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Rear end ratio upgrade??

844 Views 8 Replies 7 Participants Last post by  66PonyFB
Well, I have a 68 with a mildly pumped 289 (maybe 325 HP), my rear end is a 2-79......looking for a little more juice out of the hole and was looking at 3-55's. Called a few places and was quoted about $1,400.....seems a little much, any thoughts
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1400 seems a little high to me depending on what they are doing vs. what you are doing - basically if they're doing all the work (pulling/dropping/swapping/reassembly and getting the parts) that may be around what it costs (I'm not sure).

Got a buddy of mine that pulled his pumpkin himself, took it to a shop locally here and they cleaned up the casing and did the actual swap, and he put it back in. That was around $400 labor charges, and he provided all the parts. I'm planning on doing the same thing once I get another job (sucks just looking at my car).
Its pretty easy to do it yourself. Just follow detailed information to make sure gaps and clearances are within spec. You can get FRPP's at summit for cheap, maybe cheaper elsewhere, not sure. Get the trac-lok rebuild kit too while youre in there.

Im guessing you have a 8.8 with a Trac-Lok?
you got an 8" removable carrier right? check a few more places, if you pop that sucker out and bring it to a shop like that it shouldn't cost you more than a couple hours labour once you've bought the gears (about 200 for those) a complete install kit will cost less than 75 and includes shims and all said and done you need not pay more than 500 all told, and any reputable mechanic can do it if he has the right tools
'Sup neighbor. I'm over in Hidden Lake...

Tracy Driveline on 11th quoted me like $400 for a gear change. That was with me bringing the 3rd member in already removed...
If your engine is producing the approximate 325 HP, your 8" is approaching its strength limits. The problem with the 8", as well as some 9" carrier housings, is in the amount and strength of the material that supports the pinion pilot bearing. Don't want to spoil the party, but it's something to consider.

The aftermarket sells strengthened 8" carrier housings or if your carrier has a large letter "N" cast into it, (Usually above the pinion), you may be OK. The "N" cases were cast with a high content of nickel in the alloy, adding to strength. This was how the factory could ID those units.
Thanks for all the replies. Sounds like I can do the removal and replace myself. Just need to get the gears and install kit from Summit.....question, if I do that, when I re-install the "pumpkin", do I need to measure and get shims, or is that stuff done inside by the rear end shop. Thanks!!!!
The shop will do that - sounds like you have a "quick change" rear end. Just drop the pumpkin out - you'll need to slide the axle tubes out a little bit and unbolt it to drop out. Then take that plus the new gears and shim/install kit to the shop and they'll do everything else. The only thing you need for re-installation would be a new housing gasket and rear end fluid.

Take what The Greek had to say into consideration though - you may want to look into a complete rear swap. I guess it just depends on how you're going to drive it - really get on it all the time, or just upgrading the gears for better cruising.
Consider another option... I don't want to open debate about 8" vs. 9", but a properly built 8" can handle your hp. I was in the same position as you just recently. I found a local reference to a guy in PA. He will ship a new 3rd member anywhere in country for $55.

He rebuilds 8's rated up to 550hp with 6 month warranty. He uses extra ribbed case, 4-pinions (not 2), billet steel hat (not cast), nodular carrier, all new bearings, races, etc. He has options for ratios, etc.

8's are all 28 spline, same yoke, so you won't have compatibility issues.

This guy was very local to me, so I had him do the work. (I have no life, limited tools, etc.) It is not hard to swap 3rd member yourself, though. So, I was able to meet this guy (TJ) and check out his operation. He does quality work and has a lot of experience.

He sells on eBay, so you can check out his stuff there at link below. Tell him Rodney sent you. I get NOTHING for this, by the way, I like referring solid people. Just another option for you.

FORD MUSTANG 8 " EIGHT INCH REAR TRAC-LOC POSI 550hp 9: eBay Motors (item 330448016071 end time Jul-11-10 20:29:07 PDT)
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