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Transmission makes noise when letting off clutch in 2nd gear
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kowpeki
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PostPosted: Sat Jan 28, 2017 11:39 am    Post subject: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

I have a 1979 VW Bus / Transporter with a manual transmission. I think the engine and transmission are correct for the year.

The problem is it makes a grinding sound when letting off the clutch in 2nd gear. With the foot on the clutch it shifts into all gears just fine. The problem only occurs when letting off the clutch in 2nd gear.

I already removed the engine and transmission from the bus. I can repro the problem on the bench. This is my procedure:

- Lock the differential by bolting each end of a metal strap (the kind with holes all along it) to each of the joint flanges
- Put the transmission in 2nd gear
- Use a tool that slides onto the driveshaft to turn the driveshaft

When I turn the driveshaft and look at the 1st/2nd gear selector shaft in the nosecone section of the transmission I see it sliding in and out and hear a metal clicking sound. So I don't know if it is a much grinding as something not going into place properly.

Any advice on what to do next? Any advice on a good transmission repair manual? I already have the Bentley shop manual, but wonder if there is a better manual that covers only the transmission.
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VIN: 2292134777
Engine Code: EC004375 (1974 Porche?)
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SGKent Premium Member
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PostPosted: Sat Jan 28, 2017 1:26 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

are you saying that the 1-2 selector shaft pulsates in and out when the input shaft is turned?

This is what the gear cluster looks like out of the case. It is not an easy repair and special tools are required. I've built many transmissions in my life, automatic and manual but by far rebuilding my 091 was the most expensive and troublesome. It also required specialty tools that were costly.

My first suggestion would be to drain the oil and see if there are any pieces attached to the magnet other than the normal sludge and filings that will be about 1/2" long. I would also inspect the pilot bearing in the crankshaft end to be sure it isn't your culprit by not letting the clutch work correctly.

Image may have been reduced in size. Click image to view fullscreen.

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Last edited by SGKent on Sat Jan 28, 2017 1:35 pm; edited 1 time in total
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kowpeki
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PostPosted: Sat Jan 28, 2017 1:31 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

SGKent wrote:
are you saying that the selector shaft pulsates in and out when the input shaft is turned?

Yes, that is a good description of what is happening, plus making the clicking sound.
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VIN: 2292134777
Engine Code: EC004375 (1974 Porche?)
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kowpeki
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PostPosted: Sat Jan 28, 2017 2:09 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

SGKent wrote:
My first suggestion would be to drain the oil and see if there are any pieces attached to the magnet other than the normal sludge and filings that will be about 1/2" long.

There were definitely filings, but nothing larger than about 1/2". The oil looked a little metallic, kind of like metallic paint.
SGKent wrote:
I would also inspect the pilot bearing in the crankshaft end to be sure it isn't your culprit by not letting the clutch work correctly.

Thanks, I will take a look at that bearing. But the problem isn't with the clutch not working, right? With the foot on the clutch, I easily shifted it to 2nd gear. On the bench, I easily shifted it into 2nd gear. It's just that when load is applied the selector shaft "pulsates", a good word for it. I'm hoping that's a hint that the problem is easy.
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PostPosted: Sat Jan 28, 2017 2:12 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

selector shaft is attached to the shift fork. The 1-2 hub is on the pinion shaft - the one on the left in the photo. It almost sounds like the pinion nut is loose but were that the case I would think it would whine in all gears.

Why not make a video of it and post it, That way folks can see how much movement there is.

In this photo you can see the 1-2 selector shaft is the closest one to the bottom. You can see the bolt that holds the 1-2 fork and how it is slid into the 1-2 hub. It is mounted in a fixture that allows the adjustment.

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kowpeki
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PostPosted: Sat Jan 28, 2017 4:29 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

SGKent wrote:
It almost sounds like the pinion nut is loose but were that the case I would think it would whine in all gears.

I'll see if I can check the pinion nut. I saw a YouTube video where a guy said the pinion nut is often loose on these transmissions. It's my son's VW and he claims the problem was starting to happen in 1st gear too, but I couldn't repro that. He also said that it doesn't happen when you downshift to 2nd gear and engine brake. That seem relevant.
[/quote]

SGKent wrote:
Why not make a video of it and post it, That way folks can see how much movement there is.

I like that idea. I will try to get one out in the next few days.

SGKent wrote:
In this photo you can see the 1-2 selector shaft is the closest one to the bottom. You can see the bolt that holds the 1-2 fork and how it is slid into the 1-2 hub. It is mounted in a fixture that allows the adjustment.

Thanks for the great information.
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Wildthings
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PostPosted: Sat Jan 28, 2017 9:29 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

I am going to guess the loss of pinion bearing preload, likely the nut coming loose. The 1-2 slider is on the pinion shaft and would thus be effected more than the 3-4 slider which is on the mainshaft. If the bearings have lost their preload for whatever reason the gears should whine more than normal.
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PostPosted: Sun Jan 29, 2017 11:39 am    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

Here is a link to a video showing how we bench tested the transmission and demonstrating the problem:

Link

In redoing the test we discovered different driveshaft rotation directions caused different results, as shown in the video.
Rotating the direction of engine rotation ("correct direction"):
    Problem (pulsating of the 1-2 selector shaft) is intermittent
    Problem usually goes away by pulling on the 1-2 selector shaft as shown in the video
    Problem always goes away with repeated reversing the rotation, rotating in the correct direction then pulling the 1-2 selector shaft

Rotating the wrong direction
    Problem always occurs.
    No amount of pulling on the 1-2 selector shaft makes it go away


Another piece of information I forgot to mention: My son says the problem with 2nd gear only started happening after he attempted to push start the bus in reverse, something he says he has done a lot of in the past. He says the bus reacted differently on that attempt than any other time he pushed started in reverse.

I have a new speculation. He accidentally had the bus in 2nd gear instead of reverse when he tried to push start it in reverse on the attempt that led to the problem. If that is true, I'm guessing the fix won't be an easy one, but want to hear others opinions.

One last thing, I checked the pinion gear nut and it was loose. I could rotate the pinion nut just slightly with my fingers one direction and then the other. I couldn't totally unscrew it though. And I didn't feel any play in the pinion gear or any bearings.
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Engine Code: EC004375 (1974 Porche?)
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PostPosted: Sun Jan 29, 2017 1:09 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

I would consider trying to push start a VW in reverse to be a form of abuse. I prefer to use third gear if I can get the vehicle going fast enough, and failing that to use second. First is bad and reverse is abuse.
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PostPosted: Sun Jan 29, 2017 1:11 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

As soon as you mentioned jump start in reverse, before I read any further my feeling was he was in 2nd and not reverse as you said. Easy to do if you're not careful.
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PostPosted: Sun Jan 29, 2017 1:14 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

Wildthings wrote:
I would consider trying to push start a VW in reverse to be a form of abuse. I prefer to use third gear if I can get the vehicle going fast enough, and failing that to use second. First is bad and reverse is abuse.
I agree, but sometimes you're just facing the wrong damn way on the hill..... Cool
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PostPosted: Sun Jan 29, 2017 1:53 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

I agree with everyone on jump starting in reverse. He says he first tried it due to facing uphill with no one to help push start. I googled it and didn't find anything conclusive. If nothing else the chance of breaking your transmission due to accidentally having it in 2nd gear instead of reverse is reason enough not to do it.

Moving on, any recommendations on the fix? Does it make sense to just fix 2nd gear? Is there any way that would be less costly than an entire rebuild? I don't know what is involved in an entire rebuild.

I might be able to borrow or rent the special tools required. Any recommendations on a good book on rebuilding VW bus transmissions? Is Bentley all I need?
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PostPosted: Sun Jan 29, 2017 2:20 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

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The square cut gear on the 1-2 slider is part of the reverse drive. Somehow something was overloaded in this gear or some other part of the reverse drive.

You really can't tell all that needs to be done until you tear into the box. It is easy to pull the bellhousing and see part of the reverse gear setup. No special tool needed to do this minor part.

Your son is certainly not the first to damage the reverse gears in one of these boxes. It is a very weak setup.
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PostPosted: Sun Jan 29, 2017 6:25 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

Wildthings wrote:
It is easy to pull the bellhousing and see part of the reverse gear setup.

Thanks for confirmation on that. I think we even saw a video on it. I was worried that I might have to remove the differential before removing the gear housing.

Wildthings wrote:

Your son is certainly not the first to damage the reverse gears in one of these boxes.

The reverse gear is not the problem. 2nd gear is the problem. I think he damaged 2nd gear by popping the clutch going in reverse while having it accidentally in 2nd gear.
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PostPosted: Sun Jan 29, 2017 8:54 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

kowpeki wrote:
Wildthings wrote:
It is easy to pull the bellhousing and see part of the reverse gear setup.

Thanks for confirmation on that. I think we even saw a video on it. I was worried that I might have to remove the differential before removing the gear housing.

Wildthings wrote:

Your son is certainly not the first to damage the reverse gears in one of these boxes.

The reverse gear is not the problem. 2nd gear is the problem. I think he damaged 2nd gear by popping the clutch going in reverse while having it accidentally in 2nd gear.


I am going to guess that the reverse gear shaft is has snapped and also has a bend and that somehow the reverse sliding gear is staying engaged with the 1-2 slider. Your vibration is the bend shaft and reverse slider putting alternating pressure against the 1-2 slider. VW trannys are far from a specialty for me though.
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PostPosted: Sun Jan 29, 2017 10:10 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

Wildthings wrote:

I am going to guess that the reverse gear shaft is has snapped and also has a bend and that somehow the reverse sliding gear is staying engaged with the 1-2 slider. Your vibration is the bend shaft and reverse slider putting alternating pressure against the 1-2 slider. VW trannys are far from a specialty for me though.


Hm, interesting theory. Thanks for taking the time to explain. So, maybe he did have it in reverse, but the abuse caused by push starting it in reverse caused the damaged to the transmission. I'll keep this thread posted with our progress. We can only work on it one day a week, so won't be until next weekend.

I would still like a pointer to a good transmission guide. I guess I will start by looking at the various classic VW online parts stores.
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PostPosted: Sun Jan 29, 2017 10:49 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

you would be better off to send the transmission to one of the specialists. I prefer Eric Laundrie at Transworks in EL Cajon CA. Rick Long at Long Enterprises retired.

You'll spend more on tools to rebuild the trans than to pay someone to do it. Reverse is the weakest gear.

Here is the thread when I rebuilt mine. It was a fun challenge but I would not do another. I'd send it to Eric. http://www.thesamba.com/vw/forum/viewtopic.php?t=6...hlight=091

Here is a photo where the reverse gear can be seen. It is the small gear closest to the top middle of the photo. There is an arm that is engaged in a slot in the gear. Right now it is engaged in reverse.

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PostPosted: Sun Jan 29, 2017 11:26 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

I will tell you that first off that trying to push start ANY air cooled VW in REVERSE gear is asking for trouble. Embarassed

Any time you mesh a small gear with a large gear backing up is going to put extreme stress on the smaller gear. Think about this when you have a gear that
is 2 inches in diameter meshing to a 5 inch gear. trying to 'push' it backwards
with 4,000 of pressure. As for pulling the bell housing and seeing damage One
will have to dig deeper and pull the gear carrier in order to SEE the reverse gear that engages into the 1st & 2nd slider which is the PART that DRIVES
the DRIVEN gear

REVERSE driven gear is the one you see when pulling the bell housing and
really has no effect on the DRIVE gear. as this is the WEAK link.

I have built many of these units and have seen quite a few failures due to
thinking they could push start a bus in reverse without any damage. let alone
our little ol' bugs.
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PostPosted: Tue Jan 31, 2017 12:41 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

SGKent wrote:
you would be better off to send the transmission to one of the specialists. I prefer Eric Laundrie at Transworks in EL Cajon CA. Rick Long at Long Enterprises retired.

Thanks for the advice, and I should follow it, but we are gluttons for punishment I guess and plan to dig deeper into this transmission ourselves. I have a classic VW mechanic friend with the tools he'll let us borrow. He doesn't do transmissions anymore, the reason we just didn't take it to him. No one in Austin works on VW transmissions anymore. We may end up taking it to a specialist, but I just have to see the reason for the failure with my own eyes first.

I found Long Enterprises mentioned in another forum: http://www.shoptalkforums.com/viewtopic.php?t=84906. I purchased his "091 Performance VW Transaxle Rebuilders Course CD". Here is a link to his site: http://www.longenterprises.com/. As you mention, he is out of business, but is still selling his instructional CDs and his remaining parts.
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Engine Code: EC004375 (1974 Porche?)
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PostPosted: Sat Feb 25, 2017 12:53 pm    Post subject: Re: Transmission makes noise when letting off clutch in 2nd gear Reply with quote

After borrowing the specialty transmission tools from a friend and purchasing a 30 ton press on craiglist, we took the gears apart. It appears the main problem is that 1st and 2nd gears are worn where they meet the synchro rings. I will post some pictures of that later, but would like to get some opinions about the pinion gear wear. Do I need a new pinion shaft/gear?

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.

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Engine Code: EC004375 (1974 Porche?)
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