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chrismsnt
Samba Member
Joined: March 06, 2018
Posts: 247
Location: Cumming, GA
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 Posted: Thu Dec 01, 2022 6:32 pm Post subject: Transmission rebuild |
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This could possibly be an easy question for some, however, when getting a transmission rebuilt on a van which has a rear differential, is it implied that the rebuild automatically includes rebuilding the differential or is that optional?
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Chris
1989 T3 Vanagon 16" Syncro
1967 Squareback
https://vwvandiesel.com
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MarkWard
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Joined: February 09, 2005
Posts: 17153
Location: Retired South Florida
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| Posted: Thu Dec 01, 2022 6:59 pm Post subject: Re: Transmission rebuild |
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You can’t get to the gear sets without disassembly of the ring and pinion. If the ring and pinion teeth look good. A rebuilder would replace the pinion bearings and the gear carrier bearings. Rechecking and adjusting preload, backlash, and pinion depth.
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tpinthepack
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Joined: July 11, 2004
Posts: 816
Location: clearwater,florida
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| Posted: Fri Dec 02, 2022 3:14 am Post subject: Re: Transmission rebuild |
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Chris
I am in the same position. My 90 Auto works fine, but I want mine gone through. I know from reading Bently and The Samba that the two come apart and a Double Seal exists that keeps Gear oil on the Diff side, and ATF on the Automatic side. My plan is to separate that myself and drop the Diff off at a local Gear shop that pretty much only does Diff work, then have the Auto done by another shop. My Van had some odd clunks at time that sound more like something in the diff, but the auto part appears flawless.
Tony
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TP in the Pack (I am a cyclist)
1968 Manx N.O.S. w/ Barrett Chassis
1960 Single Cab 1914 w/ 40 DLRA's
1990 Vanagon DOKA
1972 Super Beetle
1979 Super Beetle Convertible
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MarkWard
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Joined: February 09, 2005
Posts: 17153
Location: Retired South Florida
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| Posted: Fri Dec 02, 2022 5:40 am Post subject: Re: Transmission rebuild |
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The automatic is a different bird to the manual. You can drop the differential pan and easily inspect the ring and pinion visually. You can also check backlash. You could also replace the differential carrier bearings all with the automatic installed.
Mating the differential to the automatic can be tricky and there is a measurement you need to make before mating. My recommendation would be to have one specialty shop do the complete job. For your clunk, I’d do some inspections before pulling it and dropping it off. Your clunk could something else. The differentials are pretty stout if they are kept full.
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Silverghost500
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Joined: August 01, 2018
Posts: 1088
Location: Atlanta, GA
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| Posted: Fri Dec 02, 2022 6:28 am Post subject: Re: Transmission rebuild |
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Chris, I believe I would go ahead and have the differential taken care of while the transaxle is out. The rebuilder may not find anything wrong, or may find other components like the transmission that have issues. At least you'll know.
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1986 Volkswagen Vanagon Westfalia "Von Westy"
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MarkWard
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Posts: 17153
Location: Retired South Florida
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| Posted: Fri Dec 02, 2022 10:30 am Post subject: Re: Transmission rebuild |
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If you are asking about the ring gear carrier, it likely gets disassembled for cleaning. Not sure what new parts are available for the spider gear assembly any more.
If I had a gear carrier on a syncro that was too worn out, I'd install a Peloquin TDB and locker. Its a direct replacement and would be an improvement over an open differential with a locker. You'd want to do that while the transaxle is disassembled. GT was also working on having ZF limited slip lockers which would be a nice option to an open differential as well. Having the rear fully locked has some limitations on twisty trails. They prefer to go in a straight line.
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Sodo
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Joined: July 06, 2007
Posts: 9610
Location: Western WA
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| Posted: Fri Dec 02, 2022 11:49 am Post subject: Re: Transmission rebuild |
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| chrismsnt wrote: |
| This could possibly be an easy question for some, however, when getting a transmission rebuilt on a van which has a rear differential, is it implied that the rebuild automatically includes rebuilding the differential or is that optional? |
There's a little ambiguity perhaps because you wrote 'rear differential'.
1) Rear differentials (the spider gears and stuff) often only require cleaning and reassembly. They don't usually 'wear out'. The tapered roller bearings (carrier bearings) and oil seals at the differential are always replaced with new. Sometimes the side-screw adjusters that hold the carrier bearings are replaced. But assessment of the condition of the differential is a requirement of a Transaxle rebuild, so YES the differential should be ready for 100,000 miles. Replacement with a new Peloquin differential is an option too <---this is a complete replacement.
2) The other major component of the 'rear end' is the Ring&Pinion gears. The ring gear is bolted to the differential. This pair of OEM quality gears can last 300, 400,000 miles, and longer with proper maintenance and not too big an engine. But it can be ruined quickly if driven after the transaxle has started to make 'noise'. Or if driven real hard. Or if driven 'sorta hard' after noisy, the teeth can break easily. And many steps in-between. Most previous owners didn't maintain their gearboxes _at all_, so the R&P is often run-out by the time many of us got our vans - all headroom to go another round, got deleted in the first run.
3) And there's the "pinion bearing". This should always be replaced with new. Sometimes a builder will "grind down" a used bearing. Better hope that builder has the proper tools to do that precision task. I had a rebuild where the guy used a belt sander on an old bearing. That gearbox lasted less than 20,000 miles.
The R&P is replaced "as a matched set". The pinion gear is part of the lower shaft that goes all the way thru the transmission (front-to-back). It pokes into the decoupler at the front end and engages the ring gear at the rear end. If it's not "good for another 100k" then you won't get 100K from that rebuild. A good R&P set/pair costs about $1500. It's assessment, by a professional, as "go/nogo" is a crucial step a transaxle rebuild. Transaxle rebuild MUST include a Ring&Pinion set that will go another 100k miles.
So the answer to your Question is "YES". The differential (and R&P) is an integral part of the transaxle rebuild. It's can't be done any other way or it's "reassembly" not "rebuild"
--------- and for your 'new' gearbox which will have some used & some aftermarket parts -----
Any gear or bearing that starts to shed steel into the gearbox lubricant, will start taking the transaxle down (at that time). So you want a rebuilder who is capable of assessing the suitability of every used part that goes back in. If any part has only 40,000 remaining miles, then the beginning of your rebuilt's demise starts after 40,000 miles. If you instruct a rebuilder to stay under "some price"; re-using your old parts be the only way for him to hold that price.
Pretty much everything is "run out" these days, from non-maintenance AND from big miles.
20 years ago a lot of gearboxes (or the rare 'maintained' gearbox) could get another good long run just changing bearings (and the 3/4 hub).
That horse has left the barn.
And on your end you should continually monitor the condition of your gear oil, the easiest method being to simply change it before it gets infested. Don't use "new car intervals" like 60,000 miles. The gear oil may have been infested at 20k, and now you've run 40k with steel circulating in your oil, denting your bearings. You have lost significant gearbox lifetime i that case, maybe all of the remaining lifetime. When the gearbox was "new" it had a good long run where it didn't 'make much steel' in the oil. But now with the possibility that one or two (old, or low-quality new replacement) items might start contaminating your lubricant, ya gotta up the maintenance, and 'check' more often.
Don't fall into the trap of buying $100 gear oil, then 'delaying maintenance' it because you're apprehensive of dumping $100 of oil. If that's going to be your MO, you are way better off buying $30 oil. You need to get the steel OUT of your gearbox ! The $100 oil is just ever-so-slightly better (if at all ? ) than $30 oil like Valvoline, Kendall, Shell and many many other industrial gear oils. $100 oil that's infested with steel is much more damaging than $30 oil that's clean, so you are doing "known damage" ....for an unknown. There are very simple, low-effort methods to purify the $100 oil and re-use it, if that's your preference.
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chrismsnt
Samba Member
Joined: March 06, 2018
Posts: 247
Location: Cumming, GA
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| Posted: Sat Dec 03, 2022 10:14 am Post subject: Re: Transmission rebuild |
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Thanks all... after speaking with Rancho (who performed the work), they address it all since you need to disassemble the diff to get to everything else! Now I hope I'll be on the road this Monday or soon thereafter! It's a LONG time coming!!
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Chris
1989 T3 Vanagon 16" Syncro
1967 Squareback
https://vwvandiesel.com
Instagram @VW_VanDiesel |
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