Rearend Upgrade Suggestions

66StangFastback · Dec 25, 2006

First off, let me say happy holidays to all.

I've managed to reel in some cash for Christmas and am looking to upgrade my stock rearend. I have the stock 8" rearend with 2.79:1 gears and an "open" type differential under my 66 Fastback. I was wondering what you all might suggest to me.

I'm looking to spend 750 or less, and the only requirements I have are that it has 3.55 or 3.73 gear ratio and a limited slip unit.

I've seen the full pumpkin units on ebay for about that price and was wondering what you guys thought of them? Seems a little high to me until you consider the demand on the webbed type casings as well as the cost for gears, LSD, and the install prices.

Basically I just want to know what all of you think I should do with my money. I've been saving up for gears for a few months now and am set on upgrading this stock rearend.

Thanks all.

Z06killinSBF · Dec 25, 2006

Summit 3.80 gears - $150
Locker center - $450
install - $200

It's what I'm gonna do.

rbohm · Dec 25, 2006

a powertrax and a set of 3.55 gears makes for a very good streetable combination, that will work well at the track as well.

dennis112 · Dec 26, 2006

Z06killinSBF said:
Summit 3.80 gears - $150
Locker center - $450
install - $200

It's what I'm gonna do.

I hope your Summit 8" gears are better than the 9" 3:70's I bought from them last summer. First set of Summit brand had rust and corrosion on them and I sent them back. Second set was a little better, but still had a little rust where the cosmolene wasn't fully applied. I felt desperate and decided to install them anyways. This set whined worse than the ole' lady at her time of the month. I dropped them out, rechecked the pinion depth, tightened the backlash to the low end of the specification, and rechecked the pattern. All it did was make them sing at a slightly different mph. I've never had this issue before when setting up gears.

My cure was to drop them out and purchase an identical set of used Ford manufactured gears off of Fleabay. Now it runs quieter than a church mouse.

My point is that you need to watch those aftermarket gears--many of them say that gear noise is normal and should be expected. Buy some Ford manufactured gears (which are preferred by Nascar) or some Richmonds. Stay away from the cheaper alternatives if you can.

67Dylan · Dec 26, 2006

dennis112 said:
I hope your Summit 8" gears are better than the 9" 3:70's I bought from them last summer. First set of Summit brand had rust and corrosion on them and I sent them back. Second set was a little better, but still had a little rust where the cosmolene wasn't fully applied. I felt desperate and decided to install them anyways. This set whined worse than the ole' lady at her time of the month. I dropped them out, rechecked the pinion depth, tightened the backlash to the low end of the specification, and rechecked the pattern. All it did was make them sing at a slightly different mph. I've never had this issue before when setting up gears.

My cure was to drop them out and purchase an identical set of used Ford manufactured gears off of Fleabay. Now it runs quieter than a church mouse.

My point is that you need to watch those aftermarket gears--many of them say that gear noise is normal and should be expected. Buy some Ford manufactured gears (which are preferred by Nascar) or some Richmonds. Stay away from the cheaper alternatives if you can.

I bought only one set of 'alternative' gears myself... lesson learned. I like the FMS stuff and have used Richmond once as well, neither gave me any noise problems.

I also agree w/the powertrax rear. If you can install everything yourself you could save some of your cash for more parts. I wouldn't recmnd tackling it by yourself if you've never done it. Not a difficult job mind you, but it's nice to have the help of someone who's done it before.

ultrastang · Dec 26, 2006

If you've never set rear end gears up and don't have the tools to do it with, let someone with experience and the proper tools do the job.

www.ultrastang.com

dennis112 · Dec 26, 2006

ultrastang said:
If you've never set rear end gears up and don't have the tools to do it with, let someone with experience and the proper tools do the job.

www.ultrastang.com

Sound Advice!

66forfun · Dec 26, 2006

my builder set me up with auburn pro posi/motive gear ribbed case. my drum brakes are in good shape and i just replaced the axle bearings 2 yrs ago. should be good for street tires. no drive till spring though...

coolblue65 · Dec 26, 2006

rbohm said:
a powertrax and a set of 3.55 gears makes for a very good streetable combination, that will work well at the track as well.

Ditto, thats my exact setup, and I have been very happy with it...especially with the Tremec.

Pbum5 · Dec 26, 2006

You can always buy a rebuilt pumpkin that's ready to slap in.

http://cgi.ebay.com/ebaymotors/FORD...019QQitemZ290065183122QQrdZ1QQsspagenameZWDVW

Shop around a bit.

You can also get a complete 9" with gears for about that price if you wanted to go that route.

66StangFastback · Dec 26, 2006

More on said powertrax? Where can I get one and about how much are they?

Does a "ribbed" type case for the 8" really make that big of a difference over the regular type?

I'm basically trying to do this right the first time, but with minimal cash spent because I'm also hoping to get a torque converter and tranny cooler in before spring. Thanks for the help guys.

66StangFastback · Dec 26, 2006

By the way, this is a daily driver.

danny clemens · Dec 26, 2006

If it is a daily driver and you're not going to punish it too much I would think that the early center would work. I don't know anyone who's broken one but I don't know anyone who's drag raced them much with a lot of hp over stock. The ones with the extra ribbing are stronger but I really don't know how much.

66StangFastback · Dec 26, 2006

danny clemens said:
If it is a daily driver and you're not going to punish it too much I would think that the early center would work. I don't know anyone who's broken one but I don't know anyone who's drag raced them much with a lot of hp over stock. The ones with the extra ribbing are stronger but I really don't know how much.

I don't pound on it too much, but at the same time it does have stock wheels so I've only got a set of 215/70r14s on there, so it's not like I could get any traction. It most likely will see some track time in the spring, but will probably stay on cheapy street tires. The engine only puts out about 300 hp anyway. I've thought about nitrous but don't want to damage the rearend, so it'll have to wait until I can do a rearend swap.

So, checked out this Powertrax system many suggested. It seems like a really good deal at only $250, but would it be safe in my daily driver? It seems like a cross between a spool and a real LSD unit. Do any of you have first hand experience with one. I don't want to be chirping the tires at every turn, and I do drive it in the rain/ice/snow. Terrible I know, but I'm just a kid and can't afford to park it and buy another car.

67Dylan · Dec 26, 2006

66StangFastback said:
More on said powertrax? Where can I get one and about how much are they?

Have you tried looking in Summit or Jegs?

67Dylan · Dec 26, 2006

Pbum5 said:
You can always buy a rebuilt pumpkin that's ready to slap in.

http://cgi.ebay.com/ebaymotors/FORD...019QQitemZ290065183122QQrdZ1QQsspagenameZWDVW

That's not a bad price for someone that wants to just slap one in and be done w/it. If you know what you're doing and have the tools they are fairly simple to install yourself, as I stated earlier. I've installed three sets after I was shown how to install my first set.

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