Topic: please chime in if running 33's or 35's with auto and 4.56 gears

[4banged]

 I'm running 31's now and 3rd gear winds out too fast and od bogs down. I'm thinking that 33's with od off would work pretty well but wanted some real world feedback. I'm especially interested in rpm's at highway speed (I've looked at the charts but autos have some slip so I don't trust them).  I went with the 31's thinking I would keep decent highway performance but I ended up with a bad set up and smaller tires then I wanted.
I have a 2" budget boost now and should be able to just add a 1" body lift to get the 33's on.

[Jeffy]

I've run 32's with 4.56's, 33's with 4.56's and 35's with 4.56's.  I like 33's, especially the skinny ones.  35's are a lot heavier and that weight really makes the Jeep feel a bit sluggish when you want to try to pass at highway speeds.  I don't remember the 32's too much but it was peppy.  The thing I don't like about 32's is that they're not a standard size like 31/33/35/etc...

I always liked this applet since it gives you a graph.  http://jeeptech.com/javaAps/Speedo.html  Any slip at highway speeds would be minimal if any.  Easiest way to tell if the graph is accurate is to plot your current setup and see if it lines up with what you experience.

[4banged]

Thanks Jeff, I keep driving myself nuts with this. Its funny...if someone gave me the choice right now of a free regear from 4.56 to 4.88 on my current 31s or free 33" tires on my current 4.56 gears I honestly don't know which I would pick. I know I'm not happy on the highway now...I can't really cruise at 65-70 even on slight inclines without alot of od on/off aggravation. I feel like going with the 33s would work much better cruising in 3rd on highway but the downside is I lose od all together and lose a little performance around town. I know the regear to 4.88 is a relatively small change (7%) but I actually think it might be enough to make highway driving much better because it feels like I'm just barely out of the power band. If I could do the regear myself for cost of the gears I think i'd go that way, but to spend $1,200 and end up still not being happy would be really bad. I really don't want to sell it and start over...frustrating.

[Jeffy]

Thanks Jeff, I keep driving myself nuts with this. Its funny...if someone gave me the choice right now of a free regear from 4.56 to 4.88 on my current 31s or free 33" tires on my current 4.56 gears I honestly don't know which I would pick. I know I'm not happy on the highway now...I can't really cruise at 65-70 even on slight inclines without alot of od on/off aggravation. I feel like going with the 33s would work much better cruising in 3rd on highway but the downside is I lose od all together and lose a little performance around town. I know the regear to 4.88 is a relatively small change (7%) but I actually think it might be enough to make highway driving much better because it feels like I'm just barely out of the power band. If I could do the regear myself for cost of the gears I think i'd go that way, but to spend $1,200 and end up still not being happy would be really bad. I really don't want to sell it and start over...frustrating.

Just to make sure, you have a 2.4L with a 4-speed auto?

[4banged]

Yup, I have the 2.4l with 4 speed auto but I think that the older 2.5l auto was only a 3 speed with 3rd being the same 1:1 ratio as my 3rd gear. I've got plenty of power . . . I can wind out 3rd to like 75mph at 4k rpms even up hills but there's no good cruising speed ... if i try to go slower say 60-65 in od it bogs down even quicker at slight inclines (then harsh kick to 3rd, rinse & repeat) and I can't really just keep od off because i'm over 3k rpms doing 60 mph in 3rd.

[stan98tj]

I just regeared to 4.56 with 33s. I have a 2.5l auto 3spd. We're still in the middle of the swap, I should be driving the jeep later this week. I'll let ya know how it handles. I settled on this gear ratio after talking with 2 other members on this forum with 3spd autos and 33s with their jeeps as daily drivers. They both agreed this ratio was best. Took me a while to finally settle on it, but most of the research I did indicated 4.56 would be best for the autos. I'm not too sure if there would be a great difference in your application given the 2.4 and 4spd auto.
Are you throwing in a locker? Do you have a Dana 35 in the rear?

[sharpxmen]

Thanks Jeff, I keep driving myself nuts with this. Its funny...if someone gave me the choice right now of a free regear from 4.56 to 4.88 on my current 31s or free 33" tires on my current 4.56 gears I honestly don't know which I would pick. I know I'm not happy on the highway now...I can't really cruise at 65-70 even on slight inclines without alot of od on/off aggravation.

i would go 4.88 if that's the case - just based on what you describe, i have a manual.

what's your rpm in o/d at 70mph? (just so i can get a comparison with my manual)

[4banged]

I just regeared to 4.56 with 33s. I have a 2.5l auto 3spd. We're still in the middle of the swap, I should be driving the jeep later this week. I'll let ya know how it handles. I settled on this gear ratio after talking with 2 other members on this forum with 3spd autos and 33s with their jeeps as daily drivers. They both agreed this ratio was best. Took me a while to finally settle on it, but most of the research I did indicated 4.56 would be best for the autos. I'm not too sure if there would be a great difference in your application given the 2.4 and 4spd auto.
Are you throwing in a locker? Do you have a Dana 35 in the rear?

I have the 30 in front and 35 in rear and I was thinking about a locker in the front eventually (probably a Spartan that I would install myself). To tell you the truth I'm holding off on any offroad mods until I'm happy with it on the road. Please let me know how you like your setup once your rolling.

i would go 4.88 if that's the case - just based on what you describe, i have a manual.

what's your rpm in o/d at 70mph? (just so i can get a comparison with my manual)

I'm at about 2,750 rpms at 70 in od but the 2.4l squerells don't start getting really angry until 3,000 rpms so I'm almost there. I'm really happy around town and the 4.88 would only make that better. On the other hand, I'm seeing gently used 33" tires for like $500 on Craigslist so that would be a lot cheaper then regear (I can sell my nice 31s and maybe only spend $200 in the end). I'm still worried hat 33s on steep hills on highway might bog down...then I'm looking at a kick to 2nd gear.

[4banged]

Ive got another idea, I can look for 2 really cheap 33" tires on craiglist (no tread is fine) and throw them on the back and see how it does on the highway in 3rd with od off.

[stan98tj]

I have the 30 in front and 35 in rear and I was thinking about a locker in the front eventually (probably a Spartan that I would install myself). To tell you the truth I'm holding off on any offroad mods until I'm happy with it on the road. Please let me know how you like your setup once your rolling.

I'm at about 2,750 rpms at 70 in od but the 2.4l squerells don't start getting really angry until 3,000 rpms so I'm almost there. I'm really happy around town and the 4.88 would only make that better. On the other hand, I'm seeing gently used 33" tires for like $500 on Craigslist so that would be a lot cheaper then regear (I can sell my nice 31s and maybe only spend $200 in the end). I'm still worried hat 33s on steep hills on highway might bog down...then I'm looking at a kick to 2nd gear.

The advice I've been given my many ppl, including the 4x4 shops when I was shopping around for a price was not to put ANY money into a dana 35 because of how weak the axle is. A buddy of mine (who has been helping me with my swap) has gone through 4 of them (2 times were due to a heavy foot, the other 2 were regular use). The fact you are looking to run 33s on there should be a point of caution. I wheeled carefully with the 33s on my dana 35 but I often opted out of sections of the trail for fear of blowing the rear. Another concern would be your front end. Some of the shops I was talking with were telling me 4.88 is really pushing the limit with the dana 30. Not a lot of tooth for it to grab onto. Also, the front axle being a low pinion axle means they turn in such a way that pinion is pulled rather than pushed in when driving.this can be a point of failure. A high pinion axle would take care of that. They can be found in XJ front ends and would fit your gears. I found out kind of late about that otherwise I would have done it, but my gear guy kind of put me at ease saying you're only at 4.56 and not pushing too too much power with that motor. Front high pinion dana 30 could be found for around 100 bucks. Your gears and locker should fit in no problem (if i understand that correctly). Given your extra gear (4spd auto) it could make 4.88s possible, OR make 4.56 perfect given that you have an extra gear to use. What ratio do you get when you use a gear calculator? Mine came out to 4.32 or close to that figure which is why i went with 4.56 since 4.32 doesnt exist. Some members may disagree with the stuff I posted, but this is the slew of advice I received when I was looking to regear.

[4banged]

The advice I've been given my many ppl, including the 4x4 shops when I was shopping around for a price was not to put ANY money into a dana 35 because of how weak the axle is. A buddy of mine (who has been helping me with my swap) has gone through 4 of them (2 times were due to a heavy foot, the other 2 were regular use). The fact you are looking to run 33s on there should be a point of caution. I wheeled carefully with the 33s on my dana 35 but I often opted out of sections of the trail for fear of blowing the rear. Another concern would be your front end. Some of the shops I was talking with were telling me 4.88 is really pushing the limit with the dana 30. Not a lot of tooth for it to grab onto. Also, the front axle being a low pinion axle means they turn in such a way that pinion is pulled rather than pushed in when driving.this can be a point of failure. A high pinion axle would take care of that. They can be found in XJ front ends and would fit your gears. I found out kind of late about that otherwise I would have done it, but my gear guy kind of put me at ease saying you're only at 4.56 and not pushing too too much power with that motor. Front high pinion dana 30 could be found for around 100 bucks. Your gears and locker should fit in no problem (if i understand that correctly). Given your extra gear (4spd auto) it could make 4.88s possible, OR make 4.56 perfect given that you have an extra gear to use. What ratio do you get when you use a gear calculator? Mine came out to 4.32 or close to that figure which is why i went with 4.56 since 4.32 doesnt exist. Some members may disagree with the stuff I posted, but this is the slew of advice I received when I was looking to regear.

I'm not planning on doing any really crazy offroading and I've heard that the d30 and d35 are okay up to 33's . . . 35's would almost certainly break something. The gear charts are a good place to start but they don't take into account the added mass of the larger tires and they are usually talking about sweet spots for 8 cyl engines . . . as you know, our 4 bangers don't wake up until the higher rpms so it's even tougher to find that perfect compromise between power and rpms. And in reality, my jeep came stock with 4.56 gears and 28.5 tires based on the .69 od so it's different then the yj 3 speed that was geared for 3rd gear 1:1 (I don't have the ability to go to say a 5.13 with my axles). How do you like your 33's and 4.56 gears?

[sharpxmen]

I'm at about 2,750 rpms at 70 in od but the 2.4l squerells don't start getting really angry until 3,000 rpms so I'm almost there.

i wouldn't mess with that to be honest, sounds very reasonable imo

[stan98tj]

How do you like your 33's and 4.56 gears?

I'll prob be finishing the swap early this week. I'll let you know asap. Again, even on 33s a dana 35 can become compromised. A lot of ppl just say don't waste money on it at all. With the new gears and 33s you are prob at some point be tempted to take it off road esp if you are thinking of running a locker front (don't even dream about locking that 35). If you were staying on 31s or even 32s I would tell you just to be careful but I wouldn't lie to you and pretend I didnt wheel the hell out of my jeep when it was on 31s; so in your case which includes mostly road driving and occasional (maybe rare?) wheeling you would be fine. Of course you could always go with a 33x10.5 which would reduce the overall weight of the tire and reduce the strain on that axle (prob help with the gearing as well).
I used a calculator like this one:
 http://www.rocky-road.com/calculator.html
and this one:
http://www.jeep4x4center.com/calculators/index.htm
there are others which get more involved and allow you to insert your actual transmission such as this one: http://www.manoian.net/jeep/gear_ratio_calculator.html
Again, your extra gear COULD make 4.88 a better choice or 4.56 a better choice. Just beware that 4.88 is sort of pushing it with a low pinion front axle.

[stan98tj]

Please let me know how you like your setup once your rolling.

99% done. Got the axle in and everything tightened up. The jeep is totally drivable now. I put on about 80 miles on it and have to say the power is there with the new gears. My speedo is still WAY off so I'll have to address that. 72-74mph seems to be 65mph and i'm right around 3100-3200 RPM at that speed. I'll be wiring the locker up tomorrow or this weekend and hopefully hitting the trail and that will give me a full idea of the 4.56 on the trail and street.

[4banged]

99% done. Got the axle in and everything tightened up. The jeep is totally drivable now. I put on about 80 miles on it and have to say the power is there with the new gears. My speedo is still WAY off so I'll have to address that. 72-74mph seems to be 65mph and i'm right around 3100-3200 RPM at that speed. I'll be wiring the locker up tomorrow or this weekend and hopefully hitting the trail and that will give me a full idea of the 4.56 on the trail and street.

Thanks for the update. So do you have enough power now to hold 65 up hills or do you kind of get a running start? I haven't done anything and I may not...I like having overdrive on flat or down hill and when I think about it I can climb steep hills in 3rd at 65 without winding it out too bad. It's always going to be a compromise for me with such a big gap between 3rd and 4th no matter what. Even if I regeared to 4.88 and stayed on 31s it would help me use od more but 3rd would wind out quicker. Think I just need to get used to what I have but I like knowing I could go to 33s and forget about od as an option.
Thanks again for update...glad you like it!