I don't know if I'm the best person to answer this, but I'll give it a shot. I'm just a cheap SOB and don't like parting with cash unless it's absolutely unavoidable.

"drum to drum axle".... you mean "drum to drum rearend" right?

Yes,in mycheapass opinion $500 is way too much for an open rearend. If it's a locker AND the seller will guarantee it, try and talk him down (obviously), but that's about the going rate for a used 28 spline 9" complete rearend. If it's a 31 spline unit, jump all over it.

Is the rearend a direct bolt-in? In other words, is the rearend housings track width identical to that of your car? Just because it's a 9" rearend out of a Mustang, does not mean it will fit your year Mustang.

If I were in your position, I'd really consider an 8.8 rearend. The Ford 9", although tough as freakin nails, weighs a ton, and is a "dieing component"... in other words, Ford isn't using it anymore and they're getting harder and harder to find and even when you do find one, the guy wants an arm and a leg for it.

The 8.8 is a tough rearend, usually comes with rear disc brakes, a limited slip differential and can be found EVERYWHERE in even the smallest junkyard for usually well under $200. There's just so many of them out there that supply outweighs demand. Do some research and find the best one to fit your application and then weld some spring perches onto it and you're good to go.

Limited Slip center section AND disc brakes for half the price you're looking at. It's tough to walk away from a deal like that.

Dave

 

Please tell me that you don't actually believe this to be true? Do you self a big favor and "step away" from the biased articles in the car rags. The car rags exist to sell parts for their advertisers, not to actually enlighten you with any factual information.

The magazine is trying to "sell"AFR heads. In the "real world", there's no way a set of AFR165's bolted onto an otherwise stock 5.0 will make anywhere near 400HP at the crank.... probably closer to 320 at the crank.

We can argue HP figures all day long and it's pointless, dyno the car and get real numbers, until then the car "makes good power and goes fast".

Dave

 

Davesanborn, yes, the 9 inch is a complete bolt in deal. It is out of a 71 Mach 1. It will bolt right in, which is what I am looking for. I can weld, no problem. But swapping in an 8.8 is a little more work than I want to get into, as there is no 8.8 that is close to the right width. Most are either an inch too wide, oran inch too narrow, or have the pinion offset to one side. In any case, if it isn't the correct width thenI will have to completely modify the housing, or buy different wheels/tires for the back because they barely fit now, and would definately hit if the width was changedthat much (I could get away with about a half inch narrower on overall width and thats it).

I am like you, I don't want to spend a lot of money to get a posi and gear (the only real reason for doing any of this), so I am just looking at the easiest and most cost effective way of reaching my goals.

There are pros and cons of both rearends (8 vs 9), and the 8.8 is a good swap for a lot of things, but it would be a ton of work to get into my car. However, like you said, they are really cheap and easy to come by.It is an option, but also a last resort due to the work involved in making one fit right. Not to mention I would have to get custom axle shafts, which would cost $300 or slightly more, to fit the modified housing.

 

Well, I just found out... 3.00 gear, OPEN in the 9 inch that guy had. He said he has 4 more of the cars and he thinks they all have 9 inch rears, so he is going to look in the morning and see if they are and if any of them have trac locs in them.

That 8 inch third member sure is looking really good right now...

 

Don't know what your engine plans are or will be, but if it includes building an engine that puts out a lot more than the stock engine, it would bebetter to go with a 9-inch.

I also don't know what transmission you have,whether it's a non-overdriven one or one with overdrive?

If you don't have an overdrive, then the rear end ratio is whatever it is: 3.00:1 is 3.00:1. 3.55:1 is 3.55:1, etc.

If you do have an overdrive, then the final drive equivalent is not 3.00:1, it's 2.04:1 [if the transmission is something like an AOD or [non-Z spec] T-5. If it's a Z-spec T-5, the final drive would be 1.89:1.

An overdrive with a T-5 and 3.55 gears would be a final drive of 2.41:1 [when in 5th gear]. With the addition of an overdrive, you can run a significantly lower ratio than a 3.00:1 and still come out way higher in ratio than the 3.00:1, when in overdrive.

You get the best of both worlds with an overdrive: low rear end gears without the RPM penalty on the engine.

http://ultrastang.com/Page.asp?PageID=8

http://ultrastang.com/Page.asp?PageID=9

With this arrangement, there isn't a big hassle of swapping out 3rd members to switch from a low ratio to a high and back again.

 

Did you not read the previous posts/sig??? I already have my engine built, and it may be getting a 100 shot of the go fast juice to help it get down the track on the rare trips to the strip.

The trans is a C4, so no overdrive. And yes, bear in mind that I am a mechanic, so I understand how all of this works. That is why I am going with the 3.55. It will be good for most of the back road driving I do, and at the strip, so basically the best of both worlds. However, if I go with the 8, I can just quickly swap out the 3rd member if I decide to go on long interstate trips, such as the mustangs across America 45th aniversary run.

 

i admire people that change 3rd members for the type of journey :-]
nice one tyler!

 

It isn't that quick of a procedure....

Remove rear wheels
Remove rear brakes
Remove the 4 nuts/bolts securing the axle retaining plate
Slide each axle out a few inches
Disconnect driveshaft
Remove center section nuts/washers
Remove heavy a$$ center section

Check housing gasket for servicability

Install heavy a$$ center section
Install center section washers/nuts
Reconnectdriveshaft
Install rear axles
Install 4 bolts/nuts securing axle retaining plates
Install rear brakes
Install rear wheels

Install 3-4 quarts of 90 weight plus a bottle of FoMoCo friction modifier for the trac loc into the rearend.

It's takes about 3-4 hours the first time you do it, but the more you do it, the easier and quicker it gets.

Dave

 

then there are the lazier and smarter enthusiasts with two car garages and two classics.

same car different rear ends. hahaha. jk. sorry OT.

 

It doesnt take that long to do if you have access to a lift and iair tools. I think that 3 hours is a good estimate, but would be time well spent if you were going on a long trip. Im pretty sure you dont have to remove the rear brakes, just the drums and the 4 nuts that hold on thebearing retainer/backing plate,. The youcan slide out the axles.You'd be getting paid for the work in the gas money you'd save. I Am waiting on the guy to email me back about payment and when he will ship me that 3rd member for the 8. I believe i am goint to go this route since I cant find a nine inch with a trac loc in it that will bolt in to my car.It will be A LOT cheaper to do it this way, and a lot of people seem to believe that the 8 is tougher than someother people give it credit for. I don't plan on doing any other engine work really (except for the N2O), so it should hold up for a long time.