3.73's going in as soon as i have time to do it

7

7 sek mark

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i just got back from a swap meet and picked up a brand new set of ford 3.73 gears, full install kit, and posi rebuild kit still sealed in the ford boxes for $140. i picked up a posi unit awhile back at the same swap meet for $60 and i will do the install here at home. so i will have $205 (about 5 for the posi loc stuff) in my rear end set up with brand new Fo.Mo.Co. parts. im not sure here but from what i have seen and heard i just about stole my set up.

so how bad did i get ripped off on this stuff? are the 3.73s worth $200 installed?
 
New gears are around 160 and a new traction lock is anywhere between 200 and 260 so yea, you did just fine. I just bought 3.73's and a traction lock for 175 off of a buddy. :D
 
and this stuff is all brand new in the box ford stuff. the install kit comes with bearings ring gear bolts with the thread locker on them and new bearing cap bolts. the only thing i did not get is the axle seals. the kit i got came with seals but the guy said its for a 8.8 straight axle and the seals wont fit. for what i paid for this stuff i think i can afford to go buy some axle seals and still be way ahead of the game.

the guy i got them from said he works for a lincoln dealer and sets up rear ends and stuff for them there at work and he has a shop on the side working on mustangs and putting gears in there. he is currently working on building a 9 sec 1/4 mile mustang for him self so he sounds like he knows what he is talking about.
 
one quick question can i just go to the ford dealer and order the 3.73 speedo gear and be fine or would i still need a chip or tune to get my shifts right?
 
The dealer isn't gonna know which gear to use because they don't do custom work like that....expecially to M8's. They also don't sell them based on tooth count so unless you have a part number for the white speedo gear, you're better off finding one on eBAy.
 
oh ok i thought i could go in and get one for a stang or a f-150 that had 3.73 gears in it from the factory would that work?

how much do yal think the 3.73s will improve my track times? right now i have not been to a 1/4 but in the 1/8th i run 9.4 with a 2.0 60' times. i have a 3200 stall and a shift kit if that might help any. im pretty sure i might need a set of slicks or drag radials for the car. as it is right now on my 245/50 r16's it will spin for about 5-6 feet unless the track prep is prefect leaving the line at about 2500 rpm off the spray. i have never hit the juice out of the hole i usuley hit it about 10-15 feet out. the 9.4's are off the bottle on the spray it runs 8.9's
 
I wouldn't get slicks or anything just yet. I was running 1.8 60ft times on street tires with a 3200 stall and 4.10's/trac-loc on street tires with NO wheel spin. You'd hear my front struts "top out" when I'd launch, lol. You are running NOS though so you may need the slicks if you're gonna hit it from the line.

You can't just buy a gear for another vehicle because it mounts to the speed sensor differently.
 
oh ok so i guess ill have to find the part number somewhere for the ford part for the mark. where is the speed sensor even on these cars? i know its towards the rear of the trans somewhere but im not 100% sure where its at. oh ya i wont get slicks for a while if i have to ill just baby it untill i can save up again for the tires.
 
7 sek mark said:
oh ok i thought i could go in and get one for a stang or a f-150 that had 3.73 gears in it from the factory would that work?

how much do yal think the 3.73s will improve my track times? right now i have not been to a 1/4 but in the 1/8th i run 9.4 with a 2.0 60' times. i have a 3200 stall and a shift kit if that might help any. im pretty sure i might need a set of slicks or drag radials for the car. as it is right now on my 245/50 r16's it will spin for about 5-6 feet unless the track prep is prefect leaving the line at about 2500 rpm off the spray. i have never hit the juice out of the hole i usuley hit it about 10-15 feet out. the 9.4's are off the bottle on the spray it runs 8.9's
Click to expand...

I'm gonna take a wild shot in the dark, but i figure you'll pick up 1/2 a second in the 1/4 with the 3.73's, so around 3/10ths in the 1/8th. :)
 
Going from 3.07's to 3.73's won't pick you up a 1/2 in the quarter...expecially since I believe he's running a 3200 stall converter.
 
I concur. Simply going from 3.07s to 3.73s will not net 5 tenths IMHO. My guess is 2-3 tenths all things else being equal.
 
Wow. I surely would've figured that with the stall converter, he would pick up a half second, since he's launching in the powerband, plus the car will pull that much harder with the shorter ratio. :confused:
 
I don't know if I just drive different that you guys, or if I have some kind of freakish Mark VIII (which I doubt) and honestly I hesitate to throw my hat in the ring here because of the bashing I have gotten on other threads (I *DO* in fact maintain a 28 mph average on the highway regardless of how "impossible" that is) but here goes anyway.

I went from a consistent high 14.9 to a consistent low 14.5 on motor with nothing but a gear swap from 3.08 open diff to 3.73 track-lock and a re-tune to accomodate the gears from Reinhart.

I run my car _every_ Friday and I have literally hundreds of time slips.

That's 4/10ths. In my book saying "about a half a second" is maybe a little enthusiastic, but not totally warping the facts either. If he only picks up 2/10ths then something is wrong.
 
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