Internet Armchair Diagnosis: transmission

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Thom Fitzpatrick
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Internet Armchair Diagnosis: transmission

#1 Post by Thom Fitzpatrick » Sun Jun 24, 2018 3:18 pm

I took the '57 A to Euro Sunday today, about 12 miles away, and I took mostly surface streets. About 3/4 of the way there, I was noticing a rhytmic "clunk...clunk...clunk" from the rear - in my mind it seemed to be coming from the right side - as I would slowly coast up to a stoplight. There was a short freeway section, and after that, I noticed a very distinct whine from the transmission. It also seemed to be clunking when I turned. After the event, I limped it home. The whine got a little worse, and I also noticed a weird rhythmic "booming" sound when coasting in-gear with the clutch engaged. Shifting was perfect.

When I got home, I had a bunch of other stuff to do so I haven't been able to spend any time on it. I also have another car dismembered on the lift, so I won't be able to do a decent inspection any time soon.

At the event I took a quick look underneath and I didn't see any evidence of an axle boot explosion or leak of any sort. I replaced the boots and trans fluid in April of last year. According to the "documentation" I got with the car, the transmission was rebuilt by some shop in Florida, and it did look like it had received some attention, as the case was spotless and tidy. When I changed the fluid back then, there were no sparkles or chunks in the old fluid.

With my limited knowledge of transmissions, I'm going to say that either a diff/ring&pinion bearing is going south in a big way, or the diff wasn't setup correctly and destroyed itself. I'm going with the former, as having mis-configured a VW diff once (I flipped the ring and pinion to put a reduction box transmission in a baja bug) I didn't get very many miles out of it before everything broke.
1956 VW Single Cab
1957 Porsche 356A Sunroof Coupé
1957 VW 23-window Deluxe
1957 BMW Isetta
1960 VW Panel
1963 Type 3 Karmann Ghia
1963 Mercedes Unimog 404
2003 BMW M3

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C J Murray
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Re: Internet Armchair Diagnosis: transmission

#2 Post by C J Murray » Sun Jun 24, 2018 5:28 pm

I would drain the oil and see if anything comes out. Feel around with your pinky looking for chunks.

Some common failures are...cracked diff carrier, broken R&P bolts(if they are originals), intermediate plate bearings(can cause diff setting problems, wheel bearing failure(if you are lucky) and maybe a diff carrier bearing.

If it failed soon after a rebuild the setting of the clearances could have been wrong.
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Bill Sargent
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Re: Internet Armchair Diagnosis: transmission

#3 Post by Bill Sargent » Sun Jun 24, 2018 10:03 pm

In addition to Cliff's suggestion, or possibly a first step, check the rear axel nuts for tightness/torque. Should be ~ 400 ft lbs. I had similar noises in my 59A on the way back from Santa Fe to Seattle in 2013 and a loose axel nut was the cause. Found a VW place, tightened it up and made it home. Then got the splines in the drum replaced to really cure the problem.
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Re: Internet Armchair Diagnosis: transmission

#4 Post by John Lindstrom » Sun Jun 24, 2018 11:54 pm

The last time that my 356 made that noise it was the clutch disc and pressure plate not playing fair in the sandbox together. Sounded like there was a train inside my engine compartment..

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Re: Internet Armchair Diagnosis: transmission

#5 Post by Thom Fitzpatrick » Sun Aug 12, 2018 8:10 pm

I finally got around to looking at my transmission noise! I had my 23-window torn apart on the lift, and I didn't want to get it all put back together just to look at the 356.

Interestingly, when I fired up the 356 and drove it into the shop and onto the lift, the back end didn't make a peep.

So, I drained the transmission fluid first. There was some hair on the drain plug magnet, and a fair amount of sparklies in the oil. I don't recall off the top of my head how much oil there is supposed to be, but I got about 3 quarts or so out of it.

I took the wheels off, and there is definite evidence of axle seal leaks on both sides.

I removed the brake drum and wheel bearing on the side that seemed to be making the noise. There is a substantial amount of wear on the inner spacer - something wasn't playing nice. The wheel bearing on this side (haven't removed the other one yet) looks and feels great.

I think my plan of attack should be to replace the crufty pieces, install new spacers, seals and wheel bearings, re-fill the fluid and see where the night takes us.
2018-08-12 14.28.46.jpg
2018-08-12 14.29.35.jpg
2018-08-12 16.53.36.jpg
2018-08-12 16.57.28.jpg
2018-08-12 16.53.03.jpg
1956 VW Single Cab
1957 Porsche 356A Sunroof Coupé
1957 VW 23-window Deluxe
1957 BMW Isetta
1960 VW Panel
1963 Type 3 Karmann Ghia
1963 Mercedes Unimog 404
2003 BMW M3

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David Jones
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Re: Internet Armchair Diagnosis: transmission

#6 Post by David Jones » Sun Aug 12, 2018 8:57 pm

My "C" made a clunking noise so I shut it down and trailered it home. The picture tells the story. I hope your is less expensive.
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C differential 012.jpg
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Thom Fitzpatrick
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Re: Internet Armchair Diagnosis: transmission

#7 Post by Thom Fitzpatrick » Sun Aug 12, 2018 9:14 pm

What caused that? Doing smoky burnouts while leaving Cars and Coffee?
1956 VW Single Cab
1957 Porsche 356A Sunroof Coupé
1957 VW 23-window Deluxe
1957 BMW Isetta
1960 VW Panel
1963 Type 3 Karmann Ghia
1963 Mercedes Unimog 404
2003 BMW M3

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David Jones
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Re: Internet Armchair Diagnosis: transmission

#8 Post by David Jones » Sun Aug 12, 2018 10:23 pm

Might have been the throttle steering on those twisty flat roads in the mystic hills to the East of Fort Wayne in Ohio.
If I had known I would live this long I would have pushed the envelope a little harder.
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Doug McDonnell
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Re: Internet Armchair Diagnosis: transmission

#9 Post by Doug McDonnell » Mon Aug 13, 2018 12:33 am

Must be quite a ways East of Ft Wayne David. Flat Van Wert is a huge wind farm now.
1965 356C There is never enough time to do it right, but always enough time to do it over.

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Re: Internet Armchair Diagnosis: transmission

#10 Post by Martin Bruechle » Mon Aug 13, 2018 12:54 am

Always good idea to grab the tire (when off the ground) and check for play. 9 & 3 - 12 & 6 positions.
Do that before you pull wheels and axle nuts (next time).

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Re: Internet Armchair Diagnosis: transmission

#11 Post by Thom Fitzpatrick » Mon Aug 13, 2018 9:40 am

Martin Bruechle wrote:Always good idea to grab the tire (when off the ground) and check for play. 9 & 3 - 12 & 6 positions.
Do that before you pull wheels and axle nuts (next time).
I actually did that - and couldn't get any play (like prom night all over again...)
1956 VW Single Cab
1957 Porsche 356A Sunroof Coupé
1957 VW 23-window Deluxe
1957 BMW Isetta
1960 VW Panel
1963 Type 3 Karmann Ghia
1963 Mercedes Unimog 404
2003 BMW M3

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Re: Internet Armchair Diagnosis: transmission

#12 Post by Ron LaDow » Mon Aug 13, 2018 10:03 am

Thom Fitzpatrick wrote:[...]and couldn't get any play (like prom night all over again...)
http://instantrimshot.com/
(you been saving that, haven't you?)
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Vic Skirmants
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Re: Internet Armchair Diagnosis: transmission

#13 Post by Vic Skirmants » Mon Aug 13, 2018 10:30 am

David; that is an early ring gear you had; was it a 6-bolt?

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David Jones
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Re: Internet Armchair Diagnosis: transmission

#14 Post by David Jones » Mon Aug 13, 2018 10:57 am

6 bolt Vic even though it was on my 64C. This was because the initial trans rebuild was by Eric wills and I supplied another diff carrier because the first diff carrier had the bearing carrier snapped off. It lasted about 5K miles before the tooth snapped off and then you rebuilt it and it of course has been fine ever since.
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C differential 013.jpg
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Mike Wilson
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Re: Internet Armchair Diagnosis: transmission

#15 Post by Mike Wilson » Mon Aug 13, 2018 1:37 pm

On my '58, I had the same problem David did, a broken tooth on the ring gear. I found out that the previous owner had disassembled the transaxle, rebuilt the innards but didn't flush out the case. A chunch of a broken part found its way in between the ring and pinion. The clunk was very loud but since I was close, nursed it home.

Mike
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