gear ratios

oops crap i did not even notice the camaro in the picture. Its actually not lifted,LOL just bad camera!lol

No its a 9in the came out of a thunderbird,LTD something like that, i believe. 73-75, somewhere around there.
 
How much of a nightmare are gears to do in a d60 and d70 from my 97? Any good writeups out there and any differences in doing one of these dana rears vs. a 12 bolt chevy rear?
 
guys are you saying that if i switch from 410's to 373;s, ill get a faster quarter mile.i thought i saw a post here a while back, where a guy went from 410's to 373's and gained 3mph, and no time
 
mulisha said:
guys are you saying that if i switch from 410's to 373;s, ill get a faster quarter mile.i thought i saw a post here a while back, where a guy went from 410's to 373's and gained 3mph, and no time
Click to expand...

The fact his MPH improved shows he was putting down more power for more of the track. He probably just needs to tweak his launch for the newer gears. It is always a bad idea to expect ET changes from gears when you are close. It is hard to get everything correct at the same time. But if I can run the same et and more mph I am all for it since that means I can now improve the short game and go faster and quicker.
 
well i know your 60ft isnt gonna be as good with 353's or 373's compare to 410's , so how do ya figure.
 
mulisha said:
well i know your 60ft isnt gonna be as good with 353's or 373's compare to 410's , so how do ya figure.
Click to expand...

Not necessarily, if the vehicle has to shift before the 60' mark with the lower gear then the 60' time can actually increase.

I know this from experience, not directly from diesel truck drag racing, but from over 16 years of regular sedan drag racing experience.

Also lower gears can attribute to more wheel spin especially on mostly stock suspensions that are not as tunable as for instance a 4-link on an all out car. this of course hurts 60' time as well.

Again in your scenario I assume mostly stock in this application.
 
mulisha said:
well i know your 60ft isnt gonna be as good with 353's or 373's compare to 410's , so how do ya figure.
Click to expand...


This is a very limited discussion but you are mostly wrong. It is not fist gear that usually suffers from a ring and pinion swap. You are usually reved up or stalled against a converter so a little bit of a gearing change shouldn't cause a "bog". If it does you know you went to high. I live in a world where you pick ALL your gears so you don't have to compromise. But in the mostly stock diesel truck world you are gonna have to sacrifice some where.
You will probably see the "bad" of a taller rear gear in 2nd and 3rd where the long spread of ratios COULD cause you to drop too much rpm. But with the big torque of diesel trucks most factory trucks are over geard for racing once the engine has been modified. You can't just say that slapping the tallest gear you can get in will make it better, nor can you say a short gear will get you the best short times. You have to be logical and consider all the gears and your power level and goals. You want to be geared just tall enough on the starting line that you don't bog and keep the vehicle from being too violent, AND you want to be geared short enough on the big end that you don't leave lots of revs in high gear so you get to the traps just after peak horsepower but not out of your power band. It's a tough road when you have what you have and that's it for trans ratios.
 
Wouldn't this also depend on what size tire he is running? Im on 35's and 20s and I cannot get any better than a 1.9 60'. I am on 3:73s. I broke a spider gear and damage my pinion gear so I am now having 4:10 put in. So if someone is running stock size tires with 3:73s or taller they would be fine? But 35s+ a little lower gear is probably needed?
 
Anyone running 3.31 or 3.07 on a d80..? Wondering what kind of cruising mph your getting at 1800-2000rpms? 80+mph?
 
For drag racing,, and safety reasons, you dont want to run too tall of a tire. A 32 or 33 " tall tire is pretty much the maximum height that you would want to run. I am running a 3 73 gear right now, I would love to be running a taller gear, but the tallest that I have been able to find so far is a 3 42.. and even that has been hard to come up with. My biggest issue for me is that I run out of top end... I am at 128 MPH right now with a 32 " tire ,, I am pretty much out of RPM
 
4.10s were too low last year for us. We were topped out before we hit the traps. The truck will spin 5k but it just like other 12v cummins it won't make any power there. A good example was a run where our truck didn't go into overdrive. The truck was spinnig 4500 but the trap speed was only 99mph.
Swapped in 3.54s this year, we will see what happens. Oh and 30in tire.
 
smokee94 said:
how much is it to go from a 4:10 to a 3:54
Click to expand...

from what i've found for new gears its 1600 alone for the front and rear gears, but then the labor would be bad. so your better off finding a set of used axles with 3.54's in them i have 4.10's in my truck as well and i don't see there being much of a problem with having short gears, i am and will be running a 32-33" tire and currently have no problems hitting 115 on the highway. and thats not near 4k so my goal of 11.99-11.50's should be quite possible with the gears i have. but my truck will also be in 3rd gear by 20mph if not even 15mph so im not worried about loosing et while my truck shifts.
 
DodgeCTD said:
Wouldn't this also depend on what size tire he is running? Im on 35's and 20s and I cannot get any better than a 1.9 60'. I am on 3:73s. I broke a spider gear and damage my pinion gear so I am now having 4:10 put in. So if someone is running stock size tires with 3:73s or taller they would be fine? But 35s+ a little lower gear is probably needed?
Click to expand...

I'm going to guess your 60ft time has more to do with the type of tire- mudders- than the tire size. I've had 1.78's with 10psi launches.
 
sleepin-sport said:
Anyone running 3.31 or 3.07 on a d80..? Wondering what kind of cruising mph your getting at 1800-2000rpms? 80+mph?
Click to expand...

I haven't been able to find a 3.07 for either the D80 or AAM 11.5". Anyone have any sources.

3.31 is the lowest I have found for 11.25" and 11.5" ring gear housings.
 
You must log in or register to reply here.
Back
Top