Thanks guys. I have been going back and forth on the Grimm calculator. It's not a real big difference between the 2 really. About 152 rpm at 75 mph 3100rpm at 75 for 5.13, a 91 1st gear final crawl ratio vs 87 with the 241.
What's your MPG with large tires and re-gearing?
- Thread starter jeep_boss
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With your 241 I wouldn't worry about the crawl ratio. I'm not so sure I'd like the 5.13 rpms for long at 75.
You're correct - I kept the 5.13 geared D30HP/Dana 44 from my TJ and put them into my LJ. If I were to regear these fresh, I'd probably go with 4.88's since the 0.84:1 OD ratio brings on the harmonic vibes that are common with CV shaft usage at right around 72-73 MPH. Our highways nearby are 70 MPH speed limits and I routinely go 75 MPH to keep up with traffic (I hate having big rigs come barreling from behind and passing me!). The harmonic gets annoying, so I drop to 71-71 MPH to keep it away when I can.
Now that said, it's a NSG and it's gonna do NSG stuff before too long. When it does, I'll AX15 swap and be happy I kept the 5.13's (which is my preferred ratio on 35"s with an AX)
Yeah, good point. If the NSG were a more consistent, well known long lasting trans, then 4.88 would make sense. When it does go and you go the AX route, you'll for sure be properly equipped for that change with the 5.13 just like on the TJ before.You're correct - I kept the 5.13 geared D30HP/Dana 44 from my TJ and put them into my LJ. If I were to regear these fresh, I'd probably go with 4.88's since the 0.84:1 OD ratio brings on the harmonic vibes that are common with CV shaft usage at right around 72-73 MPH. Our highways nearby are 70 MPH speed limits and I routinely go 75 MPH to keep up with traffic (I hate having big rigs come barreling from behind and passing me!). The harmonic gets annoying, so I drop to 71-71 MPH to keep it away when I can.
Now that said, it's a NSG and it's gonna do NSG stuff before too long. When it does, I'll AX15 swap and be happy I kept the 5.13's (which is my preferred ratio on 35"s with an AX)
Good info on the harmonic issue.
My luck I would regear to 4.88s now then my 6 speed would go out. Though it only has about 84k on it. They are definitely not the smoothest shifting manuals with the 1st to 2nd taking some practice to get right. No speed shifting from 1st to 2nd.
My luck I would regear to 4.88s now then my 6 speed would go out. Though it only has about 84k on it. They are definitely not the smoothest shifting manuals with the 1st to 2nd taking some practice to get right. No speed shifting from 1st to 2nd.
I'd definitely be pissed if I built it around one transmission and then ended up needing to swap to a different one and lost 6% overdrive. Would have been nice if the NSG could have had the same .79ish OD that the other two have so that you could gear them all the same.
The driveshaft speed doesn't care about your transmission. If your rig resonates with 4.88 and an nsg370, having 5.13 with the same tires would bring the resonance to a lower speed, even with an Ax15. In that regard, a 6 speed is best because it doesn't tempt you into gearing as deep as the other transmissions do (32RH being the exception).
The overdrive wouldn't be what I would miss the most in an Ax15 swap though. It would be the 4.46:1 first gear. I figure if I ever have to swap I'll probably do a 241 at the same time. I'll have to do something eventually but if it crapped the bed tomorrow I'd have to think on it a lot to decide whether to grab a rebuilt nsg or swap to ax.
The overdrive wouldn't be what I would miss the most in an Ax15 swap though. It would be the 4.46:1 first gear. I figure if I ever have to swap I'll probably do a 241 at the same time. I'll have to do something eventually but if it crapped the bed tomorrow I'd have to think on it a lot to decide whether to grab a rebuilt nsg or swap to ax.
Interesting...
On my TJ and YJ before that, I didn't get the harmonics until ~78-79 MPH and was able to cruise at 80 MPH without being annoyed (anything over 80 MPH it was notable and loud, even with top off). Granted, I did have the driveshaft lengthened a bit to work on the LJ but everything else is the same. I guess in my head I would have expected the harmonic to change to a higher speed with the lengthened shaft, but honestly haven't thought about it much (plus 2nd and 3rd order harmonics are well outside my knowledge zone). On my LJ, I can run 5th gear out until I'm pushing 75 MPH without a notable harmonic (noting that I can just barely notice something if I'm keeping RPM constant for a few seconds, say climbing a grade). However, the instant I shift into 6th, the harmonic starts right up. Also, when cruising in 6th at say 75-80 MPH, I can depress the clutch pedal and the harmonic changes a bit; it doesn't necessarily go away 100% but the frequency and amplitude changes noticeably. My TJ reacted similarly, though obviously at different speeds. This is why I always assumed the transmission was at play with the harmonic...
interesting indeed. yours seems to behave differently than most of the others that report having this issue. Mine keeps right on humming in neutral, clutch in or out in 5th or 6th, as does I think most. And we have examples of people experiencing it with the NV3550, AX15, and 42RLE. There are more NSG370's reporting the oscillating vibration, but it was equal in proportion to other transmissions.
if you don't mind, go ahead and add yours to the data:
https://wranglertjforum.com/threads...providing-some-basic-info-on-your-jeep.59804/
done! I added my YJ info in there as well...
I've actually been toying with the idea of removing my rear CV shaft in my LJ and replacing with a slip-shaft style 2-joint driveshaft.
To clarify - the pulse is still there when I push the clutch in, it just changes drastically. However when gaining speed, it seems to only truly start pulsing/resonating when in OD. It seems like once it starts, it only stops by reducing speed below the resonance rate.
One other interesting tidbit: I did note a few times where the pulse would suddenly disappear as load changed. For example, back in AZ, there was a stretch of highway between Phoenix and Mesa (on the Loop 202 for the locals!) that climbs a slow but steady grade (maybe 1% over 4-5 miles). On more than one occasion, in both the TJ and YJ, the pulse completely stops on this stretch! It wasn't every time - but I definitely noticed it a few times and even noticed it with a passenger inside.
Another interesting tidbit: the pulse changed when towing a trailer (even a lightweight, empty trailer). It would drop the MPH at which the pulse started by ~2-3 MPH with the YJ (I never towed on the TJ to see if that changed the pulse there).
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I know what you mean and glad you mentioned it. I notice the same change between 5th and 6th, but it is such unusual and minor change, that i always write it off as something else like being too picky or road condition gets worse or some other tinfoil conspiracy conspiring to drive me insane with this vibrations. My speeds are lower than yours though.