Quote:
Originally Posted by frankym
Been searching the forum unsuccessfully to find out the best way get my car to be useful in first gear. ... Im almost better off launching the car in second gear. I can hit the rev limiter in first gear after going 10 feet. Curious if folks have had good results for a little more driveability with a shorter final gear set.
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A shorter final drive will cause you to run the engine higher in the rpm than you do now at any given vehicle speed. If you want to slow down the engine then you want a taller gear which would be a smaller number numerically. If you want more engine speed at all vehicle speeds then you need a shorter final gear, which would be a bigger number numerically.
Depending on your SPF chassis number there are several different rear ends that you might have. If you are familiar with what the different housings look like, you should take a look underneath to determine which you have before ordering gears. Some gearsets can be impressively pricey. If you are not familiar enough to do a visual identification then call Hillbank and ask them what rear end your vehicle number has.
Quote:
Originally Posted by jhv48
I have a newer SPF with the 3:46 rear end. I would like to swap out the rear end for a 3:15-3:27 ratio. Not sure what’s best. Buy a new rear end or just the gears.
Anyone done this?
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You either have an Australian BTR unit or one of the Getrag center sections. I don't remember when the change over from the BTR's occurred. The BTR ring and pinion will impress you with how expensive it is. I am not sure about the Getrag.
I had the BTR center and converted mine back to the Ford 8.8 for easier access to parts, stronger parts and lower costs for parts. If you do that you will need a chassis shop to fabricate the mounts unless you possess those skills. You will also need replacement axles. I recommend the G-Force half shafts with their HD 930 Porsche CV joints, click here =>
GForce Cobra Axles. Those particular axles are made for an 03/04 Cobra with a 31 spline 8.8 center. The axle shafts will need to be slightly different length for a replica but GForce can easily accommodate that.
All in all you will be in the tank for about $3,500 including the chassis work, but you will have a bullet proof rear end — done correctly. Be sure to get the billet steel carrier caps from MW and use an aluminum 8.8 center out of a 2007-2010 Explorer they are more robust.
The housing on the left, in the epic below, is the one you want. It is from a 2007-2010 Explorer. The one on the right is the passenger car version. The Explorer version is more robust.
Ed
p.s. Go over to the Second Strike Gearing calculator to help you make informed gearing choices. Click here =>
Gearing Calc