Toyota Van 2-speed Transfer Swap into AWD Previa

[batook]

I remember Tim mentioned a while back that he was considering the possibility of fitting a 2-speed transfer from a 4WD TV to an AWD Previa. There's an 88 4WD M/T TV at the self-serve junkyard and it got me thinking.

I have a 91 AWD M/T Previa that I picked up for pretty cheap b/c it had front-end damage, and got it running by replacing the radiator, fan, expansion tank, and re-aligning the SADS. So far, I've just used it as a parts van, but since it's mobile, I was thinking of turning it into a plow so I can plow the 100 yard-long driveway at my mountain house that often gets buried in 2-3' of snow in the winter. Initially I was thinking of just doing Tim's 2" lift, fitting some BFG All-Terrain T/A KOs, and figuring out a way to mount a plow to the frame, probabliy through a combination of welding and brackets/bolts. But when I saw that 2-speed transfer at the junkyard today, I realized how much better the "plow van" would be with the option of 4H/4L instead of just AWD.

1) Does the 4WD TV transmission/transfer setup provide any RWD option (like a 4Runner), or is the drivetrain either in 4H or 4L and that's it? Would the 4H setting basically be the same as the Previa's AWD transfer?

2) I think my AWD 5MT Previa has the G59 transmission (EDIT: Turns out I was wrong...AWD Previa MT is G57...G59 is RWD). What transmission was used in the 88 4WD M/T TV? Was it the same gearbox? If not, will the transfer from the TV bolt up to the G59, or would I need to fabricate an adapter? If it's not the same transmission and the TV transfer wont bolt onto the Previa's G59 gearbox, could I use the 5MT from the TV in the Previa, along with it's transfer (i.e, will a 88 4WD M/T TV gearbox bolt up to the Previa's 2TZ-FE engine?) I'm guessing I could probably figure out a way to make that work, but I might need to also bolt the flywheel from the TV onto the 2TZ-FE crank and use the TV clutch if the splines on the input shaft are different between the two gearboxes.

3) Driveshafts might not fit right if the transfer is a different size/width. I'm guessing I would probably need to get custom shafts built or modify the existing shafts to make it work. Since I wont be driving this van on the road, just on my property, it doesn't have to be perfect, it just has to work. If anyone's tried this, I'd like to hear how this issue was resolved.

4) I would need to cut a hole in the sheetmetal near the existing shifter in order to install the 2-speed transfer shifter. I'd also probably need the shift cables that link the 2-speed shifter to the transfer. Any other parts I'd need to pull from the donor TV? When I looked at the 4WD TV transmission today, there was a strange hose (hydraulic?) connected to what looked like the speedometer driven gear (at least where the speedometer driven gear is on my Previa's G59 M/T gearbox)...what is that thing? On the G59, the only thing connected to it is a wiring harness at the speedo-gear.

I'm hoping someone (Tim?) has looked into this and can provide some proof of concept or at least some insight into the TV 4WD drivetrain. Even if I am entering uncharted waters, the junkyard allows returns for up to 30 days, so I'm very inclined to pull the transfer, shifter, and shift cables and give it a shot, since I don't really have anything to lose if it doesn't work out.

Thanks for any input.

Eric

[timsrv]

Hi Eric, It's great to see you back on TVT! That's a great find & you should snatch it up regardless. The 87-89 manual transmissions w/2 speed transfer cases are rare and hard to find. I still haven't acted on my plans to do this but I believe it would be a bolt-on mod. I already know the 87-89 van transfer case will bolt right up to the Previa transmission. I also know that it's dimensionally the same (externally). I also compared DS splines on auto Previa vs auto 87-89 van and they are identical (front & rear). OD of DS yolks are also the same (so the seals will also engage correctly). The only question I haven't completely researched is the TC input shaft splines. For whatever reason Toyota used different splines on automatics than the manuals (TC inputs/trans outputs). They did this on the Previa as well as the 87-89 vans.........but are the auto Previas the same as the auto 87-89 vans??? Are the manual Previas the same as the 87-89 manual vans??? This is the only unanswered question in my research.

My plan for this mod was to take the input shaft out of an 87-89 auto van single speed TC case and swap it into an 87-89 manual 2 speed TC case, then swap the modified 2 sp TC with my original TC on my auto Previa. Of course I'm assuming that Toyota kept the same spline arrangement on the auto Previas as they did on the 87-89 auto vans........if that's the case, then I'd have to assume they kept the same spline arrangement on the manual Previas as they did on the 87-89 manual vans.

If that assumption is correct, then yes, you should be able to take that 2 sp TC and bolt it right up (unaltered) to your manual Previa. And yes, these transfer cases have 2H, 4H, and 4L. The auto 87-89 vans just have 2H & 4H. Of course the hubs on the Previa cannot be unlocked, but separating the front drive train from the TC would make it turn smoother because the earlier TCs don't have a viscous coupling. Who knows, separation of the front drive train might even save you a little gas too?

If you get that TC be sure to also get the shifter mechanism and the shift cable. You may be able to rig up another way to shift it, but the factory stuff would certainly be the easiest way to set it up. You would probably want to build a platform between the seats so it's easy to grab (for shifting on the fly), but floor level would probably work too. Tim

PS: If you decide not to do this, please save that transmission, transfer case, and the shifter/cable set-up as these are rare and sought after. You shouldn't have any problem getting your money back (and then some) if you decide to sell. Even though I already have a couple of spares, I'd be willing to pay your cost + something for your time + shipping. Tim

PPS: Take a look at this thread: http://www.toyotavantech.com/forum/s...vations-(long)

[timsrv]

A few things I forgot to mention. The Previa transmissions are different from the van transmissions, but the bolt pattern for the transfer cases are the same. I believe that tube you see coming from the speedo housing is the speedometer cable (earlier vans actually use a mechanical cable to drive the speedo, Previa is electronic).

BTW, the G59 is used in 2wd naturally aspirated Previas, so I assume you have a G57

Transmission for 87-89 automatic 4wd Van= A45DF
Transmission for naturally aspirated automatic All-Trac Previa= A46DF

Transmission for 87-89 manual 4wd Van= G53
Transmission for naturally aspirated manual All-Trac Previa= G57

I don't have information on super charged All-Trac Previas, but I believe they are externally identical. I think they just use tougher internal parts and are geared slightly different. Not sure what numbers Toyota uses to designate these transmissions. Tim

[batook]

If that assumption is correct, then yes, you should be able to take that 2 sp TC and bolt it right up (unaltered) to your manual Previa. And yes, these transfer cases have 2H, 4H, and 4L. The auto 87-89 vans just have 2H & 4H. Of course the hubs on the Previa cannot be unlocked, but separating the front drive train from the TC would make it turn smoother because the earlier TCs don't have a viscous coupling. Who knows, separation of the front drive train might even save you a little gas too?

That's great news! I was really hoping it would be a simple bolt-on mod. I also have a feeling your assumption is correct in that a manual transmission from either a TV or a Previa will have the same output splines as the input splines on the M/T transfers from both types as well. I havn't been able to find the model code of the 1988 4WD M/T from a TV, but I wouldn't be surpised if it's the same G59, or a VERY similar predecessor.

If you get that TC be sure to also get the shifter mechanism and the shift cable. You may be able to rig up another way to shift it, but the factory stuff would certainly be the easiest way to set it up.

Yeah, I will be using the TV shifter and cables for sure...placement of the shifter might be dictated by the cables' reach. Transfer case is $80 + $20 core, so around $100 will get me that one for my Previa. The other parts shouldn't be more than $50 tops, so I'm looking at around $150 for this upgrade. Totally worth it!!

PS: If you decide not to do this, please save that transmission, transfer case, and the shifter/cable set-up as these are rare and sought after. You shouldn't have any problem getting your money back (and then some) if you decide to sell. Even though I already have a couple of spares, I'd be willing to pay your cost + something for your time + shipping. Tim

Haha, we're like-minded. 5-speed Previas are also something of a rare bird, and I have a complete spare 5MT+transfer on hand already, plus the manual transmission and transfer in my "parts van" which is getting the 2-speed transfer from the TV, so I'll have that spare M/T AWD transfer as well.

I wasn't planning on pulling the transmission if I didn't need it, but I will pull it for you if you want to buy it. I'd hate to see something like that go to the crusher, and I'm sure you would too. They charge around $100+$20 core +10% "environmental fee" + tax, so probably around $150 for just the manual transmission out the door. For clarification, do you want me to grab the *transmission* shifter cables and the *5-speed* shifter for you too? It also has a fully intact motor if you would like me to grab any parts off that as well (VSV? injectors? large intake hose?), or any interior trim, door handles, whatever. Oh yeah, I noted that there's 269,000 miles on it. BTW--I pulled the drain plug on the transmission for a second, and a small stream of nice clean gear oil drained out, so it looks like it was well maintained. I think it is most likely in the junkyard due to engine failure. Eric

[batook]

BTW, the G59 is used in 2wd naturally aspirated Previas, so I assume you have a G57

My research showed G57 = Previa M/T RWD, and G59 = Previa M/T AWD.
http://en.wikipedia.org/wiki/List_of...sions#G-series
(EDIT: Wiki was WRONG (shocker!)...I edited it to reflect the correct info, which is the AWD G57 and the RWD G59).

I know I have an A46DF in my 91 Auto AWD, so that info you have looks correct.

I don't have information on super charged All-Trac Previas, but I believe they are externally identical. I think they just use tougher internal parts and are geared slightly different. Not sure what numbers Toyota uses to designate these transmissions. Tim

I've attached a PDF I found a while back that lists Automatic Transmissions for all vehicles. FYI, the S/C Prevs use either the A340E (RWD) or A340F (AWD), which is used in a LOT of Toyotas (4Runner, Tacoma, Tundra, T100, etc).

I can't wait to get started on this. I don't really have time to go back tomorrow to pull everything, but I will try to clear some time next week, or next weekend for sure. I'll be photo-documenting the swap and will post it here. Thanks for your help Tim! Eric

[timsrv]

I don't need the shifter cables but if it's got a dash-pot on the throttle body please grab that (they are NLA from Toyota). I already have several throttle body hoses, so unless it looks new I wouldn't want it.......somebody else here might though. There's always so many things I want, but in reality not much I need..........probably shouldn't even take that transmission.........just hate to see it wasted. I'm not worried about price, but shipping might be a hassle..........then I have to find a place to store it. Tim

PS: if the siding door handle isn't cracked/broken I'll take that. I also need a latch mechanism w/handle for the rear hatch

[batook]

I've been planning a trip to the Pac-NW in the back of my mind for quite some time now (want to drive through Red Woods, then Portland, Seattle, and BC). If it happens, it will probably be some time this summer, and I could easily bring it along for you. Would be cool to meet in person too. Otherwise, I can tie it to a pallet and freight ship for around $100 I would guess. I think I'll pull it regardless given it's rarity; sounds like I should be able to find an interested buyer even if you decide you don't need another spare. I think they only charge $3 for each cable, so I'll probably just get those too since they're virtually free (and if I leave them connected they'll probably just include them with the price of the transmission). The shifter is around $25 I think. Eric

[timsrv]

If you can deliver..........oh man that's sweet! Yeah, I'll take it. I'm in no hurry as I've got spares already. BTW, the Previas have the tranny code on the driver's door pillar. Tim

[batook]

Couldn't help myself from going outside and checking on one of my MT Prevs. You were right -- G57 in the AWD. I'm going to edit the wiki.

I know the first part (C/TR) stands for "Color/Trim" (6L3 and FC11 in your photo). Do you know what the "A" stands for that has a value of F282?

[timsrv]

Thanks for posting that chart, but I see they don't list the 5 speed Previa (that's a rare option). I did however find it in my service manual:

[batook]

Thanks for posting that chart, but I see they don't list the 5 speed Previa (that's a rare option). I did however find it in my service manual:

Yeah I had it backwards based on mis-information on the web. The chart I attached only lists automatic transmission types. Eric

[timsrv]

Lol, I keep posting while you're reading and visa versa

[batook]

Haha, yeah, we had posts cross over a few times there. I'm going to bed now, so that shouldn't happen anymore. Night.

[Burntboot]

Batook - Please collect those tranny cables when you go for the other bits, I will buy them from you in a heart beat.
(assuming of course the ball-joints on the cable ends (at the trans) are not seized)
Thanks
BB

[batook]

OK, will do. There was zero rust on the frame, so I'm guessing they're probably not seized up, but I'll check 'em out for ya. Anything else you want me to grab while I'm in there?

[Burntboot]

Ummm, well as far as a wish list goes, steering rack, fr propshaft and fr ext pipe come to mind but I suspect they would be a bugger to pull and worse to ship. But if you're up to the task I will start a parts fund in my sock drawer.....
If it is too much bother, I understand.
As far as things that will fit in a mailer, maybe the cruise control actuator cable??
Thanks
BB

[batook]

Hi BB,

Front DS should be no problem since it has to come out anyway to remove the transmission. They charge like $25-30 for that I think. Steering rack is a bit more work but I'm up for it assuming the trans pull doesn't take too long. That will be more like $40-50 I think, it includes inner tie rods but not outers. What is "ft ext pipe"? Front exhaust pipe? I'm not too familiar with the TVs...on the Previas the manifold connects to a "Y" pipe, then flex pipe, then cat, then pipes back to the muffler. The front exhaust on a Previa would be the section from the Y pipe back to past the cat and 2nd o2 sensor, where it bolts to another pipe that leads to the muffler. They can't legally sell used cats so they always cut those out, so the front exhaust is in 2 pieces and would need to be welded together with a new cat. Magnaflow makes a good aftermarket front exhaust for the Previa for around $200 that most of us use to replace it if we don't weld in a new cat. I could get you the exhaust manifold ($40) or whatever pipes run from that to where the cat would be ($25?). Let me know.

On the CC actuator cable, please post a pic of it so I can easily identify it and wont have to hunt around. If you can get pictures of where it attaches on both ends, even better. Thanks, Eric.

[Burntboot]

Hi Batook

Yes I di mean front EXHAUST pipe runs form the manifold straight to the cat, too bad they won't sell them too, I already have an A/M cat on there, amazing how in 1 yr it already looks older than the original did after 23 yrs.
Steering rack (and lines if they will come off) are the important part but if too much hassle, no worries.
As to the CC cable (am computer illiterate so pictures are beyond my scope, heck sometimes spelling is too) it is about 2 ft long and runs from the cruise actuator to the pedal assembly. The cruise actuator is actually hiding under the left foot rest.

Still crying about it being rust free and in the yard. If I could afford it I would just have the whole thing shipped up but that would definitely end in divorce.

As far as pricing goes, all good there and will pale in comparison to the shipping but what is a boy to do.

[batook]

Still crying about it being rust free and in the yard. If I could afford it I would just have the whole thing shipped up but that would definitely end in divorce.

Haha, I hear ya! I have three Previas (one has front end damage and I don't drive it) and I *really* want an 88-89 4WD MT TV...but I think she'll make me get rid of one of my Previas, and I have too much of my time, money, heart, and soul into all of them to ever part with them, plus I wouldn't get back half of what I've spent getting them reconditioned.

I know this yard just buys these vans from auto auctions...I should start going to them and find a TV for a few hundred and then fix whatever mechanical issues it needs. Virtually all of the cars here are rust-free (no road salt, they use magnesum chloride and dirt) and very often 4WD due to the winter weather. I wonder if they would sell me the whole 88 4WD TV that's there now (not sure how picked over it is at this point, but if it's not too screwed up, could be worth it..)

I'll let you know what I'm able to pull, but I probably wont get there until this weekend at the earliest. Eric

[Burntboot]

Sounds like a forward thinking state. I wish we didn't use salt, not just from a rust perspective but more so from the contamination standpoint. It is very hard on lakes and rivers and anything that is alive, the trees along the major highways are all brown from salt damage.

No worries on timing, whenever is fine, It's not like Red is going anywhere soon, much to my wife's chagrin.
Wives, they just have NO sense of humour.

I always like the Previas, especially the S/C AWD versions, maybe someday.
I think the idea of saving "wrecks" is a laudable one, just tell your wife it will be a new stream of income, that should work for a little while.

I think I have hijacked this thread about as far as one can.
Sorry Tim.
Perhaps the rest should go via PM?

BB