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Its a non syncrod straight cut collar shift, so make sure to double clutch it. Haha. High speed shifting may not actually go so well.
I think I may have solved this issue. Now granted since this is all hypothetical, I wont know until I apply this in a physical application, so here it goes. My first thought was that since I know how to clutchless shift that might be helpful, but id rather not occasionally grind gears, so I wanted to come up with something a little more fool proof. Then this occurred to me, with this many gearing sections why not take advantage of the neutral points? Isolate out the spinning gears so that they're not spinning, or rather not spinning so fast? I plan on dividing out my 4x4 and hi/low gearing so ill have a triple stick setup. Why not take advantage of this by shifting into neutral on both the tranny and t-case and then upshift into the overdrive? of course doing all of this while coasting in neutral. And then once the overdrive is engaged, shift back into fifth from neutral?
For the sake of MPG, one nut can be adjusted and acheive more than regearing will ever get.... THE DRIVER! Not joking, my corolla is rated epa 26mpg average, I get 40-45mpg... no gear changes, and some very slight wind resistance mods. Yes gearing up the axles would give you better MPG *IF* if drive it right, if not you'll probably get the same, if not worse because it feels like less power, so you give it more gas.
Not to push people to other sites, but http://ecomodder.com is a good site to read up on, they look at facts, ABA testing etc to validate claims and get realistic numbers. One guy swapped out a gear set in his trans from another version of the same trans which gave him something like +5% gearing, and he gained very close to 5% better MPG with his already soft driving habits. I achieved 25-30mpg out of an 86 2wd pickup fairly easy with a front caliper hanging up and carb float level too high. Also have gotten 22-25mpg out of my 5vzfe tacoma 4x4 with 4.10 gearing in the summer with no mods.
Dual transfer case would only make sense if you geared up your axles so much that low range was too high geared for your typical offroad needs (if any). Swapping the big and small gear *might* work, but if memory is correct it's something like 2.7:1 typically and sometimes closer to 5:1, so you'd be reversing that ratio. Transmission overdrives generally max out around 0.75:1 or 1:1.33 depending how you look at it. With an overdrive of 1:2.7, you'd cut your rpm over half and you'd probably never be able to use 5th gear, 4th gear would be like a highway only gear and the transfer case gear set would have much higher stresses than it was orignally designed for IMHO. If you could get a transfercase gear set closer to 1.5:1 for "low range" and reverse the install of the gears (if possible), might net good results with the transfer case not going to have too many problems in theory.
Either way, I'm subbed encase something actually is built/tested. Would be neat to have a little 2wd (with 4wd trans) with the option of super overdrive *if* mpg is improved a lot (goal in my mind would be 40-50mpg @ ~45-50mph). A TDI diesel might be a better option than all of this though, I'd guess a typical driver would get around 35mpg with it in a pickup, 40 maybe 45 in 2wd application with a bit softer driving and closer to 50 with an eco driver.
For the sake of MPG, one nut can be adjusted and acheive more than regearing will ever get.... THE DRIVER! Not joking, my corolla is rated epa 26mpg average, I get 40-45mpg... no gear changes, and some very slight wind resistance mods. Yes gearing up the axles would give you better MPG *IF* if drive it right, if not you'll probably get the same, if not worse because it feels like less power, so you give it more gas.
Not to push people to other sites, but http://ecomodder.com is a good site to read up on, they look at facts, ABA testing etc to validate claims and get realistic numbers. One guy swapped out a gear set in his trans from another version of the same trans which gave him something like +5% gearing, and he gained very close to 5% better MPG with his already soft driving habits. I achieved 25-30mpg out of an 86 2wd pickup fairly easy with a front caliper hanging up and carb float level too high. Also have gotten 22-25mpg out of my 5vzfe tacoma 4x4 with 4.10 gearing in the summer with no mods.
Dual transfer case would only make sense if you geared up your axles so much that low range was too high geared for your typical offroad needs (if any). Swapping the big and small gear *might* work, but if memory is correct it's something like 2.7:1 typically and sometimes closer to 5:1, so you'd be reversing that ratio. Transmission overdrives generally max out around 0.75:1 or 1:1.33 depending how you look at it. With an overdrive of 1:2.7, you'd cut your rpm over half and you'd probably never be able to use 5th gear, 4th gear would be like a highway only gear and the transfer case gear set would have much higher stresses than it was orignally designed for IMHO. If you could get a transfercase gear set closer to 1.5:1 for "low range" and reverse the install of the gears (if possible), might net good results with the transfer case not going to have too many problems in theory.
Either way, I'm subbed encase something actually is built/tested. Would be neat to have a little 2wd (with 4wd trans) with the option of super overdrive *if* mpg is improved a lot (goal in my mind would be 40-50mpg @ ~45-50mph). A TDI diesel might be a better option than all of this though, I'd guess a typical driver would get around 35mpg with it in a pickup, 40 maybe 45 in 2wd application with a bit softer driving and closer to 50 with an eco driver.
I appreciate your thoughts, getting any kind of realistic input on this subject has been rather difficult. I realize that my thought process may not be very conventional but I wanted some brainstorming from people that actually have knowledge they can offer. To give you some background into my driving, I'm fairly nice to my rig. I upshift whenever possible, trying to squeeze every little bit of mpg out of her. So driving an "underpowered" gearing isn't really a problem for me. My plan, if I can get it working, is to use this setup as a freeway gas saver. For example in a cross country run where I will be shifting rarely. Ill definitely check out ecomodder.com, anything to help me break down my thoughts is helpful. in terms of the dual t-case gearing, I honestly don't offroad enough to need an intensely geared underdrive. An overdrive would be more helpful in this rig. You had mentioned torque being an issue, if this works out I could always get new shafts/gears created for the application. Of course that would be expensive but worth it if the desired affect is reached. Gearing up my final drive keeps being mentioned, but to be honest I like my current gearing. I don't really want to slow down my off the line acceleration than it is now. Hence why I want a variable control, able to have the best of both worlds. As opposed to being stuck with just snail pace (over-exaggeration I know). On the subject of engine swaps, im kind of a purest when it comes to parts. If possible id rather stay with TRD, and I like the 3.4. Again thanks for your intput. its greatly appreciated. Unless I find its 100% impossible I will most likely be getting the parts to try it for real.
Unless I find its 100% impossible I will most likely be getting the parts to try it for real.
On this subject, if there's anybody out there in the Baltimore, md/tri-state area with yota parts and knowledge that could help me out I would love to find you. Ill be looking for parts real soon and anybody that has anything helpful, ill take anything I can get(of course a price tag is assumed). Thanks in advance.
Dual transfer case would only make sense if you geared up your axles so much that low range was too high geared for your typical offroad needs (if any). Swapping the big and small gear *might* work, but if memory is correct it's something like 2.7:1 typically and sometimes closer to 5:1, so you'd be reversing that ratio. Transmission overdrives generally max out around 0.75:1 or 1:1.33 depending how you look at it. With an overdrive of 1:2.7, you'd cut your rpm over half and you'd probably never be able to use 5th gear, 4th gear would be like a highway only gear and the transfer case gear set would have much higher stresses than it was orignally designed for IMHO. If you could get a transfercase gear set closer to 1.5:1 for "low range" and reverse the install of the gears (if possible), might net good results with the transfer case not going to have too many problems in theory.
I completely forgot about this part. Are you talking about flipping 1/2 and 3/4? So that 1 is on bottom and 4 is on top?
I have a fair share of machines for parts, but I'm in Michigan. Shipping smaller stuff wouldn't be a problem though.
Just to point out, dual cases wouldn't make sense unless you want to keep your low range and have the extra overdrive.
I haven't searched it out, but you might be able to locate a 6 speed trans from a newer toyota, or maybe even a newer auto that *might* work with the ecu. The primary spec you'd be looking at is the gear ratio in the highest gear, and of course make sure it has the TC lockup. Overall cost vs benefits, cheapest and easiest way to bump up 10% in gearing to see if it's acceptable takeoff speeds and such is to throw on tires 10% larger than you currently run. The 86 pickup had tiny tires, like 26in and I threw on the jeep tires just to try it out. The 22r has great bottom end grunt, so it didn't really drive any different, just the high end you could tell the take off was a bit slower (45mph+).
Depending how extreme you'd be looking to go, dual transmissions can work really well but the fab work is pretty extreme. My dad's done that before for the opposite effect (super low range). The rear drive shaft ended up like 12-16 inches long and I don't think he ever got it completed to drive it much more than around the yard. I remember he used some slip yoke style diff, probably for a front axle.
I think I understand your plans as wanting to use the transfer case as a sort of 6th gear. The older transfer cases don't like shifting at high speeds so much, tacoma based ones can do so upto 50mph (owners manual spec). I think the older trucks it's 35mph. Realistically speaking, I'd think best usage/application if it does work out is to put it in "super high range" and drive it as a 5 speed with nets out to be basically higher geared axles or over sized tires. You'd also want to add an inline switch to disable the 4wd ADD VSV valves (or splice both vacuum lines together to keep the axle unlocked for testing). Shifting the transfer case at speed w\o the front axle being locked in might allow for higher speed shifts (no front drive shaft would be best case, but unlikely you want to convert to 2wd lol).
Realistically if I were in your shoes, I'd look into the option of reversing the transfer case gears (buy a spare and bench test or w\e). If you can swap the OEM ones, you should be able to swap aftermarket. Turn the low range into overdrive range and try it out. It'd be much cheaper than dual cases, no extra fab work (drive shafts etc) to deal with. If all works out well, then look into dual cases to keep your standard low range while also having the modded overdrive range.
This is defo a neat thought exercise. About the closest thing I can think of to achieve your goal is a engine/trans transplant with a 6 (or maybe 7) speed trans, but I don't even know if their overdrive is any extra overdrive or not. You'd be wanting something like 0.6-0.7:1 I'd think. Also just to point it out, RPM isn't everything when talking MPG. Efficency of the engine (power output vs fuel input) is generally around 80% load at the given RPM. In a perfect world with no hills, no wind, and drive line always being an exact load, you'd have a target speed (say 55mph), figure out how much drive train/tire rolling resistance, and areo drag will be, and get the exact HP rating you need to keep the speed with the 80% load in mind (80% load is NOT 80% throttle). Generally speaking it takes something like 15-20hp to maintain 55mph, so you'd need the rpm that gives max HP of somewhere around 25hp.
Looking at the 4th one down (black background), it goes down to around 1500 rpm = 30HP, so I suspect 1500RPM to be traveling 55mph would be close to ideal since it gives a small overhead for wind etc. Of course that chart isn't a 100% factory engine or account for mileage/wear differences. Hills and 70mph will be killer, might even have to run 4th gear (the areo drag increases FAST at higher speeds) for anything over 55mph or on a windy day. My T100 3.4L R150 5 speed and 4.10 axles runs around 2100rpm @ 55 with the slightly oversized tires, so you'd need around a 25% increase in gearing based on my truck.
All of this can look good on paper, but should put the disclaimer up that real life isn't as predictable, such as the 80% load spec isn't the same for all engines, and the HP charts are done at wide open throttle which isn't even close to 80% throttle, at a point the computer generally dumps extra fuel above the ideal 14.7 ratio. I think it's something like 90 or 95% + throttle, not sure if Toyota's are programmed that way or not.
Talking about MPG and such, another thing you could look into is increasing the mechanical efficiency of the internals for your engine. Very few people post unbiased results on engine mods, so there isn't much for details out there. Seems generally roller bearings are better than friction bearings (if possible to choose, like roller rockers in domestic v8s, roller cam etc), increasing compression increases the mechanical advantage some typically, larger valves could be good, but that goes into air flow/fluid dynamics which is beyond what I know and OEM is generally pretty good. Another thing to help low rpm power is long tube headers, there is actually math behind it to get the best results and ideal length, very similar to how 2 stroke expansion chambers work, or the super old 2 strokes with basically a straight pipe. Same goes for the intake, long tube intake gives better bottom end, the 2.7L and 3.4L engines have quite long intakes, I think the 22re is a bit shorter. Ironically a smaller exhaust pipe *could* give better MPG @ low rpm since it'd be tuned more for low end, you would defo loose out at the top end though. Larger could help in some cases too, but that's only when the pipe is the restriction, generally based on other mods like turbo etc. You need velocity in the exhaust to encourage the scavenge effect, so too big is very bad for MPG is is more ideal for high rpm/big hp.
There are some very knowledgeable users on ecomodder in the aerospace and fluid/aerodynamics so making a post over there too might give a good 2nd check on ideas/theory's.
EDIT:
@skullhead
I'm pretty sure that is OP's idea, it keeps the same distance apart from the gears, and reverses the gear ratio. I'd guess it might be possible to switch. I haven't done the math to figure out what gear would be ideal to shift to from 5th to the custom 6th, just guessing with ~2.7 it would probably be 2nd or 3rd + the transfer case in "low" with the reversed gears.
If this idea is plausible Michigan is doable. I have some friends in the area and could always make a trip out of it. Of course Im not trying to be an imposition, but if I could actually make this work it would be well worth it.
My reasoning for dual cases is to maintain my crawling capability but also to facilitate on the ease of shifting. Having two different neutrals may take some pressure off of shifting. I would also be planning on a triple stick mod so as to separate my 4x4 from hi/low so Im only affecting my hi/low settings.
On the subject of tires I believe im currently running larger than stock (please forgive me I don't know much about tires), this size was on it when I bought it so I just stuck with it. 265/75/15
Id rather stay away from a secondary/different transmission just because of fab requirements. This idea just seemed a little too convenient to pass up.
Of course I wouldn't plan on using the t-case overdrive for much more than just coasting. If I needed to downshift I would shift out of overdrive and back into a standard gearing. Im fairly proficient at shifting and gearing/clutch control so Im sure I could figure out how to work it, even if complex.
Last edited by skullhead690; 02-16-2017 at 09:29 AM.
Tire sizes are a pain, I just use google to help convert to the height.
265/75/15 = 30.6"x 10.4"
I run really close to that but with 16 in rims, so it's an inch taller.
Looking up the factory size, it looks like there was two options.
225/75R15 = 28.3"x 8.9"
265/70R16 = 30.6"x 10.4"
Since your truck has 15in rims, I'd guess it doesn't have the tow package (larger tire size), so likely it's a 4.10 axled truck. If it's aftermarket rims, it might make sense it had 16in and they kept the same size of tire, but with 15in rims. In this case it might have 4.56 ratio which is a little on the lower geared side. 4.10 in that case would help quite a lot with mpg. Both my tacoma and T100 with the 3.4L I run ~32in tires with 4.10 gear ratio, and it takes off fine for my driving style.
Since you have the old style R150 trans (pre tacoma) the dual cases adapter you'll have to be careful with, since the 3.4 had a R150 trans as well that uses a different transfer case. For the dual cases what ones would you need to run, or are there multi able options now? I have transfer cases from the old style R150 and a couple that mate up to W/G series (most common for dual cases last I knew). The W/G series ones would most likely be 21 spline, I think the R150 and the transfer case from the turbo 22re trucks have 23 spline. I'm almost positive you can convert 21 to 23 spline though.
I'm from the mid Michigan area (Midland's general area) so if that works for you I'd be happy to sell some parts .
I looked up some info on the transfer cases, and the V6 transfer case should be 2.57:1 ratio in low range. so just over 2.5 turns of the output shaft per turn of the input shaft is still quite an over drive (1.33 per turn of the input with a trans of 0.75:1 overdrive ratio). My fear would still be the transfer case being the weakest link. Might sound like a lot of effort, if you do get far enough to test drive, I'd say atleast get a way to monitor the temp of the transfer case while in overdrive. You might have to install a couple of lines in the case and add an inline pump and cooler to keep heat down enough. I'm sure there are some extreme off roaders that have done similar so there's probably a write up somewhere on it and what works.
The more ideal ratio sounds to be the ones that came with the W/G series transmissions. It would be 2.28:1 ratio would be a little less of a major overdrive, and another transfer case to research if what you have doesn't work.
Seems like good info here, I read a couple spots but not the whole thing.
Tire sizes are a pain, I just use google to help convert to the height.
265/75/15 = 30.6"x 10.4"
I run really close to that but with 16 in rims, so it's an inch taller.
Looking up the factory size, it looks like there was two options.
225/75R15 = 28.3"x 8.9"
265/70R16 = 30.6"x 10.4"
Since your truck has 15in rims, I'd guess it doesn't have the tow package (larger tire size), so likely it's a 4.10 axled truck. If it's aftermarket rims, it might make sense it had 16in and they kept the same size of tire, but with 15in rims. In this case it might have 4.56 ratio which is a little on the lower geared side. 4.10 in that case would help quite a lot with mpg. Both my tacoma and T100 with the 3.4L I run ~32in tires with 4.10 gear ratio, and it takes off fine for my driving style.
Based on what youve said here iv probably got the 4.10 final drive ratio. Iv got stock toyota alloy rims.
Originally Posted by atcfixer
Since you have the old style R150 trans (pre tacoma) the dual cases adapter you'll have to be careful with, since the 3.4 had a R150 trans as well that uses a different transfer case. For the dual cases what ones would you need to run, or are there multi able options now? I have transfer cases from the old style R150 and a couple that mate up to W/G series (most common for dual cases last I knew). The W/G series ones would most likely be 21 spline, I think the R150 and the transfer case from the turbo 22re trucks have 23 spline. I'm almost positive you can convert 21 to 23 spline though.
With the R150 ill have to trade my current t-case over to the W/G series t-case since (at least according to marlin crawler) there is no adapter for the R150 chain driven t-case. And I would be inclined to trust that information. In marlin's dual t-case kit they provide 23 spline input/output shafts for the w/g t-case(s), do you think that would take care of any of your durability concerns?
Originally Posted by atcfixer
I'm from the mid Michigan area (Midland's general area) so if that works for you I'd be happy to sell some parts .
Awesome, im sure we can work something out once the time is ready for this test run to actually occur.
Originally Posted by atcfixer
I looked up some info on the transfer cases, and the V6 transfer case should be 2.57:1 ratio in low range. so just over 2.5 turns of the output shaft per turn of the input shaft is still quite an over drive (1.33 per turn of the input with a trans of 0.75:1 overdrive ratio). My fear would still be the transfer case being the weakest link. Might sound like a lot of effort, if you do get far enough to test drive, I'd say atleast get a way to monitor the temp of the transfer case while in overdrive. You might have to install a couple of lines in the case and add an inline pump and cooler to keep heat down enough. I'm sure there are some extreme off roaders that have done similar so there's probably a write up somewhere on it and what works.
Since I would be trading over to the w/g t-case the gearing would be dropped a little like you had said. I had planned on putting temp sensors in the t-case to monitor things while in overdrive. And if necessary an inline oil cooler is definitely an option.
Originally Posted by atcfixer
Seems like good info here, I read a couple spots but not the whole thing.
Out of curiousity, whats the difference between the w/g t-case and the one for the R150? Iv read one is top shift and one is front shift, but what does this information refer to?
Top shift is in reference to the 4x4 shift lever being located directly ontop of the gear unit of the transfer case. The forward shift is when the shift lever is bolted to the transmission housing, and has shift rods it uses to shift it. One style can be converted to the other with the correct parts, forward shift gear units will have a block off plate on top where the top shift shifters bolt on. Also the w/g style came in both options, top shift is more desirable and was more common in 4runners. All of mine came from pickups, so they are forward shift. I think the SR5 pickup had top shift.
The 21 vs 23 spline isn't were my concern is. Normally the highest stress is when the transfer case is in 1:1, and it's more or less a pass though. I can't really think of an ideal example, but turning the input shaft one and getting say 2.5 turns on the output shaft is a huge gearing increase. The teeth of the gears is where I'm concerned, and maybe the housing. I guess an example would be like having your pickup with factory 30 inch tires, and then putting on 70 inch tires and expecting the rear end to not have any problems in the long run. Even if you dual transfer cased it, that's quite extreme for the internal gears. Seems generally accepted is 35-37in is about the max you can go w\o rear diff mods, but that's more in the context of mudding.
Pretty much, if it's possible, it'd be interesting to see the outcome, but reliability I'm almost sure will be lowered quite a bit even if your not hauling loads or off roading while in the overdrive range. I don't have a whole lot of experience with how strong the transfer cases are, I do know some people put chevy v8s in front of them and they hold up well. If you have the spare time/money and you plan for the possible failure, I think it would be neat to see what you can achieve. I'd be most interested in what kind of mpg you get since there is more or less only 1 person I've seen that logged their MPG well and re-geared higher and proved it increased their MPG. This mod would probably be pushing the max mpg via gearing possible, and you would really need an instant mpg meter to see what combo gives the best mpg at different speeds.
I keep forgetting you have a 3.4L in the 4runner, so the rpm commits before would be even lower rpm for 30HP, but 1500 is quite low still for a v6. My dad did have an oldmobile v8 geared up to run around 1200rpm at 55 mph and he pulled something like 17mpg out of it. Not too bad for a 350ci (5.7L) 4x4 and a truck that weighed around 3 tons.
i still think that dual transmissions would be easier. they even have adapter plates. and itll double your 5th gear without having to rebuild a whole transfer case. but, im still going to follow this to see what you make of it.
Top shift is in reference to the 4x4 shift lever being located directly ontop of the gear unit of the transfer case. The forward shift is when the shift lever is bolted to the transmission housing, and has shift rods it uses to shift it. One style can be converted to the other with the correct parts, forward shift gear units will have a block off plate on top where the top shift shifters bolt on. Also the w/g style came in both options, top shift is more desirable and was more common in 4runners. All of mine came from pickups, so they are forward shift. I think the SR5 pickup had top shift.
Ok, this makes sense, and was what i figured. But i wanted to ask the stupid question so i knew for sure. would i then need to convert both t-cases to a top shift before i could do anything?
Originally Posted by atcfixer
The 21 vs 23 spline isn't were my concern is. Normally the highest stress is when the transfer case is in 1:1, and it's more or less a pass though. I can't really think of an ideal example, but turning the input shaft one and getting say 2.5 turns on the output shaft is a huge gearing increase. The teeth of the gears is where I'm concerned, and maybe the housing. I guess an example would be like having your pickup with factory 30 inch tires, and then putting on 70 inch tires and expecting the rear end to not have any problems in the long run. Even if you dual transfer cased it, that's quite extreme for the internal gears. Seems generally accepted is 35-37in is about the max you can go w\o rear diff mods, but that's more in the context of mudding.
Pretty much, if it's possible, it'd be interesting to see the outcome, but reliability I'm almost sure will be lowered quite a bit even if your not hauling loads or off roading while in the overdrive range. I don't have a whole lot of experience with how strong the transfer cases are, I do know some people put chevy v8s in front of them and they hold up well. If you have the spare time/money and you plan for the possible failure, I think it would be neat to see what you can achieve. I'd be most interested in what kind of mpg you get since there is more or less only 1 person I've seen that logged their MPG well and re-geared higher and proved it increased their MPG. This mod would probably be pushing the max mpg via gearing possible, and you would really need an instant mpg meter to see what combo gives the best mpg at different speeds.
I keep forgetting you have a 3.4L in the 4runner, so the rpm commits before would be even lower rpm for 30HP, but 1500 is quite low still for a v6. My dad did have an oldmobile v8 geared up to run around 1200rpm at 55 mph and he pulled something like 17mpg out of it. Not too bad for a 350ci (5.7L) 4x4 and a truck that weighed around 3 tons.
Ok, that is understandable. Im curious to see how this works out. im deffinately going to give it a try. either im going to waste a bunch of money and have dual t-cases, or itll work out. thats not bad odds.
i still think that dual transmissions would be easier. they even have adapter plates. and itll double your 5th gear without having to rebuild a whole transfer case. but, im still going to follow this to see what you make of it.
My issue with dual tranny is the amount of weight involved as well as the amount of room it takes up. It may be easier but not necessarily more efficient. Ill take all the support I can get.
You cant just swap gears on a shaft, youll have to make or have made the gear set for the tcase overdrive. This is what the low range gear set looks like not installed. The bearings come off, but thats it. Youll need to make a new "high range" gears and input gear, so you might as well have it be 23 spline.
Originally Posted by skullhead690
Based on what youve said here iv probably got the 4.10 final drive ratio. Iv got stock toyota alloy rims.
With the R150 ill have to trade my current t-case over to the W/G series t-case since (at least according to marlin crawler) there is no adapter for the R150 chain driven t-case. And I would be inclined to trust that information. In marlin's dual t-case kit they provide 23 spline input/output shafts for the w/g t-case(s), do you think that would take care of any of your durability concerns?
You just change out the whole case. Put a gear drive case in, there are adapters for that.
If your thinking about going to an r series, the r154 may work for you. It originally came behind a 3.4 has a little taller 5th gear. .753 vs the r150 .838
Last edited by rattlewagon; 02-16-2017 at 04:09 PM.
With dual transmissions, if you desired higher than the double 5th gear, you could run the 2nd transmission backwards, so 5th gear would actually under drive slightly 4th would be straight though, and 3rd and lower would be larger over drives. This setup I could see holding up much better than the transfer case as long as you're not running the 2nd trans in 1st or 2nd gear.
Benefit of having both in the normal direction is both transmissions in 1st gear is a nice slow creeper gear something like 16:1 w\o counting low range. If I ever wanted to go beyond the normal 5th gear ratio and maintain the "normal" gearing for the lower gears, the 2nd trans setup would probably be the best setup reliability wise. A transmission isn't that heavy in respect to total vehicle weight, just an extra rider with you is about the same weight depending on the person's size. Several people run around with tools in their truck, and tools add up in weight pretty quick big time when you introduce tool boxes and such.
I haven't looked up the difference, but Tacoma vs T100 is quite a weight difference I'm sure, yet the EPA MPG rating is only 1mpg off if memory serves me right.
EDIT:
Everyone posting at once lol. Pretty sure the R154 is a supra transmission. My Tacoma came with an R150, and my T100 came with one as well (96 and 98). I also have 89 and a 90 pickup with the 3.0L that came with the same transmission code, R150. The input shaft and bell housing is different, but as long as the correct bell housing is used, it can be bolted to either the 3.0L or 3.4L.
The gear set swap kind of sinks it isn't swapable. The other pics looked like the gears went on similar to how the internal transmission gears are setup. Might be a bit more work, but that might be another way to get the OP's idea in place. Again I haven't worked with the internals on the transmissions, but maybe the gear set for 3rd gear could be put in where 5th gear goes, and put the gears where it will reverse the normal 3rd gear ratio for an extra extra overdrive 5th.
You cant just swap gears on a shaft, youll have to make or have made the gear set for the tcase overdrive. This is what the low range gear set looks like not installed. The bearings come off, but thats it. Youll need to make a new "high range" gears and input gear, so you might as well have it be 23 spline.
And thats something i was afraid of, based on that info i would be inclined to believe that dual transmission may be an easier route. I appreciate backing up what youve said with visual reference. Deffinately much easier to understand than just its impossible.
ill do some research into dual transmission to see what to do next. but im still going to try and exhaust the dual t-case overdrive just to see if its possible. thanks guys!
Just hear me out, what if you put stock duals in your truck to retain off road driveability, then just put larger tires on your otherwise stock drive train. Haha.
Last edited by rattlewagon; 02-16-2017 at 04:44 PM.
02-13-2017, 09:19 AM
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