4.27 or 4.30 gearing is also an option for Dana 44 and 8.8 differentials only and might be suitable for that tire and transmission. If you have a front Dana 30 that ratio is not currently available to my knowledge
Will a 32RH work well with 4.88 gears and 35s?
- Thread starter Eddie Greenlee
- Start date
OP
I have a 32rh, 4.88 gears and 35" tires. 65 mph is around 3100 rpms. I plan on regearing to 4.56 soon so 70 can be 3100 rpms.
OP
Look back a few posts. The factory ran it much higher.
I am currently on that combination. It’s okay around town but lacks freeway merging power. It’s livable on the freeway if you don’t mind cruising at 70 or less and the 12 mpg that comes with almost 3000 rpm. At elevation the lack of gear selections is quite apparent. Mountain passes are long second gear, high 2000’s rpm grinds. Definitely a comprise setup vs the other options with an overdrive. It’s livable enough that I’ve driven mine on four 3300+ mile trips out west and would do it again. As far as low range, first low is good enough for crawling around on rocky stuff and has good engine braking. Second gear low is okay for mildly rough trail and seems to allow the torque converter to make good use of the low rpm grunt from our tractor-like 4.0 liter. Second low does not have very good engine braking. The difference in engine braking and top comfortable speed between first and second low is bit too much for my liking. Second runs away and first just creeps along.
Oklahomacheapjeep
Member
4.10 is generally the recommended ratio for 33s with the 32rh. a higher ratio would probably be better.
Amen. I was all over it as well, even talked to SilverStar. My 03 is a manual...my 06 is an auto. Thankfully our Rubi 4:1 transfer cases make the manual very workable, but the auto allows you to concentrate on the obstacle entirely.
I nearly sold my 03 to get one I found, but is was so badly built and had a snorkel cut into it, it just wasn’t my type TJ and the cost to rebuild made it prohibitive.
I eventually ran into a cool, very very sound, mostly stock Rubi with an auto and 78.000 and wheel it the most.
All that to say I don’t know what I was thinking buying a manual, autos were rare and on the tree, sort of looked down at in the CJ days.
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I did the exact same conversion to a 32RH with my previous TJ that had 35's and 4.88 gears for its original 5-speed manual. It was AWESOME, all I did differently afterward was slow my highway speeds down a tad from 65-70 to 55-65 in the slower lanes with occasional runs at 65-70 to keep up with traffic in the slow lane. The rpms are absolutely not even close to an issue for the 4.0 so don't let the rpms alone dictate your decision.
If your TJ is primarily a highway cruiser I might not but if it's primarily for fun with occasional highway trips I wouldn't hesitate. Slowing my cruising speed down a tad was no big deal and I often took 250-500 mile trips in it.
If your TJ is primarily a highway cruiser I might not but if it's primarily for fun with occasional highway trips I wouldn't hesitate. Slowing my cruising speed down a tad was no big deal and I often took 250-500 mile trips in it.
Say that about a different transmission and you'll have people worried about blowing the same engine up.
If it’s any value I just regeared to 4.56 with 35s and a 32RH and it’s really good everywhere. 4.88s might be better if I was serious rock crawling...might be better is the key word. I drive mine for much much more and I personally think 4.88s would be screaming trying to run down the highway, the 4.56 is already revving pretty good at 65-70.
OP
Thanks Jerry. I really want to get it even though it has to be overhauled. Id love to try it .
The biggest driveability issue I see with 4.88 and the 32RH is that 2nd gear is not usable at higher freeway speeds. You would be relying on 3rd gear at 3100-3300 RPM to climb hills and pass people as well as to cruise. With 4.10, you can easily downshift at 70-75 mph to 2nd and run right in the powerband at around 4500+ RPM to climb hills and pass with ease.
What years were they, and what all had to be done ...and did everything work, gauges etc. I would imagine it was great. I’d rather have an auto that winds one a tad tight than the lazy 42LRE if i swapped one in anyway.
OP
So your telling me 4500 rpms is in the powerband???? ive never run my tj at 4500 rpms
Then I'd suggest you try it out.....
I don't suggest your run your 4.0 @ 4.5K rpm's for a long time but it can be done to pass someone or to climb a steep hill. There are always going to be times you will need to back off the skinny pedal but it doesn't hurt your engine to run it up above 4K now and then.
OP
You can simulate what it would be like to have the 32 RH by just driving your rig in 4th which would be 3rd gear in the auto. That will tell you what it would be like.
And 2nd gear in your AX-15 is 2.33 just like 2nd in the 32RH so you can see what that is like also. Use the GrimmJeeper gear calculator to see what your RPM's will be.
Yup. Peak torque is in the range of 3000-3500 RPM. Peak power is around 4500 RPM.
At a given road speed, you will put the most torque to the wheels in whichever gear gets you closest to peak power. For all TJ transmissions, this basically means whichever gear gets you closest to redline without exceeding it.
(Within a given gear, you will put most torque to the wheels at whatever road speed gets you closest to peak engine torque. However by downshifting, although you lose some engine torque, you gain some gearing advantage that multiplies the torque to the wheels.)
If you need to merge or accelerate really quickly, floor the pedal and shift at 5000-5200 RPM. Once you reach your crising speed, upshift to a more relaxed RPM. Be aware there is a slight lag on the tachometer when the engine is spinning up quickly.
Sane applies to climbing long, steep hills. Keep downshifting until you find a gear that allows you to hold a speed you want. Go as far as you need to as long as you don't pass redline.
I've never driven a 32RH so I don't know but doesn't it have a kick down gear like more auto's? So when in 3rd and you need to accelerate more you tromp on it and it kicks down but it isn't shifting into 2nd gear? Does it have a lockup torque converter?