Hey Gents gotta question for you. How difficult would it be to swap a V-6 rear end and put in the Ford 9in rear end? How clean of a swap is it to do?

 

Hard to say..... brain surgery might be "easy" for a brain surgeon, but I don't think you'd want ME cutting inside your skull. Know what I mean??

But in relative terms, it's pretty easy if you buy a rear already adapted to fit one of these cars. You'll also end up with a pretty much premium, high-perf-designed, racing product. It's MUCH harder if you go get some junk one and try to do it yourself. And of course, if you go that route you'll end up with some junk rear end that's decades old, isn't much better in stock trim than one of these 10-bolts, and you'll get the opportunity to learn all the bad things that can happen, by way of trial and error. Your own personal tolerance for "easy" might be at one of those extremes or somewhere in between, I can't even begin to guess at that.

Not sure I understand "clean"? I guess it would be, if you wiped up spills, kept the floor swept, and so forth? Not sure there.

What are you REALLY asking? Do you just want a Frod 9" because that's the buzzword and "everybody" says you gotta have one or you're not cool? Or are you trying to set your car up to reach some specific goal in terms of ET or something? Or what?

 

Im a big believer in performance but a bigger believer in reliability in the performance you intend on reaching. Ive read that the Ford rear end has a reliability unmatched by any other. When I said I wanted it to be "clean" I meant that I wouldnt have to do alot or any fabricattion to make the rear end fit. Thanx for the reply though.

 

A Frod 9", as it comes out of a vehicle, is no more "reliable" than any other junk rear. It's not a particularly good piece in any way. In fact, some might even say it's a piece of crap. The thing that makes that platform popular isn't that it's so good as manufactured; it's that it's a great PLATFORM. Which is to say, all sorts of good parts are made that have the same bolt pattern and stuff; NOT that all Frod 9" rears are great. So yeah, an AFTERMARKET one, built out of an aftermarket housing to fit whatever suspension a given car has, aftermarket center section, aftermarket carrier, aftermarket axles, aftermarket brakes, new gears, and so on, can be made damn near indestructible. But a rear you find in a junkyard has NOTHING WHATSOEVER to do with any of that, except that the bolt patterns are the same (mostly); and of course, that the junk one won't fit your car unless you have a Frod of whatever model the rear is out of.

In fact, the only vehicle I can ever recall seeing burn to the ground because its rear end burst into flame (an axle bearing caught fire), had a Frod 9". It was about a late 60s pickup.

No there are no Frod vehicles that come with the rather unique 82-up Camaro/Firebird rear suspension. So there are no Frod 9" rears that are ANYWHERE CLOSE to a bolt-in. A considerable amount of fabrication is required. And because of certain design features of that model of rear, even one specifically designed for it is never a very good fit into one of these cars, without SUBSTANTIAL alteration of the car as well. They can be made (aftermarket) to "bolt up" and "go in", but they don't "fit" very well.

Where are you going with all this? Maybe a Frod 9" isn't the best choice, anyway?

 

Ive got an 89' RS V-6, that I would like to turn into a LS1/T56 combo. Been looking at rear ends to round out my drivetrain. Been looking at the Ford 9 and the Strange Engineering 12 bolt. Any opinions?

 

The 12-bolt is plenty for that combo. Fits good too, better than a 9". Of course, it's not a junkyard item, either.... it's a purpose-built, special part, just for the application, that 12-bolt stuff (car, not truck) bolts into.

I think there's others besides Strange, although that one is perfectly fine. Just other stuff you can check into.

Whose 9" are you comparing it to?

 

That being said, price isn't a consideration. If you have good fabrication skills then the question about installing a junkyard diff wouldn't have been asked. That leaves spending the money for a reliable bolt in differential which makes the swap very easy. Either a bolt in complete 9" or 12 bolt can be had for around $2500+. The direct bolt in diffs for a third gen are not cheap and there are no production 9" or 12 bolts which are a direct fit.

Find a junkyard diff the proper width isn't that hard but there are only a handful of donor vehicles which have a diff the proper width. Then it's a matter of cutting all the mounts off the donor diff and welding third gen mounts onto it. The difficulty begins when you find out there's no easy way to attach the torque arm onto a junkyard diff. Other problems that occur are that the Ford bolt pattern is different than Chev so your rims won't fit. Try to convert the brakes lines and park brake cables and the project starts to become big. By the time you're done fabricating and modifying to get it to work, you'll spend more money than buying an aftermarket bolt in diff.

I like to just tell people to run what you have until it breaks then decide how much it's worth to upgrade. There will come a time when $3000 for a diff is cheap.

My first 9" came out of a 1970 F100. All I used from it was the housing because it was the closest I could find to the width of a third gen diff. I bought aftermarket 31 spline axles, picked up some Ford drum brakes and use a rim with the Ford bolt pattern. The center section I picked up at a local swap meet with 4.56 gears and a 31 spline spool. I used all the third gen mounts from a 10 bolt and welded them onto the 9" but instead of a torque arm, I installed ladder bars since the car was only used on the dragstrip.

I now have a narrowed 9" under my car when I back halved it last year.

There is no such thing as a V6 rear in a third gen. Other than the few cars that received the BW 9 bolt, all third gen use the same 7-1/2" 10 bolt. It changed slightly over the years going from 26 to 28 spline axles in 1990 and getting a slight increase in ring gear size from 7-1/2 to 7-5/8 around 86. The only thing different from a V6 to a V8 rear is the gear ratio from the factory.

 

v6's normally had a better gear ratio for after a swap. 3.42's mainly good v8 auto gear.