 Need transmission problem diagnosis..., Or best guess |
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| Porsche Rescue |
 Jun 28 2009, 02:45 PM
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#1
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Saving and Enjoying Old Porsches  Group: Members Posts: 2,978 Joined: 31-December 02 From: Bend, Oregon Member No.: 64 Region Association: None  |
Started my '70 tail shifter this morning, attempted to engage reverse and heardf/felt a horrible grind (kind of like the clutch pedal was not depressed, but it was). Quickly returned to neutral and tried again. I engaged reverse OK and backed out of the garage. But I heard a grinding/growling noise while moving and felt the sensation of something restricting movement (like brake on, but it wasnt'). Moved it back and forth in the driveway in all gears. It makes the same noise in all 5 forward gears as soon as I release the clutch. Reverse now seems almost OK.
Where do I start? Could it be a linkage issue (the front two bushings were new a few months ago)? It shifts smoothly when clutch pedal is depressed. Is something broken in the tranny? All opinions welcome. |
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| Katmanken |
Jul 11 2009, 10:24 PM
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You haven't seen me if anybody asks... Group: Members Posts: 4,738 Joined: 14-June 03 From: USA Member No.: 819 Region Association: Upper MidWest |
Well, does it growl when the clutch pedal is in and the tranny in gear?
When you select a gear, the synchros and dog teeth engage the selected gear with the pinion shaft so the pinion shaft can be driven by the selected gear. When the clutch pedal comes out, the clutch disk contacts the flywheel and begins to spin the mainshaft and the selected pair of gears, the pinion shaft, the differential, the axles and wheels. Note, this description is for a stationary car. If the rear wheels are turning, then it's a bit more complicated. So in an unshifted position, the pinion shaft and all it drives are stationary,and it doesn't matter if the clutch disk is engaging the flywheel or not. All is quiet. When the car is in gear AND you engage the clutch, it gets noisey. The pinion shaft becomes driven and starts to spin as well as the differential, axles and wheels. That says the problem is either motion or load dependent. For the noise to occur, the pinion shaft has to spin and the tranny and clutch have to be transmitting torque . Two things make noise when going bad under load- gears begin to whine, and bearings begin to grumble..... I'd recheck the pinion shaft bearings, the differential bearings, and look at the pinion and ring gear for chips. They are super hard but are brittle and can chip. I can assure you it's one or more of the items discounted in this thread. |
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Posts in this topic
Porsche Rescue Need transmission problem diagnosis... Jun 28 2009, 02:45 PM
Cap'n Krusty Jack it up, put it on stands, loosen the fill plug... Jun 28 2009, 03:22 PM Dr Evil Sounds like you have a clutch tube or other clutch... Jun 28 2009, 03:40 PM
Cap'n Krusty
Sounds like you have a clutch tube or other clutc... Jun 28 2009, 04:56 PM Dr Evil
Sounds like you have a clutch tube or other clut... Jun 28 2009, 06:01 PM Cap'n Krusty
[quote name='Cap'n Krusty' post='1186428' dat... Jun 28 2009, 08:54 PM J P Stein
Sorry, Doc, I'm callin' it like I see it... Jun 28 2009, 09:13 PM Dr Evil
Sorry, Doc, I'm callin' it like I see i... Jun 28 2009, 09:54 PM Cap'n Krusty
[quote name='J P Stein' post='1186504' date='Jun ... Jun 28 2009, 10:24 PM Porsche Rescue I first tightened the clutch adjustment nut as I h... Jun 28 2009, 05:21 PM Jacob
As soon as I begin to engage the clutch I hear t... Jun 28 2009, 05:39 PM Cap'n Krusty
As soon as I begin to engage the clutch I hear ... Jun 28 2009, 08:04 PM Porsche Rescue Not sure of clutch age. Major engine work about 5K... Jun 28 2009, 05:52 PM Dr Evil
Not sure of clutch age. Major engine work about 5... Jun 28 2009, 06:05 PM Porsche Rescue Thanks Dr. I have a second confirming opinion from... Jun 28 2009, 06:08 PM J P Stein I have a good (2 actually but one is NFS) intermed... Jun 28 2009, 06:51 PM Porsche Rescue Ok, but can someone tell me if the "guts... Jun 28 2009, 09:51 PM Cap'n Krusty
Ok, but can someone tell me if the "guts... Jun 28 2009, 10:07 PM Porsche Rescue Thank you Cap'n. Sounds like I need to repair ... Jun 28 2009, 10:16 PM Dr Evil
Thank you Cap'n. Sounds like I need to repair... Jun 28 2009, 10:32 PM RobW C'mon you guys :hugme: Jun 28 2009, 10:29 PM Porsche Rescue OK, now what? While in the process of removing the... Jul 2 2009, 09:53 AM Dr Evil How it acts under hand torque is completely differ... Jul 2 2009, 10:42 AM J P Stein Tore appart Jim's trans this afternoon.
The gu... Jul 9 2009, 09:02 PM Dr Evil That is the problem with doing diagnosis over the ... Jul 9 2009, 09:21 PM J P Stein Everything I can see looks very nice & turns s... Jul 9 2009, 09:51 PM Jax914 pilot bearing in the flywheel? Jul 10 2009, 12:52 PM Porsche Rescue Pilot bearing feels good to the pinky finger, look... Jul 10 2009, 01:08 PM kwales You sure it's not the throwout bearing???
I... Jul 10 2009, 04:13 PM Porsche Rescue TO bearing is smooth and quiet in my hand and in t... Jul 10 2009, 06:12 PM Dr Evil Has your flywheel been resurfaced before? If the s... Jul 11 2009, 10:52 AM kwales Ok, let's think this through.
Tranny is out o... Jul 11 2009, 11:51 AM Porsche Rescue Growling noise only when tranny in gear (any gear)... Jul 11 2009, 12:03 PM Porsche Rescue No noise when in gear with the clutch "in... Jul 12 2009, 09:27 AM kwales I'm gonna put on my Patent Law and my engineer... Jul 12 2009, 10:58 AM Porsche Rescue Noise begins with first clutch contact with flywhe... Jul 12 2009, 11:05 AM Porsche Rescue Here are some pics. One theory is that the center ... Jul 12 2009, 11:08 AM kwales Looks glazed to me. The clutch disk is a two piece... Jul 12 2009, 11:22 AM Bleyseng use the 6 spring clutch disc for a early 911, yes ... Jul 12 2009, 12:19 PM |
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