Front ring and pinion

[pardegt]

I am trying to decide if I want to upgrade my 2001QC 4x4 9.25" 3.55 ratio to either 3.92 or 4.10's.

I found the rear ring and pinion and master install kit on your website (great prices by the way) but I am having trouble locating a front set.

Do you carry a front 3.92 or 4.10 set and an install kit as well?

Thanks,
Brent

[caulk04]

Search for "VIP gears" on his site, he offers package deals for a good price.

Also, definetly go with 4.10's and don't rule out 4.56 gears. If you find the highway RPM is too high for you, you can do a simple computer swap for the transmission which will 'add' another overdrive (4th gear is .75:1, you can add 5th gear .67:1). This is not too good to be true, lots on info available on it if you're interested.

[AIR_RAM]

The additional overdrive is when going from a 45RFE to a 5-45RFE PCM. The only difference is the PCM as both transmissions are identical. I could be wrong but the 45RFE was introduced in 2002... again I could be wrong. So first he will need to figure out what his transmission OVERDRIVE gear is and the actual tire height. This will help us figure out mathematically what rear gear would be best.

I would lean heavily on a 4.10-4.56 gear ratios.

What front end do you have... we should have it up on the site. Have you tried the search bar at the top? If I dont have it listed I will get it listed for you...

SPEED SAFE, AIR RAM

[caulk04]

Dakotas didn't start getting the 5spd version until the 2003 MY. He's got the 4spd. Front axle is the c205mm or 8".

As mentioned, currently his top gear is 4th and is .75:1. If he wanted to lower that with a second overdrive (swapping the computer), he would have 5th gear which is .67:1.

[AIR_RAM]

I did not know the "RFE" was available in 2001 I had thought it came out in 2002.... So your saying the "RFE" was in fact available in 2001? I know about the gear ratios... I myself have a 2002 (45RFE) and you are correct it is a .75 overdrive. I run 32" tall tires and 4.56's... hands down the best gear for my application.

Thanks for sharing that... Its good to know the RFE was available in 2001.

I personally feel if you have a .75 or lower then and 30"+ tall tires then should be at the top of your list.

SPEED SAFE, AIR RAM

[pardegt]

Wow, thank you both for the great info. I have been trying to find out what size the front 12-bolt diff was. I found info that led me to know that in the rear: 12-bolt = 9.25 and 10-bolt = 8.25 but could find nothing about the front.

And yes, I do have the 4sp 45FRE trans, I just put a the HD2 Transgo kit in it. I had read a post concerning the pcm upgrade and it is on my list.

Also, I am running 17" RT rims with 255/65 tires giving me a tire diameter of about 29". I had been leaning towards the 4.10's over the 3.92's but am willing to listen to your thoughts on 4.56's.

FYI: The original issue is that the rear pinion bearing is howling. I was trying to decide between rebuilding my current axle (throwing in larger gears for fun!) or finding a 2003-04 axle with 3.92's and disk brakes. But, I have not been able to find a 03-04 axle under $1K. I did find an 05 but I don't know if it will bolt up directly and I would have to buy the rotors and calipers which would push the $$ up. So, I think I am leaning towards rebuilding my current setup.

So, if the front diff is 8" then I would need the following (even though it says for 2002+)?

Master Install Kit (Seems worth it as little price diff between mini kit)
http://www.airram.com/product.php?categoryid=755&productid=235

CHRY. 8.0" FRONT RING & PINION - MOTIVE
http://www.airram.com/product.php?categoryid=755&productid=601

Also, I posted this in the suspension forum section but would like to know your thoughts:
"...I am pretty handy with tools and usually comfortable fixing my own rides. Also, I've setup and run 4-axis cnc mills before. I've never done a rear end before but I am aware of getting backlash, gear mesh, collar crush etc set correctly. I have just never done it and not sure I possess all the necessary tools, although I do have quite an assortment and probably can borrow if need be.

Do you think I could successfully attempt to do this myself?"

I really appreciate all your help so far!!!

P.S. I searched for "VIP Gears" and did not find any info. Can you help me a little further there?

[caulk04]

AirRam - The 45RFE actually started in Dakotas in the 2000 MY when the 4.7 was introduced. It's first usage was in the 1999 Jeep Grands, that's when the 4.7 debuted.

pardegt - Your axles is indeed the 8" corporate. The 2002 MY designation AirRam is referring to is when the 1500 Rams went to IFS and they also use the 8" up front. Fear not, you have the 8". Definetly go with at least 4.10's. Find a gear calculator and find out what RPM you're comfortable cruising at. 3.92 isn't a big jump from the 3.55's you have now.

As for gear setup, I'm in the same boat. I've got a fair assortment of tools and am comfortable in my knowledge, but there are a couple of goofy tools you need and also a real tough impact gun to set the pinion bearings (the crush sleeve). I'm going to pay to have mine done because I'm not SURE I want to do it myself and I've got no time to do it.

Also - The rear axle from a 2005+ Dakota will not work. At least not easily...they have 5-lug wheels so the axle shafts would have to be swapped, if they're even compatible with the older trucks.

[caulk04]

Here's the VIP gears link. The combos listed include a LSD for the rearend, not sure if you want to go that route also or not. http://www.airram.com/product.php?categoryid=0&productid=1012&searchquery=vip%20gears

[pardegt]

Thanks once again.

So now I'm having several debates in my head (damn voices!!!)

I have read that the 4.56 gears can whine under load, but then I think I also read this about 4.10's The 4.10's would raise my rpm about 300 (65-75mph) and the 4.56's would add another 300rpm. (Definitely would need the 5th gear pcm upgrade.) Hmmm...

LSD: I don't believe I have a stock one as I had the rear end off the ground and you can hold one tire still while the other rotates - in drive or reverse. (I was checking to validate the howling noise was the pinion bearing.)

I guess I've never had a posi so it's hard for me to compare. There seems to be a lot of opinions on which LSD to use but the DTT seems to get a lot of attention. I am here in Nebraska and this is my main vehicle which has to navigate the winter weather of rain, snow, and ice. But, occasional burnouts would be really cool! I just need to convince myself that the extra $400 (diff between individual kits/gears vs DTT combo) is worth it for my application.

Sorry for my confusion on the VIP gears..I misread and thought you were pointing me to another vendor within the forum.

Any more thoughts after my ramblings??

[AIR_RAM]

Thanks once again.

So now I'm having several debates in my head (damn voices!!!)

I have read that the 4.56 gears can whine under load, but then I think I also read this about 4.10's The 4.10's would raise my rpm about 300 (65-75mph) and the 4.56's would add another 300rpm. (Definitely would need the 5th gear pcm upgrade.) Hmmm...

LSD: I don't believe I have a stock one as I had the rear end off the ground and you can hold one tire still while the other rotates - in drive or reverse. (I was checking to validate the howling noise was the pinion bearing.)

I guess I've never had a posi so it's hard for me to compare. There seems to be a lot of opinions on which LSD to use but the DTT seems to get a lot of attention. I am here in Nebraska and this is my main vehicle which has to navigate the winter weather of rain, snow, and ice. But, occasional burnouts would be really cool! I just need to convince myself that the extra $400 (diff between individual kits/gears vs DTT combo) is worth it for my application.

Sorry for my confusion on the VIP gears..I misread and thought you were pointing me to another vendor within the forum.

Any more thoughts after my ramblings??

I went from 3.55's to 4.56's and only gained 300RPMs @60MPH... My tire height was 32" tall. You need to do the math on this one... going on what others have said will lead you astray.

MATH has only one correct answer...

Find your overall gear ratio
TRANS OVERDRIVE x REAR GEAR = OVERALL GEAR RATIO (OGR)

Find your RPMs at ANY speed
SPEED x OGR x 336 / TIRE HEIGHT = RPM

Use the above math for your current gears and then with your gear options.

SPEED SAFE, AIR RAM

[pardegt]

At 60mph with my 29.5" tires, the 3.55's equal 1625rpm and 4.56's equal 2088rpm or a gain of 463rpm. My previous post related more to comparisons at 75mph where the difference from 3.55's to 4.56's is a 578mph gain.

Sorry for the confusion.

Now I just found a 2004 Dak 9.25 4x4 rear end locally. Maybe I will get my disk brake upgrade after all.

Thanks,
Brent

[AIR_RAM]

At 60mph with my 29.5" tires, the 3.55's equal 1625rpm and 4.56's equal 2088rpm or a gain of 463rpm. My previous post related more to comparisons at 75mph where the difference from 3.55's to 4.56's is a 578mph gain.

Sorry for the confusion.

Now I just found a 2004 Dak 9.25 4x4 rear end locally. Maybe I will get my disk brake upgrade after all.

Thanks,
Brent

I see your point and was not trying to point out flaws in your information. I was just trying to help you make the best possible choice... Gears are expensive and its best to do them ONCE without regret. Im just trying to help make the best informed choice... This is a subject I have quite a bit of experience with.

Keep in mind that RPMs alone do not dictate fuel economey. Its the LOAD on the engine at any given RPM that has more to do with fuel economey then RPMs alone.

I tell recommend that our customers chose a gear ratio that puts them at 2000RPMs@60MPH for best all round performance. It appears through your math tat the 4.56's would be optimal for your vehicle. Meaning you will have improved performance and will likely see a gain in MPG from 0-65MPH. Performance will be night and day as well... its having your cake and eating it too.

So from your math it appears 4.56's would be the best choice.

Also, I did not see a "LOSS" in top end... I was able to go 5400RPMS in overdrive... Since my speed-o only goes to 120, doing the math puts me OVER 140MPH.

Good luck with your decision... gears should be the FIRST mod on every ones list!

SPEED SAFE, AIR RAM

[pardegt]

Decisions, decisions....
I have found 2 rear ends (2004 with disks) locally that are similarly priced. Both are 9.25 with 3.55 gears. One is a factory posi with 55K mileage and the other is an open diff with 103K.

I will probably for now, get a rear end and get the disk brakes operating to get me back on the road. Later, I would still like to upgrade the gears as all of our talk has got me anxious to go to the 4.56’s!

But for now, my question is should I go with the posi with fewer miles or the open with twice as many? I have read that the factory lockers are not that good (and may make installing an aftermarker locker more difficult?) but with only 55k maybe it is a better choice than the 103K open one.

Any thoughts?

[caulk04]

The factory LSD doesn't last that long really, the clutches wear out. But it won't make a difference come time to do a gear swap.

[pardegt]

Well, I now have an 04 rear end on my garage floor! It is the open diff setup. The yard had 3 of them but the first one with the locker they opened up was full of clutch material, the second was mislabeled in their system and was an 8.25, but the third one was the charm as they say as it seems to be in good shape upon their inspection. I have not popped the cover yet but everything turns freely.

I also got rotors and calipers with it. I will start off with them and then upgrade later to slotted ebc's to match the front. The bad part is they cut the brake lines so I will have to find some or get some made. Also, there is the parking brake issue to deal with. First, I'll just get the brake lines figured out and get the axle bolted in to get it running to make sure everything is ok.

Off to the parts store!

[caulk04]

Pull the rotors off and check out the parking brake shoes...they often go bad and separate.