3.55 gears and 727

[Seagulls n Eagle]

Greetings everyone.

I'm wondering if anyone has run TF 727 with 3.55 gears. I'm in the middle of getting my eagle up and going and the fasted route would be to install my TF 727  with the 3.55 gears. I know the numbers aren't that good for the highway but wondering if anyone has real world Experiance with this combo.

I have a 4.2 currently installed but could also swap in the 4.0.

I would really like to install my ax15 but it would be much faster and easier to go with the TF727

Thanks

[carnuck]

You won't have a lot of top speed (probably 60 mph depending on tire size) 3.08s and 235/75/15 are about perfect and it's straining RPMs a bit at 70 mph.

[Seagulls n Eagle]

I was afraid of that. It's kind of what I figured. I'm guessing I need to proceed with the Ax 15 swap. I'm nervous about mods that are going to be required. I need to get the car up and running.
I'm going to be posting pictures with my ideas on crossmember mods and questions.

The TF727 would be faster and easier but I just installed an 8.25 3.55 rear but it woulnt work well at highway speeds.

It seems as if the ax15 and the 3.55 work quite well, by the numbers anyway.
My tire size is 225/75/15

If I remember correctly carnuck you have run the ax15/np242/3.55 combo I'm guessing you like it?
How do you do for milage?

Might I be able to pick you brain and bounce some ideas off you regarding the ax15/np242 swap, carnuck?

[carnuck]

I had AX-15 with NP208 in my full size '83 J10 pickup which worked well with 3.31 gears till I went to 33" tires. Then my 4.2 lost a piston and I was swapping in a 4.0L before I broke my shoulder. Now I can't drive stick (got only 3 months running it) and I was going to convert to AW4 but gave the truck to my oldest son for parts. (was originally a T5 rig)
   I also sold the 360, T-177 4 speed and NP208 from my '83 Honcho so I could put my '77 AMX 304 and '93 Grand Cherokee AW4/NV242 in and be able to drive it. My '84 J10 has a '93 Grand Cherokee 4.0L/AW4 that I am putting a NV241 OR up to for 4:1 low range 4.10 gears and 36" tires. I was going to do Dana 60 front/D70 rear with 5.13s and 52" Michelins but my injuries would keep me from being able to climb in as easily as I used to.

My Eagle wagon has 727/NP229 in it and SOTE (Spirit of the Eagle) had 4.2L AW4 and NP242 (we converted the Spirit to 4x4)
There is 1.5" difference between AX-15 and AW4. I used to have all the lengths written down but my old site disappeared and wasn't cached. IIRC, the AW4 was 3.5" longer than 727/9XX (I do measurements flange to flange so from the joint at the motor to the round flange of the tcase mounting)

Sorry: I have to keep editing as I remember stuff.

Stock Jeep ran 4.0L/AX-15/NV231 (and not 242 stock) due to shock loads of std trans. Not saying 242 can't take it, but you have to be gentler in 4x4. They also ran 3.08 gears with 205/75/15 tires for power/economy. If you run 30" tires then 3.55s will be fine. You will at least be able to do highway speeds.

I tested my Comanche with a 4.10 rear axle and 33" tires and I was totally shocked at how much power/speed I lost over 3.73s. It felt like I was always running around in low range! If you haven't modded your 8.25 much, I would find one that has 3.08 gears and keep your current front one. *(all std trans XJs with 4.0L should be 3.08)

[Seagulls n Eagle]

Thanks Carnuck! Great info. As I progress with getting "Joy" on the road I'm perplexed with all the possible routes to take. I'm going to be posting some pictures of an idea I have for the rear crossmember mods to accomidate the AX15. The ax15, 3.55 and 225/75 seems like it would work well  but I only have so much time and money. If it can continue to work out ill stay on this path. If not ill have to go back to the TF727/NP229 and ill have to find another rear with the 3.07. Ill be posting the crossmember ideas on my "1984 eagle" build thread: