Hello guys,

I've bought my car without any test drive because it was unsed many years. Now my transmission is on my todo list. I already opened the case to inspect the 1st gear. I saw a syncro ring which seems to be less used but the dog teeth and the slider speeks other words. My impression.. I have to change slider, dog teeth and syncro. I added some pictures, who can distinguish between poo parts and reusable ones.

Your slider looks fantastic. The gears show typical wear. I do not see any galling in the pics so they should be good to go

Oh, while you are in there, you should change out the band and teeth. The teeth are not worn out, but they are on their way.

Thanks for answer , new teeth are expansive can I reuse them from other gears(transmission)? Are the teeth the same in 911 transmissions? Where to get (companies) teeht in US, also used ones? Are the now available ones genuine Porsche ore reproductions?

Do you have a picture of a worn out slider, just to see the differences?

I added additional pictures just to show other 914 friends how it can look like?

no pic of a worn out slider but its the teeth, just like the replaceable dog teeth on other gears that start to round and ground down. the less pointy at top, the worse.

I now know how new teeth should look like, but is there an indication/threshold when they are worn out. Is there any measurement method for indication ore just experience.

Let's talk a lite bit about the function of the teeth. As far as I know the slider shoult only slide ove the syncro ring if the rotating speed of the cogs are the same. Are the teeth edgy the shift will be easy are the worn(rounded,flat) the shift will snag. So the importent part is always the syncro ring also if the teeths are a litte bit flat..ore? So the grinding noise
is forced by worn syncro rings and will lead to flat teeth.

You can reuse teeth from other gears as long as you use all the internal parts with it (all the bands and blocks). I sell good used parts at a deep discount from new with no loss in longevity or function. You can also try Mittlemotor in Germany for new parts since you are over that way.

As for your question about the teeth points on the slider, the teeth need to be pointed so that they allow for the interlocking of the slider and the dog teeth on the gear. The synchroband works as both a friction devise that speeds up the gear to the shaft speed, and as a lock to hold the slider onto the dog teeth. When your teeth get dull, the slider and dog teeth have difficulty interlocking and this causes the grind you hear. A worn synchro band contributes to this. The reason the teeth need to be pointy is because the points offer less surface area to block the transition of the slider into its engaged position with the dog teeth of the free gear.

The way the 901 type of transmission is designed, the parts tend to wear in this fashion:
Synchro band -->dog teeth --> slider

If one addresses the problem early, then they have less to fix. Also, the cost of the parts goes up significantly as the problem progresses and other parts wear:
Synchro band (about $175) --> dog teeth (about $175) --> Slider (from $220 to $500)

As for wear limit, I do not know of an indicator. The manual would just have you change anything worn. I use my experience to dictate when something is used up. My threshold is 70%. If I do not feel confident that the part has 70% or better life left, it is considered garbage.

Hello

I continued my transmission rebuild and have additional questions. First I like to show bad news. I think the root cause is cavitation caused by ??.

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The number for the ring gear and pinion shaft is the same. The roller bearing outer part can be rotated in the case.. ist this normal.. the manual says different.
Is there a need to solve this and If how?

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I also have now the problem to get a used ring gear and pinion shaft.
The clearances must be adjusted again, I do not have the tools. Are there different approaches to do this without these tools?

That is toast. The race in the case should not move.

I have good used ring and pinion. If you can not get someone local to you to adjust the ring and pinion, you can use the method that other makers use in that they apply dye to the ring and check where the pinion contacts and adjust from there. I had a guy in New Zealand use this method as he did not have access to the tools or a shop with them. His results were fine, but you may have to do it a few times, I dont know. I always use the tools.

So, it'S not possible to get ring and pinion in Austria, so if you have a good used one I will take them. Also I'm looking for original case transmission nuts, you also have this.

The tools I dont have but I'm going to ask some shops maybe I can rent them.

The other big issue is the roller bearing outer part in the case which can be rotated. How to solve this..new case ore other options?

Thanks Georg

Georg,

Regarding the bore for the roller bearing, I have remove a number of those bearing races. They are not very tight, but they are also not finger loose either. If you must have that case (it is an original case for the car and you want to keep it), then I am sure there are options. I know that Loctite makes products for this situation (I think it is Loctite 640 and/or 648), but I have not tried those products so I can't vouch for their effectiveness. At a minimum I expect that once used, it would be very difficult to remove the outer race in the future.

If it was me, I would try to source a new case. I don't know how easy they are for you to obtain, but in fact, it might be more cost effective for you to source a complete core transmission and then hope for the best that it may be a better candidate for rebuild. It may have a good ring and pinion to start with and you wouldn't have to mess with trying to set pinion depth, backlash, pre-load and your current transmission already looks to have good examples of the commonly worn items (such as a 1st/Reverse slider).

Good luck and I hope it all works out. Continue to post if you have more questions.

Richard

I agree that another core would be a better investment. Must you have this particular case? If not, you need a core and will save lots of money and time. As for the OE nuts, I do not have any new.

Thanks for the answers! I also think it makes sence to use an other case but my transmission is a genuine 914-6. As far as I know some gears are different to the 914-4. If I use an other case I have to move this gears. At the end the clearances are again wrong and measurement is necessary.. or??

If the outer race moves and and I use locite than I hope it will be very difficult to remove. That's at the end the goal a stable outer race which never losse under normal operation. If I like to remove them later I can also use than an other case.

I'm going to ask loctite, maybe they also have solutions for that case which also includes the workflow how it can removed afterwards.

I have no fear for the measurments, I like the work and have the time. There ist the option to make a fault but I will learn a lot! If its not posible to get the tools I'm going to make it by my own. Lathe and milling is possible. If this is necesarry I will post my tools.

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There is another alternative to changing cases. The original /6 box I just rebuilt has both bearing races in the case loose. Since I use good used parts in my rebuilds where ever I can, I measured all of my stock and found that there is just enough variance in outer race diameter to take up that slop. The end result was a better bearing with appropriate interference with the case. If you measure the outer race of the loose bearing, I or someone else may have a larger one for you. If you go the lock-tite route, I would use a very good bearing or a new one to ensure you do not need to remove it anytime soon. You should get another 30-40 years out of the bearing that way.

As for swapping gears, that is easy. You just measure the thickness of the gears (in the center), compare them to the thickness of the ones you are swapping off (you only need to measure the pinion shaft), and then adjust for the difference either at the gaskets between the intermediate plate and case if you can, or the shims on the pinion itself.

I will measure the outer race of the bearing, do I also have to change the other parts of the bearing? You know my ring and pin is toast I have to pull them of. On wednesday I will have the result and will send it to you. I try to go with his case, tha's my goal.

Yes, the bearing should be replaced as a unit to be done correctly.

Hello,
I measured the ring 72.00mm!

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Next step of transmission rebuild, 1st gear dogteeth replacement and new synco ring. I used the special tool to remove the dogteeht ring and a shop press...without success. 4 up to 5 ton a big bang and a brocken ring

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I got them off with a dremel whitout any grinding of the gear.

Next step installation of new dogteeht.
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Last step the check according the manual. Perfect.. fully in range.

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Dr. Evil, regarding the roller bearing, ring /pinion and the nuts (used) let me know If you have these parts for me! If pls. gif me the info what you are asking for and how we can finish the deal.

regards

Georg

Hey Georg,

Great work. I have had only one ring break like yours, and that was recently. I use a hammer to beat the dog teeth off. I will check my bearing collection and see if I have what you need. I definitely have the R/P, I do not have the nuts as I use new stainless ones in my rebuilds. PM me your contact and shipping info and I will get you a price quote for what I have.

Did you need the smaller bearing that goes above the larger one in the case as well?

Georg,

As Mike mentioned above, sometimes the ring section breaks off the syncho hub like yours did. Sometimes the hubs seem to be pressed onto the gear extremely tight (as if they have been welded, or as if someone used loctite).

When you use that tool you can either pound it off using a hammer or use a press. I like using the press (as you showed in your photo). However, I have a suspicion (can't say for sure) that for the ones that are on extremely tight, they are more likely to break if you use a press. I suspect that the hammer approach may help break something free without causing a stress fracture along the ring if you just keep applying pressure via a press. While I use the press on a regular basis, if I have one that is stubborn, I remove it from the press, give it a few hits with the hammer and then put it back on the press and give it a second try. I haven't done it enough to determine if this is helping or not as the vast majority of them pop off without requiring lots of pressure on the press.

If they the hub breaks, just grind a notch in like you did and the then it should split and come off. It's a pain, and takes a bit of work, but if you are careful it does no damage to the gear.

Richard

I continued my work with cleaning some parts of the transmission. Blasting oft parts which are later will be zink plated and case parst

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I use WD40 to stop corusion of the magnesium case. If all is done and the case is closed after the rebuild I will use wax for that.

If I have the nissing Parts I will teardown the two shafts. I like to replace all syncros with new ones.

Georg

I will go out and measure the bearing right now. I had to get a battery for my caliper

I'll PM you, too.

That's fine, If I have all parts I will finish my work. I have to beat blast the case too.
This is still open. And the new syncors are still not deivered.

I have to leave for today, I will anwser your mail. My address you should already received.

Thanks in advance!

more pictures from my transmission rebuild. I made a contact pattern of the ring and pinion, the pattern is just made with hand load. The measured backlash is 0.16mm. I always put the dye on the ring. I gues the R&P is a Gleason style and not Klingenberg.. hope so.

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What is your opinion about this contact pattern, can I go with this?
This is my first setting, I made a scound one, see next post

Georg

2nd option of S&P setting.

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Pls. tell me your knowledge.

I bought the tool (VW 385)to measure the pinion depth. These tools are made by MATRA a German company. In addition I like to show the result of my transmission rebuild.

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That is a beautiful transaxle you have there. Congratulations on your rebuild.

wow. Nicely done!

Good job, Georg What was the price for the tool? I have a similar one that does the same thing that was being sold for $400.

Hello,

the price was match more than 400. The tool is completely new, it's the configuration which is described in the transmission manual:

1 x VAG VW 385 /17, Messplatte d=50 mm 100.07EUR
1 x VAG VW 385 /15, Messuhrverlängerung 9,3 mm 13.06EUR
1 x VAG VW 385 /30, Universaleinstellmeister 490.61EUR
1 x VAG VW 385 /14, Meßstößel 30 mm 29.86EUR
1 x VAG VW 385 /4, Zentrierscheibe (2 Stück) 397.73EUR
1 x VAG VW 385 /1, Messdorn 827.68EUR

It' s a big investigation but I tried to work with dye.. contact pattern..not good, needs much time.
Just two service stations in Austria are up to the task to set the backlash and pinion depth. For the job they are asking 400 up to 1000€.

I have as second transmission I like to rebuild from my 2.0 liter 914.

An additional reason, the VW tools which start with number 3 will just produced until 2014. Afterwards these tools are not longer purchasable!!

I also like to do the job for other 914 and maybe 911 drivers.

Can you show your tool, where does it come from?

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Ciao

Georg

....oh no....he wants to see the Doc's tool...... watch out....

My tool is made out of an old differential and was sold on ebay. I will try to post a pic of it.

The time and cost it takes to set the R/P often exceeds the cost of just buying another core transmission here in the USA. Buying another core generally has the side effect of having extra parts and cutting the parts cost down in the end. As such, I have not had to use my R/P tool yet.