What transmission do I have

[86 Comanche]

Hello I'm new on here, bought a 1986 jeep comanche 2.8l 4wd 5 speed manual I guess it was the California addition or something. But I was wondering what Transmission I had if any of you knew of the top of your heads. Because I heard horrible things about the 2.8 so I want to just put a 5.3 and all the pages I've read say the ax15 will hold up and work great but I'm not sure what I have. Thank you for your time. 

[Green Mesa XJ]

Ah. The 2.8 is weak sauce, paired with poor exhaust and bad carburetor and intake . It can be an ok motor but never really great like the 4.0, most drop a 3.4 Camaro motor in its place just about bolt per bolt a drop in for the 2.8.

 

You should have a ax5 paired with a np207 if it’s a command trac, select trac I forget which transfer case but it’d have a vacuum switch somewhere in the cab if it’s select trac, Cherokees had it in the console behind the shifter

 

Ax15 was I think 1990 up jeeps, xj mj yj

 

 

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[86 Comanche]

Thank you is the ax5 any good as well as how much better power would come from the 3.4?

[Green Mesa XJ]

Ax5 some people don’t like it but it’s a decent medium duty truck transmission. Essentially a Toyota transmission. But it will not take power of a v8 or 4.0 Jeep.

3.4 is basically a stroked out 2.8, the final version of the 2.8 rear wheel drive engine in our jeeps. 3.4 is supposed to be noticeable improvement over the 2.8. Combined with a better carb and good intake it’s a decent upgrade. Others who have done the swap can speak to the positives and negatives better.

Biggest positive is it’d drop in the same place with little modification depending how you chose do if.

There’s a good thread her on some gm swap options, I don’t remember who’s thread it was but it’s got lots of cool information and options




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[Pete M]

v8 swaps can be found in the Epic Tech forum.  

 

as to the 3.4, it's a good engine if you're on a budget.  It'll reuse most everything you've got attached to the current block (you'll need a balanced flywheel and inline fuel pump).  or, for maximum improvement, you can swap in the entire camaro 3.4 including accessories and fuel injection.   the FI harness is stand alone and I'm told pretty easy to deal with.  

 

in the end though, it's no v8, so if you've expecting tire shredding, neck snapping acceleration, a 6 cylinder won't necessarily do that. 

[zomeizter]

OP, I have the same truck you describe, minus the Cali emissions. The 2.8L is gutless compared to an LS and yes, it can be a crappy motor if not taken care of, these engines are not hardy and blow up quickly if abused. I keep mine well tuned and it takes me there and back ok, occasional wheeling is ok too, but it is a dog in sand unless you keep the RPMs up. I too am gathering all necessary parts for a V8 swap but for me this process is slow...good luck.

[CheapXJ]

I've heard the AX5 behind the 2.8 has some bigger internals. It takes a different throwout bearing and should already be external slave so it's a little more desirable than most ax5s of that era.

 

Never ever had any issues with the ax5 in my old 85 2.8 XJ...

 

That engine was a different story altogether.

[zomeizter]

1 hour ago, CheapXJ said:

...should already be external slave so it's a little more desirable than most ax5s of that era.

 

 

 

It is external slave cylinder, but extremely "fun" to replace! I wondered why the previous owner made a "door" on the floor hump at the passenger side, until the slave failed me, haha!

[CheapXJ]

LS4 bolts to that transmission.

 

I'd be curious to see how long it holds up. You can get a AX15 that fits from 2.5L/5-speed dakotas for when that motor shreds the AX5

[zomeizter]

25 minutes ago, CheapXJ said:

LS4 bolts to that transmission.

 

I'd be curious to see how long it holds up. You can get a AX15 that fits from 2.5L/5-speed dakotas for when that motor shreds the AX5

It sure does, but a tranny-mounted starter and flexplate side throttle body. I do like the clearance mods made to fit the FWD GM sedans though, but not sure I'd keep the ax5 behind the beast...on the lookout for a deal on a GM/Dodge NV35-5600.

[CheapXJ]

Got some go-fast parts for the a904 auto in my 84 XJ. Was gonna build a gen2 3800 for it but I I have my eyes on an LS4 now.

[CheapXJ]

On 1/28/2019 at 7:26 PM, zomeizter said:

OP, I have the same truck you describe, minus the Cali emissions. The 2.8L is gutless compared to an LS and yes, it can be a crappy motor if not taken care of, these engines are not hardy and blow up quickly if abused. I keep mine well tuned and it takes me there and back ok, occasional wheeling is ok too, but it is a dog in sand unless you keep the RPMs up. I too am gathering all necessary parts for a V8 swap but for me this process is slow...good luck.

Ya know, I used to ride with a bunch of s10/blazer guys with 2.8s. all of them ran edelbrock 4bbl intakes and holley 390s + HEI distributor & comp 272 cam... and honestly... they did pretty good. definitely more stable off angle than my rochester 2se EVER was.

 

that holley setup almost made them "grunty" like the 4banger (2.5 made more torque all day)

[zomeizter]

I don't think I could convince myself to do anything with the 2.8L, although the one in my 'manche came from a Camaro and supposedly it was "refreshed the right way", whatever that means, according to the guy that sold it to me. I did remove the valve covers and oil pan and to my surprise, it was pristine clean, like fresh out of the machine shop. So I threw in a HV/HP pump and installed it, replacing the original 2.8L with a rod knock. Once the installation was completed, the damn thing started on the first crank and has been taking hell since the summer of 2016. I will run it till it dies or I find a manual tranny for the GM or Dodge V8 swap.

[Green Mesa XJ]

I’ve beat the hell out of my 2.8, and never had a problem but it’s not a power house and sucks where there’s hills.
Thing about a “camaro” or s10 engine is if it’s out of a 1985 or 1986 they have an improved head design GM put in service late 1984 early 1985 using them through 1995 and the 3.4 engine. Although GM sourced the engines for AMC and others they sold their old engines. The heads I’ve seen come of 1986 jeeps were supposed to be the new gm design but gm gave amc the old heads. One thing some 1986 jeeps did get was the new block design with bigger mains, in theory those blocks with the new one piece rubber rear main seal should last better and if somebody were inclined to do it could be rebuilt with 3.1 parts making it a stroker engine.

The 2.8/3.1/3.4 is more popular with mg and fiero car fans because it’s a light small 6 cylinder that fits in their engine bays. Jeeps can fit a small v8 pretty easily so the 2.8 doesn’t make a lot of sense to keep.
Although once the crap intake, carb and exhaust are replaced it can be a better performer it’s just by the time anyone sources all of those parts I doubt it’s cost effective.


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