Gear question

RedRice589 · Feb 20, 2015

TyCorr said:
Wow, you guys run super tall gears...

Id maybe run a 4.10 with 37s...4.30 is too much....you'll be running 2500rpms on the interstate or higher...

I dont agree with gearings accepted rules for tire size increases. I find stock gearing to be sometimes high for cruising at 75...which is fine if you dont do it for long periods.

I run 3.73 and 35s....it was fine with stock tuned power and with 450 hp worth of fuel it was perfect even towing. With 550ish its not even a thought lol.

One place id say its ok to "overgear" a truck to 4.30s running a 37 is if you run two lane higways and just jump from one town to the next. The extra pull down low would be welcomed.

What you don't get from us is that tall of a gear is better all around for some people.chow much interstate driving do you actually do. The good powerband for our stock motors is 2100 rpm or within a hundreds rpm of that. I have a dually with 4.30s. Albeit different tranny and final drive ratios slightly but with my 6.4 with a 5r110 and 4.11s it wasn't bad at all. And even on my dually to be at 2500 rpm at 80 isn't as bad as you think. But at 72mph I'm a t 2150 rpm and it should tow awesome. Not to mention the strain it takes off the tranny and motor is worth the swap. IMO. If it's a daily I'd go 4.11s with 37's if you're going to use it for work. Then 4.30 all the way.

On edit my dually on 4.30s I have stock tires on which are like 31" tall. I'd drop significant rpm going to 37's.

jban126_f350 said:
Where can I get a kit? What's the best place? Online or whatever?

Sunrisefordparts.com price it out or give them a call. They're good peeps.

jban126_f350 · Feb 20, 2015

RedRice589 said:
What you don't get from us is that tall of a gear is better all around for some people.chow much interstate driving do you actually do. The good powerband for our stock motors is 2100 rpm or within a hundreds rpm of that. I have a dually with 4.30s. Albeit different tranny and final drive ratios slightly but with my 6.4 with a 5r110 and 4.11s it wasn't bad at all. And even on my dually to be at 2500 rpm at 80 isn't as bad as you think. But at 72mph I'm a t 2150 rpm and it should tow awesome. Not to mention the strain it takes off the tranny and motor is worth the swap. IMO. If it's a daily I'd go 4.11s with 37's if you're going to use it for work. Then 4.30 all the way.

On edit my dually on 4.30s I have stock tires on which are like 31" tall. I'd drop significant rpm going to 37's.

Sunrisefordparts.com price it out or give them a call. They're good peeps.

No towing. just street truck kinda want it to be racey. I don't want it to be laggy at all. If I have to run a bit higher rpm on the highway than whatever. I want my truck to seem stock on 37's so I don't loose hp. That's why I want to re gear it. So a big turbo and big tires can work together.

TyCorr · Feb 20, 2015

Then gearing it like a tractor really isnt necessary. 4.10s and 37s on a street truck would be fine. If you tow alot and dont mind listening to a wound out 6l ad infinitum, then pick whatever. Having been around a lot if years and tried a bunch of things, I wouldnt run real low gears unless I planned on top speeds of 65mph...

My duramax has the 3.73 and the 265s on the 18s...they are 33 some inches tall. 3.73 is plenty of gear...running over 2k rpms pretty much all the time.

Hey do what you want. I just tried to give different oerspective. Gears have a huge effect on turbo spool and powerband too. Choose wisely.

swinky · Feb 20, 2015

TyCorr said:
Then gearing it like a tractor really isnt necessary. 4.10s and 37s on a street truck would be fine. If you tow alot and dont mind listening to a wound out 6l ad infinitum, then pick whatever. Having been around a lot if years and tried a bunch of things, I wouldnt run real low gears unless I planned on top speeds of 65mph...

My duramax has the 3.73 and the 265s on the 18s...they are 33 some inches tall. 3.73 is plenty of gear...running over 2k rpms pretty much all the time.

Hey do what you want. I just tried to give different oerspective. Gears have a huge effect on turbo spool and powerband too. Choose wisely.

He's wanting to go non vgt. 4.30s wouldn't wind this thing out by any means.

TD-5 · Feb 21, 2015

QUOTE"I've swapped gears in a rear multiple times someone told me 4.30 wouldnt work in my rears. So I was just checking to make sure I don't have to buy another rear(s)"

Sterling 10.5/10.25 differentials don't have a case break when it comes to gearing. All ring & pinion ratios will work in a Sterling case up to 2011. However there were several change ups over the years so you need to make sure you get the corect bearings for what your going to use.
The front Dana 60 has a case break @ 4.10:1. Only differential housings designed to accept Ring & pinions of 4.10 ratio & down will fit these housings. Then they also make a housing to accept 4.30:1 gears & up. That being said, most Aftermarket manufacturers make what the refer to as thick gears that will allow the lower gear ratio's to work in the 4.10 & down housings.
Find yourself a knowledgable supplier like "Randys Ring& Pinion" who can answer ALL your questions & set you up with what you need.

I run a 37" tire that has an actual workin diameter of 36.25". I travel a lot on highways @ 70-75 mph a lot of the time. I finally decided to go with 4.10's. this gave me decent rpm on the highway but still improved my off the line snap over the OEM 3.55 ratio. The 4.10's also allow me to drop to a 35" tire in the future if I need to.
When I was trying to decide what ratio to go with I calculated a couple of graphs that allowed me to pin point any RPM & speed in any gear with either ratio. This helped with my decision.

jban126_f350 · Feb 21, 2015

TyCorr said:
Then gearing it like a tractor really isnt necessary. 4.10s and 37s on a street truck would be fine. If you tow alot and dont mind listening to a wound out 6l ad infinitum, then pick whatever. Having been around a lot if years and tried a bunch of things, I wouldnt run real low gears unless I planned on top speeds of 65mph...

My duramax has the 3.73 and the 265s on the 18s...they are 33 some inches tall. 3.73 is plenty of gear...running over 2k rpms pretty much all the time.

Hey do what you want. I just tried to give different oerspective. Gears have a huge effect on turbo spool and powerband too. Choose wisely.

I appreciate that info like I said I'm new to re gearing I've installed new ring and pinions at work and stuff but I'm new with after market. Like what works better wth what and what will give me the best results.

jban126_f350 · Feb 21, 2015

swinky said:
He's wanting to go non vgt. 4.30s wouldn't wind this thing out by any means.

What non Vgt would work best with 4.30?

Would 4.10 be alright for a stage 3 Vgt?

I just don't want extreme lag off the line I like having that initial launch off the line. But I don't wanna run out of rpms on the high way

Will 4.10 be laggy at the line at all? Cause there will be highway driving when I start school. I'm sure 4.10 will be best for highway but 4.30 would be good for that launch. I want a poll to see what you guys with experience modifying the gear ratio think

TyCorr · Feb 21, 2015

Having lower gears will reduce spoolup not help. With larger turbos and more fuel the closer to stock gearing will keep a load against the motor and help spool the charger. But yea, with 37s id stay with the 4.10...

swinky · Feb 21, 2015

TyCorr said:
Having lower gears will reduce spoolup not help. With larger turbos and more fuel the closer to stock gearing will keep a load against the motor and help spool the charger. But yea, with 37s id stay with the 4.10...

ehh I see what you're saying but two trucks with the same turbo and injector one on 33s and the other on 37s.... The one on 37s Won't act nearly as responsive. More rpm helps spool them too ya know.

TyCorr · Feb 21, 2015

swinky said:
ehh I see what you're saying but two trucks with the same turbo and injector one on 33s and the other on 37s.... The one on 37s Won't act nearly as responsive. More rpm helps spool them too ya know.

Thats the tradeoff of having large tires. I have things both ways. Im not trying to dissuade him from his 37s but rather trying to help him understand how best to live with them. With stock fuel my 7.3 had 37s and was as expected pretty shttiy due to power to rolling resistance relationship. It was fine in hotter tunes. Adding another 100hp of fuel made the issue even less of an issue.

Now 3.73 and dropping down to a 35 with 500+ hp is PERFECT! There is nothing to be desired. Im assuming a 6l with 190/100s has plenty of power to be had....with a 37" tire I think a 4.10 would be his best balance of nice cruising rpm and nit being undergeared.

4.30s maybe but now if you do any sustained interstate driving you've got a modded, piped, lifted, noisy as diesel running an rpm where molars begin to rattle.

scparrish · Feb 21, 2015

Non vgt on a 6.0 and 35s on 3.73 leaves plenty to be desired especially if you are talking about a s366. A fmw turbo is slightly better but with 37s you will want to do 4.30 to get back to stock powerband. Plug everything into that formula the math doesn't lie.

jban126_f350 · Feb 21, 2015

TyCorr said:
Thats the tradeoff of having large tires. I have things both ways. Im not trying to dissuade him from his 37s but rather trying to help him understand how best to live with them. With stock fuel my 7.3 had 37s and was as expected pretty shttiy due to power to rolling resistance relationship. It was fine in hotter tunes. Adding another 100hp of fuel made the issue even less of an issue.

Now 3.73 and dropping down to a 35 with 500+ hp is PERFECT! There is nothing to be desired. Im assuming a 6l with 190/100s has plenty of power to be had....with a 37" tire I think a 4.10 would be his best balance of nice cruising rpm and nit being undergeared.

4.30s maybe but now if you do any sustained interstate driving you've got a modded, piped, lifted, noisy as diesel running an rpm where molars begin to rattle.

I'm sorry what benefits would I get out of 4.10 rather than 4.30 and vise versa

swinky · Feb 21, 2015

scparrish said:
Non vgt on a 6.0 and 35s on 3.73 leaves plenty to be desired especially if you are talking about a s366. A fmw turbo is slightly better but with 37s you will want to do 4.30 to get back to stock powerband. Plug everything into that formula the math doesn't lie.

X2..

jban126_f350 · Feb 21, 2015

swinky said:
X2..

i want to start a poll to see what people think!

RedRice589 · Feb 21, 2015

If you don't tow and it's a tow. Just go with 4.20s it allows you to maintain good drive ability at 70-75 and at 80 it's not wound out. Not that'd it'd be but it'll be at a good rpm to spool but you'll run out of rpm at 100 or so. If you towed then I'd say go to 4.30

jban126_f350 · Feb 21, 2015

RedRice589 said:
If you don't tow and it's a tow. Just go with 4.20s it allows you to maintain good drive ability at 70-75 and at 80 it's not wound out. Not that'd it'd be but it'll be at a good rpm to spool but you'll run out of rpm at 100 or so. If you towed then I'd say go to 4.30

I don't tow at all I just want to haul ass