SBF Gear Recommendation Please

FireSale · 09-06-2016, 01:19 PM

I'm going to scrap the 3.89 gears and Detroit Locker in my 3355 lb Mustang and am looking at a spool and gear combo for a Strange Pro Iron 9 inch carrier. 28 spline street gears will probably do it strength wise but I could afford the 35 spline Pro Gears that would require a different pinion support. More $$.

Does a "built for SS/MA 302" that pushed a street legal car to a best ET of 12.65 and a top speed of 116 mph need all that beef in Pro Gears?

Axles are 31 spline alloy Strange street. Tires are 26X10 MT at the present time. 28s for the next set now that I know they will fit.

I'm thinking 4.29 or 4.56 as a gear ratio.

Thanks in advance.

Dale

Sean Marconette · 09-06-2016, 03:18 PM

Dale,

The issue I ran into with street gears in my 8.8 stick stocker was stress fractures of the pinion teeth. Your engine will make quite a bit more power and not be as violent as a stick car, I would run a Pro gear if available.

Sean

pmrphil · 09-06-2016, 06:43 PM

With an automatic car that runs 12's (or even 11's) a pro gear seems unnecessary. Don't forget that the pro gear will wear much quicker than a standard gear, and while we're at it, needing a pro gear when using only 31 spline axles is kinda overkill as I see it.

FireSale · 09-06-2016, 07:22 PM

Thanks for the info. Forgot to mention that the trans is a C4. Current converter stall is 3500 (I drive it to the track). That will be replaced with 4500 or above as part of the differential upgrade.

Index for GT/MA is 11.75. Looking for 11 flat or better to be competitive around here.

Dale

Lou Jeffery · 09-07-2016, 07:27 AM

Standard gears will be more than sufficient. I ran a 8 inch rear axle in my Maverick going 11.30s, only upgraded to a 8.8 for more ratio options.

HR9121 · 09-07-2016, 07:48 AM

I would also think the standard gears would be fine also and I would think you would need the 4.56 to get you up in rpm power range also.
I ran a 302 in a fox body bracket car, it was only 2950# but ran a 30" radial like stockers run and ran a 4.88. It ran 10.50-10.60 and would trap at 6900-7200. With those little motors rpm's are your friend.

09-06-2016, 01:19 PM	#1
FireSale VIP Member Join Date: Feb 2014 Location: Lakewood Washington Posts: 1,407 Likes: 29 Liked 237 Times in 126 Posts	SBF Gear Recommendation Please I'm going to scrap the 3.89 gears and Detroit Locker in my 3355 lb Mustang and am looking at a spool and gear combo for a Strange Pro Iron 9 inch carrier. 28 spline street gears will probably do it strength wise but I could afford the 35 spline Pro Gears that would require a different pinion support. More $$. Does a "built for SS/MA 302" that pushed a street legal car to a best ET of 12.65 and a top speed of 116 mph need all that beef in Pro Gears? Axles are 31 spline alloy Strange street. Tires are 26X10 MT at the present time. 28s for the next set now that I know they will fit. I'm thinking 4.29 or 4.56 as a gear ratio. Thanks in advance. Dale __________________ Dale Shearon 68 Mustang 6394

09-06-2016, 03:18 PM	#2
Sean Marconette Senior Member Join Date: Mar 2006 Posts: 977 Likes: 786 Liked 274 Times in 76 Posts	Re: SBF Gear Recommendation Please Dale, The issue I ran into with street gears in my 8.8 stick stocker was stress fractures of the pinion teeth. Your engine will make quite a bit more power and not be as violent as a stick car, I would run a Pro gear if available. Sean __________________ Sean Marconette 84 Mustang 5060 SS/N

09-06-2016, 06:43 PM	#3
pmrphil Member Join Date: Aug 2010 Location: CT Posts: 454 Likes: 1,771 Liked 345 Times in 149 Posts	Re: SBF Gear Recommendation Please With an automatic car that runs 12's (or even 11's) a pro gear seems unnecessary. Don't forget that the pro gear will wear much quicker than a standard gear, and while we're at it, needing a pro gear when using only 31 spline axles is kinda overkill as I see it. __________________ Phil Molski PMR Performance S/C 1623

09-06-2016, 07:22 PM	#4
FireSale VIP Member Join Date: Feb 2014 Location: Lakewood Washington Posts: 1,407 Likes: 29 Liked 237 Times in 126 Posts	Re: SBF Gear Recommendation Please Thanks for the info. Forgot to mention that the trans is a C4. Current converter stall is 3500 (I drive it to the track). That will be replaced with 4500 or above as part of the differential upgrade. Index for GT/MA is 11.75. Looking for 11 flat or better to be competitive around here. Dale __________________ Dale Shearon 68 Mustang 6394

09-07-2016, 07:27 AM	#5
Lou Jeffery Junior Member Join Date: Nov 2013 Posts: 91 Likes: 0 Liked 0 Times in 0 Posts	Re: SBF Gear Recommendation Please Standard gears will be more than sufficient. I ran a 8 inch rear axle in my Maverick going 11.30s, only upgraded to a 8.8 for more ratio options.

09-07-2016, 07:48 AM	#6
HR9121 Live Reporter Join Date: Jan 2011 Location: New Bern, NC Posts: 3,467 Likes: 146 Liked 3,363 Times in 731 Posts	Re: SBF Gear Recommendation Please I would also think the standard gears would be fine also and I would think you would need the 4.56 to get you up in rpm power range also. I ran a 302 in a fox body bracket car, it was only 2950# but ran a 30" radial like stockers run and ran a 4.88. It ran 10.50-10.60 and would trap at 6900-7200. With those little motors rpm's are your friend. __________________ James Williamson W200 J/SA. SS/JA