Hello,
I have 289 A code fastback (Auto). The rear end has started to "howl" at certain speeds so I believe it is time to repair or replace the diffs. I figured this would be as good a time as any to modify gearing for better acceleration and add posi. I was thinking that it may be cheaper and easier to purchase a replacement third member. The following two are links to Ebay auctions selling them. The questions are...

1) What gearing would be best suited for a daily driver with better acceleration?
2) What is involved in the installation and how much would it cost to have done?
3) Which of the twooptions look better?

http://cgi.ebay.com/ebaymotors/ws/eB...m=280081332899
or
http://cgi.ebay.com/ebaymotors/ws/eB...m=230089613275

....I am opento other suggestions

Thanks in advace!

 

I'd stay under 3.55 for the daily driver. Personally anything over 3.25 would kill me on the highway, but 3.55 is about as far as you want to go. Unless of course you get an overdrive.
Pumpkins are easy, remove axles, unbold, put in new one, bolt up, put in axles and lube up.
I say you're good with either one, just get the cheaper one IMO
or you could get one from these guys or directly from currie (BRAND NEW) for a few more bucks!
http://mustangdepot.com/OnLineCatalo...rd_members.htm

 

A few more bucks? Hell, I could buy a new Mustang for what Currie gets. Go to the bone yard and get a 9 inch with a posi traction for pennies on the dollar for what Currie will sell you one for. Yeah, 3.25 gears are great for everyday driving in town and on the open road. If you are mostly in town, then the 355's might be the ticket.

 

few is relative

 

I had mine rebuilt for $400 without any traction device. I would be leary of a $700 rear that's rebuilt with a traction device. A good LSD is $300-$400 by itself.

 

3.25 or 3.55??
hmmm, I do most of my driving during the week in the city, but at least once a week I make a trip out to the suburbs (50 miles HWY round trip).

How much acceleration do I lose with the 3.25?How much mileage do I lose with the 3.55?

Thanks again...

 

i don't think you'd notice much of a difference

 

hey sentipede, Valley Springs isrightdown the road from me, a long 45 min or so. I've spoke with the guys at V.S. Diff's some time back, and plan on cruisin out there in the next week or two. I'm interested in the 3:25 Trac Loc for my 66 coupe. If I recall, he does have othersetup's available, but I might be wrong. Regardless how you look at it, it's a reasonable price.

Ya, go ahead and go with the 9", you'll be in to it at least $1K by the time you shorten thetubes,axles, anddrive line. Of course the other option is to change the offset on your rear tires and wheels. It's all the stuff they don't tell ya about that costs. Seriously, if you plan on 400+HP, with a standard tranny, then spend the $ and build a good 9 using Auburn, Eaton, etc, and do it right. If you're running an automatic, then the rear doesn't see the sudden shock as seen with aclutch, so an 8" should be fine for our application.

Think I'll hop in the stang, take a drive, just to give these guysthe one-eye. If it's ligit, I'll be coming home with a center section. P.S spend the money and replace your axle bearers and seals at the same time: cheap insurance. Just saw a 65 stang today on the road, back-end up in the air, and two well-dressed educated professor typesunder the back end looking at the axle, scratching their heads.

 

groho,
Please let me know your initial thoughts and which you decide to go with. I would like to get this right the first time around....

Thanks!

 

I got THIS ONEabout 3 weeks ago, like they said is pretty easy to install, the only hard part was to fill it with gear oil again i made a mess lol

I got a 3.55 and its a hugeee difference from the 2.79 i had before also it is Posi Track.

Very good Quality diferential.