6 speed with 37s on a rubicon

coolcj7

Well-Known Member
Joined
Jul 17, 2019
Messages
53
Reaction score
26
Location
New York City
Vehicle(s)
2020 Wrangler Rubicon 2-door
Vehicle Showcase
1
Haven’t seen this combo yet. Curious how the drivability is. Live close to sea leve but planning a Moab trip in april. Would prefer not to regear in case I get the lifetime waranty but f/r gear sets are only a grand so it’s tempting.

Brett
Hi Brett. I would like to know if you got your setup as you initially wanted: 37" with 6-speed and stock 4.10 on your Rubicon. I am looking into the same exact thing and would like to know from your experience how things are going. i mainly need it for the street and highway. Is it doable? Thanks!





Advertisement

 
OP
rustyshakelford

rustyshakelford

Well-Known Member
Rock Sponsor (Level 1)
First Name
Brett
Joined
Sep 14, 2018
Messages
2,308
Reaction score
2,580
Location
Navasota, TX
Vehicle(s)
2019 JLUR-8 speed 2020 F-350
  • Thread starter
  • Thread Starter
  • #17
Hi Brett. I would like to know if you got your setup as you initially wanted: 37" with 6-speed and stock 4.10 on your Rubicon. I am looking into the same exact thing and would like to know from your experience how things are going. i mainly need it for the street and highway. Is it doable? Thanks!
I lasted about 900 miles before regearing to 5.13s. Was a dog and lost 6th before and drivability. After the regear it drives great and we average 16/17 mpg. Offroad the gears really help too

Brett
 

chevymitchell

Well-Known Member
First Name
Shawn
Joined
Feb 18, 2018
Messages
1,215
Reaction score
2,252
Location
K-Vegas, NC
Vehicle(s)
2020 Rubi Recon
Occupation
Nerd
Vehicle Showcase
1
Haven’t seen this combo yet. Curious how the drivability is. Live close to sea leve but planning a Moab trip in april. Would prefer not to regear in case I get the lifetime waranty but f/r gear sets are only a grand so it’s tempting.

Brett
You should absolutely re-gear. It's the best mod you can do for the Jeep and yourself, especially if you're going to wheel it. I'm running 37's with 4.88's and it's perfect. Holds 80 on the highway and increases the crawl ratio a little bit over factory. I would go with 4.88's just for the added insurance of having the thicker pinion. Re-gearing will make it feel like a brand new Jeep. You'll get 6th gear back and you won't stall out on steep, technical climbs.
 

chevymitchell

Well-Known Member
First Name
Shawn
Joined
Feb 18, 2018
Messages
1,215
Reaction score
2,252
Location
K-Vegas, NC
Vehicle(s)
2020 Rubi Recon
Occupation
Nerd
Vehicle Showcase
1
Hi Brett. I would like to know if you got your setup as you initially wanted: 37" with 6-speed and stock 4.10 on your Rubicon. I am looking into the same exact thing and would like to know from your experience how things are going. i mainly need it for the street and highway. Is it doable? Thanks!
Doable, yes. Annoying, yes. I drove mine for about a month before I got everything together and enough time to do the gears. Once I did the gears, I was sooo much happier.
 

LunchBoxFab

Well-Known Member
Joined
Jan 7, 2019
Messages
290
Reaction score
233
Location
NOLA
Vehicle(s)
19 JLUR
Vehicle Showcase
1
You should absolutely re-gear. It's the best mod you can do for the Jeep and yourself, especially if you're going to wheel it. I'm running 37's with 4.88's and it's perfect. Holds 80 on the highway and increases the crawl ratio a little bit over factory. I would go with 4.88's just for the added insurance of having the thicker pinion. Re-gearing will make it feel like a brand new Jeep. You'll get 6th gear back and you won't stall out on steep, technical climbs.
can confirm. i went with 5.13s and its night and day over the 4.10s. it feels VERY close to factory gearing again. i would definitely recommend
 

urr2slo

Well-Known Member
First Name
Rick
Joined
Jan 12, 2019
Messages
70
Reaction score
119
Location
Phoenix
Vehicle(s)
Denali Duramax, Chevy Camaro, Jeep CJ7, C7 Corvette, MB S63
I have a set of 35's and a set of 37's for my Rubicon, 6th gear becomes useless with the 37's both power and fuel economy wise.
I'm taking a different approach as to addressing that problem. I'm adding the new Magnuson supercharger being released next month, being a PD supercharger it will give me the add power/torque at lower rpm so its still crawl friendly as well as the added power to use 5th and 6th gears on the freeway.
Another issue I have noticed is the clutch, it sucks. The stock clutch is to light both pedal and holding power. I am working with Centerforce to develop a new clutch for the JL. Currently running the prototype in my Rubicon. It's a game changer on an off road over the stock POS. The stock one is a lightweight twin disc with a dual mass flywheel so its touchy to say the least, the new Centerforce is a single disc design with a heavier flywheel which helps an incredible amount when crawling up steep terrain as its less likely to stall but also around town and in traffic. The heavier flywheel allows you to easily take off in 2nd gear from a stop without giving it any gas so in stop and go traffic it makes it easier to drive.
Once the added power from the supercharger gets added I think it will be perfect.
I'll be doing a full write up on the clutch and supercharger install once they have more miles on them, the clutch only has 250 miles so far and waiting on the supercharger.
 

Remmy

Well-Known Member
First Name
Corey
Joined
Jun 22, 2019
Messages
59
Reaction score
42
Location
Alaska
Vehicle(s)
2019 JL Rubicon, 2017 F250 6.7, 2018 Expedition
Good luck, be sure to let us know how the SC turns out. Hopefully they are able to address the higher compression in these motors with pulling timing exc. I know the forced induction has been a nightmare so far with the JL 3.6s...
 

ChattVol

Well-Known Member
Joined
Jun 29, 2018
Messages
2,304
Reaction score
2,227
Location
Chattanooga, TN
Vehicle(s)
JLU 6 Speed, 2016 Odyssey, 2014 Accord
Build Thread
Link
I have a set of 35's and a set of 37's for my Rubicon, 6th gear becomes useless with the 37's both power and fuel economy wise.
I'm taking a different approach as to addressing that problem. I'm adding the new Magnuson supercharger being released next month, being a PD supercharger it will give me the add power/torque at lower rpm so its still crawl friendly as well as the added power to use 5th and 6th gears on the freeway.
Another issue I have noticed is the clutch, it sucks. The stock clutch is to light both pedal and holding power. I am working with Centerforce to develop a new clutch for the JL. Currently running the prototype in my Rubicon. It's a game changer on an off road over the stock POS. The stock one is a lightweight twin disc with a dual mass flywheel so its touchy to say the least, the new Centerforce is a single disc design with a heavier flywheel which helps an incredible amount when crawling up steep terrain as its less likely to stall but also around town and in traffic. The heavier flywheel allows you to easily take off in 2nd gear from a stop without giving it any gas so in stop and go traffic it makes it easier to drive.
Once the added power from the supercharger gets added I think it will be perfect.
I'll be doing a full write up on the clutch and supercharger install once they have more miles on them, the clutch only has 250 miles so far and waiting on the supercharger.
How's it going with the new clutch? Update on the Magnuson supercharger?
 

urr2slo

Well-Known Member
First Name
Rick
Joined
Jan 12, 2019
Messages
70
Reaction score
119
Location
Phoenix
Vehicle(s)
Denali Duramax, Chevy Camaro, Jeep CJ7, C7 Corvette, MB S63
How's it going with the new clutch? Update on the Magnuson supercharger?
The new clutch is amazing, so much better than stock. I have about 2k on it now, off road it’s a game changer over stock. Weather I’m in 4hi or 4lo, just put it in the right gear and let it crawl. No stalling issues, it just drives over anything with ease. The heavier flywheel makes a huge difference.
Supercharger is on order, waiting on delivery.
After regearing a few other JLs recently I am going to regear mine. After doing a lot of math I figured that after the supercharger install if the engine is lugged in the wrong gear during our summer heat that detonation is probable which is risky with a high compression engine with boost. I’m not so concerned about it when I’m driving it but several people in my family drive it as well.
 

ChattVol

Well-Known Member
Joined
Jun 29, 2018
Messages
2,304
Reaction score
2,227
Location
Chattanooga, TN
Vehicle(s)
JLU 6 Speed, 2016 Odyssey, 2014 Accord
Build Thread
Link
The new clutch is amazing, so much better than stock. I have about 2k on it now, off road it’s a game changer over stock. Weather I’m in 4hi or 4lo, just put it in the right gear and let it crawl. No stalling issues, it just drives over anything with ease. The heavier flywheel makes a huge difference.
Supercharger is on order, waiting on delivery.
After regearing a few other JLs recently I am going to regear mine. After doing a lot of math I figured that after the supercharger install if the engine is lugged in the wrong gear during our summer heat that detonation is probable which is risky with a high compression engine with boost. I’m not so concerned about it when I’m driving it but several people in my family drive it as well.
Were you stalling crawling in 4lo with the 4:1 transfer case and in 1st gear? I dont know why folks would want to crawl in 4hi and haven't read where people are having issues crawling with stock clutch. I wheeled many times on 35s and stock 4:10 gears and it crawled over obstacles in 1st without touching the clutch. Even did it with 4 adults in the jeep and it didn't stall. With 37s and 6 speed, many folks are regearing to 4.88 or 5.13 and reporting crawling well over obstacles. What's the justification for spending big $ on an aftermarket clutch + labor if you're gonna spend $ regearing which by itself will allow you to crawl well?
 

urr2slo

Well-Known Member
First Name
Rick
Joined
Jan 12, 2019
Messages
70
Reaction score
119
Location
Phoenix
Vehicle(s)
Denali Duramax, Chevy Camaro, Jeep CJ7, C7 Corvette, MB S63
Were you stalling crawling in 4lo with the 4:1 transfer case and in 1st gear? I dont know why folks would want to crawl in 4hi and haven't read where people are having issues crawling with stock clutch. I wheeled many times on 35s and stock 4:10 gears and it crawled over obstacles in 1st without touching the clutch. Even did it with 4 adults in the jeep and it didn't stall. With 37s and 6 speed, many folks are regearing to 4.88 or 5.13 and reporting crawling well over obstacles. What's the justification for spending big $ on an aftermarket clutch + labor if you're gonna spend $ regearing which by itself will allow you to crawl well?
The new clutch has better feel overall, and out here in AZ we have some trails were you can cruise along at a good clip (4hi) with difficult stretches in between. Before I needed to drop to 4lo as it was to much for 4hi, now with the heavier flywheel it just goes right up and over. In 4lo in the really difficult areas it goes over it really easy.
When I first got my JLR the clutch was the only real disappointment, no feel, to soft, the new Centerforce dual friction is a huge improvement. Knowing I was going to supercharge it as soon as the Maggie became available I had a good feeling that the stock clutch probably wouldn’t last. After comparing the stock and the Centerforce side by side I’m sure it would fail. The cost of it wasn’t bad either, under $1k. Each Centerforce comes with a build sheet and tested to see how much torque it will hold. With holding power of over 600 ft. lbs. of torque I’m pretty confident it will hold up really well. Honestly I was surprised at the stock clutch and it’s design, it’s going to be a weak point long term in the manual JL. Jeeps engineers failed in my opinion, the current unit is focused more for rookie manual drivers whose primary use is street driving. They didn’t focus in on the hard core off road user.
I have several vehicles to choose from daily and I didn’t purchase my JL to daily drive, I wanted a sold off road toy. I find myself using it more as a daily when I’m doing local runs, city driving, since it’s so much nicer to drive since I upgraded the clutch.
I run Centerforce clutches in my race car, CJ and sports cars and they have always been great, I’m pleased that they were proactive and developed an upgrade for the JL right off the bat. I still haven’t seen another option yet.
 

Az-jewel

Well-Known Member
First Name
Julie
Joined
May 1, 2019
Messages
233
Reaction score
403
Location
Sunny AZ
Vehicle(s)
‘18 JLU Sport S
Build Thread
Link
Occupation
SAHM
The new clutch has better feel overall, and out here in AZ we have some trails were you can cruise along at a good clip (4hi) with difficult stretches in between. Before I needed to drop to 4lo as it was to much for 4hi, now with the heavier flywheel it just goes right up and over. In 4lo in the really difficult areas it goes over it really easy.
When I first got my JLR the clutch was the only real disappointment, no feel, to soft, the new Centerforce dual friction is a huge improvement. Knowing I was going to supercharge it as soon as the Maggie became available I had a good feeling that the stock clutch probably wouldn’t last. After comparing the stock and the Centerforce side by side I’m sure it would fail. The cost of it wasn’t bad either, under $1k. Each Centerforce comes with a build sheet and tested to see how much torque it will hold. With holding power of over 600 ft. lbs. of torque I’m pretty confident it will hold up really well. Honestly I was surprised at the stock clutch and it’s design, it’s going to be a weak point long term in the manual JL. Jeeps engineers failed in my opinion, the current unit is focused more for rookie manual drivers whose primary use is street driving. They didn’t focus in on the hard core off road user.
I have several vehicles to choose from daily and I didn’t purchase my JL to daily drive, I wanted a sold off road toy. I find myself using it more as a daily when I’m doing local runs, city driving, since it’s so much nicer to drive since I upgraded the clutch.
I run Centerforce clutches in my race car, CJ and sports cars and they have always been great, I’m pleased that they were proactive and developed an upgrade for the JL right off the bat. I still haven’t seen another option yet.
Hmmm, this is interesting! I have an ‘18 6-sp JLU Sport and am in AZ too. I’ve had some trouble stalling in 4lo when crawling up some steep climbs. I blamed it on not having regeared yet. (35’s and lift has really sapped the power). I did worry I was riding the clutch too much on the trail.
did you install that clutch yourself? Do you think it would have any impact on the warranty? I’m not able to do anything about it right now, but definitely interested in this down the road.
Thanks!
 

ChattVol

Well-Known Member
Joined
Jun 29, 2018
Messages
2,304
Reaction score
2,227
Location
Chattanooga, TN
Vehicle(s)
JLU 6 Speed, 2016 Odyssey, 2014 Accord
Build Thread
Link
Hmmm, this is interesting! I have an ‘18 6-sp JLU Sport and am in AZ too. I’ve had some trouble stalling in 4lo when crawling up some steep climbs. I blamed it on not having regeared yet. (35’s and lift has really sapped the power). I did worry I was riding the clutch too much on the trail.
did you install that clutch yourself? Do you think it would have any impact on the warranty? I’m not able to do anything about it right now, but definitely interested in this down the road.
Thanks!
I've been in this situation struggling wheelin with a jl sport 6 speed...it's a classic spot where most try and improve things by spending $ on several smaller things that end up costing alot when they've could've made a slightly larger investment upfront and had a much more capable setup and save $ in the long run. A $1000 clutch isnt going to overcome that your wheelin a 6 speed with 35s, 3.45 gearing & 2.72:1 transfer case. If you want to make it alot easier climbing, you need to improve the crawl ratio quite a bit with proper diff gearing and if possible...4:1 transfer case. Considering it costs approx. $2k to regear, you would get alot more bang for the buck buying some takeoff rubi axles for $3500 that come with 4.10 gears, lockers, upgraded brakes and overall stronger/wider axles. E-lockers alone are $1k per diff. You could prob get everything installed for $800 or less. Sell your old axles for $1k and it makes alot of sense. You'd have a fully locked jl on stronger axles with 4.10s and better brakes.:rock:
 

ChattVol

Well-Known Member
Joined
Jun 29, 2018
Messages
2,304
Reaction score
2,227
Location
Chattanooga, TN
Vehicle(s)
JLU 6 Speed, 2016 Odyssey, 2014 Accord
Build Thread
Link
The new clutch has better feel overall, and out here in AZ we have some trails were you can cruise along at a good clip (4hi) with difficult stretches in between. Before I needed to drop to 4lo as it was to much for 4hi, now with the heavier flywheel it just goes right up and over. In 4lo in the really difficult areas it goes over it really easy.
When I first got my JLR the clutch was the only real disappointment, no feel, to soft, the new Centerforce dual friction is a huge improvement. Knowing I was going to supercharge it as soon as the Maggie became available I had a good feeling that the stock clutch probably wouldn’t last. After comparing the stock and the Centerforce side by side I’m sure it would fail. The cost of it wasn’t bad either, under $1k. Each Centerforce comes with a build sheet and tested to see how much torque it will hold. With holding power of over 600 ft. lbs. of torque I’m pretty confident it will hold up really well. Honestly I was surprised at the stock clutch and it’s design, it’s going to be a weak point long term in the manual JL. Jeeps engineers failed in my opinion, the current unit is focused more for rookie manual drivers whose primary use is street driving. They didn’t focus in on the hard core off road user.
I have several vehicles to choose from daily and I didn’t purchase my JL to daily drive, I wanted a sold off road toy. I find myself using it more as a daily when I’m doing local runs, city driving, since it’s so much nicer to drive since I upgraded the clutch.
I run Centerforce clutches in my race car, CJ and sports cars and they have always been great, I’m pleased that they were proactive and developed an upgrade for the JL right off the bat. I still haven’t seen another option yet.
If the new clutch is $1k, how much for labor?
 

alphalife9

Well-Known Member
First Name
David
Joined
Nov 6, 2017
Messages
366
Reaction score
176
Location
Rio Rancho, NM
Vehicle(s)
Z51 C6, Sting Gray JLUR
I have a set of 35's and a set of 37's for my Rubicon, 6th gear becomes useless with the 37's both power and fuel economy wise.
I'm taking a different approach as to addressing that problem. I'm adding the new Magnuson supercharger being released next month, being a PD supercharger it will give me the add power/torque at lower rpm so its still crawl friendly as well as the added power to use 5th and 6th gears on the freeway.
Another issue I have noticed is the clutch, it sucks. The stock clutch is to light both pedal and holding power. I am working with Centerforce to develop a new clutch for the JL. Currently running the prototype in my Rubicon. It's a game changer on an off road over the stock POS. The stock one is a lightweight twin disc with a dual mass flywheel so its touchy to say the least, the new Centerforce is a single disc design with a heavier flywheel which helps an incredible amount when crawling up steep terrain as its less likely to stall but also around town and in traffic. The heavier flywheel allows you to easily take off in 2nd gear from a stop without giving it any gas so in stop and go traffic it makes it easier to drive.
Once the added power from the supercharger gets added I think it will be perfect.
I'll be doing a full write up on the clutch and supercharger install once they have more miles on them, the clutch only has 250 miles so far and waiting on the supercharger.
Please keep us posted. This is what I'm planning to do as well. Currently stock motor, 6 speed, 37s. Great MPGs in town (18-19MPG), poor on the highway (80+mph, 15-16.5MPG) because 6th is so high. It takes a lot of work to drive it on the highway, especially for me going between 5200 to 7300 ft of elevation on my commute. I worry about the stock clutch handing a power adder.
 

Advertisement




Tazer JL - Z Automotive
 



Advertisement
Top