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Gear Swap time 4.10's or 4.56's?

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I've been stuck with 3.55's for almost 2 years now in my 10' RCSB 4x4
and the time has finally come to upgrade!

I've been running 28" M/T DR's on 17" wheels at the track to drop my effective gear ratio to around 4.30:1
The 295/45R17 Mickey Thompson ET's (x4 for my 4x4) shaved 5 tenths off my quarter, and got me into the 13's (13.8/98.5)
...along with the basic intake/exhaust/tune mod's everybody runs.

Most recently I stepped up to an Edge Torque Converter that stalls at about 3000 rpm,
and dropped another 3 tenths off my 60' down from 2.1's to 1.8's but traction is dependant on perfect conditions/prep now.
My new headers just arrived this week (JBA coated shorties)
and before I go much further adding power it's time to address my traction issues due to my open rear diff and 3.55's
I'm getting to the point that I often need to use an AWD (4WD Auto mode) and 4 drag radials for traction.

Since a Locker will keep me from doing a 1 wheel peel,
I may as well upgrade my gears when the rear carrier comes out in favour of a Detroit Tru-Trac limited slip.
I've been doing some calculation,
and I "think" ideally I should be aiming for about 5800 RPM at the finish line in a 1:1 3rd gear. Right?
I'm currently running a Diablo 93 tune, shift points are maxed out 6200-6400.

So what do you think? 4.56's too low? are 4.10's a better choice?
For daily driving I roll heavy 305/50R20 Terra Grappler's on stock 20's
90% city commuting and very rarely see any highway time.
I've recently found some good on-line calculators here...
http://www.hotrodpitstop.com/tool.php#6
Not sure what number to use for torque converter slip so I just used 10%



Here's where I'm at currently with 3.55's on my 28" tires:
3rd gear is falling on its face at 4600 rpm at the traps

with 4.10's put me at 5300, much closer to being in the powerband at the traps

and 4.56's put me right on the edge before 4th gear kicks in after crossing the 1320' mark

Anybody here running lower gears for racing confirm those numbers?
That last thing I want to do is end up shifting into 4th (overdrive)because I've gone too low with 4.56's.
I have to regear both front and rear diffs,so I need to get it right the first time.
I suppose if I end up with too short a gear,
to correct it I could just get new taller tire 30"-31" tires and sell the 28's.

FWIW, my best times at the track on my heavy Grapplers/20's are 14.4's with 3.55's
I bet I could get high 13's on them on 4.56's and my new headers :D
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Discussion Starter · #22 · (Edited)
28" is about as small as I care to go, and buying lower tires instead of lower gears still doesn't address my open rear diff ;)



My bad for not spelling it out clearly enough in my opening post,
allow me to simplify things...

Has anyone ran a 4.56 geared Ram at the track on 28" tires
and have you managed to avoid hitting 4th (over drive) gear before the end of the quarter mile?

or Has anyone ran 4.10's and thought they could use a little more gear to get the rev's up an extra 500-600 rpm?
From Drag Race forums I've been on it would seem you want to be at your max RPM at the line.

My best guess is the RPM would be 5900 RPM, in 3rd (1:1) with 4.56's and 28" tires, is that close?
 

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I will let you know. I am running my 4.56's and 28" slicks this sat! I will give you some real numbers!
 

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you know me..i am a staunch 4.56 guy...I still trapped 113 mph with 28" tall dr's in 3rd gear...but, with that said, for you I'm leanin towards 4.10's because your a regular cab and have the 3k stall...

also, with the gearing and tires i run, i hafta to shift to 2nd at 5k rpms to hold 3rd thru the traps..
 

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Discussion Starter · #27 · (Edited)
you know me..i am a staunch 4.56 guy...I still trapped 113 mph with 28" tall dr's in 3rd gear...but, with that said, for you I'm leanin towards 4.10's because your a regular cab and have the 3k stall...

also, with the gearing and tires i run, i hafta to shift to 2nd at 5k rpms to hold 3rd thru the traps..
Thanks Fred, without spray, I'm not going to be anywhere near 113mph

Yes a Reg Cab, but being a 4x4, it weighs as much as a 2wd QC
and has a little more rolling drive train resistance due to the front diff and CV shafts always turning, powered or not
and I have a transfer case that could be turning two drive shafts when traction is poor and I use awd.

I was mostly concerned about staying in 3rd at around 99 mph. 4.10's would be the safe bet, 4.56's sounds right on the border.
 

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is there any way you can force your gen 4 to hold 3rd like we 3rd genners do? I manual shift at track and I go 1-2-D-2 , if I miss downshifting, I hit 4th everytime and lose my e.t.'s ...I've run both 4.56's and 4.10's at the track with 28" M&H dr's as well as 28" Hoosier slicks...it won't shift into 4th with the 4.10's but will with the 4.56's... but, with that said..the 4.56's are much more fun to drive on the street than the 4.10's... my stock tire is only 30" tall as well.
 

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i've seen 4th gens race at the track but I've never seen one as evil and wicked lookin an sexy at the same time...I can see why others are wary to run you...
 

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Discussion Starter · #30 · (Edited)
Thanks Fred! you're too kind

That's very helpful info

I'm going to see if I can downshift after 3rd at WOT
My only concern is the downshift will go to 2nd prime, not to 2nd.
it sounds like it may just be a matter of getting the timing right and doing it very shortly after hitting 3rd.

... I can always adjust shift points with my Diablo too.

The 4G's don't have a "D" when you switch to manual (ERS) mode
just 1-2-2p-3-4.

on my larger street tires/3.55's
I can almost get to the line in 2pr in manual mode...it's just shifting to 3rd at the line.

if I just use D, it goes 1-2-3 with 3rd gear coming well before the traps.


The benefit on the street with 4.56's appeals to me too,
my heavy ass grappler's on 20's need all the help they can get.
 

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when you downshift at 5k rpms, it's suppose to hold the shift and not actually shift down, then after I pass the traps, i wait til the speed comes down to around 60 before putting it back to D...
 

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..and I change my mind, your daily driver wheel setup will benefit most with the 4.56's, so if you can confirm or see if anyone has tried the downshifting on 4th gens, go with the 4.56's...
 

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Discussion Starter · #33 · (Edited)
4.56 might be cutting it too close, (4th gear at the 1320')
if there was a 4.30:1 option in between for a Dodge it would sure make things easier

As you can probably tell, I'm doing all I can to try and make 4.56's work
Part of its for a mid 13 pass at the track on DR's But....

I still want to be able to get a 13.9 pass with street tires too
for when I feel too lazy to do a 4 wheels swap to my DR's.
(Hey, I'm gettin' old and it happens)

Best runs so far on my 305/50R20 Terra Grapplers is 14.4's
I'm kind of hoping 3.55's to 4.56's will shave 4-5 tenths

I know 4.10's would come up short.
 

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believe me, i was in the exact same position in 06..we thought if we could find 4.28's to 4.30's, that would be perfect... but with the 4.56's, it's alot more fun to drive on the street (less stress on tranny too)
 

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Discussion Starter · #35 ·
Okay, I'm Sold ! 4.56's :smiley_thumbs_up:
You make it sound like Way too much fun to resist.

Good to hear it from someone who's been, there done that.
When the track re-opens for the season (1 more month to go)
I'll try some different shift combo's with my DR's/3.55's.

If it's too much gear and I can't shift it to hold 3rd to the line,
I guess my next move could be a slightly taller DR ;)
 

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I've been both ways bro...first had 4.56's and it was a kick in the pants to drive... then i heard it from others "it's too much gear.....you'll gain mph at the track..." to the point where i was second guessing my decision so I went to 4.10's and 'gave' my .56's to another member on another forum.... talk about regret, If i didn't have 56's to begin with, the 4.10's probably would have felt ok...but i tasted it and the .10's just felt like blah to me... so I ran them til a budy of mine who sold his ram, found a set of 56's when he was cleanin out garage and gave them to me...had it installed the next week and I've been happy as a clam ever since...I did lose a lil mileage on the highway but I'm still in the 20's (mpg's)
 

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Well did the track Sat night and no bueno on the gears for me. We did have much higher DA and that affected me as well. I believe i blew through my boost range too fast with the 4.56's. I lost 4 tenths and 3mph at the top end. 60ft was the same...
 

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Discussion Starter · #39 ·
Ouch! hope that turns around for you in better air,
but that's a lot of tenths to make up. Crap, I feel for you man.

What are your shift points at?

I just got my Headers on last weekend, and I'm booked for a custom dyno tune on the 14th.

I'll see what my CMR has to say,
and will track test my new setup on the 27th before making a major commitment on gears now.

I'm not rushing into this, it aint cheap to do both diffs on a 4x4
and I may wait unitl mid summer to do it when its too hot to race.
 

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I'm shifting at 6400. I think I might go down to a 4.10 or maybe put my 3.92s back in. I am going to keep the trutrac, I was coming off the line a lot straighter than with my stock LSD.
 
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