My tires are loud so I added an amplifier to the stereo system
Is 33s on a stock 2006 TJ with 3.73 gears asking for trouble?
- Thread starter CMTJ
- Start date
I think your Jeep looks just like I'd like mine! All I have to go is 33's and 4.56 gears. May try with my 3.73 6-speed for awhile...Thanks for sharing. What an improvement...
Yours with 4.56 will actually be identical in performance to 33's with 4.88 in the 5-speed. Let me know how you like it, because I want more opinions on 4.88 with 33's and the 5-speed.
I've driven it once and loved it but would another opinion, if it's available. Keep us posted when you finally regear.
4.56's with the 5 speed is perfect for me. I DD mine, so I need it to be friendly on the tarmac.
Bob Darenberg
New Member
That is my target rpm. Did you have the speedometer recalibrated? If not your probably doing at least 70mph.
jeepndogs
TJ Enthusiast
Keep in mind that 4:88 gears with 33's and the 42rle trans has potential to cause vibrations at speeds above 60. There are quite a few of us that have not been able to eliminate it after the gear change. To be honest adding the 4:88 gears to my Lj has been the worst mod I have done because of the vibration. What started as a simple gear change that is as you can see highly recommend turned into spending days upon days inbthe garage, 3-4K additional cost to try to eliminate a problem that came from the higher driveshaft speeds, and I still can't drive the jeep on the expressway with the front driveshaft in it. My only solution is going to be doing a locking hub conversion so I can stop the frontnshaft from spinning, by the time that is said and done I will have another 3k spent because of the gear swap.
He is accurate. With 4.56 it goes:
2500-2550 at 65
2700-2750 at 70
2900-2950 at 75
All depends on the variable of how tall your tire actually is. His is spot on with the norm.
That all sucks big time. However, 4.88 and 4.56 are a very small difference between each other, only 6%. Let's say you get vibes at 60 mph, 4.56 would get the same exact vibes at 66 mph. Going from stock 3.73 up to the bigger numbers is a large difference in how much more that driveshaft has to spin now.
It seems some people get lucky and some people get unlucky. Unfortunately you can't really predict who will end up with what and if the guy in question chose 4.88 and ends up with vibes, he would have ended up with the same vibes with 4.56 once he increased his speed just a few mph.
jeepndogs
TJ Enthusiast
This is true, however any time you see anyone recommending gear swaps you never hear any mention of the vibration problem that can be associated with the 42rle trans and the higher gear ratios. When the problem comes up you have a lot of people commenting that it's somewhat of a common problem. Information like that is good to know prior to making the decision. Even more so if the op is looking for a daily driver that will see expressway speeds.
I have the 42rle, geared to 5.13, for 33's. I had some vibrations, and found out my driveshaft was bent. I had a new one built, and now my jeep is vibration free.
jeepndogs
TJ Enthusiast
There are a lot of guys running higher gears and no vibration, there are also a lot that can't get rid of the vibes and have gone with lockout hubs. It is hit or miss.
I have ran 4 different front shafts, two sets of tires, rims, mounts, control arms, axel shafts, 100's of different pinion angles and still have the vibration.
Had I known then what I know now I most likely would have kept a 31in tire on the jeep.
Jeepersteve71
TJ Enthusiast
I have an 06 LJ. We have a 2 inch suspension and 1 inch body with a 1 inch motor mount lift. Factory 3.73's and 33x10.50x15. Drives with no issues. Get it in 6th gear just about every time we drive it. The speedo is 5 mph off. Could buy a $250-$500 programmer to take care of that but we just do the math instead lol.
Jeepersteve71
TJ Enthusiast
If so post the link! I'm obviously a newb lol. I have an SYE brand new in the box sitting in the garage. Waiting to install it until this winter. That and I still need to pick up the driveshaft.
Yeah, TJs don't use programmers for the speedometer. They use speedo gears, unless it's a Rubicon.
In the case of a Rubicon, you wire in a converter box and then following its instructions, you end up doing things to the converter that set up proportions to fix your speedo based on the input and it gives you a actual speed based on math.
I posted a chart for figuring out your gear, but actually I haven't found that chart to be accurate for 3.73 and higher (lower number) gears. I just posted it so you'd have it. I had 31's and 3.55 and so I went with the 32 tooth gear. It was off by 3 mph (75 was actually 72) which means I actually needed a 33 tooth gear to slow the speedometer down a tad.
33" and 3.73 is actually very close to the 31" and 3.55 combo that I had so I'd either get a 32 or 33 tooth gear. 32 would be most accurate for now, but 33 would become more accurate as the tires wear down. It's not too critical.
You can buy them at places like Morris4x4, Quadratec, Amazon, eBay, etc. The best place to go was the dealer for years and years but my dealer can't ever get the one I need so I don't bother there anymore. They were like $12 at the dealer compared to the $30-40 the sites sell them for.
Jeepersteve71
TJ Enthusiast
Interesting. Thanks for the chart! Still considering re hearing one day. I'll have to check this out and hang on to it!
It is likely a combination of many things; faster drive line speeds, steeper drive line angles, larger tires and wheels, completely different suspension, etc. Unfortunately for your situation you have been unable to nail down the issue.
KMET
TJ Enthusiast
What they said. Your Jeeps looks fine.
At least you're not one of those people who bolt-on a lot of useless crap.
Nice Jeep Lee. With age comes since of practicality, I'll be there soon.
What I find so strange about your particular case is how the problem is with the front drive shaft...don't most people's vibration issues after a lift/regear stem from the rear DS?