Rear gear question

Bob F · 10-06-2024, 12:19 PM

3400#
440”. 1.80 1st gear 4.10 rear 28? tire.
Car isn”t performing to expectations.
Only running low tens @ 133. 1.45 60?
Think it needs a lower gear?

Billy Nees · 10-06-2024, 12:39 PM

Well, that would depend on your finish-line RPM. Just looking at your dyno numbers and not knowing much else, I would probably gear it to hit the FL at 7000/7200. But that's a Stocker guy talking. That would to me be conservative. Not knowing what's in your stuff.

1320racer · 10-06-2024, 01:01 PM

Can’t read the graph. At what RPM, does it make peak HP and peak torque. What does your converter flash to and fall back on the gear change and what RPM are you shifting at?

Billy Nees · 10-06-2024, 01:04 PM

Peak HP, 6700
Peak TQ, 5300
1.80 1st, it's gotta be a PG.

1320racer · 10-06-2024, 01:12 PM

For optimum ET, If it was mine, it would have a converter that flashes to 5800, I’d be shifting at 7200 and gear it so it’s crossing the stripe at 7700. I would also get a 30” tire under it if you can not go wider.

Bob F · 10-06-2024, 02:54 PM

Quote:

Originally Posted by Billy Nees

Well, that would depend on your finish-line RPM. Just looking at your dyno numbers and not knowing much else, I would probably gear it to hit the FL at 7000/7200. But that's a Stocker guy talking. That would to me be conservative. Not knowing what's in your stuff.

It?s 7100 at the finish line now.
Convertor is around 5800 I believe.

1320racer · 10-06-2024, 03:03 PM

If you don’t have a data recorder get one or at least a playback tach so you have real data. That said, definitely needs more gear

Billy Nees · 10-06-2024, 04:41 PM

Quote:

Originally Posted by 1320racer

definitely needs more gear

And more tire.

Dyno · 10-06-2024, 05:30 PM

Rarely does more gear hurt! Depends on what your wallet can stand.

1320racer · 10-06-2024, 05:46 PM

Quote:

Originally Posted by Billy Nees

And more tire.

As I stated in post #5

10-06-2024, 12:19 PM	#1
Bob F Junior Member Join Date: Sep 2007 Location: Bucks Co Pa Posts: 68 Likes: 16 Liked 14 Times in 10 Posts	Rear gear question 3400# 440”. 1.80 1st gear 4.10 rear 28? tire. Car isn”t performing to expectations. Only running low tens @ 133. 1.45 60? Think it needs a lower gear? Attached Thumbnails

10-06-2024, 12:39 PM	#2
Billy Nees VIP Member Join Date: Oct 2002 Location: On a hilltop in Pa. Posts: 4,385 Likes: 3,415 Liked 7,321 Times in 1,645 Posts	Re: Rear gear question Well, that would depend on your finish-line RPM. Just looking at your dyno numbers and not knowing much else, I would probably gear it to hit the FL at 7000/7200. But that's a Stocker guy talking. That would to me be conservative. Not knowing what's in your stuff. __________________ Billy Nees 1188 STK, SS I'm OK..........it's everybody else.

10-06-2024, 01:01 PM	#3
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 2,144 Likes: 105 Liked 577 Times in 284 Posts	Re: Rear gear question Can’t read the graph. At what RPM, does it make peak HP and peak torque. What does your converter flash to and fall back on the gear change and what RPM are you shifting at?

10-06-2024, 01:04 PM	#4
Billy Nees VIP Member Join Date: Oct 2002 Location: On a hilltop in Pa. Posts: 4,385 Likes: 3,415 Liked 7,321 Times in 1,645 Posts	Re: Rear gear question Peak HP, 6700 Peak TQ, 5300 1.80 1st, it's gotta be a PG. __________________ Billy Nees 1188 STK, SS I'm OK..........it's everybody else.

10-06-2024, 03:03 PM	#7
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 2,144 Likes: 105 Liked 577 Times in 284 Posts	Re: Rear gear question If you don’t have a data recorder get one or at least a playback tach so you have real data. That said, definitely needs more gear Last edited by 1320racer; 10-06-2024 at 03:24 PM.

10-06-2024, 01:12 PM	#5
1320racer VIP Member Join Date: Nov 2007 Location: New Jersey Posts: 2,144 Likes: 105 Liked 577 Times in 284 Posts	Re: Rear gear question For optimum ET, If it was mine, it would have a converter that flashes to 5800, I’d be shifting at 7200 and gear it so it’s crossing the stripe at 7700. I would also get a 30” tire under it if you can not go wider. Last edited by 1320racer; 10-06-2024 at 01:20 PM.

10-06-2024, 05:30 PM	#9
Dyno Senior Member Join Date: Dec 2002 Posts: 885 Likes: 998 Liked 615 Times in 183 Posts	Re: Rear gear question Rarely does more gear hurt! Depends on what your wallet can stand.