Debating....I am thinking of changing rear gears from 3.08 to 3.55 with a fms limited slip, or possibly upgrading the ported GT40's setup in my sig below with a set of aluminum heads. I really don't think I want higher than 3.55's due to the amount of highway time my truck sees. Looking for opinions on which way you would go. Of course, both would be the best, but unreasonable at this point.

 

well an 8.8 rear diff can be picked up for less than $200 bucks all day long on craigslist with 3.55's and a limited slip. this will give you the best seat of the pants gains compared to aluminum heads.

since the rear diff is cheaper go that route you will only be out a little and will know if heads are really necessary at this point.

 

Exactly what I was thinking. Acceleration is not really an issue, traction is, although I don't expect traction to be that much better with ls 3.55's. Just looking for that last bit of snap.

 

Going from a 3.08 open? If so you're in for a surprise.. it takes a LOT more to break both tires loose... on dry pavement anyway, so you should see a vastly improved holeshot with a tight LS and the additional gearing.

 

Yes 3.08 open. I can do 100' burnouts with it as it sits. You think it will be that much difference? Sounds good to me. This is definitely the way I am going...thought about rebuilding my rear end and installing new gears and LS, but with what you can buy and entire used one for...what's the point? I have begun perusing the yards, craigslist, etc.

 

I know it will. The problem with an open diff is once a tire breaks loose you lose all weight transfer to the drive axle and all engine power goes into that one tire so there is no chance it will ever regain traction until you let up. With a tight LS or locker it takes at least twice as much TQ just to break the tires loose and even if you do you retain forward motion and some weight transfer so it's unlikely the slippage will continue very long.. unless you got one hell of a motor under the hood. Bottom line is once you get the LS diff under her you can kiss goodby to big smokey burnouts and say hello to axle wrap, a pinion nut that seems to work loose all the time.. which is actually because the crush sleave is being further crushed by the massive TQ loads you're now exposing it to, frequent driveshaft U-joints replacement or worse breakage, and eventually traction bars when you figure all this out.

 

Makes perfect sense. I guess I will deal with that when i get there. I can deal with no burnouts if it means launching out of the hole. Know way to know for sure until it is done. I am also going to 275 rears from 255's. So far I have only found 1 3.55 and it is not LS and the front pinion seal needs replacement and they want 375. No thanks.

 

that is crazy high for an 8.8 used. I wouldnt pay more then $150 honestly. just keep looking on craigslist for someone parting out a wrecked bronco or f150. either will work.

 

I offered 75 for non ls and will install my own ls...we will see if they accept.

 

Got it for 75 and 90 for the ls. Now down to getting it all installed and dialed in.

 

What are you running for a transmission??

 

Sorry...been working on this thing....it is a 4r70w. I cleaned everything up, painted, checked bearings, swapped in LS and installed this weekend. I think I am really going to like. I can still spin (now both ) but only for 10 foot or so and the 3.55s give it that extra pop I was looking for. Only thing now is I can actually feel the pinion come back down after letting off the throttle so I know it is trying to point skyward under wot.