Centrifugal blowers and preferred rear gear - hmmm?

straightliner1 · 04-20-2008, 01:41 AM

I'll be putting together a stout rear end soon (8.8, 9" ends, tapered roller bearings, 33 spline clutch posi, etc.) and was curious on what everyone's preference for rear end ratios were? I had 3.55's when the car was N/A and might just get a new set of those, unless you sway me another direction.

I'm likely to wind up with 600+ to the wheels through a 6 speed. This will be a weekend "fun car" with the occasional trip to the track (both road and drag).

modo · 04-20-2008, 01:44 AM

Quote:

Originally Posted by straightliner1

I'll be putting together a stout rear end soon (8.8, 9" ends, tapered roller bearings, 33 spline clutch posi, etc.) and was curious on what everyone's preference for rear end ratios were? I had 3.55's when the car was N/A and might just get a new set of those, unless you sway me another direction.

I'm likely to wind up with 600+ to the wheels through a 6 speed. This will be a weekend "fun car" with the occasional trip to the track (both road and drag).

26 " tire 3.27s, 28" 3.55s

swinerton · 04-20-2008, 06:45 AM

I have always been partial to 3.73's in my rigs.

Carbuff91 · 04-20-2008, 01:35 PM

subscribing...I have a blown setup and am moving to a 28" tire this year and have 3.55's currently.

keesor · 04-20-2008, 01:56 PM

I have 3:73's on mine and 1'st gear is worthless. I'll be switching to 3:55's sometime this spring.

swinerton · 04-20-2008, 07:59 PM

Quote:

Originally Posted by keesor

I have 3:73's on mine and 1'st gear is worthless. I'll be switching to 3:55's sometime this spring.

Don't switch to 3.55's just to think your gonna hook better in first. With the power your making, 1st will still be useless. I went to 3.55's from 73's, and to be honest, it wasn't worth the change, but I had a howl from the previous install that I couldn't stand.

StarrMan · 04-20-2008, 08:34 PM

I have 3.55's and thinking of going to 3.73's because of the closer ratios in my TKO-600, but I find it hard to justify the cost to only go 1 step in ratio

straightliner1 · 04-21-2008, 02:08 AM

Lots of good opinions here -

I agree with the power the blower cars are making now, 3.73's or higher in my opinion would be worthless. Just running my HCI 302 with the 3.55s it would blow the tires off in first but 2nd and 3rd were a delight!

94tealGT · 04-21-2008, 03:54 AM

I had 3:73's with my old 26's..useless.

Now have 3:55's and 28's on order

Chris

Carbuff91 · 04-21-2008, 07:14 AM

Quote:

Originally Posted by swinerton

Don't switch to 3.55's just to think your gonna hook better in first. With the power your making, 1st will still be useless. I went to 3.55's from 73's, and to be honest, it wasn't worth the change, but I had a howl from the previous install that I couldn't stand.

What causes that howl anyway? The pinion gear wasn't installed correctly and the gears aren't aligned?

swinerton · 04-21-2008, 09:13 AM

Quote:

Originally Posted by Carbuff91

What causes that howl anyway? The pinion gear wasn't installed correctly and the gears aren't aligned?

Yes, very poor carrier shimming, and pinion mesh.

JimsYellow88 · 04-21-2008, 11:10 AM

I tried the 3:27's in my car and ended up going back to the 3:55's. With the 3:27's, it just felt alittle doggy when cruising at 50mph. It was too fast to drive in 4th, but not enough RPM's for 5th. This was with A TKO and 26" tires.
I would say that with your 6 speed that you may want to even go with the 3:73's for a street car. But I like my 3:55's in my fox.
Jim

hbk_136 · 04-21-2008, 06:11 PM

yeah same here, im likin my 3.55 gears. Still have traction issues, but my tires are kinda small.

muttstang · 04-21-2008, 06:31 PM

I really like my 3.73s with the vortech

ryans88gt · 04-21-2008, 06:47 PM

Quote:

Originally Posted by swinerton

Yes, very poor carrier shimming, and pinion mesh.

I thought so too, the previous owner of my 89 had the 3.55s installed and they whine at about 45-55 mph only. I thought it was a gear mesh problem, but the backlash was perfect at 0.011", the gear mesh was centered using marking compound, and there was no runout on the ring gear. There was no unusual wear either and it has an aluminum drive shaft. Why was it whining? I still don't know, but I just buttoned it up and it has been fine ever since, but still whines.

buddha · 04-21-2008, 09:35 PM

Quote:

Originally Posted by modo

26 " tire 3.27s, 28" 3.55s

x2

I'm running a set of 3.27's with a 5-speed and less rwhp. Rolling in 2nd and matting the gas at 30 mph will put down as much BFG Drag Radial rubber as you like!

That being said, it can still be managed by pedaling it if your goal is traction............somewhat. LOL!

Macs Stang · 04-21-2008, 10:28 PM

I am going to be the one crazy guy and say I have 3.90's out back with my t-trimmed boss 347. Granted I can rev a little higher then a standard 302, but we'll see once it gets tunned and I get to the track. I am planning on mid 130's to 140 mph traps. I have 26x11.50-15 et streets so we'll see.

I might have to go with a 28" tall tire. Regardless if you have the proper suspension things will work out in the spin to win department.

JimsYellow88 · 04-22-2008, 09:11 AM

Quote:

Originally Posted by Macs Stang

I am going to be the one crazy guy and say I have 3.90's out back with my t-trimmed boss 347. Granted I can rev a little higher then a standard 302, but we'll see once it gets tunned and I get to the track. I am planning on mid 130's to 140 mph traps. I have 26x11.50-15 et streets so we'll see.

I might have to go with a 28" tall tire. Regardless if you have the proper suspension things will work out in the spin to win department.

You may have some issues getting through the traps at those speeds with the 3:90's and 26" tires. Maybe someone else can chime in but, I "think" I was at about 6000 rpms in 4th at 131 with my 3:55's and my 275/40/17 dr's (which are 25.75" dia). FWIW
Jim

I do think the original poster may be able to go with a little more gear for the street considering he has the six speed.

Macs Stang · 04-22-2008, 10:48 AM

Quote:

Originally Posted by JimsYellow88

You may have some issues getting through the traps at those speeds with the 3:90's and 26" tires. Maybe someone else can chime in but, I "think" I was at about 6000 rpms in 4th at 131 with my 3:55's and my 275/40/17 dr's (which are 25.75" dia). FWIW
Jim

I do think the original poster may be able to go with a little more gear for the street considering he has the six speed.

I have 26" bias ply tires that will grow on the top end, but probably not enough. I will more then likely just buy a set of 28" tall tires for the track.

My old et streets lasted me 6 years so I think it might be time to replace them.

TonyG · 04-22-2008, 02:29 PM

I've had 3.27s, 3.73s, and 4.10s, and honestly I like the 4.10s the best. The gears pull hard at low RPMs, then the centri blower takes over and pulls even harder to the redline.

Here's a video with the 4.10s on street tires, to give you an idea of how the RPMs and MPH match up:

http://videos.streetfire.net/video/S...mph_153846.htm

On the dragstrip, I trap 122+ so I run a taller tire (28"). The 28"/4.10 combo is similar to a 3.73 ratio with stock tiress. Here's another clip on the dragstrip:

http://s132.photobucket.com/player.s...fs=1&os=1&ap=1

As you can see, 1st gear isn't "useless" at all. You're putting more torque to the tires, so you need more traction. Bogging the car down with taller gears isn't the answer.

buddha · 04-22-2008, 06:06 PM

Let's remember that the poster is looking for a gear for the street 99% of the time.

With the 6-speed you can definitely get away with more gear, but I still personally wouldn't run more than a 3.55 gear with the power output he's looking at.

And yes, 1st gear on the street will be useless, regardless of the what gear is out back.

phillie356 · 04-22-2008, 09:39 PM

3.73 works for me.....

OWENMUSTANG · 04-23-2008, 11:08 AM

I have 3.73's now. I have a set of 3.55's in the garage..

I love the 3.7's w/ the T-5.

Not sure wich way to go when I get the rear set up.. (also have a TKO 60 to install)

I have 245 drag radials... doesn't hook until 3rd with the 3.73's

408fox · 04-23-2008, 05:27 PM

4.30's here with a t-trim

StarrMan · 04-24-2008, 12:18 AM

Quote:

Originally Posted by OWENMUSTANG

I have 3.73's now. I have a set of 3.55's in the garage..

I love the 3.7's w/ the T-5.

Not sure wich way to go when I get the rear set up.. (also have a TKO 60 to install)

I have 245 drag radials... doesn't hook until 3rd with the 3.73's

If your TKO600 has the 2.87 first gear then keep the 3.73's. The first gear in the T5 is 3.35 and with my 3.55's it was a real stump puller, but with the 2.87 first gear it seems a bit doggish and I have to launch at quite a bit higher rpm to keep it from bogging. Just my opinion though and my car is a bit heavier than yours

straightliner1 · 05-17-2008, 07:48 PM

Back from the dead!

I'll be ordering gears and a 33 spline carrier Monday. Anyone else care to chime in? I'm leaning towards my usual 3.55 setup but I have never driven a 6 speed car before, wondering if the jump to 3.73's would be a wiser choice?

Decisions...decisions...

Thunder5.0 · 05-17-2008, 08:45 PM

410's 28" tire here

fastgreen94 · 05-17-2008, 10:36 PM

355s even with the 6-speed.