looks like the bearings were not done. That could be your problem.

[Uwon]

Originally Posted by kevingross

Looks like the bearings were not done. That could be your problem.

Ya got me!
Which ones?
Johan

[Trackrash]

On your turbo?

My first guess is a worn 5th gear set. But you say it is not gear dependent.

Could be ring and pinion. Were those bearings replaced and was the backlash and preload checked?

[john walker's workshop]

I would guess pinion bearing in the diff housing, possible loose pinion bearing outer race in the diff housing, bearing retainer plate worn so the bearing(s) have end play, maybe even worn R&P from above issues. Teardown and see.

[Jonny042]

Originally Posted by john walker's workshop

I would guess pinion bearing in the diff housing, possible loose pinion bearing outer race in the diff housing, bearing retainer plate worn so the bearing(s) have end play, maybe even worn R&P from above issues. Teardown and see.

Agree with the above - there's a reason why the 915 is commonly fitted with the one piece bearing carrier. Good info here:

Porsche 915 Rebuild - One Piece Bearing Retainer Plate

Keep in mind, for those that don't know, - Johan now has probably close to half a million KM on this 915, with a healthy boosted motor feeding it as much torque as it can swallow..... so it doesn't owe him much!!

[Nick Triesch]

This happened to me years ago on a VW Vanagon. I tuned up
My radio and that worked for a few more thousand miles! But then. Went to shop for ring and pinion.

[kevingross]

Originally Posted by Uwon

Ya got me!
Which ones?
Johan

I'm not a fan of doing "some" of the bearings. Some previous did "some" of the rebuild, and here you are today. Just do them all: do it once, do it right.

[Uwon]

Well, thank you all for your valued analysis and suggestions. Looks like the consensus is bearings and ring/pinion.
Seeing my winter project list is not that long this year, I have the time to educate myself and tackle the rebuild. Never done this before so I have some reading to do. I plan to drop the Powertrain on the RST in January and will post my progress on this thread. I’m sure that I’ll be soliciting your collective help from time to time.
Cheers,
Johan

[Matt Monson]

Originally Posted by Nick Triesch

This happened to me years ago on a VW Vanagon. I tuned up
My radio and that worked for a few more thousand miles! But then. Went to shop for ring and pinion.

The way to avoid the cost of a ring and pinion is to stop driving it and do the bearings now.

[Jonny042]

Originally Posted by Uwon

Well, thank you all for your valued analysis and suggestions. Looks like the consensus is bearings and ring/pinion.
Seeing my winter project list is not that long this year, I have the time to educate myself and tackle the rebuild. Never done this before so I have some reading to do. I plan to drop the Powertrain on the RST in January and will post my progress on this thread. I’m sure that I’ll be soliciting your collective help from time to time.
Cheers,
Johan

I'm going to be doing one too (for Project Heavy Metal)..... so not only will it be fresh in my mind, my tools will be warm - you're welcome to borrow them.

Transmissions are fun, and easy, to work on. Well, relatively, at least. I'm sure you've seen peter zimmermans tutorial, it's a good place to start, and Gordo (or is it Gordo2?) has a few excellent threads as well.

Given that you may have to send out the diff housing for repair, the sooner you can tear into it, the better. Things have a habit of dragging out, and if it takes 4 or 5 weeks (return) for that, it may end up cutting into your spring driving time.

[Uwon]

Originally Posted by Jonny042

I'm going to be doing one too (for Project Heavy Metal)..... so not only will it be fresh in my mind, my tools will be warm - you're welcome to borrow them.

Transmissions are fun, and easy, to work on. Well, relatively, at least. I'm sure you've seen peter zimmermans tutorial, it's a good place to start, and Gordo (or is it Gordo2?) has a few excellent threads as well.

Given that you may have to send out the diff housing for repair, the sooner you can tear into it, the better. Things have a habit of dragging out, and if it takes 4 or 5 weeks (return) for that, it may end up cutting into your spring driving time.

Wow, thank so much for your kind offer. I’ll email you to coordinate.
I need a new challenge so I’m starting my tutorials per your suggestions. You have an excellent point on timing and possible repair to the diff housing. Got to finish lowering the 997S right away.
Cheers,
Johan

[Uwon]

Update!!!!
Well, Jonny042’s handy toolS came to the rescue. Thank you Jon.
Partially dismantled the transmission and differential, but could not find anything amiss. Replace all seals and gaskets.
The whining, as best as I could diagnose, was a very noisy release bearing which I have now replaced.
Cheers,
Johan

[fanaudical]

Whew! Sounds like you got lucky...

[Bill Douglas]

Excellent outcome.