Who has 3.73s with V-6?

I am thinking of swapping to 3.73s in my Jeep. Just wondering how you guys with them like them. I have 5.38s now, and its nice to be able to crawl, but I also have a T-98 so I can make up the difference with Low gear. Really I am wondering how those gears work off road for you. I run 33's and don't plan on doing any real rock crawling but would appreciate the highway speed without the 3xxx RPMs. I already have a rear axle with 3.73s in it, so thats a no brainer easy swap. Would just have to rework the front.

Your thoughts???

 

id say if you do go with that rear with the 3.73 why not go with a d30 front some years were common with 3.73's

 

I've got that combo, and with 33s I can cruise at 70 - 75 MPH on the freeway in 3rd no problem. I don't have much off-road exp with 'em tho.

 

I actually have a dana 30 with 3.73s in it, but I think the carrier or a side gear is broken.... I also have another D30 with 2.73 IIRC. And a Dana 27 with 3.73s. I am after a dana 30 with disks though.....Or I could graft disks onto that model 27.... this is the dilemma after I decide to go with 3.73s.

 

Got V6, 3spd, 3.73's. Going to 4.27's as soon as I can. .

 

have 225, T18 low first, 3:73, 34 inch rubber. Use daily on road 50-55 mph, never enough off road but do venture. My expereince on road is, starting out use first but can use 2nd if flat with minimal clutch slippage, engine really lugs in fourth gear trying to hold 50 on slight grade and have to downshift to 3rd, engine may be a little tired. Do able if flat and also 3rd plus overdrive works well. Off road, low range 2nd, 3rd and 4th gear works great. Real steep rock could use lower axle gears.

 

have that combo (w/28" tires), wish i was a little slower on trails. plan on going 4.27's next winter.

 

Back in another life, when I was doing a lot of off road jeeping (1970's-1980's), I had a 1971 basically stock 225 V6 CJ. This jeep had 3.73 gears, T14 tranny, single lever transfer and 31.50 x 15 Desert Rats. Did lot of hill climbing and really rough climbs through the upstate of SC and Parts of NC and GA. Never had any major problems with the drive train or its ability to negotiate most trails in 4 wheel drive. Traversed some pretty rough trails at the time before the government closed a lot of the roads in the area.

Drove this same jeep across the us and back across Canada during one summer. Was able to get around 18 miles per gallon average on the trip. I was pulling a 1/4 ton army trailer with camping gear.

I also had a 1952 M38 military with 225 V6 and 4.11 gears with same tranny, transfer and tires. Very little difference in off road ability and road milage. Drove this Jeep to Colorado with same trailer and gear. Milage was in the 17 range.

The only thing that did fair very weel was the tires. They were great for off road but did last very long on the highway. Money was tight and couldn't afford 2 sets for each Jeep.

Hopes this give you some info about this gear ratios ability.

 

Thanks gents. I am thinking I'll go witht he 3.73s, especially since I already have axles with them in them. Then I can use my overdrive on the willys truck

 

Brannon - I've got 3.73's in Lulu. I've driven her at Tellico several times now, with no problem. Sure, it's not a "super-crawler" or anything, but I've never thought to myself "Boy, I sure wish I had lower gears". I'm running 32's, by the way.

Edit: I should also clarify that I'm running the stock T-14 3spd.

 

It's be worthwhile to compare the crawl ratio of various Jeeps, normalized to tire size. The easiest to calculate, and most realistic IMO, would be crawl speed at 1000 RPM. For example, my truck has a T15 (3.0:1 1st), Dana 20 (2.03:1 low range) and 3.54 gears. My crawl ratio is 3.0*2.03*3.54 = 21.6. You can also use the Novak gearing calculator http://www.novak-adapt.com/knowledge/gearing.htm to find your crawl ratio.

My tire height is 27", so that means pi*27 = 84 in/rev. My normal crawling speed would be 27*pi/12/5280*1000*60/21.6 = 3.72 mph.

More simply, <tire height> * 2.975 / <crawl ratio> = <normal crawling speed>

m38willys has a crawl ratio of 57 with 3.73s, and a normal crawl speed of 1.7 mph - pretty darn slow.

IMO a crawl ratio of better than 50 with a CJ should be good enough for everything except all-out rock crawling. My '73 had 4.27 gears with a T15 (crawl ratio 26, crawl speed 3.5 mph), and was fine for the stream beds and talus slopes that I frequented.

Of course, different uses will require different gearing. For hill climbing or sand dunes (for example), you wouldn't care so much about the ultimate reduction, and instead about whether you can pick the gear you need to keep you in the power band at the speed you need to keep from getting stuck.

 

Thanks Tim, and all else for the input. I think 3.73s are the way to go for me....

 

I have a D27 with 3.73's that I am looking to sell if you are interested?

 

I have 3.73's and a V6 but I have a TH400 automatic. It seems to work OK except jumping into gear because of no source for the correct torque converter for this setup. Once you are going it works great.

Josh

 

I have one also, but thanks for the offer. I am really just debating now on whether to convert the D27 to disks using my D30 disk stuff, or regear the D30 to 3.73. Man its tough to be cheap.....

 

One more data point. I have (had) 3.73's and a T14. Not low enough for me - forced me to go over stuff faster than I woulda like to in low and overdrive is fairly useless at speeds I feel safe driving. As long as your not worried about the crawl ratio too much and you're putting the overdrive elsewhere though - cheep is good.

 

The 6.4 1st gear of the T-98 will make the difference I think. I hope. I never had that low a first gear in any other CJ that I off roaded with and never really was unhappy before so this should work out OK.

 

4.09s or 4.27s would be a good compromise. I found the 4.27s with 31s quite ok on the street, and I would commute to work at 70-75 (v. early in the morning) and drive to the desert and back almost every other weekend. Turning 3K with other than the F4 isn't a problem. Makes a lot of noise, but any of the modern engines will turn 3K to 4K all day. My VW and my truck both turn 3K at 70 mph, and I would not hesitate to run either at that speed. I drove the VW at 85 mph on the NJ turnpike from Delaware to the Garden State Parkway, and it was loafing along at just under 4K. Not a problem for a modern engine.

If the noise bothers you, get an electric fan and add some insulation in the floor.

<deit> BTW my CJ-6 with a hard top had 3.73s, and I was often going for 2nd on long grades. IMO 4.27s would have been better. Remember that power = torque * RPM; increased engine speed means more power, till you reach the point where torque starts to fall off.

 

Personally, I would consider keeping the low gears and spend the money on an overdrive. I would imagine it would be cheaper than having somebody re-ring your axles, escpecially since you could install the OD yourself.

I've got a V6, T14, 3.73s, and 32" swampers, and it's a little weak on the highway (N GA with lots of hills). I am going to a higher axle gear as soon as I can. Jus my .02

Jon