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epowell
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Location: Czech (mostly) Vancouver (sometimes)
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 Posted: Sat Mar 23, 2019 1:25 am Post subject: Swapping gearboxes: how to? ['81 DIESEL] |
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Major surgery so I will do this in April so that the van will have a chance to "settle" before making our Summer trip in June/July.
I'm looking for specific advice on how to do this, and what else I should do while I have the gearbox out.
The situation is this: my current gearbox is working well but it is unknown and very old. I am concerned that it can break in the middle of a trip. I have TWO supposedly working, 2nd hand spare gearboxes I bought in Poland... so what I intend to do is to swap in there both of them in order to TEST them out and know if they work and how they compare in health to what I have in there now. This way I can keep the best of the 3 permanently in there and have the other 2 (hopefully) as trusted spares. My long long term goal is to combine the 2.5 extra gearboxes I have into one excellent rebuilt gearbox > but that will be for later in the future.
So, as far as I know now I need to have a good sturdy floor jack and to construct some sort of jig on which to hold the gearbox while it is ON the floor-jack. Best to drain the tranny fluid first to lighten it up - otherwise the procedure I've heard, is pretty straight forward?
If anyone knows of any particularly good tutorials or threads dealing with this, I would greatly appreciate. After posting this I will begin my search for old threads here and youtube tutorials....
Last question: once I have that area opened up what else should I take care of? So far I am intending to do something with the rear bearings, CVs, clutch, needle bearing, main shaft oil seal, and or course deal with any body rust hidden back there.
Thanks again in advance for any help or advice....
Ed
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epowell
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hdenter
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| Posted: Sat Mar 23, 2019 8:46 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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I think your plan is flawed... Since the other two are unknown to you and the one in there now works fine, what do you hope to gain from all this work? At best, the other two will be the same as the one you have now--sounds ok, but don't know how many miles or when it may loose it's slider hub. There are things you can learn from a trany outside of the vehicle. Use a bore scope or remove the bell housing to check the wear pattern on the ring and pinion. Someone could test the lash on the r&p as well as the play on the output flanges. Maybe a bore scope can be poked in at the fill plug to get some idea of the gear condition. My point is that you can determine some major flaws in the two spares without actually installing them. Your worst case scenario is that you go through all the trouble of swapping in these other two tranies only to find out that they have bad r&p or main bearings (which you could have determined on the ground). Then you put back the original trans and it looses it's slider hub shortly thereafter. Even if one of the two spares checks out with good tolerances and a nice looking r&p, it could loose it's slider hub a week later, too. IMHO, leave the seemingly good trans in the van and work towards having one of the spares rebuilt.
Hans
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?Waldo?
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| Posted: Sat Mar 23, 2019 9:14 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| I think hdenter makes a good point. While it isn't a particularly difficult task to swap transmissions it is a fair bit of work. Putting the work/money into rebuilding one of the two that are not installed makes a lot of sense. Then swap in the rebuilt one and keep the current one as a spare. |
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Jeffrey Lee
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| Posted: Sat Mar 23, 2019 10:04 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| epowell wrote: |
| My long long term goal is to combine the 2.5 extra gearboxes I have into one excellent rebuilt gearbox |
This plan to "build the perfect beast" assumes that all parts within 3 identical gearboxes are interchangeable between boxes. In fact, transmission parts and gears in particular tend to wear into their neighbors, and may be unhappy when pulled out and placed into another box with new neighbors. Lash, wear patterns, fine-tolerance alignments all change when swapping parts between boxes, and can lead to problems.
Besides, even if possible, such a plan would require simultaneously opening and inspecting all three boxes, cherry-picking the best parts from each, then assembling them all into one 'perfect' gearbox. An obsessive enthusiast like you or I might have the time and wherewithal for such a task, but likely lack the required skills and tools. Conversely, someone with the knowledge and tools likely lacks the patience for such maddeningly fiddly work, or would charge an understandably prohibitive fee for it.
I agree that, unless you have specific reason to suspect a flaw, you should continue running your current gearbox. Meanwhile, send out the best of the other two boxes for a quality rebuild, knowing that you have the third box as a source for OE parts if needed.
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epowell
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| Posted: Sat Mar 23, 2019 10:44 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| ?Waldo? wrote: |
| I think hdenter makes a good point. While it isn't a particularly difficult task to swap transmissions it is a fair bit of work. Putting the work/money into rebuilding one of the two that are not installed makes a lot of sense. Then swap in the rebuilt one and keep the current one as a spare. |
Yes...
...and thanks HANS for the "heads up".
My motivation regarding that original plan/draft is:
1) to make sure ASAP that I have a spare - at least something that could get me home - lest my slider "goes" in the middle of our next trip. My understanding is that even tho a tranny can 'feel OK' this infamous 'slider' can "go" at any time unannounced.
2) the 2nd motivation is to get an idea from my 3 supposedly "working" boxes, which one of them is the best and therefore the best candidate for a full re-build.
But as HANS pointed out, perhaps these boxes can be appraised adaquately 'on the ground'... in fact, I think it is now obvious which one is the best. The one I paid the most for has the nicest case and clearly looks to be by far the best cared for and least used.
I also sort of hesitate to dig in and do this major surgery considering all of the stuff back there seems currently to be working so well > maybe best not mess with it right away??
But on the other hand, who knows what my clutch now looks like, and what about the needle bearing etc etc... wouldn't it be wise to get in there now while I have the time and check all of that unknown stuff out? Better to mess with it now in the comfort of home as opposed to who knows where - who knows when?
Thanks for these queeries - I want to think this thru and make sure I have a GOOD PLAN.
| Jeffrey Lee wrote: |
This plan to "build the perfect beast" assumes that all parts within 3 identical gearboxes are interchangeable between boxes. In fact, transmission parts and gears in particular tend to wear into their neighbors, and may be unhappy when pulled out and placed into another box with new neighbors. Lash, wear patterns, fine-tolerance alignments all change when swapping parts between boxes, and can lead to problems.
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I think more realistically I should re-phrase what my intention is--- yes I also assume that the likelihood of actually being able to swap gears from one OLD gearbox to another won't happen - probably because they will be worn out in the same areas.... so more likely, I think, is that I won't actually be "combining" parts, but rather, just taking the best candidate and keeping in there as much as possible, and just putting in NEW parts that will be required.
Honestly, I obviously still have not thought all of this thru completely. Maybe it would be a good idea to open both "spare" DM's that I have. I also have a DM with a great case but broken 1st gear and without R&P/bellhousing... and finally I have all of the innards of a DK minus R&P. >>>> so I DO HAVE a ton of options... just not yet sure which route to take.
| Jeffrey Lee wrote: |
I agree that, unless you have specific reason to suspect a flaw, you should continue running your current gearbox. Meanwhile, send out the best of the other two boxes for a quality rebuild, knowing that you have the third box as a source for OE parts if needed. |
Yes.... probably it is now time to decide affirmatively if in fact I will do the rebuild myself of not. I do have a press, and the LONG REBUILD CD... but would have to buy the special sockets etc. I would like to do it myself.... but I have also heard of a VW tranny GURU in a city not too far away, and Czech shop prices are still very cheap. Perhaps I should talk to him first. Maybe I could take all of my parts and boxes to him and let him 'have at 'er' ???
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dobryan
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| Posted: Sat Mar 23, 2019 1:19 pm Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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The phrase "If it ain't broke don't fix it" applies here.
If I was in your situation I'd make sure the existing trans had a gear oil change and that no chunks of metal or unicorn blood came out. If there are no nasty whines or growls and the gear oil is reasonable I'd run it this summer.
In the meantime I agree that you should remove the bell housing from the two spare trans and see what the inside looks like. Post pics so the trans experts here can comment. Get the better of them rebuilt and you can swap it in after the camping season.
Have fun and don't do more work than you need to.  (Besides you know that once you start working on the trans there will be many other things to work on as well, thus risking your summer trips and creating a lot of stress.)
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Wildthings
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| Posted: Sat Mar 23, 2019 1:37 pm Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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If you aren't getting excess swarth on your drain plug or have any odd noises, I wouldn't worry too much about the gear box you are running failing.
If you have the funds, then just have one of the spare boxes gone through and keep it ready to ship as a spare so if you do have problems out on the road with your present box, someone can take your spare in to a shipping agent and get it to you in short order. |
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?Waldo?
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| Posted: Sat Mar 23, 2019 1:45 pm Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| While I generally agree with the comment that if there isn't undo swarf or excessive noise then the gearbox is probably fine, that does not apply to the slider hub issue. I had the slider failure without swarf or any trans noise. Trans worked exceptionally well and silently until it stuck in 4th gear a couple times. I promptly pulled it and sent it off for rebuild. On a trip it could have been a real hassle. |
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Wildthings
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| Posted: Sat Mar 23, 2019 2:35 pm Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| ?Waldo? wrote: |
| While I generally agree with the comment that if there isn't undo swarf or excessive noise then the gearbox is probably fine, that does not apply to the slider hub issue. I had the slider failure without swarf or any trans noise. Trans worked exceptionally well and silently until it stuck in 4th gear a couple times. I promptly pulled it and sent it off for rebuild. On a trip it could have been a real hassle. |
The slider was an 091-1 problem more than a 091 problem which the 81 models had IIRC. That said I have lost a slider in a high mileage 091. For the OP rig, I think this would largely depend on the intensity of the torque spikes from his diesel. |
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?Waldo?
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| Posted: Sat Mar 23, 2019 3:20 pm Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| I have heard that the same part was used in the 091 and the 091-1 and the more common failure of the 091-1 hub was not due a difference in the trans but rather a result of the engines fitted. The 091-1 failed more often (or at lower mileage) due to the higher torque of the later engines. |
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epowell
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| Posted: Sun Mar 24, 2019 1:33 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| dobryan wrote: |
The phrase "If it ain't broke don't fix it" applies here.
(Besides you know that once you start working on the trans there will be many other things to work on as well, thus risking your summer trips and creating a lot of stress.) |
While I certain see the reason for this viewpoint, I have also been thinking from the opposite point of view > which is in fact to open up this can of worms with the expectation of finding hidden troubles that need "righting" before causing problems on the road. I also planned this year to have all of April to devote to my van, which can even spill into all of May if necessary. But we have to hit the road on June 1st.
Are there not plenty of things in there that can have sudden death that won't give warning? Stuff like the needle bearing? ...what about the clutch? Wouldn't it be good to have a look at that?
What is the greater risk: 1) to leave what is working well now alone, even though what is inside is totally unknown ...or 2) now with 2 months free time, to open up the unknown and correct what is on the verge of breaking > but have this new work load drag on so long that we miss our trip?
What I don't get is what kinds of things could go so wrong as to tie me up for 3 or 4 months potentially? Clutch, CVs, pilot bearings, and rear wheel bearings can't be so potentially troublesome. Probably only the if the gearbox itself would for some reason not work again when reinstalled?? ...or?
| ?Waldo? wrote: |
| I have heard that the same part was used in the 091 and the 091-1 and the more common failure of the 091-1 hub was not due a difference in the trans but rather a result of the engines fitted. The 091-1 failed more often (or at lower mileage) due to the higher torque of the later engines. |
This brings up another issue --- the 3-4 slider. Many comments here so far assume that I can be at high risk of this particular slider cracking even if right now my box sounds smooth. I would like to clarify if this is actually true. I have heard that the DM which is an 091 which is basically still from the same generation of T2 van's boxes was "PRE-wimpy 3-4 slider" installation, no? So the DM should not have this vulnerability any more than a T2 van.
The other thing to consider well when appraising my own situation is that my driving habits are not normal. I drive very very slow and never on freeways. It is rare that I go over 80KPH, and my JX pulling the loaded hightop... I don't think the gearbox is experiencing any massive amount of torque. [???]
- - -
Lastly, another advantage of getting in there now for a box swap is that I will thereby learn how to do it - and learn something about that part of the van, and get my 'repair chops' up > so IF there are problems on the road I will be better able to deal with them...
...of course it would be nice just to kick back and do nothing on my van now, and just hope for the best. . . . but I know that mechanical problems can pop up anywhere, anytime, when you least expect them, and always in those neglected areas where "I just didn't get around to looking at that".
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epowell
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| Posted: Sun Mar 24, 2019 1:44 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| Jeffrey Lee wrote: |
| epowell wrote: |
| My long long term goal is to combine the 2.5 extra gearboxes I have into one excellent rebuilt gearbox |
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...another possible long term game plan [considering time and money] might be simply to have a stash of old DMs to use as spares and keep swapping them in and using them until they break. This is assuming that the DM perhaps does not have the 3-4 slider vulnerability, and also assumes that I am a very very slow driver with an underpowered engine.
It strikes me that these days nobody wants these old DMs and they are available cheaply. If I can pick one up for $150 and use it for 5-10 years then actually this might be a very good tactic. $15- $30 per year and almost zero repair time for gearbox forever....? not so bad?
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crazyvwvanman
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| Posted: Sun Mar 24, 2019 2:16 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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Tranny, clutch and CV axle removal is about 50+ bolts and nuts to remove or loosen. Some may be rounded, stripped, or frozen by rust. Better to find and correct this at a convenient time. Plus you will know how to do the job if ever needed on the road and you will know you have the tools, or which ones you are short.
The 3/4 slider/hub is a different part number for 091 than for failure prone 094/091-1 tranny models. Don't know what the relative failure rates are.
I once had a 091 4 speed break inside and loose all gears while headed home on a cross country trip in an 82 TD Westy. I was towed to a motel on the edge of the closest town, walking distance to an autoparts store. I had a spare tranny already boxed up at home. A relative shipped it out to me that same evening. FedEx delivered it to the motel next morning, 1000+ miles from home. I swapped it in a dirt lot behind the motel, and was back on the road later that afternoon. I bought a cheap floor jack, gear oil, drain pan, etc at the autoparts store. Had to swap bell housing and input shafts. I had all the other tools with me. My passenger helped.
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epowell
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| Posted: Sun Mar 24, 2019 3:21 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| crazyvwvanman wrote: |
| Tranny, clutch and CV axle removal is about 50+ bolts and nuts to remove or loosen. Some may be rounded, stripped, or frozen by rust. Better to find and correct this at a convenient time. Plus you will know how to do the job if ever needed on the road and you will know you have the tools, or which ones you are short. |
Yeah this is what I have been thinking. For sure getting these items out will see me dealing with some f***ed up fasteners which would be a shear nightmare on the road. Not to mention, as you say, currently having no experience with this job, and probably not the right tools. To my way of thinking, I have been really lucky up til now not to have had any rear end problems on the road, so why push my luck. Once I just go thru the whole process of opening and closing a particular neglected area of the van, I am forever confident that even if there is a problem, I am familiar with everything down there, PLUS opening something a second time is a piece of cake compared to what has been standard for this van: OLD BOLT REMOVAL NIGHTMARE EVERY SINGLE TIME.
Thanks Mark, yes, there is no question that now is the time to open it up back there and see what's going on. 
| crazyvwvanman wrote: |
I once had a 091 4 speed break inside and loose all gears while headed home on a cross country trip in an 82 TD Westy. I was towed to a motel on the edge of the closest town, walking distance to an autoparts store. I had a spare tranny already boxed up at home. A relative shipped it out to me that same evening. FedEx delivered it to the motel next morning, 1000+ miles from home. I swapped it in a dirt lot behind the motel, and was back on the road later that afternoon. I bought a cheap floor jack, gear oil, drain pan, etc at the autoparts store. Had to swap bell housing and input shafts. I had all the other tools with me. My passenger helped.
Mark |
Amazing story... and this is what happens when your chops are hot and you have prepared expecting the possible worst.
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bridgetroll13
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| Posted: Sun Mar 24, 2019 5:01 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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Note that on early Vanagon transmissions the shift rod was on the end rather than the side.They also had a different shift linkage with a larger diameter shaft up front that doesn't work with the early rod support over the fuel tank. It can be swapped out but you need to install the bulkhead support bearing and bend or remove the original so it isn't in the way.
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epowell
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| Posted: Sun Mar 24, 2019 5:18 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| bridgetroll13 wrote: |
Note that on early Vanagon transmissions the shift rod was on the end rather than the side.They also had a different shift linkage with a larger diameter shaft up front that doesn't work with the early rod support over the fuel tank. It can be swapped out but you need to install the bulkhead support bearing and bend or remove the original so it isn't in the way.
Erik |
Are you talking about early DIESEL gearboxes? Doesn't sound like it. On my DMs the shifter is on the side. Also my shift rods are the same diameter - front and rear halves.
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MarkWard
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| Posted: Sun Mar 24, 2019 5:36 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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Both versions are side shift, but completely different. I'd go through the fire drill of swapping in one of the spares and seeing how it did. Without stripped or seized bolts is a 1 day project.
CV's regardless need to be serviced. Clutch and pilot bearing can be addressed with the transmission out. But would wear independent of the other driveline parts.
The 091 vs the later versions is actually a little more complicated to rebuild. You need a jig to support the gear carrier assembly to adjust the shift forks. You can make a jig out of a used case. Maybe use one as a donor for hard parts and sacrifice the case for the jig.
These are not that difficult to go through. I paid to have a 4 speed built, but for my syncro project, tackled it myself. I bought some tools and fabricated others. Came out fine.
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epowell
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| Posted: Sun Mar 24, 2019 5:41 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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| MarkWard wrote: |
Both versions are side shift, but completely different. I'd go through the fire drill of swapping in one of the spares and seeing how it did. Without stripped or seized bolts is a 1 day project.
CV's regardless need to be serviced. Clutch and pilot bearing can be addressed with the transmission out. But would wear independent of the other driveline parts.
The 091 vs the later versions is actually a little more complicated to rebuild. You need a jig to support the gear carrier assembly to adjust the shift forks. You can make a jig out of a used case. Maybe use one as a donor for hard parts and sacrifice the case for the jig.
These are not that difficult to go through. I paid to have a 4 speed built, but for my syncro project, tackled it myself. I bought some tools and fabricated others. Came out fine. |
...this is about how I feel about it too. Thanks
GB rebuilders here in Czech are cheap, but I also have to consider my new Canadian van which will also need GB work one day. Shop time in BC is at least 5X more costly than in Czech.
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dhaavers
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| Posted: Sun Mar 24, 2019 6:41 am Post subject: Re: Swapping gearboxes: how to? ['81 DIESEL] |
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FWIW...can't imagine diesel is much different, but here's a good basic DIY primer: http://volksweb.relitech.com/clutch.htm
Also: no special jack or fancy jig required...just a couple straps has worked for me:
Git 'r done! 
- Dave
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