S/ST - 3.89 vs 4.10

DailyDriverSst · 09-14-2022, 08:38 PM

I am switching from a Chrysler 8.75 to a Ford 9 over winter. Just can't get 8.75 stuff anymore.

Right now I have a 4.10 gear and go through the traps at 6,000 RPM. I am debating ordering the new axle with a 3.89 gearset instead of 4.10 . Have a 1.98 low in the powerglide.

How much can I expect my short numbers and ratios to change, if at all?

Converter stalls to 4,000 RPM and it's a factory frame rail truck with full interior.

TIA

GTX JOHN · 09-15-2022, 03:40 AM

Not a bunch
Couple hun short times

Charlie Yannetti · 09-18-2022, 10:50 AM

Not sure of your engine combo, but 6000 sounds low to me.. it does depend on the power though.. I might be looking to go up, instead of down..

Lenny5160 · 09-19-2022, 06:24 AM

Quote:

Originally Posted by Charlie Yannetti

Not sure of your engine combo, but 6000 sounds low to me.. it does depend on the power though.. I might be looking to go up, instead of down..

I agree that 6000 RPM sounds like the low range of acceptable converter stall numbers rather than an excessive trap number, but I suspect the “DailyDriver” part of the OP’s handle has something to do with this.

DailyDriverSst · 09-27-2022, 07:57 PM

Quote:

Originally Posted by Lenny5160

I agree that 6000 RPM sounds like the low range of acceptable converter stall numbers rather than an excessive trap number, but I suspect the “DailyDriver” part of the OP’s handle has something to do with this.

You would be correct. This is also a factory casting 2-bolt block that I'm almost asking too much of. Don't really want to hang the rods out of it, and I put 2-3,000 miles a year on it between taking it to work, joy rides, Rocky Mountain Race Week, etc.

09-14-2022, 08:38 PM	#1
DailyDriverSst Junior Member Join Date: Dec 2017 Posts: 56 Likes: 0 Liked 7 Times in 6 Posts	S/ST - 3.89 vs 4.10 I am switching from a Chrysler 8.75 to a Ford 9 over winter. Just can't get 8.75 stuff anymore. Right now I have a 4.10 gear and go through the traps at 6,000 RPM. I am debating ordering the new axle with a 3.89 gearset instead of 4.10 . Have a 1.98 low in the powerglide. How much can I expect my short numbers and ratios to change, if at all? Converter stalls to 4,000 RPM and it's a factory frame rail truck with full interior. TIA Last edited by DailyDriverSst; 09-14-2022 at 08:47 PM.

09-15-2022, 03:40 AM	#2
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,682 Likes: 2,663 Liked 2,322 Times in 659 Posts	Re: S/ST - 3.89 vs 4.10 Not a bunch Couple hun short times __________________ John Irving 741 Stock 741 Super Stock

09-18-2022, 10:50 AM	#3
Charlie Yannetti Senior Member Join Date: Jan 2005 Location: Alpine, NJ Posts: 566 Likes: 187 Liked 191 Times in 82 Posts	Re: S/ST - 3.89 vs 4.10 Not sure of your engine combo, but 6000 sounds low to me.. it does depend on the power though.. I might be looking to go up, instead of down..