Advertisement |
|
|
|
If this is your first visit, be sure to check out the FAQ by clicking the link above.
You may have to register before you can post: click the register link above to proceed.
To start viewing messages, select the forum that you want to visit from the selection below.
|
Ford Competition and Performance General Ford Competition and Performance Discussion |
08-26-2006, 09:39 AM
|
#1
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
What gears should I choose??
The question gets brought up often with lifted trucks regarding gearing choices with bigger than stock tires.
I've complied a little chart of sorts that shows how different gear ratios efffect RPMs with different sized tires.
Here's some info I posted awhile back in another post on another forum:
Here's a quick example of rpms with given gear ratios at 70 mph. All rpms listed are for a AOD trans with a .70 OD ratio....so they aren't dead on, but they are close (the 4R100 has a .71 or .72 OD ratio I think??). So, while the rpms aren't 100% on the money it will give you an idea of how each different gear ratio effects engine rpm at 70mph.
tire..............gear...................rpm
31.6"...........3.73....................1943 (stock truck)
31.6............4.10....................2136
31.6............4.30....................2240
34.7............3.73....................1770
34.7............4.10....................1945
34.7............4.30....................2040
34.7............4.56....................2164
36.7............3.73....................1673
36.7............4.10....................1839
36.7............4.30....................1929
36.7............4.56....................2046
36.7............4.88....................2189
38...............3.73....................1616
38...............4.30....................1863
38...............4.56....................1976
38...............4.88....................2114
38...............5.13....................2223
40...............4.10....................1688
40...............4.30....................1770
40...............4.56....................1877
40...............4.88....................2009
40...............5.13....................2112
42...............4.56....................1788
42...............4.88....................1913
42...............5.13....................2011
42...............5.38....................2109
44...............4.56....................1706
44...............4.88....................1826
44...............5.13....................1920
44...............5.38....................2013
46...............4.56....................1632
46...............4.88....................1747
46...............5.13....................1836
46...............5.38....................1926
I have most common choices pretty well covered....if you want info on a gear/tire combo that I don't have listed let me know and I'll add it to the list.
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
Last edited by DCSpecial; 08-26-2006 at 09:42 AM.
|
|
|
08-26-2006, 10:23 AM
|
#2
|
Name: Betaracer
Title: Giggity Giggity Goo
Status: Not Here
Join Date: Apr 2006
Location: Whistler, BC, Canada
Member`s Gallery
Posts: 904
|
Nice work, Dan.
Does this mean I should move to 4:10s? Or are 3:73s still fine for 35s?
__________________
2016 F350 XLT FX4 CCLB. 7" One Up Offroad/Icon/Fox, 38x13.50-18 Toyo MTs
|
|
|
08-26-2006, 10:46 AM
|
#3
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
Thanks.
For 35s, I think 3.73s are fine....as long as you are happy with the performance.
I ran 35s and 3.73s for 24,000 miles......got better mpg on the highway due to the lower rpms. I was happy with it.
If you didn't like it's performance with the 35s, I'd go with 4.10s.
Once you get up into 36s and 37s is when I'd start thinking to regear. Due to the size and weight of the tires.
38s+ I feel it's definately a must to do. I hated running 38s with 3.73s. I went with 4.56s and like the combo. Could have gone to 4.30s as well....little better mpg on the highway.
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
02-18-2007, 01:29 PM
|
#4
|
Name: smoken02
Title: Too Much Time
Status: Not Here
Join Date: Feb 2007
Location: Streator, Illinois
Member`s Gallery
Posts: 1,412
|
hey, im thinking of going to a 37 inch tire. would you recomend 4.10s. i do alot of highway driving. some of my friends that have gas trucks say that when putting on a larger tire like a 35 they lost about 4 to 5 miles per gallon. does this not happen to diesels because the engine makes so much more torque it doesnt notice the tire or would it be the gear?
__________________
14' Cummins C/C DRW 3500 4x4 G56
94’ Reg Cab 4x4 Just Rollin
R.I.P
02 Dodge QC/SB 4x4, Drag Comp,BD RAD, ARP studs, DDP HRVP44, HTT 62/71/14,SDX 200's,Killer B, Goerend trans,Billet input shaft, Billet Flexplate, AirdogII 200gph pump
13.16 @ 104mph 1/4 mile
Aaron
|
|
|
02-18-2007, 02:08 PM
|
#5
|
Name: McRat
Title: Too Much Time
Status: Not Here
Join Date: Apr 2006
Member`s Gallery
Posts: 1,571
|
Here's the simple version of the math.
Take your new tire dia (NDia) and divide your stock tire dia (SDia):
NDia / SDia = Correction (C)
To keep the same highway RPM, you now multiply the correction by the existing gears (SGear), to get new target ratio (NGear).
Example:
NDia/SDia = C
40" new tires / 30" old tires = 1.33
SGear x C = Target gear ratio.
3.73 x 1.33 = 4.97:1 gearing.
Now you have a decision to make. If you want a little more RPM, go to the 5.13? size, if you want a little less RPM, go to the 4.88 size. Seldom will the math be perfect.
The reason you do not use PI (3.14) in the calculation is because it divides out anyhow.
__________________
Pat McSwain
2007 Kodiak Duramax "Home Base"
2006 GMC 2500HD "Wendy" 12.50@107.44 Tuning+MikeL Trans.
2005 GMC 2500HD "Casper" 197mph+ clocked at Bville. 10.59@130. SuperStreet 3.0 Sledpull winner. Same truck.
2004 GMC 3500 "Big Blue" 13.10@103. Sledpull Winner.
|
|
|
02-25-2007, 05:44 PM
|
#6
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
Quote:
Originally Posted by smoken02
hey, im thinking of going to a 37 inch tire. would you recomend 4.10s. i do alot of highway driving. some of my friends that have gas trucks say that when putting on a larger tire like a 35 they lost about 4 to 5 miles per gallon. does this not happen to diesels because the engine makes so much more torque it doesnt notice the tire or would it be the gear?
|
No, your mpg will go down with a 37.
Mine were good with 35s and 3.73s.....not as good since the 38s and 4.56s though
What gear do you have stock?
4.10s and 37s would help keep your highway rpms low for better mpg.
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
02-25-2007, 08:15 PM
|
#7
|
Name: Robts
Title: Proud Fummins Owner
Status: Not Here
Join Date: May 2006
Member`s Gallery
Posts: 2,321
|
Geezz Dan You did some hoework..
Nice write up.
I love my 4.56 with the 37's
__________________
2016 Ram 2500 Cummins Laramie Crew
2013 Ram 2500 Cummins Laramie Crew Cab 4x4 Loaded. 6" lift on 35" Toyos on 22x12 gear alloys sold
2004 Ford F350 Lariat with a Fummins **under construction...Money pit
|
|
|
02-25-2007, 08:20 PM
|
#8
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
I try
I may have done a few writeups and how-tos over the years
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
02-28-2007, 09:34 PM
|
#9
|
Name: Lifted94XLT
Title: Diesel Enthusiast
Status: Not Here
Join Date: Aug 2006
Location: Shawnee, KS
Member`s Gallery
Posts: 137
|
hmm..... very good chart, has got me thinking..... with my 35's and 3.73 gears, the best mileage I've EVER gotten chip or not was 13mpg in the city, and about 17 on the highway (at 70mph). Now, IIRC, a stock 6.0 with 3.73s gets around 16-17city, and ?? highway (from what I've been told, never had mine stock height), so accoreding to that chart, if I were to go to 4.10s, or even 4.30s (I'm leanin 4.30s), I'll loose highway mileage (possibly gain highway towing mileage), but will I be gaining in town mileage?? Just a quick question to help me clear up my own mind. thanks.
--Ryan
__________________
2003 Dodge Ram 3500 QC SRW 5Spd
- TST Powermax CR, 4" MBRP TB, Fass Lift Pump w/ Big Line upgrade, South Bend Clutch
|
|
|
02-28-2007, 10:38 PM
|
#10
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
The 4.10s or 4.30 will make it easier on the the motor to get the meats moving. But, higher speeds the mpg won't be too hot.
I'm surprised that's your mileage.....I get 13-15mpg around town with 38s and 4.56s
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
03-01-2007, 09:41 AM
|
#11
|
Name: imelmo
Title: Go away, I'm 'batin'!
Status: Not Here
Join Date: Jun 2006
Location: Slidell, LA
Member`s Gallery
Posts: 8,878
|
A little side note, I used to have 4.56's in my truck. For daily driving they were awesome, but I busted 2 or 3 sets of them at the track. I was told because there really wasn't enough material on the ring to hold the power. I've got 4.30's now which are great and haven't had any problems with **knocks on wood**. I'm sure it has a lot to do with weight and power output, but that was my experience.
Also, for the record, I saw virtually no change in ET when I went from the stock 3.73's to the 4.56's; they just made it a lot nicer to drive around town.
__________________
ZMBYKLR, '03 Reg Cab Short Bed 4x4
Truck Source Diesel, Warren Diesel, Gardner Racing, Diesel Innovations, 1018 rear wheel llamathrust
10.38 @ 129.60mph
The FORDOTA, '86 Toyota reg cab tube chassis to be powered by a 6.0 Powerstroke; finally back in progress
.
|
|
|
03-01-2007, 09:44 AM
|
#12
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
Actually, lower gears (numerically higher) have smaller pinions.
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
03-01-2007, 10:00 AM
|
#13
|
Name: Fx4ord
Title: Man it's hot in here.....
Status: Not Here
Join Date: Jan 2007
Location: Slidell La (aka) SAINTSVILLE
Member`s Gallery
Posts: 144
|
Soooo who has a set of 4.30's or 4.56's they want to sell?
__________________
Tommy.L
2006 F-250,cc,6.0Lpsd,tow command,Fx4,lariat,ArizonaBeige,
Black accents
8'' Rize 4 Link Suspension System
American Racing Trax 8 with Teflon Coating in 22x11
37x13.5x22 Toyo Open Country Mt's
SCT Xcal2 with the street,TowAgressive and XtremeStreet from innovative diesel
Afe Stage II Mega Kit (DPPI)
MagnaFlow Stainless 4'' Straight Pipe
Isspro gauges pyro,trans temp, boost,
12.1'' flip down DVD entertainment,
1000wts of system
http://community.webshots.com/user/Fx4ord
www.innovativediesel.com
www.dieselperformanceparts.com
|
|
|
03-24-2007, 02:04 PM
|
#14
|
Name: txastuff79
Title: Too Much Time
Status: Not Here
Join Date: Aug 2006
Member`s Gallery
Posts: 369
|
my tires are 325/65r18. what does that work out to be? 35? 35.5? 36? i have been thinking of changing gears and diffs.... just not sure of the gear range, what axles i have and what diff to buy?
|
|
|
03-24-2007, 02:50 PM
|
#15
|
Name: 6.0kingranch
Title: No spark plugs
Status: Not Here
Join Date: Aug 2006
Location: 3 0 5, Fl.
Member`s Gallery
Posts: 591
|
Great write up. That's convinced me to stay with the stock 4:10 gears.
__________________
1995 Ext. Cab 3500 4x4
Cummins Diesel
|
|
|
03-24-2007, 03:46 PM
|
#16
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
Quote:
Originally Posted by txastuff79
my tires are 325/65r18. what does that work out to be? 35? 35.5? 36? i have been thinking of changing gears and diffs.... just not sure of the gear range, what axles i have and what diff to buy?
|
That works out to be a 34.6" tall tire....12.8" wide
Honestly, I'd stick with the stock 3.73s unless you tow heavy often.
I really liked my 35s and 3.73s.
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
03-24-2007, 09:38 PM
|
#17
|
Name: sredish
Title: Where am I?
Status: Not Here
Join Date: May 2006
Location: NE Texas
Member`s Gallery
Posts: 884
|
I also really really liked the 35" / 3.73 combo. the 35's are still light enough to get moving easy and with the lower rpms of the 3.73's, the truck really purred on the highway. i got 21mpg on the highway with that combo and programming.
I felt the 4.56's were a tad low with the 38" (37.5 overall) Toyos but now that i've stepped up another size on the tires with these Pro Comps, i like the 4.56's more and actually think they may be too tall if I go any higher but 4.56's are a good overal big tire setup.
__________________
2007 MegaCab - Suspended by Thuren, rollin' 37s.
"My rear seat reclines, b!tches. That way, my passengers look cool and are in style when I'm pulling 3-point turns on the boulevard." -VH
|
|
|
04-28-2007, 11:50 PM
|
#18
|
Name: BigPSD
Title: Green Behind the Ears
Status: Not Here
Join Date: Apr 2007
Member`s Gallery
Posts: 87
|
I got 38s on my truck, thinking about a gear swap up to 4.10s or 4.30s...will this help with my EGTs at all? with an innovative extreme street tune i hit close to 1600*....what to do, what to do?
__________________
05 F350HD/4"Straight Pipe/SCT/AFE/8"Lift/38"Nittos/HIDs/Kleinn/Nexus Gauges
|
|
|
04-29-2007, 02:46 PM
|
#19
|
Name: DCSpecial
Title: Mr. Sinister
Status: Not Here
Join Date: Apr 2006
Location: Psych Ward
Member`s Gallery
Posts: 3,898
|
Quote:
Originally Posted by BigPSD
I got 38s on my truck, thinking about a gear swap up to 4.10s or 4.30s...will this help with my EGTs at all? with an innovative extreme street tune i hit close to 1600*....what to do, what to do?
|
Yes EGTs will drop.
I'd do 4.30s or 4.56s....most likely 4.30s since you have a SCT and some other go fast goodies.
On my 7.3 I ran 3.73s and 38s....then went to the 4.56s with 38s and my EGTs (cruising, WOT, etc..) dropped 200-300* across the board.
Now I'm running 40s and the 4.56s, EGTs are <125* more than they were with the 38s. But, I'll be dropping back down to 38s soon.
__________________
DC
Moderator
2001 F-350 7.3 4x4 CC SWB
2007 F-350 6.0 4x4 SC LWB, Lightly Modded
Special Thanks to: TS Performance, DPPI, Power Slot, Southern Polyurethanes Inc, Silverline Exhaust, Dick Cepek Tires.
Rest of the Fleet: 99 F-450, 00 F-450, 01 F-350, 02 F-350, 02 F-550, 04 F-450, 06 F-450
|
|
|
04-30-2007, 01:52 AM
|
#20
|
Name: BigPSD
Title: Green Behind the Ears
Status: Not Here
Join Date: Apr 2007
Member`s Gallery
Posts: 87
|
Thanks DC...thats just what i want to hear!!! im having harsh EGT problems
__________________
05 F350HD/4"Straight Pipe/SCT/AFE/8"Lift/38"Nittos/HIDs/Kleinn/Nexus Gauges
|
|
|
Posting Rules
|
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts
HTML code is Off
|
|
|
All times are GMT -5. The time now is 04:30 AM.
|