Regearing AMC 20 and Dana 30 question

[Turd Ferguson]

AMC 258 i6 / 4.2l , 33" tires, T-4 tranny. New project.

My question is I'm going to be rehearing and was thinking of going 4:11 or maybe even 4.56 in anticipation of going to 35" tires. Rig will see Limited trail use and be used mostly cruising back roads and running to Wal Mart.

So my question is, will I have to change the carriers out or can I get thick gears to compensate?

Also want input on what y'all think of the ratios I'm considering?

 

[mtnwhlr]

I would go 4.11s and yes you will need to change carriers. The T-4 is going to be the weak link.

 

[Turd Ferguson]

Weak link? In what way? Suggested upgrade?

I'm a Bronco guy that's just testing the Jeep waters. I had the NP 435 in my last Bronco and really liked it.

 

[mtnwhlr]

The T-4 and T-5 is a light duty Transmission that doesn't hold up well to big tires and heavy use.

 

[gert]

Weak link? In what way? Suggested upgrade?



I'm a Bronco guy that's just testing the Jeep waters. I had the NP 435 in my last Bronco and really liked it.

A 435 is a very beefy Transmission if you have one of those it would make a great swap in the future when the T-4 pops


Take a look at Novak’s page they will tell you a lot of what you want to know

https://www.novak-adapt.com/knowledge/transmissions/manual/


Sent from my iPhone using Tapatalk

 

[jp360cj]

What gears do you have now? The AMC20 carrier break is 2.72/3.08, so unless you have 2.72s (which are common for an 82 AMC 258 i6 / 4.2l ), you won't need a rear carrier. I don't know if there are thick cut gears for the CJ Dana 30 or not.

I like my 4.10s with 35s and my 360 on the street and trail. I can run 60-65 mph without at problem ~2500rpm. I'm not sure how the 258 does with 4.10s and 35s though.

As far as the Transmission , If you liked the NP435 and think it will be a good match for how you use your Jeep, then it would be a great swap option. The Ford version will bolt to the 258 with a CJ T-150 or T-176 bellhousing. Or you may be able to modify your T-4 bellhousing, not sure. You can adapt to your Dana 300 with a Novak or Advance Adapters kit, but it runs ~$500. An AX15 5 speed wouldn't be a bad swap either, but you'd probably want at least 4.56s to take advantage of the O/D.

 

[Lumpy Grits]

The model 20 rear is your weak link. To say nut'n of the small brakes it has.
35's are a bit much and would suggest you stay with 33 if you are going to keep the 30/20 combo.
LG