I used the R452 syncro gear as the R151 was just different enough that it would not work.This is why I say you need ALL the gears and springs that touch the 5th counter gear.
R151F input shaft lengths, & 5th gear versions compatibility for R452 OD swap? (1 Viewer)
- Thread starter Chuck78
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- Thread starter
- #42
Well I'm just now getting around to ordering these parts finally, as well as some new parts to refurbish this R151F trans and HF1B(BF1B?) transfer case out of an '09 HZJ79 Canadian mining truck part-out. I tried to go back to my shopping cart from Amayama, who had better prices on A LOT of these parts, but then I noticed that the half of my cart that was in stock in Australia, said that it cannot ship from there to my location, and would not allow me to complete my order! I could have sworn it was going to allow me to ship them to the USA previously from Australia.
I shopped around partsouq, jp-carparts.com, etc and MegaZip.net was the only one who showed everything even listed in their system, let alone all available and in stock in some of their warehouses...
So I ended up using a 10% discount code from MegaZip.net which is valid for 10% off shipping as well,so I have two orders coming from them airmail in 3-6 days, from the United Arab Emirates Toyota warehouse, as well as a Japan Toyota warehouse.
I may hold off on full tear-down of this trans until I save up some cash (eBay spare parts sales!) to buy the Marlin Crawler billet anodized 7075 shift forks, cromoly thrust washer upgrade, & hardened steel bearing retainer plate upgrades. The gears are turning on this project however, but I also need Toyota (22RTE) flywheel and clutch, sell a 22RTE/R151F turbo bellhousing and buy a 5VZFE-R150 V6 bellhousing, and an expensive VW TDI to Toyota adapter plate kit...
I shopped around partsouq, jp-carparts.com, etc and MegaZip.net was the only one who showed everything even listed in their system, let alone all available and in stock in some of their warehouses...
So I ended up using a 10% discount code from MegaZip.net which is valid for 10% off shipping as well,so I have two orders coming from them airmail in 3-6 days, from the United Arab Emirates Toyota warehouse, as well as a Japan Toyota warehouse.
I may hold off on full tear-down of this trans until I save up some cash (eBay spare parts sales!) to buy the Marlin Crawler billet anodized 7075 shift forks, cromoly thrust washer upgrade, & hardened steel bearing retainer plate upgrades. The gears are turning on this project however, but I also need Toyota (22RTE) flywheel and clutch, sell a 22RTE/R151F turbo bellhousing and buy a 5VZFE-R150 V6 bellhousing, and an expensive VW TDI to Toyota adapter plate kit...
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Awesome! I'm nearing the end of a long saga with my transmission, will have to post up details here once I've finished. If you're going with a 5VZ bellhousing wouldn't you be better off to use a 5VZ flywheel and clutch also? Not sure what the differences in length, throwout bearing and starter teeth/diameter are, but it might not be compatible. BTW, I have a spare 5VZ bellhousing, not sure what shipping to Ohio would be like though.
- Thread starter
- #44
Did you get these parts but had difficulties along the way? Was yours pre-'95?
I believe the adapter plate kit to run a VW TDI engine that I'll be getting specifies to use a 22RTE Turbo pickup flywheel, FYI.
I'd be interested in that 5VZ V6 bellhousing of yours.
Where are located?
My transmission was a pre '95, and I have since rebuilt pretty much the entire thing with post '95 parts, including a new HZJ79 transfer adapter. I'm still waiting on a couple of parts that weren't anticipated, but should be able to put it together within a week or two.
Odd that a R150/5VZ to ALH adapter would use a 22RTE flywheel. I'll grab some photos of the bellhousing tomorrow. I'm located in NW Montana.
Odd that a R150/5VZ to ALH adapter would use a 22RTE flywheel. I'll grab some photos of the bellhousing tomorrow. I'm located in NW Montana.
- Thread starter
- #46
If you still are willing to sell that R150/5VZ bellhousing, I'm definitely interested. I'd also want to buy that 1986-1995 6.5" input shaft if the gear helix angles and size will mate fine with the newer gears. That would give me extra insurance that if I ever broke anything or needed a different configuration that was 1" shorter or a slightly smaller bellhousing, that I could run a 3VZ or 22RTE bellhousing.
And yes, the adapter kits I am looking at specify to use the 22RTEC flywheel. They have crankshaft adapters that the flywheel mounts to, so it likely has to do with the bolt patterns being compatible, or rather missing each other, between the VW and the 22R crank bolt patterns. Perhaps the 6cyl flywheel bolt patterns interfere with the VW IDI/TDI 4cyl crank bolt pattern.
Also FYI I have half of my parts in hand now! The Japanese MegaZip warehouse took forever picking and shipping the order, but it arrived very rapidly after that (just a few days). The other half coming from the Toyota warehouse in the United Arab Emirates was picked and shipped right away, but wow... it takes forever to get things out of the middle east, and through customs!!!!!! Geesh.
I'm now trying to ebay some things to justify the expense of the Marlin Crawler billet shift forks and hardened steel bearing retainer plate, and the cromoly steel thrust washer upgrade...
Thanks for all the support everyone,
Chuck
And yes, the adapter kits I am looking at specify to use the 22RTEC flywheel. They have crankshaft adapters that the flywheel mounts to, so it likely has to do with the bolt patterns being compatible, or rather missing each other, between the VW and the 22R crank bolt patterns. Perhaps the 6cyl flywheel bolt patterns interfere with the VW IDI/TDI 4cyl crank bolt pattern.
Also FYI I have half of my parts in hand now! The Japanese MegaZip warehouse took forever picking and shipping the order, but it arrived very rapidly after that (just a few days). The other half coming from the Toyota warehouse in the United Arab Emirates was picked and shipped right away, but wow... it takes forever to get things out of the middle east, and through customs!!!!!! Geesh.
I'm now trying to ebay some things to justify the expense of the Marlin Crawler billet shift forks and hardened steel bearing retainer plate, and the cromoly steel thrust washer upgrade...
Thanks for all the support everyone,
Chuck
- Thread starter
- #47
So...I just noticed when shopping for transfer case gears, that Terrain Tamer list a 5th gear ratio change kit for the HZJ78 etc Land Cruiser (R151F trans)!
Not quite as high ratio as the .695:1 R452 gears ratio achieved when installing those gears into an R150/R151, but pretty close!
Has anyone heard of these or had any experience with them?
They also offer parts for the R151 that are upgrades such as fully splined shafts etc. Sounds like the mods that 360GearboxesAndDiffs does to their trannies, yet will not sell just the upgrade parts separately.
https://www.terraintamer.com/en/4wd-products/transmisson-driveline-cat
Not quite as high ratio as the .695:1 R452 gears ratio achieved when installing those gears into an R150/R151, but pretty close!
| Landcruiser | HZJ79 | 8/1999- | 1HZ Diesel | 33428-HZJMOD | Gear Set 5th Modified | Ratio .711 from .838 |
Has anyone heard of these or had any experience with them?
They also offer parts for the R151 that are upgrades such as fully splined shafts etc. Sounds like the mods that 360GearboxesAndDiffs does to their trannies, yet will not sell just the upgrade parts separately.
Landcruiser | HZJ71 | 8/1999- | 1HZ Diesel | 33336-35100M | Gear Mainshaft 5th | R150F/R151F Transmission Modified Fully Splined |
https://www.terraintamer.com/en/4wd-products/transmisson-driveline-cat
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- Thread starter
- #48
So...I just noticed when shopping for transfer case gears, that Terrain Tamer list a 5th gear ratio change kit for the HZJ78 etc Land Cruiser (R151F trans)!
Not quite as high ratio as the .695:1 R452 gears ratio achieved when installing those gears into an R150/R151, but pretty close!
Landcruiser HZJ79 8/1999- 1HZ Diesel 33428-HZJMOD Gear Set 5th Modified Ratio .711 from .838
Has anyone heard of these or had any experience with them?
They also offer parts for the R151 that are upgrades such as fully splined shafts etc. Sounds like the mods that 360GearboxesAndDiffs does to their trannies, yet will not sell just the upgrade parts separately.
Transmission & Driveline Catalogues
Australia's largest range of 4wd 4x4 four wheel drive aftermarket replacement parts and accessories stores in Melbourne Sydney Brisbane Perth Adelaide Darwin Alice Springs Auckland New Zealand Fiji Recovery Gear Suspension Electric Winches and hard partswww.terraintamer.com
Link for currently available Terrain Tamer overdrive gear set:
https://online.terraintamer.com/33428-HZJMOD/#product-tab-description
,
Any updates on the trans rebuild? Also, whats the advantage of the fully splined main shaft?
- Thread starter
- #50
So I've picked up over half of the parts of an R151F 86-87 22RTEC trans, missing rear housing transfer adapter and many small parts (I got all the gears and main case, all for the average cost of just the 22RTEC R151F bellhousing), and am keeping my eyes out for a deal on an 88-95 R150F transmission (even with broken gears) to swap these gears into.
This is in addition to my land cruiser R151F version with the passenger drop rear transfer case which is slated to go into my Suzuki Samurai LWB project VW 2.0mTDI swap project. I'm looking at importing a complete left hand drive Samurai LWB currently, as opposed to spending $1700 on OEM body panels and 2x4 steel tubing to stretch the body and frame on my SWB US-market '88 Samurai... The spare trans could possibly be slated for chopping my existing rusty Samurai body into a removeable hardtop pickup cab + a Suzuki Carry or Mitsubishi Sambar 3-tailgate style "ute tray" utility pickup bed cut down to 64".
It appears that one of the two gears required to do the R456 overdrive swap on the early style R-series trannies is definitely never coming back in stock again unless Terrain Tamer happens to manufacture their overdrive upgrade kit for the early versions (unlikely) in addition to the kit they make for the 1996+ transmissions, so it looks as if the only thing available for the 1985-1995 R150/R151 trannies to upgrade 5th gear from the stock 0.838:1 is the 0.790:1 AX15 5th gears and a little machine work. Either machining up a spacer, or having the stub extension one side of the smaller gear hot wired and surface ground off...
0.838:1 vs 0.790:1 is about a 150RPM difference as calculated with 31 inch tires and a 4.10 differential ratio. Not as drastic as the R452, but might as well do this mod if you are tearing apart the trans anyway.
Read up on this mod a bit, but the info is a bit harder to dig up. The one guy who had a nice write up on it, I cannot locate the link to at the moment, but he was talking about machining up a spacer, and also about the cluster ratios and why the R154 5th gear does not work out for a good ratio due to the R150 or R151 cluster ratios. Cluster ratio = input shaft gear tooth count vs the 1st gear on the main one-piece cluster shaft with all the gears on it. The differences in each gear (aside from 1:1 4th gear) all must be multiplied by the input gear cluster ratio to get the actual transmission final output gear ratio.
Here is what I found from a quick search. I am not sure this will work on all of our R-series trannies, please research before buying:
Cobra part # 462585
Cobra part # 462585K
More info on the AX-15 5th gear swap in Posts 15, 17, 21, 29,31:
Note the mention of different inside diameters between the one AX15 gear vs the later R150. Do your homework here, as not all years swap, but it looks like the 85/86-95 R150/R151 transmissions "probably" all can fit the AX15 5th gears with mods. Either having the one AX15 gear cut down via EDM + finishing on a surface grinder, or else machining a spacer to adapt it as one person mentioned in that link.
So far I believe I have read two counts each of people installing the AX15 gears in the earlier transmission by cutting and grinding or just grinding down one of the two AX-15 gears to remove the integral hub on one of two sides, and two as well who have machined some sort of spacers to make them fit.
I'm having a little trouble understanding how adding a spacer to a gear that is already too wide will make it fit as an assembly, but these 2 people have reported they have ran it this way and it works.
EDIT - I believe the spacer machining method works because there already appears to be a spacer on the this 85-88 R151F transmission which has been fit with the AX15 5th gear in this photo, and so I'm assuming that you either simply chuck up the spacer in a lathe and cut a step on the ID on the front end of it to slip over the AX-15 gear's shoulder, or else just shorten up the spacer in the lathe to compensate for the additional should on the AX15 gear vs the R150 only having the shoulder on the front side of the gear and not on the rear.
I did some numbers crunching for RPM savings.
Compared to the stock R150/R151F 5th gear ratio of 0.838:1, dropping down to a 0.790:1 5th will save you 151 RPM @ 70mph on 4.10 gears and 30.8" ("31-inch") tires with a 1:1 high range transfer case gearing.
The taller the tires or the taller the diff gears, the less RPM savings you'll have, but for a heavier rig, this puts you out of the range of efficiency of smaller turbodiesels with a single turbo, such as 1.9TDI VW swaps in front of Toyota trannies. But even on 35's with a 4.10 gear (say you're running a 1HZ or 1KD, or OM606 or OM617 swap, or a lighter 1.9TDI swapped rig such as a Samurai or CJ3 CJ5 CJ7 etc), 35-inch tires and a 4.10 will still yield you a 70mph RPM reduction of 134rpm - 2,195rpm @ 70mph. Not quite the savings of running one of the several generations of the 1996+ R452 gears in one of the several revision versions of the 1996+ R150 and R151F transmissions, which would allow you the same highway RPM but a much deeper 1st gear and low range via a deeper differential gearing, but if you have the 85-95 R-series transmissions, this is a great option if you already have the transmission apart for servicing or upgrades to Marlin Crawler parts...
This is in addition to my land cruiser R151F version with the passenger drop rear transfer case which is slated to go into my Suzuki Samurai LWB project VW 2.0mTDI swap project. I'm looking at importing a complete left hand drive Samurai LWB currently, as opposed to spending $1700 on OEM body panels and 2x4 steel tubing to stretch the body and frame on my SWB US-market '88 Samurai... The spare trans could possibly be slated for chopping my existing rusty Samurai body into a removeable hardtop pickup cab + a Suzuki Carry or Mitsubishi Sambar 3-tailgate style "ute tray" utility pickup bed cut down to 64".
It appears that one of the two gears required to do the R456 overdrive swap on the early style R-series trannies is definitely never coming back in stock again unless Terrain Tamer happens to manufacture their overdrive upgrade kit for the early versions (unlikely) in addition to the kit they make for the 1996+ transmissions, so it looks as if the only thing available for the 1985-1995 R150/R151 trannies to upgrade 5th gear from the stock 0.838:1 is the 0.790:1 AX15 5th gears and a little machine work. Either machining up a spacer, or having the stub extension one side of the smaller gear hot wired and surface ground off...
0.838:1 vs 0.790:1 is about a 150RPM difference as calculated with 31 inch tires and a 4.10 differential ratio. Not as drastic as the R452, but might as well do this mod if you are tearing apart the trans anyway.
Read up on this mod a bit, but the info is a bit harder to dig up. The one guy who had a nice write up on it, I cannot locate the link to at the moment, but he was talking about machining up a spacer, and also about the cluster ratios and why the R154 5th gear does not work out for a good ratio due to the R150 or R151 cluster ratios. Cluster ratio = input shaft gear tooth count vs the 1st gear on the main one-piece cluster shaft with all the gears on it. The differences in each gear (aside from 1:1 4th gear) all must be multiplied by the input gear cluster ratio to get the actual transmission final output gear ratio.
Here is what I found from a quick search. I am not sure this will work on all of our R-series trannies, please research before buying:
Cobra part # 462585
Cobra part # 462585K
More info on the AX-15 5th gear swap in Posts 15, 17, 21, 29,31:
Note the mention of different inside diameters between the one AX15 gear vs the later R150. Do your homework here, as not all years swap, but it looks like the 85/86-95 R150/R151 transmissions "probably" all can fit the AX15 5th gears with mods. Either having the one AX15 gear cut down via EDM + finishing on a surface grinder, or else machining a spacer to adapt it as one person mentioned in that link.
So far I believe I have read two counts each of people installing the AX15 gears in the earlier transmission by cutting and grinding or just grinding down one of the two AX-15 gears to remove the integral hub on one of two sides, and two as well who have machined some sort of spacers to make them fit.
I'm having a little trouble understanding how adding a spacer to a gear that is already too wide will make it fit as an assembly, but these 2 people have reported they have ran it this way and it works.
EDIT - I believe the spacer machining method works because there already appears to be a spacer on the this 85-88 R151F transmission which has been fit with the AX15 5th gear in this photo, and so I'm assuming that you either simply chuck up the spacer in a lathe and cut a step on the ID on the front end of it to slip over the AX-15 gear's shoulder, or else just shorten up the spacer in the lathe to compensate for the additional should on the AX15 gear vs the R150 only having the shoulder on the front side of the gear and not on the rear.
I did some numbers crunching for RPM savings.
Compared to the stock R150/R151F 5th gear ratio of 0.838:1, dropping down to a 0.790:1 5th will save you 151 RPM @ 70mph on 4.10 gears and 30.8" ("31-inch") tires with a 1:1 high range transfer case gearing.
The taller the tires or the taller the diff gears, the less RPM savings you'll have, but for a heavier rig, this puts you out of the range of efficiency of smaller turbodiesels with a single turbo, such as 1.9TDI VW swaps in front of Toyota trannies. But even on 35's with a 4.10 gear (say you're running a 1HZ or 1KD, or OM606 or OM617 swap, or a lighter 1.9TDI swapped rig such as a Samurai or CJ3 CJ5 CJ7 etc), 35-inch tires and a 4.10 will still yield you a 70mph RPM reduction of 134rpm - 2,195rpm @ 70mph. Not quite the savings of running one of the several generations of the 1996+ R452 gears in one of the several revision versions of the 1996+ R150 and R151F transmissions, which would allow you the same highway RPM but a much deeper 1st gear and low range via a deeper differential gearing, but if you have the 85-95 R-series transmissions, this is a great option if you already have the transmission apart for servicing or upgrades to Marlin Crawler parts...
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- Thread starter
- #51
The Marlin Crawler mod using all R452 gears gives you the deeper 1st 2nd & 3rd, but nearly identical overdrive 5th. And of course as with any five-speed transmission, the same 1:1 4th.
The R452 5th gear mod (and Terrain Tamer mod), gives you the same R150 or R151 1st-4th ratios you already have,but lowers your highway cruising RPM significantly, from a 0.838:1 down to a 0.696:1.
The 85-95 R150/151 AX-15 5th gear swap gives you a 0.789:1 5th gear overdrive ratio vs 0.838:1 stock
Some technical information:
R452:
5.147 2.74 1.93 1.00 0.8305 5.04
R151F:
4.315 2.330 1.436 1.00 0.838 4.22
R150:
3.83 2.062 1.436 1.00 0.838 4.22
AX-15:
3.83 2.330 1.436 1.00 0.790 4.22
*R150:
1st gears = 31/12 (input/countershaft)
5th gears = 26/46 (input/countershaft)
cluster ratio = 1.48276
input/countershaft cluster gear = 29/43
*R151F
1st gears = 32/11
5th gears = 26/46
cluster ratio = 1.48276
input/countershaft cluster gear = 29/43
*R452:
1st gears = 32/11
5th gears = 23/49
cluster ratio = 1.76923
input/countershaft cluster gear = 26/46
*AX-15:
1st gears = 31/12
5th gears = 25/47
cluster ratio = 1.48276
input/countershaft cluster gear = 29/43
R150/151 with R452 5th gears = 0.696:1 overdrive
R150/151 ('85-'95) w/AX15 5th gears = 0.7887:1 od
Custom batch of gears being made by Spanish Land Cruiser owners via '90 Land Cruiser Prado guy mentioned on the previous page:
24/47 - 0.7572:1 5th overdrive
The R452 5th gear mod (and Terrain Tamer mod), gives you the same R150 or R151 1st-4th ratios you already have,but lowers your highway cruising RPM significantly, from a 0.838:1 down to a 0.696:1.
The 85-95 R150/151 AX-15 5th gear swap gives you a 0.789:1 5th gear overdrive ratio vs 0.838:1 stock
Some technical information:
R452:
5.147 2.74 1.93 1.00 0.8305 5.04
R151F:
4.315 2.330 1.436 1.00 0.838 4.22
R150:
3.83 2.062 1.436 1.00 0.838 4.22
AX-15:
3.83 2.330 1.436 1.00 0.790 4.22
*R150:
1st gears = 31/12 (input/countershaft)
5th gears = 26/46 (input/countershaft)
cluster ratio = 1.48276
input/countershaft cluster gear = 29/43
*R151F
1st gears = 32/11
5th gears = 26/46
cluster ratio = 1.48276
input/countershaft cluster gear = 29/43
*R452:
1st gears = 32/11
5th gears = 23/49
cluster ratio = 1.76923
input/countershaft cluster gear = 26/46
*AX-15:
1st gears = 31/12
5th gears = 25/47
cluster ratio = 1.48276
input/countershaft cluster gear = 29/43
R150/151 with R452 5th gears = 0.696:1 overdrive
R150/151 ('85-'95) w/AX15 5th gears = 0.7887:1 od
Custom batch of gears being made by Spanish Land Cruiser owners via '90 Land Cruiser Prado guy mentioned on the previous page:
24/47 - 0.7572:1 5th overdrive
Good info Chuck
i am still waiting to test mine out, engine swap is not progressing at a speed I’d like.
i am still waiting to test mine out, engine swap is not progressing at a speed I’d like.
So I've picked up over half of the parts of an R151F 86-87 22RTEC trans, missing rear housing transfer adapter and many small parts (I got all the gears and main case, all for the average cost of just the 22RTEC R151F bellhousing), and am keeping my eyes out for a deal on an 88-95 R150F transmission (even with broken gears) to swap these gears into.
This is in addition to my land cruiser R151F version with the passenger drop rear transfer case which is slated to go into my Suzuki Samurai LWB project VW 2.0mTDI swap project. I'm looking at importing a complete left hand drive Samurai LWB currently, as opposed to spending $1700 on OEM body panels and 2x4 steel tubing to stretch the body and frame on my SWB US-market '88 Samurai... The spare trans could possibly be slated for chopping my existing rusty Samurai body into a removeable hardtop pickup cab + a Suzuki Carry or Mitsubishi Sambar 3-tailgate style "ute tray" utility pickup bed cut down to 64".
It appears that one of the two gears required to do the R456 overdrive swap on the early style R-series trannies is definitely never coming back in stock again unless Terrain Tamer happens to manufacture their overdrive upgrade kit for the early versions (unlikely) in addition to the kit they make for the 1996+ transmissions, so it looks as if the only thing available for the 1985-1995 R150/R151 trannies to upgrade 5th gear from the stock 0.838:1 is the 0.790:1 AX15 5th gears and a little machine work. Either machining up a spacer, or having the stub extension one side of the smaller gear hot wired and surface ground off...
0.838:1 vs 0.790:1 is about a 150RPM difference as calculated with 31 inch tires and a 4.10 differential ratio. Not as drastic as the R452, but might as well do this mod if you are tearing apart the trans anyway.
Read up on this mod a bit, but the info is a bit harder to dig up. The one guy who had a nice write up on it, I cannot locate the link to at the moment, but he was talking about machining up a spacer, and also about the cluster ratios and why the R154 5th gear does not work out for a good ratio due to the R150 or R151 cluster ratios. Cluster ratio = input shaft gear tooth count vs the 1st gear on the main one-piece cluster shaft with all the gears on it. The differences in each gear (aside from 1:1 4th gear) all must be multiplied by the input gear cluster ratio to get the actual transmission final output gear ratio.
Here is what I found from a quick search. I am not sure this will work on all of our R-series trannies, please research before buying:
Cobra part # 462585
Cobra part # 462585K
More info on the AX-15 5th gear swap in Posts 15, 17, 21, 29,31:
Note the mention of different inside diameters between the one AX15 gear vs the later R150. Do your homework here, as not all years swap, but it looks like the 85/86-95 R150/R151 transmissions "probably" all can fit the AX15 5th gears with mods. Either having the one AX15 gear cut down via EDM + finishing on a surface grinder, or else machining a spacer to adapt it as one person mentioned in that link.
So far I believe I have read two counts each of people installing the AX15 gears in the earlier transmission by cutting and grinding or just grinding down one of the two AX-15 gears to remove the integral hub on one of two sides, and two as well who have machined some sort of spacers to make them fit.
I'm having a little trouble understanding how adding a spacer to a gear that is already too wide will make it fit as an assembly, but these 2 people have reported they have ran it this way and it works.
EDIT - I believe the spacer machining method works because there already appears to be a spacer on the this 85-88 R151F transmission which has been fit with the AX15 5th gear in this photo, and so I'm assuming that you either simply chuck up the spacer in a lathe and cut a step on the ID on the front end of it to slip over the AX-15 gear's shoulder, or else just shorten up the spacer in the lathe to compensate for the additional should on the AX15 gear vs the R150 only having the shoulder on the front side of the gear and not on the rear.
I did some numbers crunching for RPM savings.
Compared to the stock R150/R151F 5th gear ratio of 0.838:1, dropping down to a 0.790:1 5th will save you 151 RPM @ 70mph on 4.10 gears and 30.8" ("31-inch") tires with a 1:1 high range transfer case gearing.
The taller the tires or the taller the diff gears, the less RPM savings you'll have, but for a heavier rig, this puts you out of the range of efficiency of smaller turbodiesels with a single turbo, such as 1.9TDI VW swaps in front of Toyota trannies. But even on 35's with a 4.10 gear (say you're running a 1HZ or 1KD, or OM606 or OM617 swap, or a lighter 1.9TDI swapped rig such as a Samurai or CJ3 CJ5 CJ7 etc), 35-inch tires and a 4.10 will still yield you a 70mph RPM reduction of 134rpm - 2,195rpm @ 70mph. Not quite the savings of running one of the several generations of the 1996+ R452 gears in one of the several revision versions of the 1996+ R150 and R151F transmissions, which would allow you the same highway RPM but a much deeper 1st gear and low range via a deeper differential gearing, but if you have the 85-95 R-series transmissions, this is a great option if you already have the transmission apart for servicing or upgrades to Marlin Crawler parts...
Those posts and photos from Yotatech are mine, I had also replied to this thread (my post is 1st one on 2nd page). My gearbox has been running for over a year now so can confirm mod works with no issues.
I've got 4 months and 5000+ km on my R452 gear swap, and so far its great. The jump between 4th and 5th gear is pretty big, I think I drop nearly 900rpm so I really have to wind it out in 4th to keep the engine in its power band. A slightly lower 5th ratio would be nice, but I do like the cruising rpm this swap gets me. I can do 110km/h at ~2500 rpm and 120km/h at ~2700 rpm with 4.88 diffs and 235/85R16 tires. This still leaves me with good low range using the factory Toyota gearing in the split case; even in a 4600lb Cruiser I can idle steep rocky hills in 1st or 2nd.
Because of the unavailability of the pre-95 gears, I can't recommend anyone doing this swap unless they have a '96+ transmission and associated transfer adapter. The cost of parts to convert the older transmission just isn't worth it in my opinion. That said, especially in lighter applications like Suzuki TDI swaps or Pickup/4Runner TDI swaps I think this is an excellent mod to do.
Because of the unavailability of the pre-95 gears, I can't recommend anyone doing this swap unless they have a '96+ transmission and associated transfer adapter. The cost of parts to convert the older transmission just isn't worth it in my opinion. That said, especially in lighter applications like Suzuki TDI swaps or Pickup/4Runner TDI swaps I think this is an excellent mod to do.
