5.13 Strength vs 5.38
03-20-2017, 07:43 PM
#1
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5.13 Strength vs 5.38
My prorock 44 has been holding up great but my 3.8 hasn't. A v8 swap isnt an option right now ( and neither is a front 60)and do not want to supercharge a 200k mile old engine. My setup consists of a PR44 (front) with 5.13 gears, RCV shafts, ARB, Reid knuckles and dynatrac BJ's. Rear is a 60 but chromoly shafts. My Question is will going to 5.38 gears weaken by setup significantly? I have a feeling im pushing my 44 as it is...
Last edited by blowermax; 03-20-2017 at 08:11 PM.
03-20-2017, 08:15 PM
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Yeah a v8 would be awesome. Sounds like you got a lot out of the ol 3.8 though. 200k? Maybe a cheap low mile pick up from somewhere or a rebuild. Last another 100k or maybe even another 200!
Anyways, everyone I know has either 4.88 or 5.13's. The debate about the 5.38's and strength never stops. I see it sort of like 4.88's being the stopping point for the d30. I thought dirtman had once run 5.38's in a 44 but that was probably in a d60
or mabye he told me he wanted 5.38's...
Anyways, everyone I know has either 4.88 or 5.13's. The debate about the 5.38's and strength never stops. I see it sort of like 4.88's being the stopping point for the d30. I thought dirtman had once run 5.38's in a 44 but that was probably in a d60
or mabye he told me he wanted 5.38's...
Last edited by silverbullet88; 03-20-2017 at 08:31 PM.
03-20-2017, 08:22 PM
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its a oil leaker but its a runner! When I blew my trans I didnt have to money to rebuild it, so I drove it for 2 years in second gear only...I know its limits lol!! i can do 65 mph in second gear @4k rpm with 37s and 4.10s LOLOLOL
03-20-2017, 08:30 PM
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That is seriously one of the funniest thing's I have heard in awhile. Not that you couldn't afford it but the fact you drove in 2nd gear for 2 years!!! Damn. Dude that has to be some sort of record. My 3.8 has no leaks but it likes to drink the oil.
03-20-2017, 08:44 PM
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it got great gas mileage even tho the rpms were through the roof, I was using all gears and not really relying on the engine.
03-21-2017, 06:08 AM
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For the 3.8 Auto on 37s the 5.38s are perfect. 60mph at 2200rpm all day long and still get 17-18mpg. The 3.8 sweet spot is about 2100rpm and since all the highway speed limits around here are 50 or 55mph it's perfect. Over 50,000klm on my 5.38 with no issues and still whisper quiet. And 266,000Klm on the 3.8 and tranny.
As much as the 3.8 can feel underpowered with poor factory gearing, when properly geared it has more then enough power to get the job done. That and when I see all the issues local club members have had with their 3.6 pentastars (4 to 1) I am really happy with how that old 3.8 has held up.
As much as the 3.8 can feel underpowered with poor factory gearing, when properly geared it has more then enough power to get the job done. That and when I see all the issues local club members have had with their 3.6 pentastars (4 to 1) I am really happy with how that old 3.8 has held up.
Last edited by jtphoto JK; 03-21-2017 at 06:17 AM.
03-28-2017, 11:03 AM
#7
Sponsoring Manufacturer
My prorock 44 has been holding up great but my 3.8 hasn't. A v8 swap isnt an option right now ( and neither is a front 60)and do not want to supercharge a 200k mile old engine. My setup consists of a PR44 (front) with 5.13 gears, RCV shafts, ARB, Reid knuckles and dynatrac BJ's. Rear is a 60 but chromoly shafts. My Question is will going to 5.38 gears weaken by setup significantly? I have a feeling im pushing my 44 as it is...
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03-28-2017, 04:33 PM
#8
JK Jedi
Yeah a v8 would be awesome. Sounds like you got a lot out of the ol 3.8 though. 200k? Maybe a cheap low mile pick up from somewhere or a rebuild. Last another 100k or maybe even another 200!
Anyways, everyone I know has either 4.88 or 5.13's. The debate about the 5.38's and strength never stops. I see it sort of like 4.88's being the stopping point for the d30. I thought dirtman had once run 5.38's in a 44 but that was probably in a d60 or mabye he told me he wanted 5.38's...
Anyways, everyone I know has either 4.88 or 5.13's. The debate about the 5.38's and strength never stops. I see it sort of like 4.88's being the stopping point for the d30. I thought dirtman had once run 5.38's in a 44 but that was probably in a d60
or mabye he told me he wanted 5.38's...Right now I have 5.38 in my PR60/80 combo
03-29-2017, 06:41 AM
#9
Former Vendor
I'd take up that offer to chat with Dynatrac, they won't steer you wrong!
If it were me, I'd stick to 5.13s. That doesn't mean that you can't get away with 5.38s, but yeah, you are sacrificing some strength. If you're thrashing it, it would be only a matter of time.
If it were me, I'd stick to 5.13s. That doesn't mean that you can't get away with 5.38s, but yeah, you are sacrificing some strength. If you're thrashing it, it would be only a matter of time.
03-29-2017, 07:45 AM
#10
JK Enthusiast
For the 3.8 Auto on 37s the 5.38s are perfect. 60mph at 2200rpm all day long and still get 17-18mpg. The 3.8 sweet spot is about 2100rpm and since all the highway speed limits around here are 50 or 55mph it's perfect. Over 50,000klm on my 5.38 with no issues and still whisper quiet. And 266,000Klm on the 3.8 and tranny.
As much as the 3.8 can feel underpowered with poor factory gearing, when properly geared it has more then enough power to get the job done. That and when I see all the issues local club members have had with their 3.6 pentastars (4 to 1) I am really happy with how that old 3.8 has held up.
As much as the 3.8 can feel underpowered with poor factory gearing, when properly geared it has more then enough power to get the job done. That and when I see all the issues local club members have had with their 3.6 pentastars (4 to 1) I am really happy with how that old 3.8 has held up.
Sorry man but 17-18 mpg on 37's with the 3.8????? You are definitely driving a Unicorn. I have the 3.8l with a Sprintex SC with 5.38 gears on 40's and I get 8-9mpg. Currently swapping in a 6.0l V8 from RPM. I have 6 friends with pentastar JK's (including my wife) and the 3.8 is the most embarrassing motor ever with the worst transmission you could possibly pick out for a Jeep. A stock Jeep might... and I mean might get 17-18 but a JK lifted with the areodynamics of a brick wall rolling 37's with that transmission that can never find the right gear and spends 90% of it's life with the torque converter unlocked is the biggest piece of crap Jeep decision ever made. The guy who chose that should be fired. I think you have to be the first person in history to use the term "3.8l" and has "more than enough power" in the same sentence.
Sorry back on topic...
Unless you absolutely need to change gears I would stay with the 5.13 gears. They are stronger. Why weaken that point for such a little difference in gearing?