whining 915

[alexandervdr]

The transmission in my 86 3.2 is slightly whining, in all gears except in 5th (but that may be because of the lower rpm). More pronounced when going uphill. It's an original car, so exhaust noise is quite limited letting the whining get through easier. The whining is never intrusive, but more present than in my other cars.
Is this normal? And given that it shows up in all gears, is this a 'feature' or a potential gear wear problem...

[GH85Carrera]

Change the transmission fluid and check the magnet on the drain plug. Before you do that order a new drain plug with the magnet on it to use as a fill plug.

If the magnet is full of metal shavings, it is a bad sign. Refill with fresh clean oil, and use a plug on both the drain and fill plug with the magnet. The differential spins in there, and slings oil, right onto the fill plug. A magnet will catch the metal parts before they go any further.

Drive for a 250 miles of so, pull the fill plug and check for metal filings.



That was my top and bottom plug after I did that test when I heard a whine. The top plug in the photo is the fill plug. It is an expensive whine. The engine and transmission have to come out, and the transmission comes apart for full inspection. In my case it was a + $500 bearing in the differential. Of course "while yer in there" a new clutch and all those parts are a good thing to do, along with some replaced syncros, and whatever else is worn out.

Don't just keep driving it, those metal parts will eat up the innards of the transmission.

[Flat6pac]

I have seen trailing arm bearings sound like trans problems
Bruce


Wheel bearings and trailing arm big same thing as a loss for words

[GH85Carrera]

Originally Posted by Flat6pac

I have seen trailing arm bearings sound like trans problems
Bruce

Rear wheel bearing can sound like it as well.

Metal in the trans oil is only from one source. And it does not hurt to change the oil.

Bearings are a lot cheaper to fix in the axle or the trailing arms.

[Paulporsche]

It may be your ring and pinion gear. There is a field test to check this. It is something like running slowly in second gear and seeing if your shift lever moves, but I don't recall exactly what. If I remember correctly, John Walker told me how to do the test, so maybe check with him.

[MichaelSJackson]

Does it keep whining when the clutch is depressed? Maybe wheel bearings or cv joints?

[GH85Carrera]

Yea, one good test is t go down a hill and put it in neutral. If the whine is gone, it is likely the transmission.

[alexandervdr]

in my observation, it's clear the whining went hand in hand with engine rpm, not with road speed. If I did 60mph in 3rd the wining was there, moving to 4th still at 60 and the whining was far less. That excludes the differential, wheel bearings etc as the source.

[AlistairWallace]

Check your fan belt alignment and tightness. I had a belt that was out of alignment and caused a whine between 3-4k rpm.

[alexandervdr]

Originally Posted by AlistairWallace

Check your fan belt alignment and tightness. I had a belt that was out of alignment and caused a whine between 3-4k rpm.

how can alignment be adjusted?

[Matt Monson]

One of the main case bearings. It’s time for a rebuild. Don’t delay. Waiting will potentially hog out the main case bores and allow the ring and pinion to walk out of alignment, more then doubling the service cost.

PS. TwinSpark is a great place to have the work done if you don’t already have a guy or would DIY.

[alexandervdr]

Originally Posted by GH85Carrera

Change the transmission fluid and check the magnet on the drain plug. Before you do that order a new drain plug with the magnet on it to use as a fill plug.

If the magnet is full of metal shavings, it is a bad sign. Refill with fresh clean oil, and use a plug on both the drain and fill plug with the magnet. The differential spins in there, and slings oil, right onto the fill plug. A magnet will catch the metal parts before they go any further.

Drive for a 250 miles of so, pull the fill plug and check for metal filings.



That was my top and bottom plug after I did that test when I heard a whine. The top plug in the photo is the fill plug. It is an expensive whine. The engine and transmission have to come out, and the transmission comes apart for full inspection. In my case it was a + $500 bearing in the differential. Of course "while yer in there" a new clutch and all those parts are a good thing to do, along with some replaced syncros, and whatever else is worn out.

Don't just keep driving it, those metal parts will eat up the innards of the transmission.

great tip on the second magnet plug on the fill side! The plan is to do a rebuild anyway, just trying to diagnose upfront what will be involved.

[alexandervdr]

Originally Posted by Matt Monson

One of the main case bearings. It’s time for a rebuild. Don’t delay. Waiting will potentially hog out the main case bores and allow the ring and pinion to walk out of alignment, more then doubling the service cost.

PS. TwinSpark is a great place to have the work done if you don’t already have a guy or would DIY.

I am not used yet to the exact names and locations of the components. Are the main case bearings you refer to the ones that fit where the arrows are? (picture from internet 915, not mine)

[Mark Salvetti]

No, that is the differential case. The main case is the one in the middle, the bearings are in the portion of the case closest to the front of the car.

I think if the bearing bore there hogs out, the pinion or main shaft can wobble, changing the R&P engagement and causing it to wear out prematurely. This happened to my gearbox (one of the main case bearings was actually shattered). It was ugly. Listen to Matt.

Mark

[Matt Monson]

Mark,
When I say “main case”, I am talking about what you are calling differential.

I term them main case, center case, and tailcone.

The reason it stops in 5th is because it is located outside of the center section with another set of bearings between it and the problem.

[alexandervdr]

Originally Posted by Matt Monson

Mark,
When I say “main case”, I am talking about what you are calling differential.

I term them main case, center case, and tailcone.

The reason it stops in 5th is because it is located outside of the center section with another set of bearings between it and the problem.

Thanks Matt for clarifying, would explain indeed why 5th is ok.
You confirm the arrows in the picture in my previous post?

[Matt Monson]

Yes.

[evan9eleven]

Originally Posted by Matt Monson

One of the main case bearings. It’s time for a rebuild. Don’t delay. Waiting will potentially hog out the main case bores and allow the ring and pinion to walk out of alignment, more then doubling the service cost.

PS. TwinSpark is a great place to have the work done if you don’t already have a guy or would DIY.

+1

TwinSpark did the machining on my case for these bearings, excellent work and quick turnaround.

Definitely listen to Matt

[alexandervdr]

I am living in Belgium, so unfortunately US bases shops are not going to help me out.
I am planning to do the rebuild myself anyway, just need to find the time and courage to start

[Arlo911]

Twinspark Racing are in Holland Well worth a visit IMO