rimpainter.com

I second, or third, or whatever the re-gear idea. I think I have mentioned this to you before in fact...anyway, going from 4.10's to 4.30's in my 5 speed rig was noticeable. A word of warning though, my mileage went down from around 17.3 to 17.1. I have a step function on my statistical mileage chart (yes, I am a freak)

YotaTruck1986

So when we're talking about changing the rear end ratio, we're not talking about replacing the entire rear end, right? Just a gear inside the differential? I don't know what I'm talking about.

BLKNBLU

iTrader: (1)

here's a good link for you to figure out what you've got now.

http://www.brian894x4.com/Gearratiosanddiffs.html

YotaTruck1986

Thanks for the link, very helpful.

Ok, my gearcode is F372, which according to the site means: I have a 7.5" gear, a 2 pinion open differential, and a 3.383 gear ratio.

rimpainter.com

That ratio sucks for drag racing. You have some serious opportunity for improvement with a re-gear.

YotaTruck1986

So I want a lower ratio - higher number - right? Should I go 4.10 or 4.30? Are there any other options? Are we just talking about replacing a gear(s) within my differential? Thanks.

kyle_22r

i think 4.10 would be good...though 3.90 wouldn't be a bad choice either(if it's available in 7.5). i'm not entirely sure about all the different choices on the 7.5 but there should be plenty.

jimbo74

yes jsut the ring/pinion in the rear differential....

4.10s should be more then enough for a street truck... you dont want to be going all out crazy, espicially with little tires

mike_d

yes, a lower ratio is a higher number. as far as picking the ratio, just do some math and see what works for you the best.

all else being equal: the torque applied to the road will increase as the ratio of your new versus old gear ratios. for example if you go to 4.10's then you'll get 4.10/3.38=1.21 or 21% more torque to the road. but likewise you'll get a 21% decrease in top speed. if you go to 4.30s then you'll get 27% more torque to the road and a 27% decrease in top speed. choose what makes you happy.

YotaTruck1986

This is still my daily driver, so I need to be able to cruise at atleast 80mph without running into too high RPMS. So you guys think 4.10 would be sufficient? And I'd be replacing the ring and pinion only? Does this ring and pinion combinations create the "gear ratio?" Thanks again for all the help.

rimpainter.com

You can also do the math to figure out your engine speed at certain speeds in certain gears. Get the math guys to help you with that - because I am far from one of those!

Then, adjust your desired ratio accordingly.

YotaTruck1986

So I need a 7.5" 4.10 Ring and Pinion (Is that how it's written?)? Does anyone have an idea what the price of install would be? 21% increase in torque on the road would be great! Is that the same for HP? As for top speed, my truck doesn't feel to good at 80+mph, so I'm just looking for good off the line acceleration. As long as I can still do my daily commutes sufficiently (80mph tops). Thanks.

mike_d

the easy way is to see what your rpms are at 80 right now. then if you go to 4.10, they'll be 21% higher, and for 4.30's they'll be 27% higher.

yup, the number of teeth on the ring divided by the number on the pinion is the gear ratio.

jimbo74

you first need to confirm you have the 7.5" rear axle and not the 8" rear axle!!!!!!

its best to get an instal kit... total for gears, install, and the install kit @ a shop should be around $500, @ the same time if you are serious about making a faster car with more consistent luanches, you might want to look into a locker....

YotaTruck1986

Thanks.

This site looks as though it sells Toyota 7.5 Ring and Pinion sets (Very bottom of the site). They range from 4.10 to 5.71. I'm just wondering if this is the type of thing I should be looking for when shopping around? Thanks.

YotaTruck1986

According to the VIN, it's a 7.5" rear axle.

What's included in an install kit? Thanks.

jimbo74

they put stuff like bearings and otehr stuff you need, its a good idea to get it... if you dont you can save about $150 though.....

also my vin plate says i have a 4 speed and an 8" i have a 5 speed and an 8" ... so make sure you have a 7.5" befroe you buy anything!!!! i cannot stress this enough!!!!

jimbo74

http://www.pirate4x4.com/forum/showt...postid=1876052
the 7.5" and 8" thirds seem to look a little different. seems that the "slant" from the top to the pinion is unbroken on the 7.5, while the 8" has a "blocky" looking slant. here's some pics for comparison:

7.5":


8":

note how the "slant" drops off instead of just sloping towards the pinion

YotaTruck1986

Thanks jimabena74! I'll check for that tomorrow. That was very helpful.

jimbo74

see i actually took that from a response kyle 22r gave to one of my threads a long time ago... people kept describing the 7.5" as thats what i thought i had, but i did indeed have an 8" under my truck... my truck was also a 5 speed when the vinplate said it had a 4 speed....