Swapping an AX-15 5-speed out of a Jeep into a 617 Mercedes - PeachParts Mercedes-Benz Forum

Mölyapina · #1 11-01-2015, 04:18 PM

I've been trying to figure out a 717.400 alternative for a while, preferably one that is plentiful and cheap

. After doing a lot of research on the Toyota W59, I've switched focus to the AX-15 found in 2WD Jeep Cherokees and Dodge Dakotas, among others. The AX-15 is considered one of the best 5-speeds ever put into a Jeep. It's very durable, and able to take about 300 HP/300 lb-ft reliably. The ratios are pretty similar to a 717.400:

..............AX-15..........717.400
1st...........3.83.............3.82
2nd...........2.33.............2.202
3rd...........1.44.............1.398
4th...........1.00.............1.00
5th...........0.79.............0.813
R..............4.22 (!)........3.705

The first attachment on this post is a spreadsheet comparing the speeds at various RPMs of a 717.400 to an AX-15 when both are mated to a 3.07 rear end, along with an AX-15 mated to the 2.88 rear. As you can see, the ratios are extremely close (sorry for how messy the columns are). Using the 3.07 as an example, the car hits 2000 RPM in 5th at 60 MPH, 2300 RPM at 70 MPH, and ~2600 RPM at 80. This means that running average speeds on the highway with this thing would put you right at the peak of the OM617’s torque curve, a good thing for both economy and power.

Of course, the main issue with using an AX-15 is fitting it. I’ve identified and tried to resolve all the main “problem areas” that need addressing: mating to the engine, flywheel/clutch, starter, fitting in the tunnel, mating to the driveshaft, how to locate the shifter, and how to run the fluid lines. I’ve attacked them point-by-point below, starting with mating to the engine:

Mating to the engine, clutch & flywheel, starter

Mating to driveshaft

The shifter

Master/Slave/Fluid lines

Extra flywheel weight

Fitting in the tunnel

Mölyapina · #2 11-01-2015, 04:21 PM

This part is pretty easy, because Jeep guys already swap the OM617 into cars with AX-15 enough that there is actually a commercially available adapter plate that includes a flywheel adapter that allows you to use the Jeep 4.0 flywheel and jeep pilot bearing etc. It comes from mercedesdiesel4x4.com and retails for $380. It uses the Jeep starter mounted in the Jeep location, or on the bottom passenger’s-side of the engine. Here is a picture of what it looks like:

I was concerned that it might interfere with suspension components, but looking further at mounting pictures and under my hood, it doesn’t look like it would be an issue… there is a stiffening bar in the W126 that runs the width of the car, but it runs underneath the tranny bell, so it shouldn’t be an issue. There doesn’t look to be anything right in the area that the starter needs to go. Folks who have swapped the OM617 into Jeeps say that the Jeep starter is up to the task of cranking the OM617, and it is a Bosch starter, so it should be of reasonable quality. Also, since it is a Bosch starter, there is an outside chance that we could swap the gear on the starter shaft from the Jeep starter onto the MB starter and run the MB starter. The two do look to be about the same size, anyway.

Mölyapina · #3 11-01-2015, 04:21 PM

Since the MB driveshaft setup relies on having the output shaft of the tranny and the WHAT IS IT of the differential at the same level, and I am assuming that this will not be the case for the AX-15, a non-MB driveshaft solution should be explored. Something interesting I gained from Google is that there is a Chrysler flange that slips onto the MB differential, so if we use that, then we could just use the 3130 U-joints that are stock on the Jeep and have some sort of driveshaft made up for that. I’m not sure if a lengthened Jeep driveshaft, a custom driveshaft, or something else would be best. There is a driveshaft shop in Quincy, MA that I am going to call up to inquire about pricing… My guess is that it would be between $150 and $300, depending on whether a modded jeep driveshaft is used, a new one is made, etc.

Mölyapina · #4 11-01-2015, 04:21 PM

The shifter is the biggest battle. The AX-15 shifter is too far forward, meaning that we have to somehow move it back. Here are pictures of what other people have done to move shifters on random RWD trannies:

This thing looks too big for the tunnel.

https://www.youtube.com/watch?v=kEqsi4mhjnE (This was really good)

The issue with using the second pictured method is that we'd have to drill a hole through the AX-15 tailshaft to allow the shifter rod through. I was thinking that you could just weld some thin (bendable) aluminum between the hole and the shifter extender to seal it up from the weather.

As far as the actual shifter, the AX-15 is very closely related to the Toyota R154, so we could probably just use a MkIII Supra shifter to shift with... whould be more pleasant the stock Jeep one.

Mölyapina · #5 11-01-2015, 04:21 PM

I’m not sure what to do here. As I see it, there are two options: using the MB clutch master or using the Jeep clutch master. Using the MB slave would mean that the line from the brake master cylinder reservoir to the clutch master would just be the stock line, but the line between the master and the slave would have to be custom, because we’d probably have to use the Jeep slave. Or, we could use the master out of the Jeep, but then we’d have to attach it to the MB setup and have custom line running between the reservoir and the master. The only reason this might be attractive is it the line running from the MB master to the slave is hard to find… I remember seeing something about that? What o you guys think?

Mölyapina · #6 11-01-2015, 04:22 PM

One of the more exciting things about this is that the Jeep flywheel itself already weighs 30 lbs (more than the 616, less than the 617), but there is a guy at Tri County Gear who sounds like he’ll have a inertia ring for the 4.0 flywheel ready soon (I spoke with him over the phone), which hopefully would bring it very close to the 38 lb point of the 617 flywheel

. He already sells one for the 2.5L that also came in these Jeeps for $175, so I wouldn’t expect the 4.0 inertia ring e much different from that in price.

Dan Stokes · #7 11-01-2015, 06:21 PM

Quote:

Originally Posted by Jooseppi Luna

I’m not sure what to do here. As I see it, there are two options: using the MB clutch master or using the Jeep clutch master. Using the MB slave would mean that the line from the brake master cylinder reservoir to the clutch master would just be the stock line, but the line between the master and the slave would have to be custom, because we’d probably have to use the Jeep slave. Or, we could use the master out of the Jeep, but then we’d have to attach it to the MB setup and have custom line running between the reservoir and the master. The only reason this might be attractive is it the line running from the MB master to the slave is hard to find… I remember seeing something about that? What o you guys think?

No big deal on adapting the lines. My Mercedes to S-10 line was the result of a trip to our Parker-Hannifin store here in town (most towns of any size have one and/or or a Swagelok store). Just take the two components you need to adapt (in this case the Mercedes master and Jeep slave) and the length you'll need. You can run a certain amount of hard line but remember that you'll need some flex as the engine/trans assembly will move and the firewall won't (hopefully!). I had my lengths with me and had a section of Teflon lined braided stainless line made up for me and I was ready to go. I'm remembering it was about $50 but I might be high there. Also, I use SS fittings when I can so that's a bit more $$. Just don't thread SS into itself as it'll gall and you won't get it apart intact.

Dan

Mölyapina · #8 11-01-2015, 04:44 PM

PLEASE NOTE: I'm attaching the spreadsheet referenced in Post #1 later.

EDIT: Attached!

Frank Reiner · #9 11-01-2015, 08:08 PM

Rather than pics of a T-5, and a T-5 shifter, can you post pics of the AX-15?

Mölyapina · #10 11-01-2015, 08:25 PM

Quote:

Originally Posted by Frank Reiner

Rather than pics of a T-5, and a T-5 shifter, can you post pics of the AX-15?

There are none. Like I said in the post, those are just random RWD trannies that I was looking at for ideas. I'm still not sure how to resolve that, but I think it's doable.

Mölyapina · #11 11-01-2015, 09:31 PM

Found this thread about extending the shifter in an R154, one of the Toyota trannies related to the AX-15:

R154 shifter extension mod writeup w/ PICS ! - Club Lexus Forums

Here is his solution in one picture:

I wonder if I could do something like this. Probably.

Mölyapina · #12 11-01-2015, 10:24 PM

Quote:

Originally Posted by Jooseppi Luna

I wonder if I could do something like this. Probably.

Here's a crude illustration of what I'm imagining:

Simpler=Better · #13 11-02-2015, 09:46 AM

Quote:

Originally Posted by Jooseppi Luna

Here's a crude illustration of what I'm imagining:

This will probably work just fine, and hack up the radio area a little bit. Just don't make the handle/knob too heavy or it will pop out of gear when you hit bumps.

gatorblue92 · #14 11-02-2015, 05:10 AM

I didn't see anything about this in your previous posts but what are you going to do about the transfer case? Did they ever make a 2wd variety of the AX-15?

t walgamuth · #15 11-02-2015, 05:44 AM

Quote:

Originally Posted by gatorblue92

I didn't see anything about this in your previous posts but what are you going to do about the transfer case? Did they ever make a 2wd variety of the AX-15?

In his initial write up he mentions the tranny is for 2wd jeeps and Dakotas.

Very nice write up! Looks like it has real possibilities.