Bay Window 2nd Gear Grind

[RomStrom]

Hello all, first-time post here at TheSamba and unfortunately under some quite frustrating circumstances. Please bare with me as there is a lot to explain and I am at a total loss for what could be causing this issue.


What: My 1978 Bay Window with a recently inspected/resealed 091 transaxle and rebuild Type 4.

Problem: Shifting up or down into 2nd gear (and only in 2nd gear) causes a non-stop grinding noise, even without the clutch engaged (clutch pedal down). This grinding occurs at the second I enter 2nd gear (once it begins I can release the clutch pedal and enter 2nd. If I am just short of the grinding "region", releasing the clutch pedal leaves me in neutral)

Brief History: Originally got the bus 2 years ago, where it was used very frequently before. No such shifting issues existed prior except for getting into 3rd, which required you to hit a certain spot (I called it the three-spot) which otherwise would result in grinding, and reverse gave grinding noise.

Pulled engine and trans, did a full engine rebuild and also took apart the trans with the help of (what I believe to be) one of the few VW Transaxle experts in the state of Texas*. According to him, gears and synchronizes looked in good shape. However, reverse gear teeth were heavily chewed on one side, see Figure 1. The shavings were present on the magnetic drain plug.

I replaced the reverse gear, gaskets, seals, lubricated everything properly, and put in new trans fluid (essentially a re-seal, proper reassembly of transaxle done with above mentioned expert). Also replaced clutch arm spring and all the bushings that arm shaft uses which are contained in the bell housing. Also replace all nosecone "shifting" components, including the hockey stick, the plastic ball with a steal alternative, etc. Essentially all the steps outline in Ratwell's 091 Transmission Refresh article here https://ratwell.com/technical/091Transmission.html.

Also rebuilt the entire linkage, put in new bushings all throughout, new boots, new coupling set, and lubricated the shaft. Also had the flywheel resurfaced, throw-out bearing replaced and pressed into the flywheel, adjusted flywheel endplay.

Upon first drive, no more issues with 3rd and reverse, but the grinding of the 2nd gear as described above had begun.


What I've Tried Since: - Adjust my clutch free-play. Got it between 1" - 1 1/2" when pushing with one finger, the pedal feels smooth and the clutch "catches" at an appropriate distance.
- Reinstalled my clutch stop plate properly as in Figure 2, shifting feels more correct now but same problem remains
- Adjusted shifter position on the front floor panel & tried several configurations, all with same 2nd gear grinding issue
- Approach 2nd gear from several different angles, all successful entries into 2nd result in grinding noise.


I have searched through several forums and posts here on thesamba but haven't had any luck. My thoughts lean towards the sychronizer, however it seems strange that this issue arose now where it was non-existent prior to the work mentioned above (at least I can't imagine the reseal would cause an issue like this). I was going to purchase a better shifter, though I feel like this stock one does the job well aside from 2nd.

Any insights would be greatly appreciated!

- Roman


* He has been working on VW Transaxles for over 40 years and supplies several bug/bus shops in Texas with rebuild transaxles. Also specializes in racing transaxles. He is a reputable source from what I've heard from several people.


Figure 1:

Figure 2:

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1992 VW Mexican Combi Bus
1978 VW Transporter

[SGKent]

if you used gl5 fluid and the 2nd gear synchro was moly coated you made it too slippery to grab and synchronize. If you had the gear carrier out then did you make any other changes to it, and did you use the shifter jig plate to check the alignment on all the shifter forks?

Did you lube the pilot bearing and make sure the clutch disk slides on the input shaft smoothly?
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[RomStrom]

Howdy, glad to pick you brain on this. I've gotten much needed information from your past postings sir.

- I did in fact use 80W90 gl5 gear fluid.
- No changes to gear carrier while out.
- Alignment of shifter forks not verified with jig plate. My transmission guy just gave an overview of everything on the gear carrier
- Pilot bearing was lubed before I connected the transmission to the engine


Would changing to a non-gl5 non-"slippery" oil do this situation any good? Or does the tranny likely need to be opened again?
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1992 VW Mexican Combi Bus
1978 VW Transporter

[Wildthings]

[RomStrom]

[SGKent]

I have been told by several well known trans builders who said it has happened to them when one of their customers did it. You can put in a brand new moly coated synchro, run GL5 and trash it permanently instantly. The extra slippery fluids in the GL5 soak into the moly and make it too slippery to grab the gear to spin it up or down.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[airschooled]

Devil's advocate here: Why is only the 2nd gear synchronizer affected by the gear oil?

Does your 091 still have the spring-loaded neutral gate?

Robbie
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[SGKent]

[airschooled]

[Wildthings]

[airschooled]

[SGKent]

FWIW - Rick Long told me about it, Erik in El Cajon told me about it, then Big Bore not only told me about it but he was in the process of rebuilding an 091 for a rail that the guy drained the GL4 and put in GL5. The trans shifted perfectly after the rebuild with GL4 but ground terribly with GL5. Mike (Big Bore) said they tried draining and filling several times, tried light weight engine oil etc., drain and fill. Nothing worked. When the additives in the GL5 got into the moly that was it.

I used to hone blocks for moly rings. Moly coated things are special. Moly is like a tiny graphite plate. When the plates lay down on top of one another it is slippery as walking across a pile of oiled plates on an ice skating rink. When the molecules are straight up it is an abrasive. It is brittle and breaks very easy, hence blocks bored for moly rings need an extra like mirror finish - a regular crosshatch will destroy a moly ring. Why in tranmissions some GL5 oils screw up moly synchros I don't know. I do know that several other trans builders also told me they had been burned with warranty work on trans someone put GL5 into, and that is why most VW bus trans builders only use brass synchros. The sulfur compounds in GL5 will eat away at the brass and mag in a bus trans but it is a very slow process. The moly thing is an instant failure thing. Does this fellow have that problem? I don't know. The gear carrier was out - maybe something else got whacked like a shifter dog or the spring that holds them in.
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"Most people don't know what they're doing, and a lot of them are really good at it." - George Carlin

[Abscate]

[RomStrom]

[TomWesty]

[RomStrom]

Reporting back, tried the gear oil swap to no avail although it did "dampen" the grinding noise. Had to send my transaxle in somewhere to get fixed to which I chose Mr. Gas in Canon City, Colorado.

Went out for a drive a few days ago and shifts like new. Greg at Mr. Gas mentioned the shifter forks looked worn down and a few other small things, so perhaps I wasn't landing all the way into 2nd gear.

Well this time, I ended up adding GL-4 gear oil just to be safe although Greg mentioned I could use GL-5 as well. We'll see how it goes in the long run.
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1992 VW Mexican Combi Bus
1978 VW Transporter