Rear gear ratio

[black 79 sport coupe]

Who is running a lower gear ratio than a 3.42 ?

 

[1986 Buick GX1]

At least for the ‘86-
‘87 the 3:42 is optimal for a 26” tall tire and not bad for a 28” tire too. I think it depends on tire size, hp level and trap speed.
Hopefully the Hot Air guys will chime in.

 

[Turbo6inKY]

The 3.42s are optimal. If your ring and pinion are OK, there's really no compelling reason to swap them.

If your gears are not OK (I chipped a tooth off my ring gear a few years ago), then plugging a set of 3.73s in will get some low end grunt without sacrificing highway driving. Go much lower and you're going to be really winding it out on the highway. You also run into situations where you could be shifting to 4th under power where you weren't before, and if you do that and the transmission hasn't been gone through you could end up having to go through the transmission.

Like every question worth asking, the answer is "it depends".

 

[Mr.Spool]

Who is running a lower gear ratio than a 3.42 ?

🖐

 

[THensley]

and how's running more than 5500 RPM

 

[black 79 sport coupe]

🖐

What are you running

 

[black 79 sport coupe]

and how's running more than 5500 RPM

What does that even mean ? How was this helpful ?

 

[Mr.Spool]

and how's running more than 5500 RPM

Gears are a mechanical advantage in which the tire has no choice but to turn slower or faster depending on the ratio.

 

[THensley]

What does that even mean ? How was this helpful ?

your correct its no help. Im Sure MR Spool is running more than 5500 Do you want too?I do with 3.42

 

[GNVYUS 1]

I have a feeling Spool is lower than 3.42 because he's like a 3.70 on a 30" tire (3.22). Hahaha

Gear Ratio Calculator

Easy to use gear ratio calculator. Use our gear ratio calculator to find the correct gear ratio to run when changing tire sizes to keep your stock gearing.

tiresize.com

Effective gear ratio is what most of us 28" tire guys are really running, 3.42 turning into a 3.20. Most guys on here are lower than 3.42s since the 28" is a really common tire.

With my 3.70 gear and 28" I'm actually super close to the factory 3.42, I'm 3.46. Speedo is like .5mph off at 5000rpm which was a nice for the dash mph and logging.

 

[Mr.Spool]

What are you running

I have more than one Buick and the combinations are very different
From a 109 to a stage 2 with stage 2 heads
But my cars are no time cars.
So I would prefer to keep my combinations to myself at this point.
I have alot of experience with various rear gear sets.
If you ask a specific question I will help.

 

[Mr.Spool]

You can pm me if you want to keep your stuff more private.

 

[Mr.Spool]

and how's running more than 5500 RPM

Ive posted on this before but I can get a little more rpm specific.
Back in the day
On a stock motor (mild port stock iron head)build stock maf/ecm 3700+lbs
49 turbo 28 tall tire
I ran 80+mph on the highway around 2600 rpm in 4th gear.
1.4 60fts,6.6 1/8 mile,10.6@125 1./4 mile.
What was neat was it went right off the footbrake 3200 1 psi to go 1.5 60fts and it did it on the street
All on a 4.10 rear gear and a stock camshaft
It drove like a dream too.
That was a lost cost bolt on build with
High torque low rpm small cast 58mm turbo setup that chopped down the 60ft and 330 on a 28 tire.
I needed 15/20psi of launch boost with higher rpm on the leave to go 1/5 60fts on the same combo with a 3.42 gear.

 

[V6sleeper]

.355 and 28" is really nice on one of my cars

 

[Mr.Spool]

.355 and 28" is really nice on one of my cars

I did a car for someone with a stock turbo/intercooler stock motor setup in a gn years ago
It had the trans done and later we put a what we thought was a converter in it lol
On a 255 6015 drag radial on the stock rims with a 3.70 rear gear
pump gas alky car and it was nice to drive and ran 11s with a 1.5 60ft.

 

[V6sleeper]

.355 and 28" is really nice on one of my cars

I should mention you can 355s in an 8.5" 10 bolt now for an extra price i think US Gear makes them, for as long as i remember you can only get them in a Ford 9" and 8.8