Upgrade recommendations

[callerys]

I have an 84 CJ7 that is bone stock except for a lift and 33" tires. AMC 258 i6 / 4.2l with T-5 .

I am wanting to make this more highway drivable and reliable. I can't do more than 60 with the altitude here in Colorado.

Looking at doing the following:

4:10 gears in the rear AMC20 and front Dana 30 . (brands to recommend?)

Possible rear locker (recommendations on brands?) Jeep will see medium trail use here in Colorado but nothing crazy. Rest of the time will spend on the streets.

AMC20 single piece axles and beef up? Brands etc?

Dana 300 seal kit (leaks a lot) or just rebuild whole thing?

Has a stock radiator and vehicle has 95k miles. Should I replace this with another stock?

T-5 upgrades? Can I beef this up?

My goal is for it to be reliable and not lugging on the highway here in the mountains given that I am taking my 5 year old son to all these trails.

 

[hole]

How much do you want (have) to spend? Re-gearing is arguably the best since you likely have 2:73's, and it's the best/cheapest time to do lockers and one piece axles while its apart for re-gear.It's also one of the most expensive too. You would also benefit greatly from upgrades such as:
Fuel Injection ( Mopar MPI being my personal favorite)
4.0 Head Swap
AX15 or NV3500 are good T-5 upgrades if you want to keep a 5 speed, otherwise there's a handful of great H/D truck 4spds to choose from.
If you currently have no overheating issues I'd leave the radiator alone, but if you do, look for a stock 3 row to replace yours. Depending how many miles you have on your 7 is whether to rebuild or re seal your Transfer Case . Personally, I'd rebuild and upgrade to 4-1 gears while your at it. As for brands, you'll likely get a few different opinions, but Mosers for one piece axles, Detroit or Yukon for lockers would be my suggestions.

 

[Hedgehog]

Most of what your proposing to do has NOTHING to do with with either reliability or road worhyness. First off the T-5 is an over drive Transmission . If you are pulling hills and such 5th or over drive shouldn't be used at all (except for down hill). Next, regearing is your best option for 33's. You don't need to make a drastic move here though. I'd look seriously at 3.54 gears and as hole wrote above, regearing is expensive, but it would be a perfect time to upgrade to some sort of locker. Be aware, true lockers and paved roads don't get along very well. A selectable locker would be nice, but also very pricey.

Remember, with a T-5 , 4th is your high gear and you can drive all day long in 4th gear with no problems. DRopping into 5th can put your carborator on the power valve and gas mileage will suffer greatly. Over drive can actually give you worse mileage than simply driving in high gear.

 

[ThisGuyUKnow]

I have an 84 CJ7 that is bone stock except for a lift and 33" tires. AMC 258 i6 / 4.2l with T-5 .

I am wanting to make this more highway drivable and reliable. I can't do more than 60 with the altitude here in Colorado.

Possible rear locker (recommendations on brands?)

You contradict and completely cancel out at least one of your stated desired goals here.

I'd possibly even say that, on a CJ, for something I wanted to be streetable I would go no higher than 31s with an appropriate height lift for that tire and 3.54 or possibly 3.74. But then I would probably get an earful from someone out there who DDs 33" tires on the HWY everyday.

 

[IOPort51]

33s are doable but will be kind of gutless without a few engine upgrades. First upgrade should be the ignition system, a couple of hundred here will give great returns. HEI or TFI, anything you do will be better than what you have.

 

[Lumpy Grits]

Go with 4:88 R&P. Get a good LSD diff in the front and rear. You don't want the DL I run on the ice. Add 1 piece Moser axles in the rear.
Is the Jeep over heating now??
The 4:88s will let your T-5 live a long life.
LG

 

[mtnwhlr]

Go with 4:88 R&P. Get a good LSD diff in the front and rear. You don't want the DL I run on the ice. Add 1 piece Moser axles in the rear.
Is the Jeep over heating now??
The 4:88s will let your T-5 live a long life.
LG

I have the same Jeep and up here with 31's it's a gutless wonder I wouldn't even think about running 33's. With a 5th gear I would go 4.10 at least. I want to go 4.56 in mine.

 

[callerys]

Don't have a budget yet. Trying to figure out how much all this will cost first. Figure out what I can do now or what will have to wait.

I currently have 3.31 gears now based on the tag on the rear diff. So probably looking at like 4.10's.

I put on the Howell FI last year and it seemed to help however the altitude is still a killer (6300ft where I live) as I can't really even use 5th gear. I did do the larger dist cap and rotor.

I have been looking at some of the selectable lockers or maybe even LSD. Light to medium trails. Experience with OX or Auburn? I figure if I am going to do a gear change this would be a good opportunity to do something. Is the LSD even worth it or just go to a full locker?

I always hear the horror stories about the AMC20 and the axles so that is why I asked. Is superior or moser better?

Radiator is original (94k mi). No leaks or overheating currently. Should I just get it pressure tested or replace just as insurance? Hate to be that guy on the road or on a trail with a gushing radiator. Or just leave it.

T-5 is getting hard to shift into 1st. I did a gear oil change a few weeks ago and is a little better.

 

[hole]

I havent read anything bad about Auburn and heard great things about Ox. If it were me, I'd stay with a selectable over LSD. When you open the radiator cap and look inside, does it look clean at all the tube openings or is there some crud? If clean, I'd just drain and refill with coolant and distilled water every 2 years until a problem arises. Heard mixed reviews about Superior, more from a CS standpoint, and have even heard they went out of business on another site.
Mosers has been around quite a while and I've heard good things about ECGS (East Coast Gear Supply). What oil/fluid did you use in your T-5 ?

 

[callerys]

I used Lucas 75-90 Synthetic

 

[hole]

There's a handful of oils that work with a T-5 , and some that make things worse. 75/90 syn seems to be one that works

 

[Lumpy Grits]

I have the same Jeep and up here with 31's it's a gutless wonder I wouldn't even think about running 33's. With a 5th gear I would go 4.10 at least. I want to go 4.56 in mine.

Trust me on this-Go with the 4:88 R&P, w/33'' tires and a T-5 . You won't be sorry.
4:10 would be Ok with a V8. Not with the 6. 4:56 is good-4:88 is best w/T-5 .
I have had 4:88s in mine for over 25 yrs, with front and rear Detroit Lockers.
YES- on syn 75W90 gear oil for the tranny. NO, ATF!

LG

 

[Lumpy Grits]

Don't have a budget yet. Trying to figure out how much all this will cost first. Figure out what I can do now or what will have to wait.

I currently have 3.31 gears now based on the tag on the rear diff. So probably looking at like 4.10's.

I put on the Howell FI last year and it seemed to help however the altitude is still a killer (6300ft where I live) as I can't really even use 5th gear. I did do the larger dist cap and rotor.

I have been looking at some of the selectable lockers or maybe even LSD. Light to medium trails. Experience with OX or Auburn? I figure if I am going to do a gear change this would be a good opportunity to do something. Is the LSD even worth it or just go to a full locker?

I always hear the horror stories about the AMC20 and the axles so that is why I asked. Is superior or moser better?

Radiator is original (94k mi). No leaks or overheating currently. Should I just get it pressure tested or replace just as insurance? Hate to be that guy on the road or on a trail with a gushing radiator. Or just leave it.

T-5 is getting hard to shift into 1st. I did a gear oil change a few weeks ago and is a little better.

MOSER are the best!
Leave the radiator alone and put the $$$ into R&P's.
What oil did you put in the T-5 ?
LG

 

[callerys]

Lucas 75-90 Synthetic

 

[Posi]

If its hard to shift, and you changed the fluid, and it only improved a little, baring any mechanical issues chances are the fluid your using is too heavy for your climate.

Try Pennzoil 3501 synthetic 5w-20 they make it for Mopar part # 4874464

Amazon.com: Synchromesh Manual Transmission Fluid, quart (3501): Automotive
​

 

[callerys]

Thanks everyone. I'll post up what I ended up buying!

 

[Lumpy Grits]

Good choice on tranny oil.
How much clutch pedal free play do you have?
You want 1-1/4 inch.
LG

 

[callerys]

Have to check that.