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Discussion Starter · #1 ·
Some of you guys have probably read the T-56 thread and what I've been posting in there. Since I'm not talking about the T-56 anymore I thought I should create a new thread and stop cluttering up that one.

It was mentioned that Jerry knew how to make the AR5 into a 6 speed and this for obvious reasons peaked my interests quite a bit. I was really hoping for a double OD running 5.38 axles and 285 tires giving me a deep first gear and decent cruising RPMs. Unfortunately I haven't been able to find that at all. I spoke to Jerry and he did state that it's possible to convert the AR5 into a 6 speed but he didn't remember which transmission would be our "donor". All he remembered was that it was out of a Toyota sports car.

Toyota has only produced two 6 speed sports cars: the Mk4 Supra and the 2000+ Lexus IS300. The Mk4 Supra uses a Getrag transmission so it doesn't help us and the IS300 is impossible to find in a 6 speed. Luckily the IS300 uses the Aisin AZ6 which is used in quite a few cars. The problem is that it was designed for low torque applications. Nissan had it in the S15 which produced 202 lb/ft which is the highest known torque load placed on this transmission. When I played with Nissan S cars guys would opt to not place that transmission in as part of the swap because it craps out at stock power levels. I don't think it would be a good "donor" for a 6 speed conversion.

The other transmission that looked promising is the Aisin AY6. It's currently being used in the Toyota Tacoma's, 5th Gen Chevy Camaro and Cadillac CTS. Unfortunately it will not work as a "donor" because the gears inside are physically too large to the point main/secondary shaft spacing had to be increased. I've looked into putting this transmission as a complete unit into our Isuzu's but the bellhousing is completely wrong. It does have the Chevy 60* pattern but it's the 2004+ style pattern not the older Chevy Small/Metric/60* V6 pattern. I've talked to the Sales Manager, Mike, at Aisin and I'm hoping he can find me the Main Case --> Bellhousing bolt pattern but he told me right off Aisin is very hard to get exact details from. To me that translates as "You're probably gonna have to buy one and get it for yourself." In the future I may just do that and see if I can get an adapter made to work with the AR5 bellhousing.

Now onto the stuff that DOES work for us. Mike was super helpful and agreed to send me some information regarding the AR5. There's a lot of information on the net stating you can swap certain parts between the AR5, GM MA5, Jeep AX15 and Toyota R-series. There's a great reason for this.....they are the exact same transmission. By transmission I mean the Main case and everything contained within. The customer, GM/Toyota/Jeep, can pick which front/rear cover, clutch actuation, input shaft dia/length/spline count ect. I know this doesn't sound that amazing but what if you tow a lot and aren't happy with your gear ratios? Or what if you want a different t-case option? Well now you know that you can swap parts around to get what you want.

-----EDIT------
I posted on the second page of this thread that are different year ranges for the AR5 variants. From what I can tell they are EARL: 1988-91 Middle: 1992-95 Current: 1996-04. If you stay within the manufacture years parts should be interchangeable.


According to the information Mike sent me there are 8 gearsets available for the AR5 with 1st gear options ranging from 3.25(Pontiac Solstice) to 5.15(non-USDM diesel truck). There is a little catch to running anything over 4:1 for first gear though. This transmission does it's reduction at the front of the case so if you run the 4.31 or 5.15 1st gear your OD is limited to .79. On the bright side .79 is the same OD for a stock 98+ Trooper. I know Marlin Crawlers can get the gearsets but I'm not sure what they cost and if you're considering swapping I would strongly recommend finding a gear ratio calculator to run the numbers through. I like this one http://www.grimmjeeper.com/gears.html since you can compare your stock ratios to the "new" ratios for a side-by-side comparison.

-------EDIT--------
Above I stated that you can swap gears back and forth. This is partially true. The different gear ratios are done, to an extent, by changing the input drive ratio of the transmission. The main problem is that you have to change the INPUT shaft as well as the COUNTER SHAFT gear. This isn't possible on all the transmissions. By changing the input shaft/counter shaft gear you will change all ratios except 4th. So this isn't a pick and choose like I made it seem and I apologize for that. The only way we can change ratios for the Isuzu is IF we use an input shaft that is compatible with our application.


As for the t-case options, if you install the REAR cover from an R-series transmission you will be able to run a Toyota t-case. This to me is probably the best news since I wasn't a fan, no offense guys, of how the doubler setups were done with the stock Isuzu t-case. Biggest issue to figure out running the Toyota case will be shifter location but that should honestly be pretty easy for most of you guys.

------EDIT-------
Med!c posted that the output shaft for the Isuzu AR5 has a 24 spline count. This will cause issues if you're trying to swap to a Toyota t-case since they are almost universally 23 spline. It may still be possible but we'll need to find the correct R-series to swap the output shaft from.


Something else to consider. If you're going to rebuild your AR5 you may want to check into the other applications this transmission was used. There were "optional" parts installed in some of the heavier applications to make the transmission last longer. One such part is in the Hummer H3 that got triple surface carbon sycros as opposed to the single surface syncros that came in the Isuzu AR5. The triple surface syncros are only available for 1st~3rd.

------EDIT-------
Same basic idea as the Edit above. If you want to run the Hummer t-case we'll need to verify the output shaft is compatible. The triple syncros I'm going to check into a little further to make sure they will work with our version. If I find they will not work this information will be removed but until then I'm going to leave it.


I've seen quite a few listing various figures for torque handling ability of the AR5. Toyota sold a sports sedan that was rated at 280 ft/lbs stock. That was in a twin turbo application. To me that's impressive but the AR5 was also used in Toyota Land Cruisers behind a 3.0l Turbo diesel that produced 260 ft/lbs. Diesels tend to be a lot harder on transmissions because they produce max torque over a much wider RPM range. Aisin rates the transmission at 260 ft/lbs but this is obviously very conservative.

This thread http://www.jeeps-offroad.com/showthread.php?t=4740 was originally posted on Pirate4x4 and has to be the thread offroad junkies dreamed of. This guy took the time to figure out which bell housings work with which engines and which transmission bolt to which bellhousings. There's a picture in there of a 6vd1 bolted to a Ford T-5. If you were so inclined you can bolt a GM SM420 to the Isuzu engine using the 60* bolt pattern. For all you guys dreaming of a V8 swap but aren't sure how to do the drivetrain I would suggest you take a look at that thread. You would be very surprised to find that the drivetrain portion will probably be the easiest part of the swap.

If anyone has any questions let me know. I'll see what I can dig up and if you guys want I'll post up all the available gear ratios for the AR5.
 

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Discussion Starter · #3 ·
Originally when I started searching I was looking for a way to convert the AR5 into a 6 speed so I wasn't really looking for "optional" transmissions to swap. The NV3550 is a good transmission made by New Venture but doesn't have quite the OE parts availability the Aisin AR5 does. The NV3550 comes with 2 gearset options, wide: 1st-4.02 2nd-2.32 3rd-1.40 4th-1.00 5th-0.73 Rev-3.55 or close ratio 1st-3.49 2nd-2.16 3rd-1.40 4th-1.00 5th-0.73 Rev-3.55, and all the bellhousings are part of the transmission. The exception to this is the Jeep 4.0l version. That means it's a desirable transmission in the Jeep realm and will be a very expensive option. With the available gear options for the AR5, the sycro upgrades and available t-cases(if you swap the rear cover) I feel the AR5 is the best option for the Isuzu community.
 

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nasty610 said:
Originally when I started searching I was looking for a way to convert the AR5 into a 6 speed so I wasn't really looking for "optional" transmissions to swap. The NV3550 is a good transmission made by New Venture but doesn't have quite the OE parts availability the Aisin AR5 does. The NV3550 comes with 2 gearset options, wide: 1st-4.02 2nd-2.32 3rd-1.40 4th-1.00 5th-0.73 Rev-3.55 or close ratio 1st-3.49 2nd-2.16 3rd-1.40 4th-1.00 5th-0.73 Rev-3.55, and all the bellhousings are part of the transmission. The exception to this is the Jeep 4.0l version. That means it's a desirable transmission in the Jeep realm and will be a very expensive option. With the available gear options for the AR5, the sycro upgrades and available t-cases(if you swap the rear cover) I feel the AR5 is the best option for the Isuzu community.
Nv3500 has the integrated Bell whereas the nv3550 is separate.
Yea I've priced out the 3550s and they're kinda ridiculous. Since these last couple threads I've priced the AR5 out and it's impressive. Cheaper than r150f yotas and better 5th gear, if my 3800 breaks the 4wd w58 I rebuilt I'll go after an AR5 before anything else!
 

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Toyota Supra I believe.
 

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Discussion Starter · #6 ·
foytiX said:
Toyota Supra I believe.
Not sure what you mean but the Toyota Supra came with a 5 speed, R154F, until the Mk4. Then Toyota went to Getrag because Aisin didn't make a transmission that would stand up to the power the twin turbo 2JZ made. When I asked the Aisin Sales Manager he wasn't aware of any way to build a 6 speed from an AR5. He told me that if it's possible it's a pieced together item that never crossed the Aisin manufacturing line.
 

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Good info. Keep it coming!
 

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What Isuzus came with the AR5?
 

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Discussion Starter · #10 ·
98+ Troopers for sure and I think the VX but I'm not completely sure on that one. They also came in the GM Canyon/ Colorado trucks, Pontiac Solstice/Sky and Hummer H3. The Solstice/Sky had a remote style shifter as opposed to the trucks which have the top style shifter. All GM versions of the AR5(RPO MA5) have a larger input shaft than the Isuzu. The shaft came be swapped out but will require the transmission to be disassembled. The AR5 is almost a direct swap with the MA5 but will require a special harness to start the vehicle. Jerry will make this harness but need year and vehicle model. The 4l30e t-case will bolt up to the AR5 with no modifications. Per 95 t-cases have no electronics to worry about because SOTF wasnt available until 96.
 

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Discussion Starter · #11 ·
Here's the ratios that were available for the various versions of the AR5:

Solstice/Sky MA5 1st--3.25 2nd--1.96 3rd--1.31 4th--1.00 5th--.75 Rev--3.18 <----- Has triple surface sycros w/ remote shift tower
Toyota Supra R154 <----- Has same ratios Solstice/Sky MA5 w/o triple surface sycros w/ remote shift tower

Toyota R350 1st--3.83 2nd--1.44 3rd--1.44 4th--1.00 5th--.79/.84 Rev--4.22 <----- Used in Toyota Diesel Trucks/Vans Europe/Afirca/Japan
Toyota R150F <----- Has same ratios as R350. Only .84 OD used. There are 3 generations of this transmission: 88-91/92-95/95-04

Canyon/Calorado/H3 MA5 1st--3.75 2nd--2.26 3rd--1.37 4th--1.00 5th--.73 Rev--3.67 <----- Has triple surface sycros w/ top shift tower

Jeep AX15 1st--3.83 2nd-- 2.33 3rd--1.44 4th--1.00 5th--.79 Rev--4.22 <----- Found Jeep YJ/TJ/XJ/MJ 89-02 ZJ 4.0l had it for 1-2 years

Isuzu AR5 1st--3.95 2nd--2.33 3rd--1.44 4th--1.00 5th--.79 Rev--3.92 <------ Found in 98+ Troopers

Toyota R155f 1st--3.95 2nd--2.06 3rd--1.44 4th--1.00 5th--.81 Rev--4.22 <------ Found in 05+ Tacoma i4. They bitch about 1-2 gear spacing and the tall OD

Toyota R151F 1st--4.31 2nd--2.33 3rd--1.44 4th--1.00 5th--.79/.84 Rev--4.22 <------ Found 86-87 Toyota truck with turbo 4 cylinder

Toyota Rxxx 1st--5.15 2nd--2.78 3rd--1.51 4th--1.00 5th--.83 Rev--5.04 <------ Non-USDM Toyota diesel ratios
Marlin Crawlers MAR515 <------ They custom build this set using a R150 case and R452 gearset

Toyota R452 1st--5.15 2nd--3.10 3rd--1.71 4th--1.00 5th--.83 Rev--5.04 <------ This is the Box Marlin Crawlers used to build their MAR515

Any of the GM MA5 transmission have a larger input shaft that needs to be changed for use in an Isuzu.

The Toyota R-series require the front cover to be swapped so the Isuzu clutch arm can be used otherwise you have to adapt the Toyota clutch. Also any of the Toyota R-series pre-96 will not work because they have a short bell housing/short input shaft. It can be swapped for a long bell housing/long input shaft if you so desire.

Jeep AX15 may be a direct swap but you'll need to verify the input shaft length/diameter/spline count and clutch actuation.

The rear cover can be swapped to between any of these transmissions. So if you want to run the Jeep NPxxx or Atlas use that rear cover. Same goes for Toyota and GM. The H3 used an electronic t-case that is full-time 4wd. You select between hi and lo via push button. There is an extreme amount of t-case options because there are adapters for the Jeep AX15 to bolt on just about any t-case you want. The sky is literally the limit.

The AR5 does it's reduction on the input shaft. This means if you use the 3.95 and numerically lower first gear you can swap ratios as you see fit to create your own custom gear set.
The lowest first gear you will get using USDM parts is 4.31 and will require an input gear. The input gear from the 4.31 DOES NOT work with 3.95 and lower gears. To go lower would require ordering an entire R452 transmission from either Europe or Australia. If you really want the R515 Marlin Crawler has been able to build them in past but I'm not sure what the cost is. I found a post on the Marlin Crawler Forum that his cost for the R452 transmission was $400-600 but that was back in 2004. Expect it to be double that with the current market trends. The MAR515 ratios were also produced by Aisin for OE use in a Toyota commercial truck but I can't find any information on it or a designation for that specific model.

The triple surface syncros from the GM MA5 can be swapped to any of the other AR5 variants. They are only available for 1st, 2nd and 3rd.

The Isuzu AR5 already has the lowest gear set available and to go any lower requires the input gear and associated parts to be changed. You can get a lower Rev gear if you want it. Easiest place to get it would be a Jeep AX15. The R151F is considers rare and Toyota guys are willing to pay for them. I wouldn't count on finding one for cheap unless your local yard has one and doesn't know what it is.

Worth mentioning is that the Jeep AX5 and Toyota W-series are the predecessor to the AR5. They were deemed too weak to stand up to the power being produced by the newer engine. That was in the 80's. While they will "fit" onto our engine it is not recommended due to lack of strength. Some parts are interchangeable but verify it's the same P/N used on your transmission and not just compatible.
 

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nasty610 said:
98+ Troopers for sure and I think the VX but I'm not completely sure on that one.
I think all VXs were autos.
 

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Discussion Starter · #13 ·
You are correct the VX was only available with amazing 4L30E that we all love so much. I looked it up and it turns out the couple sticks I've seen were swaps done by the owners. Can't imagine why they did that. lol
 

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nasty610 said:
The 4l30e t-case will bolt up to the AR5 with no modifications. Per 95 t-cases have no electronics to worry about because SOTF wasnt available until 96.
My 95 Transfer Case bolted up just fine, but there is one less bolt holding it on as the top part of the pattern on the AR5 is slightly different than the 4L30-E. On the wiring I had to jump the auto neutral safety switch and wire the reverse wiring which is in the harness from the mode switch. Also, the TOD transfer case will require some shifter grinding to fit up to the AR5.
 

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This right here might be the answer I need for my driveline issues.
So if I get this correct, I can get an AR5 and swap the rear cover to one from a R150F and then get Yota cases behind it?
Or
Do I need to find a way to mate the R150F to the AR5 bell housing??
 

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Discussion Starter · #16 ·
Yes. According to the information I got from the Aisin Aftermarket Sales manager the transmission is exactly the same regardless of designation. The front/rear covers, gear ratios and shifter were all options chosen by the end user which would be Toyota/GM/Isuzu. Before you blindly order the rear cover from a R150 you'll want make sure it comes from a 4 cylinder transmission. They were the ones that used a gear driven t-case. The v6 model used a chain driven and from what I understand isn't as easy to convert to a doubler. I would make sure that where ever you purchase your rear cover from has a return policy just in case it the one you get doesn't line up right.
 

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I thought the 6-speed Toyota that we thought would fit was from the Tacoma, etc. It was the manual in the light trucks and it either has the same bolt pattern, or the bell housing is the same as the AR5.

-Tad
 

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Discussion Starter · #18 ·
Tad said:
I thought the 6-speed Toyota that we thought would fit was from the Tacoma, etc. It was the manual in the light trucks and it either has the same bolt pattern, or the bell housing is the same as the AR5.

-Tad
That's the AY6 and it's from the Tacoma, 5th Gen Camaro v6 and Tacoma X-runner. I know the Toyota bell housing is completely different and the Chevy bell is the new 60* pattern which completely different. I haven't been able to find any dimensions for the front case to bell housing interface. If they are the same it would be pretty awesome.

I've read some really mixed reviews about it though. A lot of people complain about vague shifting and the gap between first and second is large enough there's generally some grinding. Kind of like driving a SM420/465. It is supposed to be rated at 345 ft/lbs but there are guys breaking them at stock power levels. Most of the guys complaining have been with the X-runner and Camaro with the general consensus being they don't know how to drive it properly and it's a truck transmission not a sports vehicle transmission.

I'll do some more research and see what I can come up with. I'd prefer the close ratio 6 speed over a wide ratio 5 speed any day. We will loose the cross compatibility of the AR5 going with the AY6 is the only real negative to using it.
 

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lorenzo816 said:
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This right here might be the answer I need for my driveline issues.
So if I get this correct, I can get an AR5 and swap the rear cover to one from a R150F and then get Yota cases behind it?
Or
Do I need to find a way to mate the R150F to the AR5 bell housing??
The bolt patterns of the rear cases are likely the same and will interchange.

HOWEVER it's just as likely that the r150f output shaft will need to be swapped In as well in order to work with the corresponding transfer case. I think you might be farther ahead with an r150f and AR5 bellhousing(input shaft length may vary) or better yet (very rare) a turbo r151f which will automatically let you use gear cases WITHOUT the spendy r150f case adapter.

But it sounds like the newer AR5 is a nicer shifting trans. Newer is typically better anyway
 

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Yes, this is kind of the conclusion I am getting into now.
Find the rare R151f from the 22re turbos and have a gear driven case of a rear end on the trans as opposed to the 150 which will have been made for a chain case and I need an adapter to go to gear cases and possibly a different one altogether to go to a psd tcase output.
I'm on the hunt for an AR5 trans now.
Thanks guys - Very de ja vu of you nasty610, I have been going over this exact issue for about a week and a half now from the yotatech board, the jeeps-offroad post on the R trans and more on Marlin's old threads. I think I will end up being the guinea pig after all.

However it dawned on me, we do have one member here who owns a truck that has the Toyota r150f in it today and dual cases: Ften.
The trooper was originally built/owned by a friend of mine named Chris and he had Marlin's custom input shaft/adapter for the r150f to an AR5 bell.
I have not called Marlin yet about availability of said parts. This has been almost ten years ago this was done.
viewtopic.php?f=2&t=17714
I may call my buddy Chris to see if he has any fuzzy details on his swap.
 
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