AMC 401 conversion help

[mharakal]

Hello all! Just recently I bought an 82 CJ7 with an AMC 401 and everything else factory. The T-5 Transmission is already demolished and put me into an unplanned project to get the Jeep back on the road with the proper components. If there is anyone here who has done a 401 conversion, please help. I would really like to know everything else you have done. Right now I am looking at getting a T-18 with a Dana 20 Transfer Case , but am starting to realize this may not work so well. It would really help the process getting to hear from someone has has done all the proper mods in order to make the conversion happen. Thank you in advance! Matt

 

[LongHorn]

Hello all! Just recently I bought an 82 CJ7 with an AMC 401 and everything else factory. The T-5 Transmission is already demolished and put me into an unplanned project to get the Jeep back on the road with the proper components. If there is anyone here who has done a 401 conversion, please help. I would really like to know everything else you have done. Right now I am looking at getting a T-18 with a Dana 20 Transfer Case , but am starting to realize this may not work so well. It would really help the process getting to hear from someone has has done all the proper mods in order to make the conversion happen. Thank you in advance! Matt

My rig has a 401V8 Dana T19/ Dana 300 with Dana 60 axles front & rear.

 

[Purple77CJ7]

I run a 401 with an nv4500 5 speed with the Dana 20 . It works for me. Advance adapters or Novak Convertions can help with adapters. Others here can probably tell what parts to pull from salvage yard.

 

[mharakal]

Did you have to get a new clutch to match up with T19 input shaft?

 

[LongHorn]

Did you have to get a new clutch to match up with T19 input shaft?

The T19 came from a 2wd Ford.
I used a Ford Disc & AMC pressure plate.
So in answer to your question, yes.

 

[Jimbos76cj]

Ive got a Waggy that has the 360/T-18 /Dana 20 Combo.. Jeep used that set up alot so the T-18 should bolt right in. I am definately not the Transmission swap expert but do know they ran that same set up stock.. The 360 and 401 are the same motor.

 

[LongHorn]

Ive got a Waggy that has the 360/T-18 /Dana 20 Combo.. Jeep used that set up alot so the T-18 should bolt right in. I am definately not the Transmission swap expert but do know they ran that same set up stock.. The 360 and 401 are the same motor.

If I'm not mistaken, the problem with using the T-18 setup from a Waggy is the Transmission input shaft stick out is to long, because AMC used a long adapter between the bell housing & the Transmission to move the shift tower rearward.
AMC installed the T-18 /Dana 20 setup in CJ's too, but it is a rare combo.
It's a bolt in swap.
The main reason so many people use the 2wd Ford T-18 /T19 setup is that they are plentiful.

 

[LongHorn]

International Harvester also installed T-18 /T19 in their trucks.
They also used 401 AMC V8's & AMC 258 i6 / 4.2l 6 cyl.'s
The IH Dana 300 's use the Texas bolt pattern like the AMC Dana 20 's.
But again they are RARE.

 

[mharakal]

Well now I am just waiting on the jeep yard to locate the T-18 they said they have. Hopefully its in good shape and I can get rolling with getting this thing back on the road. Thanksfor all your help.

 

[RR401]

Still working on it?

Our is a 1979 CJ7 Ridgerunner. It was bad off. Pics attached before and after...

We got it with a AMC 304 that was mortally wounded. Since we already had a T-18a and a Dana 20 - and testosterone what it is - we found a 401 in Tampa and cleaned it up. It is an awesome powerplant. Torque monster.

We've been at it for over two years. Biggest problem was/is Limited wallet. If money was no problem D60's rule. But money is a problem so after months of searching we found a set of wide tracks (yep A Dana 44 in the rear) and lept on 'em FOR $300.00! Yea Craigslist! And here's a clue - the Jeep for parts was listed as a Wrangler - not a CJ. In the text I found the year stated as '86. Serious stroke of luck. Those axles sat in the guy's yard for MONTHS.

We also found a postal axle - if they're from the '70's they are D44s and all have Detroit Lockers. We got that for $100.00. Of note the gearing on Jeep axles is in two stages - above 3.73 and 3.73 and below. A completely different carrier is needed depending on the range. The postals have 3.73 and our wide tracks 2.72s - so they match

You may be thinking 2.72s? With 35's? Well - our original axles were trashed and were geared at 3.53. This gearing and 35's made our T-18s second gear useless. We essentially had a two speed tranny -with a very cool granny gear.

When we got the 2.72s just for kicks we bolted them up and were pleased - we now had a usable 2nd gear - so with an extremely tall granny in 1st and a working 3 speed we have the "beast" of both worlds. Can you imagine trying to run 35's on a AMC 258 i6 / 4.2l with 2.72s - shows what a powerhouse the 401 is. Also if you find or have a 401 with the Motorcraft 4350 - it can be a great carb. Handles off angle stuff with ease...

If you can find a Jeep T-18a granny/Dana 20 your life will be very easy. Can't speak to T-19s etc, but Novak can give you great advice.

We used the 11" clutch and a Novak hydraulic setup that works awesome. Also, stopping a 401 is just as important as it's get up and go.

We got a set of dual power boosted Wrangler brakes off EBay for $179.00 - an amazing difference...

Keep us posted - anxious to hear how much you lke the 401....

 

[Darren9975]

How do you plan to use your jeep? If its just a street machine get a 3 speed T-150 /Dana 20 . They are bullet proof, but suck off road. If your building a trail rig you might want to look into a ford NP435 with a Dana 300 you need an adaptor from advance adapters for the Transmission to xfer. This is a great combo for crawling

 

[CJim7]

If I'm not mistaken, the problem with using the T-18 setup from a Waggy is the Transmission input shaft stick out is to long, because AMC used a long adapter between the bell housing & the Transmission to move the shift tower rearward.
AMC installed the T-18 /Dana 20 setup in CJ's too, but it is a rare combo.
It's a bolt in swap.
The main reason so many people use the 2wd Ford T-18 /T19 setup is that they are plentiful.

This^
The Ford T-18 is very popular. A simple tailshaft conversion along with an adapter to the Dana 300 and you are in business. This settup is almost exactly the same length as the T-5 /Dana 300 so you dont need to modify drivelines. You can re-use the T-5 bell housing which eliminates having to hunt down the proper bell.

 

[RR401]

CJim7:

What gears do you run in your CJ 401? We just got ours up and running and are liking the 2.72s but would like to hear other's experiences...

 

[CJim7]

CJim7:

What gears do you run in your CJ 401? We just got ours up and running and are liking the 2.72s but would like to hear other's experiences...

Im running 4.10's (with 36's)...residual from when I was running 33's. And honestly, I like it. Plenty of onroad RPM spread and offroad, the T-18 easily makes up for the lack of gearing for the size tire Im running>
I will be gearing the D60s at 5.13 for 40+ tires

 

[RR401]

With your set up now, what rpms at highway? We're running about 1400 in 4th at 60 (uncorrected for 35s yet) and the 401 seems surprisingly happy... no lugging and when you floor it - woa...

Don't know where we're at on mpg yet but are hoping for 15+

 

[CJim7]

With your set up now, what rpms at highway? We're running about 1400 in 4th at 60 (uncorrected for 35s yet) and the 401 seems surprisingly happy... no lugging and when you floor it - woa...

Don't know where we're at on mpg yet but are hoping for 15+

That's about where Im at @60mph...maybe closer to 1600rpm. 4.10's/36's is pretty close to the powerband of 2.72/33's, maybe a little lower but not by much.
I get about 10mpg but there is nothing stock about the internals on my 401

It seems happy running at that RPM range at speed also.

 

[johnbilt]

I think the T-18 conversion with the Dana 300 Tcase you have sounds like a reasonable approach. If you have the $$, one of the newer truck 5 spds would be an option and you could get the Overdrive .

My T-18 and Dana 20 case is good offroad combo. But I often wish for another gear. I have 35" tires with 4.56 gears. I turn around 2800-3000 rpm at 60mph. If I ran a taller ratio, I could gain a bit on the road, but I like having that real low range on the trails.

My CJ5 has a AMC360 and pushes along just fine. With a CJ7 , you may have room for an Overdrive unit to solve this.

The other option is to put rather tall gears in the diffs, and install the low gear set in the Dana 300 to gain back the low range. Again, what is your $$$.

I installed a ford input shaft into my Jeep T-18 , which was from a wagoneer. Then you just get a special pilot bushing and the ford disc.

Good luck with your project! I hope you are able to find a good setup.

 

[JR74CJ5]

Make sure if you spend all this time searching for the T-18 you get the "right" one

They came with 2 gear ratio lows. the one you want would be 6.32:1 if I am remembering correctly.

I should rephrase that to "the one I'd want..." :drool: as I'm not sure your intentions on the Jeep.

 

[Saddle Tramp]

Matt-

As you have a CJ7 and not a 5 you have the room to add the adaptor (Texas to round) between the T-18 and the Dana 300 you should already have without killing your rear drive shaft length. (making it too short) This will save you some money and give you a great case. Having said that I recommend you upgrade to a short shaft tail housing on the Dana 300 if it hasn’t already been done. If you are considering re-gearing the axles give some thought as to what you really use the jeep for as the high RPMs on the road gets old fast however there is nothing like not able to slow down enough when crawling either. Crawling to me doesn’t need to be over big boulders or slick rock, it can be just ambling down a dirt road that is in disrepair trying not to beat yourself, passengers, and jeep to pieces while you go.

My CJ5 came to me with 4.56 differentials, a Dana 20 (2.03 low), and T-150 (2.99 first gear) and Buckshot Mudders that tape out to about 33”. Needless to say going down the highway at 60 mph always leaves you wanting another gear to shift up to but it’s not there (60 mph = about 2800 rpm). From a crawl ratio stand point even with the 4.56 pumpkins the stock Transmission & x-case things still weren’t all that wonderful either: 4.56 x 2.03 x 2.99 = 27.68 crawl ratio. My upgrade to a T-18 (6.32 low) and a Scout Dana 300 improved things dramatically: 4.56 x 6.32 x 2.62 = 75.51 crawl ratio. However my on road performance is just as sucky as it was prior to the swap out so my thought is to put a Teralow it (4.0) in the Transfer Case and then re-gear the differentials to something taller. (numerically smaller) For example with 3.54 axle x 6.32 Transmission low x 4.0 x-case = 89.49 crawl ratio but with that set up I estimate the RPMs at 60 MPH would be about 2150 rather than 2800 (+/-). I know all it will cost is money but it’s just a thought.

As far as T-18 transmissions go, try this:

http://www.jeeptech.com/convtrans/cjt18/

 

[mharakal]

Happy New year to you all, and thanks for all the posts so far. its been awhile since i've been on. Right now I have a T-4 in the jeep, and a T-18 sitting in the garage waiting to be installed. i'm starting to have slight doubts about putting the T-18 in, mainly due to the low first gear. there isn't going to be any serious wheeling done with this jeep, nothing that i could see needing a crawler gear. the T-176 from what i've been reading seems to be a better fit, but they are turning out to be quite hard to come by. chances are i will be going with the T-18 since i have it sitting in my garage. any thoughts from you all with the t18s in respect to minor offroading and street use? thanks again for all the replies