Re-Gearing Question - Page 2 - JK-Forum.com - The top destination for Jeep JK Wrangler news, rumors, and discussion

Notices
Modified JK Tech Tech related bulletin board forum regarding subjects such as suspension, tires & wheels, steering, bumpers, skid plates, drive train, cages, on-board air and other useful modifications that will help improve the performance and protection of your Jeep JK Wrangler (Rubicon, Sahara, Unlimited and X) on the trail.

PLEASE DO NOT START SHOW & TELL TYPE THREADS IN THIS FORUM
Advertisement
Sponsored by:
Sponsored by:

Re-Gearing Question

Old 02-01-2018, 02:38 PM
  #11  
Former Member
 
Join Date: Jan 2018
Location: Nor-East Uni-Stat
Posts: 154
Thanked 4 Times in 4 Posts
Default

Glad I had the factory install our 3.73 as part of our pre-build sheet

Last edited by TrailBadger; 02-03-2018 at 05:27 AM.
TrailBadger is offline  
Old 02-01-2018, 05:51 PM
  #12  
JK Newbie
Thread Starter
 
Pmedic920's Avatar
 
Join Date: Jan 2018
Location: Livingston Tx.
Posts: 22
Thanks: 0
Thanked 1 Time in 1 Post
Default

Thanks so much Guys.

I did a little soul searching, and decided to go with 4;56s.
I really hadn't taken into account how much highway driving vs off road. The other thing i wasn't thinking about is "actual" tire height.
This might sound crazy, I drove around they area of Houston that i work in, and found 8 different JKUs rolling on 35s, got out and put a tape on the tires. I got caught twice but explained myself and they were cool with what i was doing. Any way, not one of the 8 rigs even measured 34". Every one fell between 32" and 33 7/8".
8 is a small sample size but I have to assume my pole is fairly accurate, and my 35s will be closer to 33s when mounted and on the ground.
All being said, 4;56 is best for my situation.

I placed the order today, and I'll repeat, If you're thinking about buying gears w/rebuild kits, I couldn't find a better deal than the one in our Vendor area here on the forum. I have no clue how the customer service is but the price was right. Hopefully it all works out well.
Pmedic920 is offline  
Old 02-02-2018, 06:04 AM
  #13  
JK Freak
 
SoK66's Avatar
 
Join Date: Apr 2009
Location: Colorado
Posts: 583
Thanks: 0
Thanked 5 Times in 5 Posts
Default

I was able to get both gear sets (Yukon) & master install kits from Northridge for right at $500. There's really not much savings going with just the basic kits. Shop your install and you'll discover wildly varying estimates. Places that specialize will almost always be less expensive. If you have no better alternative Four Wheel Parts is usually competitive and competent.
SoK66 is offline  
Old 02-02-2018, 08:28 AM
  #14  
JK Junkie
 
resharp001's Avatar
 
Join Date: Jun 2013
Location: Willow Park, TX
Posts: 3,621
Thanked 148 Times in 144 Posts
Default

Originally Posted by SoK66 View Post
If you have no better alternative Four Wheel Parts is usually competitive and competent.
Maybe they're better up there in Colorado? 4WP is about as least competent around in my area. I'd think that Houston would have some quality specialty shops.

I warn a lot of people about this....but since you're not likely to find a shop right there on Lake Livingston, be sure you mind the breakin procedure for new gears. You're not gonna leave a shop and jump on the interstate to head home. Don't rely on the shop to instruct you.....some do, some don't. Those first few heat cycles are the most important. Short trips at gentle speeds are ideal, allowing gears to cool in between.
resharp001 is offline  
Old 02-02-2018, 02:11 PM
  #15  
JK Enthusiast
 
Join Date: Nov 2013
Location: Westminster Colorado
Posts: 117
Thanks: 0
Thanked 1 Time in 1 Post
Default

Just wanted to share a update....

The Jeep is in the shop as I type this getting re-geared and after talking with a couple more shops I bit the bullit and bought the master install kits for the installation.

One shop once willing to do the install with just new pinion bearings and associated parts but there really was no warranty. When you really think about it you shouldn’t lean on the cheap side when doing a re-gear job because most of us have a bit of money invested in our Jeeps so what’s a few hundred more dollars 😎

I know now that I will sleep better at night knowing I didn’t cheap out 😊

Last edited by MacRubi2; 02-02-2018 at 02:13 PM.
MacRubi2 is offline  
Old 02-02-2018, 11:44 PM
  #16  
Former Member
 
Join Date: Jan 2018
Location: Nor-East Uni-Stat
Posts: 154
Thanked 4 Times in 4 Posts
Default

Agree, I'd rather locate a quality shop & authorized seller of a product than have joe smoe do the install. I'll spend more green but as you've said I'll feel better knowing it was done right instead of under some share tree. besides I looks for shops that are kept clean. This impresses me without seeing all types of junk around the out edge of the walls. Clean shops means a better and more direct positive attitude.
TrailBadger is offline  
Old 02-03-2018, 04:19 AM
  #17  
JK Freak
 
Wrangeler X's Avatar
 
Join Date: Jun 2012
Location: Channahon IL
Posts: 658
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Originally Posted by Pmedic920
Thanks so much Guys.

I did a little soul searching, and decided to go with 4;56s.
I really hadn't taken into account how much highway driving vs off road. The other thing i wasn't thinking about is "actual" tire height.
This might sound crazy, I drove around they area of Houston that i work in, and found 8 different JKUs rolling on 35s, got out and put a tape on the tires. I got caught twice but explained myself and they were cool with what i was doing. Any way, not one of the 8 rigs even measured 34". Every one fell between 32" and 33 7/8".
8 is a small sample size but I have to assume my pole is fairly accurate, and my 35s will be closer to 33s when mounted and on the ground.
All being said, 4;56 is best for my situation.

I placed the order today, and I'll repeat, If you're thinking about buying gears w/rebuild kits, I couldn't find a better deal than the one in our Vendor area here on the forum. I have no clue how the customer service is but the price was right. Hopefully it all works out well.
Keep in mind when talking about gear ratio, it's about circumference not tire height. Meaning you need to measure the circumference then find the diameter from there to determine true tire size. The tire squats when on the ground so you can't just measure diameter. All that will tell you is how tall the tire looks.

Mark a line on your tire at the bottom and mark a line in on the pavement in the same spot. Drive the jeep forward until it makes a full rotation and the line on the tire is at the bottom again. Mark that point and measure the distance from line to line on the pavement. That is the circumference. Now calculate diameter.

When you reprogram for gears and tire height use this number.
Wrangeler X is offline  
Old 02-03-2018, 06:27 AM
  #18  
JK Freak
 
SoK66's Avatar
 
Join Date: Apr 2009
Location: Colorado
Posts: 583
Thanks: 0
Thanked 5 Times in 5 Posts
Default

Originally Posted by resharp001 View Post
Maybe they're better up there in Colorado? 4WP is about as least competent around in my area. I'd think that Houston would have some quality specialty shops......
I said if he had no better alternative. Houston isn't your basic Jeeping & off road mecca.

4WP is a good place to start because they probably do more gear swaps than any other outfit. Their estimates are generally reasonable. Good rule of thumb, when you start seeing estimates of $1,000 per axle labor you know to look elsewhere. It's a precise piece of work but if the shop is experinced and has the tools it isn't rocket surgery.
SoK66 is offline  
Old 02-03-2018, 08:45 AM
  #19  
JK Jedi
 
TheDirtman's Avatar
 
Join Date: Oct 2010
Location: Southwest Reno, NV
Posts: 5,034
Thanks: 0
Thanked 55 Times in 49 Posts
Default

Most shops that know what they are doing don't want you to bring parts to them. They get the same gears you buy at a deeper discount and it does not save you anything. I know shops that wont do gears if you bring them in or will jack the price because they have had too many problems with people bringing the wrong stuff and the shop has to deal with getting the right parts. Also if you supply parts you leave the warrantee up in the air where you blame a bad install and the installer blames the gears.
TheDirtman is offline  
Old 02-03-2018, 07:44 PM
  #20  
JK Super Freak
 
Mr.T's Avatar
 
Join Date: Nov 2011
Location: Over the hill
Posts: 1,202
Thanked 31 Times in 30 Posts
Arrow Static Load Radius and Rolling Circumference

Originally Posted by Wrangeler X View Post
Keep in mind when talking about gear ratio, it's about circumference not tire height. Meaning you need to measure the circumference then find the diameter from there to determine true tire size. The tire squats when on the ground so you can't just measure diameter. All that will tell you is how tall the tire looks.

Mark a line on your tire at the bottom and mark a line in on the pavement in the same spot. Drive the jeep forward until it makes a full rotation and the line on the tire is at the bottom again. Mark that point and measure the distance from line to line on the pavement. That is the circumference. Now calculate diameter.

When you reprogram for gears and tire height use this number.
Measuring the tire radius loaded, center of axle to the ground has worked for me. As strange as it sounds, both the rolling tire circumference and the static loaded radius change with air pressure and load. And, the rolling tire circumference is equal to the 2pi(static loaded radius). There's a lot of flexing, distortion, and scrubbing aired down.

Here's an online calculator at Kettering.edu that can illustrate this: Tire Data Calculator
  • Starting at the top box labeled "Static Data": set Tire 1 and Tire 2 to the same size. For example, let's use 285 for width, 70 for aspect ratio, 17 for rim diameter, 95 for load index and W for speed index.
  • Click calculate, Tire 1 and Tire 2 data should be the same in the "Output Spec." box.
  • At the "Dynamic Input" box, enter air pressures of 2.5 bar for Tire 1 and 1.25 for Tire 2. For both tires, set the speed to 0 km/h and the and corner weight to 400 kg.
  • The only difference in input data between the tires is air pressure. Click re-calculate.
  • In the "Output Vehicle Data" box: Tire 1 Rolling Circumference is 2436.3mm and Tire 2 is 2275.2mm. Tire 1 Static Loaded Radius is 387.8mm and Tire 2 is 362.1mm.
  • Note that 2pi times the Static Load Radius is equal to the Rolling Circumference, within the rounding error for the number decimal places.
  • Note that the difference in section height (rim to ground) for Tire1 and Tire 2 is the same as the difference in Static Load Radius.

Last edited by Mr.T; 02-03-2018 at 08:54 PM. Reason: Fxing typos...
Mr.T is offline  

Quick Reply: Re-Gearing Question


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: