3.73 to 4.10 swap

saxmanJJ · May 24th, 2010, 06:51 PM

I recently swapped my 3.73s out for 4.10s.

My typical 1/4 mile times are in the 13.00 to 13.10 range (with the 3.73 gear), with my best ever time being 12.90. My typical 60' time is between 1.75 and 1.85. I used to cross the stripe at about 5000 rpms and now I will cross at about 5500. BTW, my horsepower is about the same at 5000 rpms as it is at 5500. My peak hp is like a flat line between 5000 and 5500 rpms, where it drops off ever so slightly until about 6100 where it drops off significantly.

What times should I expect to be able to accomplish with the gear change being the only change to the car, assuming I learn to take full advantage of the new gears?

My setup is in my "garage" on the site BTW.

Also, if I am able to improve my ET, would the improvement be mostly in the 60' time or all the way down the track?

RDY4WAR · May 24th, 2010, 08:13 PM

I would say a bigger improvement in your 60' time. I could see you running a 12.7.

Where are you in SE PA? We're having a Tony Luke's Philly Cheesesteak meet in July. Check out the Northeast forum if you're interested.

saxmanJJ · May 24th, 2010, 08:25 PM

Thanks.

I'm near Norristown.
So, I'll try to remember to come to the meet.

I race at Atco about twice a month.

Next race I'll probably attend is NMCA at MapleGrove where I'll run True Street. I'll be trying to win the 13-second plaque (avg. of 3 runs - closest to 13 seconds without going under). Not that easy when I'm hot-lapping the car but you never know.

RDY4WAR · May 24th, 2010, 08:59 PM

Nice! We were discussing coming down to Cecil on that Saturday after Tony Luke's. I wouldn't mind seeing if I can push the Focus into the 13.4s. I've got it consistent in the 13.5s.

04gtblkvert · May 25th, 2010, 09:29 AM

Gears are for 60 foot, so maybe you will be able to cut 1.6s with a tire.

saxmanJJ · May 25th, 2010, 10:42 AM

A 13.5 sec Focus is one nasty Focus!

I'm using M/T ET Street Radials. They seem to hook up pretty well at my power level. I'll keep working on my launching and see where I can take it!

HickRocket1258 · May 26th, 2010, 10:11 AM

I believe the 4.10s will help you more with 60' like Smithboy said, but not help so much on the top end. I have 4.10s and several other parts waiting to be put in.

JTs03v6 · May 26th, 2010, 08:34 PM

Lowering your 60' will result in lower et.

I'm curious to see what you pick up. I'm runnin 373 and want to swap them for 4.10's bad!! Have even considered 4.56's since I run 1/8th mile mainlly.

saxmanJJ · May 27th, 2010, 11:35 AM

I imagine anytime one installs steeper gears that traction becomes more tenuous, and thus there is a learning curve to adjust ones driving to find the razor's edge of traction/no traction.

Once I find that edge I will be coming out of the hole harder for sure!

May 24th, 2010, 06:51 PM	#1
saxmanJJ Hardcore Enthusiast 2004 Mustang GT 11.463@121.50 Join Date: Jun 2007 Location: SE PA Posts: 1,644 iTrader: 1 reviews	3.73 to 4.10 swap I recently swapped my 3.73s out for 4.10s. My typical 1/4 mile times are in the 13.00 to 13.10 range (with the 3.73 gear), with my best ever time being 12.90. My typical 60' time is between 1.75 and 1.85. I used to cross the stripe at about 5000 rpms and now I will cross at about 5500. BTW, my horsepower is about the same at 5000 rpms as it is at 5500. My peak hp is like a flat line between 5000 and 5500 rpms, where it drops off ever so slightly until about 6100 where it drops off significantly. What times should I expect to be able to accomplish with the gear change being the only change to the car, assuming I learn to take full advantage of the new gears? My setup is in my "garage" on the site BTW. Also, if I am able to improve my ET, would the improvement be mostly in the 60' time or all the way down the track? __________________ MM Bracket Racing Crew Member #5

May 24th, 2010, 08:13 PM	#2
RDY4WAR I Post Entirely Way Too Much 07 Turbo Focus 12.93 @ 105mph Join Date: Feb 2010 Location: Glen Burnie, MD Posts: 6,006 iTrader: 0 reviews	I would say a bigger improvement in your 60' time. I could see you running a 12.7. Where are you in SE PA? We're having a Tony Luke's Philly Cheesesteak meet in July. Check out the Northeast forum if you're interested. __________________ 2007 Focus - 230/215, cams/head/manifold swap done, new #s soon ...going E85! 1985 Bronco - 351W & 4WD 1986 Mustang LX - 351W build in the works! David Michael Smith, 07/25/1956 - 12/08/2011 ...R.I.P dad! I miss you dearly!

May 24th, 2010, 08:25 PM	#3
saxmanJJ Hardcore Enthusiast 2004 Mustang GT 11.463@121.50 Join Date: Jun 2007 Location: SE PA Posts: 1,644 iTrader: 1 reviews	Thanks. I'm near Norristown. So, I'll try to remember to come to the meet. I race at Atco about twice a month. Next race I'll probably attend is NMCA at MapleGrove where I'll run True Street. I'll be trying to win the 13-second plaque (avg. of 3 runs - closest to 13 seconds without going under). Not that easy when I'm hot-lapping the car but you never know. __________________ MM Bracket Racing Crew Member #5

May 24th, 2010, 08:59 PM	#4
RDY4WAR I Post Entirely Way Too Much 07 Turbo Focus 12.93 @ 105mph Join Date: Feb 2010 Location: Glen Burnie, MD Posts: 6,006 iTrader: 0 reviews	Nice! We were discussing coming down to Cecil on that Saturday after Tony Luke's. I wouldn't mind seeing if I can push the Focus into the 13.4s. I've got it consistent in the 13.5s. __________________ 2007 Focus - 230/215, cams/head/manifold swap done, new #s soon ...going E85! 1985 Bronco - 351W & 4WD 1986 Mustang LX - 351W build in the works! David Michael Smith, 07/25/1956 - 12/08/2011 ...R.I.P dad! I miss you dearly!

May 25th, 2010, 10:42 AM	#6
saxmanJJ Hardcore Enthusiast 2004 Mustang GT 11.463@121.50 Join Date: Jun 2007 Location: SE PA Posts: 1,644 iTrader: 1 reviews	A 13.5 sec Focus is one nasty Focus! I'm using M/T ET Street Radials. They seem to hook up pretty well at my power level. I'll keep working on my launching and see where I can take it! __________________ MM Bracket Racing Crew Member #5

May 25th, 2010, 09:29 AM	#5
04gtblkvert Regular 2003 Mustang Cobra Join Date: Sep 2009 Location: Las Vegas Posts: 282 iTrader: 0 reviews	Gears are for 60 foot, so maybe you will be able to cut 1.6s with a tire.

May 26th, 2010, 10:11 AM	#7
HickRocket1258 Regular 2002 Mustang GT 14.01 Join Date: Apr 2007 Location: West Chester, PA Posts: 218 iTrader: 0 reviews	I believe the 4.10s will help you more with 60' like Smithboy said, but not help so much on the top end. I have 4.10s and several other parts waiting to be put in. __________________ MM Bracket Racing Crew #6 MAD Crew #16 BAMA Performance Drag Team #7

May 26th, 2010, 08:34 PM	#8
JTs03v6 Hardcore Enthusiast 2003 mustang 7.48x1.56=11.67 Join Date: Sep 2009 Location: East Coast Posts: 2,318 iTrader: 0 reviews	Lowering your 60' will result in lower et. I'm curious to see what you pick up. I'm runnin 373 and want to swap them for 4.10's bad!! Have even considered 4.56's since I run 1/8th mile mainlly. __________________ New combo: Forged SC short Block,280cfm heads, Precision 6262 turbo, cx 31x12x3 fmic http://photobucket.com/JTsTurboBuild http://youtube.com/user/JTsStang

May 27th, 2010, 11:35 AM	#9
saxmanJJ Hardcore Enthusiast 2004 Mustang GT 11.463@121.50 Join Date: Jun 2007 Location: SE PA Posts: 1,644 iTrader: 1 reviews	I imagine anytime one installs steeper gears that traction becomes more tenuous, and thus there is a learning curve to adjust ones driving to find the razor's edge of traction/no traction. Once I find that edge I will be coming out of the hole harder for sure! __________________ MM Bracket Racing Crew Member #5

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