915 R&P Whine - How do you get rid of (fix) this??

[RarlyL8]

Not a happy camper. I just threw $1000 in WEVO and other parts at my 915 to shut up the whining of the R&P. It didn't work.

The theory was that the Pinion gear had developed play and was moving the mesh with the Ring gear out of tolerance under load. When the tranny was dissasembled and specs verified nothing was out, nothing was wrong. So I figure if you tie it down with the heavy duty WEVO stuff it can't move and will stop wining.

This REALLY pisses me off. My car was down over a month, 16+ hours of my time was wasted, plus $1000 to cap it off.

So what gives? why won't the R&P line up and shut up?

[jester911]

Maybe it is just begging for mercy.
I really can't help you but hopefully someone will.

[Tyson Schmidt]

Who did the set-up on the ring and pinion? What method did they use?

The Factory runs the ring and pinion on a test jig to find the optimal settings for low noise and wear, and then marks them on the parts.

Sometimes the R&P have a wear pattern on them that is invisible. This is usually cause from being run with a flexing side cover, or worn pinion bearings and carrier bearings, which cause the ring and pinion to be outside the proper mesh when under load.

This wear pattern makes the factory setting numbers incorrect. In this instance, Prussian Blue is the best way to find the correct pinion depth setting and back-lash.

And sometimes you just have to start over with a new ring and pinion.

Can you give some history on the parts?

[RarlyL8]

The R&P were left at the factory settings. My thoughts were that if the pinion gear is not allowed to move there should be no reason to change the settings.
The tranny was rebuilt 4 years ago and still looks perfect inside. What I added was the bearing retainer (pictured above), new carrier bearings (not needed) and a re-inforced side plate.
Why would the R&P need to be re-indexed?

[Tyson Schmidt]

Because of the uneven wear caused by the flexing side cover, and/or worn bearings, etc. This causes the ring and pinion to wear on surfaces outside the normal pattern. So when you correct it back to stock, it is now incorrect.

Think of it like wearing someone elses worn-in shoes.

I'd pull the sidecover, and check the mesh pattern ala Prussian Blue.

You might also re-check the carrier bearing pre-load now that it has all been run-in.



In the past, I've had major troubles getting a good pattern on used R&P's set at the factory specs. And even moving the settings around proved futile, and it was impossible to get the proper pattern. They had uneven wear that was visually undectable, but rendered them useless.

[asphaltgambler]

I understand that the 915 has a problem with the pinion bearing failing and spinning the race in the housing. Then you have a pinion gear not in alignment with the ring gear.

Most shops that do service these do not have all the correct tools to check measure and fix the ring&pinion. Regardless of how the trans was setup, modified and new oil, if you have an issue with noise in the gearset..............houston we have another problem altogether.

[RarlyL8]

There should not be any significant wear on the R&P. This "failure" happened very suddenly, if you remember from a past thread, at a drag strip. I drove the car 100 miles home, parked it and pulled the tranny.

The pinion bearing race did spin in the case. It was repaired.

So what do I do now? Will my R&P be damaged if I drive it with this noise going on?

[rcwaldo]

Anytime any component is replaced with respect to the ring and pinion, save for seals etc., pinion depth, backlash and carrier bearing preload must be reset, or at least verified.

Best is to measure all of this before disassembly. In your case, measuring the pinion depth may not have been of any use since you had a pinion head bearing problem to start with.

[RarlyL8]

OK, now for a reeeeeealy stupid question. I know nothing about indexing these gears and know no one who has the tools. Can this be done with the tranny in the car?

[Jeff Alton]

Rarly, does it make that sound in all gears?

I too want to know about indexing or shimming the diff.....

Cheers

[atr911]

From what I understand, the tool to properly set backlash is very expensive to the point where most shops wouldn't spend the money (unless their specialty are 915s). I knew of only one shop in the Toronto area that had such a tool.

Keep in mind that this was in Canada where decent porsche wrenches are few and far between.

The tranny has to be out of the car to set this up.

Hope this was a little help and that it didn't completely ruin your day.

Adam

[Grady Clay]

RarlyL8,

Not a happy camper. I just threw $1000 in WEVO and other parts at my 915 to shut up the whining of the R&P. It didn't work.

The theory was that the Pinion gear had developed play and was moving the mesh with the Ring gear out of tolerance under load. When the tranny was dissasembled and specs verified nothing was out, nothing was wrong. So I figure if you tie it down with the heavy duty WEVO stuff it can't move and will stop wining.

This REALLY pisses me off. My car was down over a month, 16+ hours of my time was wasted, plus $1000 to cap it off.

So what gives? why won't the R&P line up and shut up?

Prior threads (good info for 915 rebuilds):
Need to be read for proper context.

The "How to beef up a 915" thread. Parts and costs?

915 Repair - What tools needed to change carrier bearings?

More Here

it's not like you are setting up a new R+P. the one in the trans was adjusted by the factory, and hopefully nobody has messed with the original setting. that setting is optimum and the R+P has matched itself to that setting with a wear pattern, however slight. moving things can cause extra noise and future wear. all i'm saying is replacing bearings won't change the original setup dimensions, but only return the R+P to the original setup position, if it's been compromised by bearing wear. if gear face wear has manifested itself during the time the gears were out of spec, then it's possible that they will remain somewhat noisy. John Walker 10/30/05

This is exactly what Tyson is saying.

Who did the set-up on the ring and pinion? What method did they use?

The Factory runs the ring and pinion on a test jig to find the optimal settings for low noise and wear, and then marks them on the parts.

Sometimes the R&P have a wear pattern on them that is invisible. This is usually cause from being run with a flexing side cover, or worn pinion bearings and carrier bearings, which cause the ring and pinion to be outside the proper mesh when under load.

This wear pattern makes the factory setting numbers incorrect. In this instance, Prussian Blue is the best way to find the correct pinion depth setting and back-lash.

And sometimes you just have to start over with a new ring and pinion.

Can you give some history on the parts? Tyson Schmidt 4/2/06

and

Because of the uneven wear caused by the flexing side cover, and/or worn bearings, etc. This causes the ring and pinion to wear on surfaces outside the normal pattern. So when you correct it back to stock, it is now incorrect.

Think of it like wearing someone elses worn-in shoes.

I'd pull the sidecover, and check the mesh pattern ala Prussian Blue.

You might also re-check the carrier bearing pre-load now that it has all been run-in.

In the past, I've had major troubles getting a good pattern on used R&P's set at the factory specs. And even moving the settings around proved futile, and it was impossible to get the proper pattern. They had uneven wear that was visually undectable, but rendered them useless. Tyson Schmidt 4/2/06

IMHO You are getting the best advice in the world here.


With failed bearings and probably everything out of place, you didn’t have the opportunity to record the original position. Without the tools, it probably isn’t even set to the factory specs. Please don’t drive it that way and ruin the shoe.

It is preferable to set the R&P to the original numbers measured with the Factory tools and see if the noise subsides. At the same time you should inspect the pinion-to-ring contact as Tyson and John have indicated. Some compromise may be necessary.

You are doing this exactly correctly – at least the best possible. So what if you are “spending” your labor, that is $1600 in your pocket and you still have your $1K in parts

Of course you can always replace the R&P with new for some $7,000.00 from PCNA. Ha. There are other possibilities through our host.

You can also start over with another (probably less than perfect) 915 and possibly repeat the exercise.


I think your current mission is to find someone with the measuring tools and the skill to interpret contact patches. That probably won’t totally cure the whine but you will have a serviceable 915 transmission.

Best,
Grady

[RarlyL8]

Thanks for the replies.
I understand what everyone is saying, I just have a difficult time understaning how the R&P would have significant wear in 100 miles to cause a permanent whine. Not saying it isn't true, just find it hard to understand.
It appears that absolutely nothing changed from the moment of the damage and now. Something MUST have changed with these new parts in place. The R&P must now be back where it belongs yet it makes the exact same noise it did post damage.
I read all of the above threads during the process of the "rebuild", problem is I found NO ONE with the proper equipment to check and set the R&P. No one. The mechanic I had run the specs on the tranny told me he has never seen a 915 with R&P damage in his 30 years of service. I guess his customers were power weenees.

[wevoid]

We are careful to make customers understand that the WEVO XT_032 one piece bearing retainer plate - or similar part from other vendors - CAN NOT repair the damage to the pinion roller bearing fit in the final drive housing.

We regularly discourage customers from buying this part when we learn that they hope that this relatievly inexpensive part will solve what is clearly described as a more complicated and usually more costly problem.

You mentioned - "The pinion bearing race did spin in the case. It was repaired." What style of repair was used? This could be very significant in why the CWP set up is noisy.

Regards

Hayden

[RarlyL8]

I simply ordered the parts, did not discuss the problem with the salesman. The parts are good and will hopefully be future insurance.

The pinion bearing race was removed (it fell out) and the area thoroughly cleaned and scuffed up then glued in place. A couple of mechanics told me of this proceedure and claimed good results using it.

[wevoid]

The main reason the pinion bearing roller race is loose in the final drive housing is due to the soft and isufficient material around the bearing race. The loads are in roughly the 11 o'clock / 5 o'clock axis and the bearing bore becomes oval wth the long axis following this path.
The fact that the bearing fell out of the case is an indicator that it was pretty loose - this fit becomes even looser at elevated temps.
It is possible that the bearing race was bonded into the case in a position that is no longer co-axial with the original location where the CWP set-up was originally performed.
I would hazard to guess that you have a combination of at least two factors making the noise.
1) Pinion head is not correctly located relative to the crownwheel gear (3D spatial location)
2) CWP has noise inducing wear pattern from when it was running out of location

Regards

Hayden

[RarlyL8]

Sounds logical.
So re-indexing the R&P will make it all good again?

[wevoid]

I am not sure what you mean by re-indexing the CWP.
I am doubtful that a careful CWP set-up will fix the noise you have, there is likely to be other residual damage that needs repair / replacement before the transmission will respond to set-up in a normal manner.
Did you take any photos of the CWP while it was apart? Thre may be some telltale signs there too.

Regards

Hayden

[tctnd]

As this all started at the drag strip I would suspect that the case is cracked allowing the pinion to squirm around. Before you spend hard earned dollars on a precision set up it would be wise to have the case thoroughly checked out.
regards,
Phil

[911nut]

Originally posted by Tyson Schmidt

The Factory runs the ring and pinion on a test jig to find the optimal settings for low noise and wear, and then marks them on the parts.

The ring and pinion are run together while "green" (before carburization) to obtain the pattern. They are then heat treated and installed together. Any replacement must be as a pair.