Best rear end ratio for getrag and 37s

[JGrefenstette]

In the middle of a full body off on my 93 and plan to put a Detroit locker in the rear. Currently I have 3.54s and 35in tires. Plan to upgrade to 37s and I do tow so I'm thinking 3.73 maybe a better choice. I don't heavy haul, usually 10k +/- and I don't want to kill my mpgs with a super low gear or have to change carrier front and back. So what's yalls experience? Should I keep the 3.54s or will I have to run 80mph to keep egts safe in 5th? Thanks in advance -Jimmy

 

[Bob4x4]

I would go at least 4.10s towing with 37's but I would not use a getrag-not durable enough for your application imho

 

[RWherley]

I like 3.54 in my truck but I only have 31.5" tires, so I think you have the right idea with the 3.73 gears, and bob is right loose the getrag and put a NV4500 in.

 

[MMeier]

I would go with the 410's and like was said above, put a 4500 in it. You going crossover when you lift it ?

 

[JGrefenstette]

Thanks for the responses. I have a few questions now. If I go 4.10 dosnt the carrier have to be changed? Also about the 4500, will the np205 couple to it? I already have a new southbend clutch and flywheel, will the 4500 input shaft fit it? I have a rebuild kit for the getrag and I'm a few days from opening it up, spent yesterday degreasing it. I understand the 4500 is much more ideal, but I'm pretty easy on a drivetrain. When I tore the truck apart the original clutch was at 300k mi and other than worn out synchros the transmission seems fine, ill know more when I open her up. Lastly does anybody know by chance what MPH I'd be looking at 2k rpms in 5th with 37s and 4.10s, howbout 3.73s? Oh and mmeier, what do you mean by crossover? I lifted the truck years ago with add a leafs in the rear and new spring pack up front with add a leafs there too. Thanks again fellas

 

[DVolk]

No change one the carrier just ring and pinion , although you might want to buy a new clutch pack for the carrrier

 

[MMeier]

Thanks for the responses. I have a few questions now. If I go 4.10 dosnt the carrier have to be changed? Also about the 4500, will the np205 couple to it? I already have a new southbend clutch and flywheel, will the 4500 input shaft fit it? I have a rebuild kit for the getrag and I'm a few days from opening it up, spent yesterday degreasing it. I understand the 4500 is much more ideal, but I'm pretty easy on a drivetrain. When I tore the truck apart the original clutch was at 300k mi and other than worn out synchros the transmission seems fine, ill know more when I open her up. Lastly does anybody know by chance what MPH I'd be looking at 2k rpms in 5th with 37s and 4.10s, howbout 3.73s? Oh and mmeier, what do you mean by crossover? I lifted the truck years ago with add a leafs in the rear and new spring pack up front with add a leafs there too. Thanks again fellas

http://api.viglink.com/api/click?fo...ffroaddesign.com/catalog/Dan...ssoverKits.htm

 

[RWherley]

I can't seem to find it right now, but there was a calculator in one of the treads that let you enter your gear for trans and rear and tire size and it would tell you speed and rpm

 

[JGrefenstette]

Ok yeah after looking it seems the carrier break is 4.56 up. I plan to put a Detroit locker in the rear an the clutch pack up front should be ok I hope since its sat still most all of its life. Thanks for the link mmeier I remember that now. I put in a 2.5" leaf pack and added another leaf to it an I've never had trouble from the steering. How critical is the cross over? Oh wow a calculator for that would be awesome! That would pretty well tell me what gears to get. Anybody know where to find it? Thanks again

 

[DVolk]

Unless its been changed already your front axel is open !!!! its not posi so a clutch pack will not help you .

 

[AEdelheit]

Here is a good chart to compare ratios

http://www.offroaders.com/tech/gear-ratio-chart.htm

Calculator

http://www.sierragear.com/differential-gear-ratio-calculator/

 

[JGrefenstette]

The front end is open... well I feel like a big dummy. Now I know thanks for the websites the chart and calculater are fantastic. Looks like 4.10s are probly going to be it. Are there any gear brands to look for or stay away from? The company who I plan to buy the locker from sells motive gear and Yukon gear. The motive gear r&p set for 4.10 is $230 and the Yukon $357.

 

[DVolk]

Id call Randys Ring & Pinion they have good prices and good customer service .

 

[cerberusiam]

With 37's you need 4.56's to tow any weight. 4.10's are not enough gear to pull 10k and it will eat the Getrag in short order.

 

[Bob4x4]

Not all 37's are created equal,many are an inch less some even more.There are a few true 37.s like my Toyos.At my power level the 4.10s work fine (no getrag)