TurboedMJ Posted February 16 Share Posted February 16 I've been looking around the interwebs trying to find upgraded AX15s and/or good ways to make the transmission stronger. During my search, I found this: https://speedtekautoracing.com/products/jeep-ax-5-close-ratio-uprated-1000nm-transmission-gearset could anyone speak to the reliability of this website? I also discovered nitride treatment, which is basically heat treating everything and hope it holds (according to my calculations, max input should be around 4-500 hp). The reason I'm looking for upgrades is because I want to retain 4wd for traction during launch and I am not looking to run a divorced tcase. I also want a 5 SPD. I'm planning on building a high power 4.0 (north of 400hp NA, with a turbo coming later) and need something to put behind it. Link to comment Share on other sites More sharing options...
TurboedMJ Posted February 16 Author Share Posted February 16 After some research on this company Speedtek, it appears that they aren't the best to deal with, but the question remains. What's breaks first on this transmission? Link to comment Share on other sites More sharing options...
89 MJ Posted February 17 Share Posted February 17 @Pete M, should this be in tech to get more eyes on it? @ghetdjc320 might know something. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted February 17 Share Posted February 17 On 2/16/2024 at 11:46 AM, TurboedMJ said: After some research on this company Speedtek, it appears that they aren't the best to deal with, but the question remains. What's breaks first on this transmission? From my research and some first hand experience: The stock gearset is plenty strong. If you need more torque handling the 2 main upgrades are the thrust washer and bearing retainer plate. 500ish HP an TQ have been run fairly reliably with those mods. If you need to speed shift and are mashing gears, then some upgraded shift forks are in order. There was a revision to the 5th gear synchro hub in later years. Main shafts have been broken occasionally and cryo treating may help but only under severe and repeated abuse. Keep in mind that most of the “upgrades” are made for the Toyota R series and are compatible with the AX15. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted February 17 Share Posted February 17 https://www.marlincrawler.com/product/chromoly-r-series-thrust-washer-kit/ https://www.marlincrawler.com/product/r-series-heavy-duty-bearing-retainer/ Link to comment Share on other sites More sharing options...
pizzaman09 Posted February 18 Share Posted February 18 Should all be possible, the Toyota R series transmissions were used in the Supra Turbo, and there are lots of people clearing 1000hp with those. I am not quite sure where to point you with that tidbit of info, but undoubtedly there are people applying parts to build up those transmissions which should translate to the AX-15. Link to comment Share on other sites More sharing options...
TurboedMJ Posted February 18 Author Share Posted February 18 Thanks all. I will do some research and follow up Link to comment Share on other sites More sharing options...
ghetdjc320 Posted February 18 Share Posted February 18 8 hours ago, pizzaman09 said: Should all be possible, the Toyota R series transmissions were used in the Supra Turbo, and there are lots of people clearing 1000hp with those. I am not quite sure where to point you with that tidbit of info, but undoubtedly there are people applying parts to build up those transmissions which should translate to the AX-15. The R154 was in Supra's for certain years in the usdm. Many more years in the JDM. The AX15 will not hold that much torque though with spirited driving. There are many factors here like vehicle weight, axle ratio, and driving style. The NV3550 that later replaced the AX15 for a time was rated at 300lbft of torque with a gross vehicle weight of just over 7k pounds. The AX15 was not officially rated on torque but new units have been advertised as capable of 385lbft with no listed GVW. That torque number likely holds true for all the AX15 years. There are new AX15s available from a few different suppliers. Advance adapters and Novak both offer to drill the tail housing to clock the tcase down a bit for XJ/MJ applications. Rockland standard gear also offers the “terminator” ax15, but it’s just a regular new ax15. All these companies advertise there units have the “latest revisions”. In my research, this has just been the 5th gear update which updates the synchro hub. That is not a strength upgrade just a functional upgrade. Marlin crawler will do a quality rebuild with all the upgraded parts for around 1900. My concern with rebuilds has always been the quality of the bearings and synchros used in these kits. Lots of low quality hardware in the off the shelf kits. You can source some quality bearings separately though. I had an ax15 rebuilt (not by Marlin) with a crown kit. Lasted all of maybe 12 months with many issues behind a jeep stroker in a YJ. Second unit was just a used ax15 with 140k miles and it worked flawlessly. So i’d trust oem components more than any of those kits. My current AX15 was original to my 90 MJ. I rebuilt the shifter, installed the newer style input shaft bearing plate for the external slave setup, and replaced the tail seal. Flushed with redline mt90 and refilled. That’s what’s in my LS swapped MJ now. I’m really not concerned about it holding up. If it does die at some point, I’ll rebuilt it with quality Japan made bearings and seals (since it’s a Japanese tranny) and add some upgraded parts from Marlin for the R151. Link to comment Share on other sites More sharing options...
89 MJ Posted February 19 Share Posted February 19 8 hours ago, pizzaman09 said: Should all be possible, the Toyota R series transmissions were used in the Supra Turbo, and there are lots of people clearing 1000hp with those. I am not quite sure where to point you with that tidbit of info, but undoubtedly there are people applying parts to build up those transmissions which should translate to the AX-15. I agree with this, but I just wanted to throw out some food for thought. I know lots of Supras are drag raced, but I have no clue how many have the manual in them. How many of these 1000hp Supras have the traction to break parts though? If you can't put the power down, you're not going to be as hard on parts. I'd bet a Jeep doing 4 wheel drive launches or aggressive offroading would cause more damage. This is all purely guessing and food for thought. Link to comment Share on other sites More sharing options...
TurboedMJ Posted February 19 Author Share Posted February 19 I'm going to call Marlin Crawler and Novak tomorrow and ask about tailhousings and input shafts. Should be able to get some conclusive info. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted February 19 Share Posted February 19 15 minutes ago, TurboedMJ said: I'm going to call Marlin Crawler and Novak tomorrow and ask about tailhousings and input shafts. Should be able to get some conclusive info. What questions do you have? There is a huge knowledge base of people here who aren’t trying to sell you anything Link to comment Share on other sites More sharing options...
TurboedMJ Posted February 19 Author Share Posted February 19 16 hours ago, ghetdjc320 said: What questions do you have? There is a huge knowledge base of people here who aren’t trying to sell you anything Haha. Just want to confirm some things. Basically an AX15 tailhousing and bellhousing can bolt on to any r series trans from Toyota? 150, 151, 154? And the Toyota input shaft will need changed to a jeep input shaft, correct? Lastly, what are the differences between the 150 and 151? Link to comment Share on other sites More sharing options...
ghetdjc320 Posted February 19 Share Posted February 19 15 minutes ago, TurboedMJ said: Haha. Just want to confirm some things. Basically an AX15 tailhousing and bellhousing can bolt on to any r series trans from Toyota? 150, 151, 154? And the Toyota input shaft will need changed to a jeep input shaft, correct? Lastly, what are the differences between the 150 and 151? Yeah Marlin can probably answer that as it’s more of a Toyota tech question. The AX15 is basically an R151 and similar to the rest of the R series but not identical. Out of curiosity, why would you want to put an ax15 bellhousing on an r series tranny? Link to comment Share on other sites More sharing options...
TurboedMJ Posted February 19 Author Share Posted February 19 26 minutes ago, ghetdjc320 said: Yeah Marlin can probably answer that as it’s more of a Toyota tech question. The AX15 is basically an R151 and similar to the rest of the R series but not identical. Out of curiosity, why would you want to put an ax15 bellhousing on an r series tranny? Sorry, should have clarified. I want to put a 4.0l bellhousing on an r series tranny. But if Marlin can rebuild my AX15 and have it hold a decent amount of power than I will just go that route. Link to comment Share on other sites More sharing options...
ghetdjc320 Posted February 19 Share Posted February 19 1 hour ago, TurboedMJ said: Sorry, should have clarified. I want to put a 4.0l bellhousing on an r series tranny. But if Marlin can rebuild my AX15 and have it hold a decent amount of power than I will just go that route. Gotcha, there is no rated torque handling differences between the R151 and AX15. The R154 I suspect is the same in regards to torque handling but on a lightweight Supra making power at higher RPM’s it’s likely adequate. Link to comment Share on other sites More sharing options...
coheed Posted February 21 Share Posted February 21 On 2/19/2024 at 1:18 PM, TurboedMJ said: Sorry, should have clarified. I want to put a 4.0l bellhousing on an r series tranny. But if Marlin can rebuild my AX15 and have it hold a decent amount of power than I will just go that route. I've been following a guy on Instagram who's swapping a 3UZ into his 3rd gen 4runner using a R150 and 35's. If the older 150 can handle the 3UZ's stock 330 ft/lbs while turning 35s I think you're on the right track. Link to comment Share on other sites More sharing options...
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