Re-Gearing 93 350 SBC TBI 35" Tires 4.56's ? - Suggestions ?

[justin93]

I have a 1993 Chevy K1500 with a 350 TBI (non-vortec) and 4 Speed auto w/ OD Transmission, i believe the 4l60E.
It has 9" of total additional lift.
3" body lift
6" lift suspension
35"x 12.5" x 15R

It has stock gears which is 3.73 - To my knowledge from spinning the DS and marking the tires (door jams don't have the numbers)

Now reason for regearing is i have SH** Mechanical leverage and after taking out my ceramic headders (cali smog reasons) the balls of my truck have shriveled up severely. With that being done, it reads almost 10 MPH over on the dash then my ACTUAL speed. Every 3.5 miles reads out 5 miles on my odo - the truck cruises hard/high rpms on freeways when going 1 exit to the next in just standard Drive it can rev up to 2800-3000 to be at a modest 70 mph..

My gas is quite terrible already and i was considering just swapping out with nothing but quality parts,sierra ring and pinion 80-90 gear oil no additives, timken bearings included with the master kit for both front and rear and was wondering if 4.56'S is my best overall gear to go with?
Anyone with similar setups as well if you guys could chime in that would be appreciated!

Im still skeptical as to how much of a difference i will see and also if its worth it? Share with everyone how much you payed or how much you think should be spent to complete this job the CORRECT way no shortcuts!

Currently the truck shows 226,*** miles and the engine and trans have 30k on the rebuild, I've done alot of work to this truck and want it to run as good as it looks as should most vehicles
- Function over form all day -

What would be the ideal gearing for my setup?
Would i require a new carrier? New Diff ?
Would i need anything more then the gear oil, Master install kit (bearings, seals etc), Ring and pinion front+back ? Suggested quality brands or great deals?
Anyone that has changed from 3.73 to 4.56's with 35's out there? Let me hear your opinions!
Anything i might have to replace while im changing out all the gears ? Things to look for after swapping the gears?..

Will my gas mileage stay roughly the same if driving through town and back/occasional uphill driving ? If yes that's what im also interested in, if i can better-benefit my performance for my already low gas mileage i would LOVE to swap it out with appropriate gearing to get the best of my power band and most out of my mechanical leverage WITHOUT sacrificing longetivity/fuel economy.

it takes SO much gas to spin the wheels i think its confused me being the lower numerical gearing provides better gas mileage except when you have to over-work to get to the equivalent speed in that with 4.56 gears would achieve - This is why im asking if i would really even see a change more/less in fuel economy from the swap.

I know i should of got a 'this', a 'that' if i was looking for gas mileage but this is what i have and what my question pertains as i just want the best performance and reliability of my vehicle just like anyone else should thats passionate about there vehicles.

Any and all information and suggestions will be greatly appreciated.
Thanks

 

[thz71]

well if you arnt planning to go any bigger 4.56 is probably about right, im guessing your not getting into overdrive when your revving so high

 

[southern_z71_92]

http://www.4lo.com/4LoCalc.htm

this will tell you what gear you will need.

 

[oohunter04oo]

I have a 93 TBI 350 with 4.56's gears. I've had 33's, 37's and now 35's. I only liked the 4.56's with the 33's. If i could do it over again id have 5.13's in it. but that is just personal preference. My truck is used for a hunting truck so its offroad most of the time. it'll never see long interstate trips. but at 70 the rpms aren't bad. the truck seems to pull good from 35mph and up. off the line it just revs up real high in 1st. but my trans is old so that may have something to do with it. if you don't do alot of interstate driving go 4.88's especially if your going to go up in tire size!

 

[Crash]

4.56's with 35's will drive like 3.73's with 31's

 

[justin93]

I have a 93 TBI 350 with 4.56's gears. I've had 33's, 37's and now 35's. I only liked the 4.56's with the 33's. If i could do it over again id have 5.13's in it. but that is just personal preference. My truck is used for a hunting truck so its offroad most of the time. it'll never see long interstate trips. but at 70 the rpms aren't bad. the truck seems to pull good from 35mph and up. off the line it just revs up real high in 1st. but my trans is old so that may have something to do with it. if you don't do alot of interstate driving go 4.88's especially if your going to go up in tire size!

Interesting, This is very useful information oohunter04oo thanks for putting it in perspective. Im either going to keep the 35's or put 37's in the future if a good deal comes around, however i'm opting for the 4.88's as ill have a little bit higher of RPM then the stock factory tire size/gear ratio with the current tires i have now - claimed a technician from richmond ring and pinion over the phone.
Im all about more mechanical leverage but this vehicle will mostly be seeing camp sites, burn trails, occasional recreational park by traveling on the freeway (not across state lines) but other than that it will be cruising on the street with my bike in the bed when i do drive it. Hunter, if you did it over again would you put the 5.13's with what tire size? Im sure you'd have alot more torque in your lower RPM's to help you get over ditches/boulders +
And also why would you recommend 4.88's if i wasn't doing interstate driving ?.. if you could tell me more about the reasoning that would help alot.




I did manage to get a quote for a set off a sellers store on Ebay for 530$ shipped no tax, let me know if anyone's used these gears in experience




Motive Gears (blue) 4.88's front (8.2) Rear (8.6)
Motive coil pinion install kit by Koyo - OEM Level or Better ... What does this mean? related to gear noise ? this wasn't the cheaper package either
This didn't come with the parts to rebuild the carrier, which im on the fence contemplating of buying while im going to be in the axle already i would think it would be a good idea while im already inside the axle - it has 226,*** with 3.73 gears and it was lifted from factory so im unsure if thats a sign that i should replace them too.. or even if i got the Auburn limited slip 4.88 package with the master kit and carrier hardware = My carrier doesn't need to be changed though so im unsure of the pros vs cons if i did this other then burning a larger hole in my pocket.




"well if you arnt planning to go any bigger 4.56 is probably about right, im guessing your not getting into overdrive when your revving so high" - thz71, I live in a more city-suburbia area so i'll only keep it in D when im going from one exit to the next which is less than 1.5 miles in between each other. When im going anything over 10 miles or uphill incline i will put it in OD but my father was always telling me not to change gears as it will 'Ruin your transmission' if anyone can vouch for this or explain proper shifting techniques without hurting my 4l60E i would appreciate that, i usually apply the brakes even if lightly before shifting gears going up and down the gears - Im unsure how this transmissions like to be shifted so i've been trying to baby it and ease off anything other than D and OD occasional 2nd for up hill inclines.




Thanks for the Link Southern Z71 92, i actually used that website to determine my suitable gearing but im still trying to find my RPO codes to input - my glove box numbers are faded and can't identify the code




Crash, i definetly don't wan't that then lol, i mean better fuel economy being numerically lower but just the performance right now is awful specially after removing the ceramic headders and i had a FAT exhaust leak then and even after getting a fabricated complete exhaust setup from manifolds back it still is a HUGE noticable decrease in power. I would just like the optimal mechanical leverage for my truck as its had these 3.73 for 225,*** and my truck overworks to move the wheels = loss of fuel efficiency/loss of power

If anyone has successfully swapped there gears out could you post your experience and what manufacturer you used for the ring and pinion to the master install kit - Also if they make noise or are loud or have had to do any maintenance also include this if possible


Ill stop typing now i know im probably killing you guys reading this damn novel but im soaking in the knowledge and learning so its all in good manner, thanks again for your responses everyone