Disadvantages of putting 9" 3rd member in an 8" housing?

[SadbutTrue]

Are there any disadvantages to putting a 9" third member in an 8" housing? A local shop says that its possible, and I think it is too. I know the housing won't be quite as strong, but from what i've heard, its rarely the housing that breaks, so maybe this isn't a problem (not that I'm really putting that much power out anyway, but in eventuality, as I keep saying... I hope to). Will the third member be compromised at all? Will the housing be an achilles heel for my car?

 

[brianj5600]

I don't think a bfh (special tool) would make that possible.

 

[SadbutTrue]

I have been assured by multiple shops that there are indeed 9 inch third members that will bolt in to my 8 inch housing and work from there. To me it seems like it may be a good idea, might even save some weight in the process.

 

[brianj5600]

A 3rd member is the r&p, diff, case, pinion support and yoke. No way to make it fit.

 

[zookeeper]

Before you start believing everything that shop tells you, go buy a gasket for a 9 inch, and one for an 8 inch. Now lay them on top of one another and tell me how in the hell you can make the round one (9 inch) fit the oval one (8 inch) This is an urban legend that has been repeated for years and isn't even close to being true.

 

[skywalker]

Before you start believing everything that shop tells you, go buy a gasket for a 9 inch, and one for an 8 inch. Now lay them on top of one another and tell me how in the hell you can make the round one (9 inch) fit the oval one (8 inch) This is an urban legend that has been repeated for years and isn't even close to being true.

After seeing some of the things I've seen...I'd say anything is possible with the right stupidity level.

 

[latamud]

It can be done. You have to chop up a 9 in housing and an 8in housing. Weld the axle tubes from the 8in to the 9in housing center. In Hawaii its hard to fing a 9in narrow enough for our 66 stangs. Doing this, we can still use our old axles.

 

[Fostang]

It can be done. You have to chop up a 9 in housing and an 8in housing. Weld the axle tubes from the 8in to the 9in housing center. In Hawaii its hard to fing a 9in narrow enough for our 66 stangs. Doing this, we can still use our old axles.

EXACTLY!!!!!!!


It's all the same no less stronger how do you think rear end housings are put together?

 

[mfp4073]

Just to add to this, I think there is some myth here that is added to by people who get confused. ford 9inch and 8inch 28 spline axles in some applications are the same. I know this for a fact because the axles out of my 67 8inch and my 70 9inch swap. Same 28spline, same length, same bearing, etc etc. Now this refers to the AXLES being the same. Not the housing, the third member, the carrier or anything else. There are some issues that also confuse people into believing they are swappable. For example, the clutch pack for a 9inch traction loc and an 8inch traction loc are the same. (just to confuse you further, you can change a 28 spline 9inch traction loc to a 31 spline by replacing only three parts) BUT THAT DOES NOT MEAN THE REST IS THE SAME between 9s and 8s!

 

[brianj5600]

It can be done. You have to chop up a 9 in housing and an 8in housing. Weld the axle tubes from the 8in to the 9in housing center. In Hawaii its hard to fing a 9in narrow enough for our 66 stangs. Doing this, we can still use our old axles.

At that point it is no longer an 8 inch housing. What would be the point? If you want a shorter housing, narrow it. You can weld 9 inch axle tube on an 8.8, but it is still an 8.8. Housings and carriers don't interchange, bottom line.

 

[1320stang]

It can be done. You have to chop up a 9 in housing and an 8in housing. Weld the axle tubes from the 8in to the 9in housing center. In Hawaii its hard to fing a 9in narrow enough for our 66 stangs. Doing this, we can still use our old axles.

So why not just narrow the 9" housing and weld new billet ends that use the same sized bearings for your 28 spline axles? Or even use your old 8" ends. I know of lots of 9" that have been narrowed using the stock small bearing passenger car ends, spring pads relocated, then used the 8" 28 spline axles in them. At least then you don't have the tapered axle tubes.

Welding 8" axle tubes on a 9" center section sounds like building a building from the top down to the ground. You still have to use a fixture to make sure that everything is aligned. I'm not saying it won't work, but dang, it sure sounds like a round about way to do it.

 

[1320stang]

Are there any disadvantages to putting a 9" third member in an 8" housing? A local shop says that its possible, and I think it is too. I know the housing won't be quite as strong, but from what i've heard, its rarely the housing that breaks, so maybe this isn't a problem (not that I'm really putting that much power out anyway, but in eventuality, as I keep saying... I hope to). Will the third member be compromised at all? Will the housing be an achilles heel for my car?

Oh, and BTW, my buddy broke his 8" housing where the axle tube is welded to the center section and then drove it about 15 miles to the shop where he had a 9" rear put in. The back end looked like a late model IRS car where the struts or springs are weak and the tires lean in. The axle housing was rubbing on the axle shaft. The guy at the shop asked, "did you DRIVE that in?" My buddy says, yeah. The guy couldn't believe it. This was a '67 Mustang coupe with a stock rebuild save for a RV cam.

I would stay away from these multiple shops that say a 9" pumpkin will fit into a 8" housing, you're bound to get screwed.

 

[WORTH]

So why not just narrow the 9" housing and weld new billet ends that use the same sized bearings for your 28 spline axles? Or even use your old 8" ends. I know of lots of 9" that have been narrowed using the stock small bearing passenger car ends, spring pads relocated, then used the 8" 28 spline axles in them. At least then you don't have the tapered axle tubes.

Welding 8" axle tubes on a 9" center section sounds like building a building from the top down to the ground. You still have to use a fixture to make sure that everything is aligned. I'm not saying it won't work, but dang, it sure sounds like a round about way to do it.

The guy from hawii has a parts problem and it is cheaper for him to use his old axles.

 

[1320stang]

The guy from hawii has a parts problem and it is cheaper for him to use his old axles.

I realize this.

8" 28 spline axles will fit into a 9" housing that has a 28 spline center section that has been narrowed to the same width as the 8" and has the same housing ends as the 8". The spring pads will need to move, but then the unit will bolt right into the car. Axles and brakes from the 8" can be used, the rear u-joint may need to be changed to a combo unit with different sized cups but you can use the 28 spline 8" axles and brakes on a 9".

Most of your passenger car rear ends have the small bearing axle housing ends.

 

[SadbutTrue]

It can be done. You have to chop up a 9 in housing and an 8in housing. Weld the axle tubes from the 8in to the 9in housing center. In Hawaii its hard to fing a 9in narrow enough for our 66 stangs. Doing this, we can still use our old axles.

Yeah thats how one of the shops described it.. the other was just trying to sell me an 8" rear, sorry for the misunderstand..

/me retreats in shame lol

 

[USMC1966]

Latmud


Hijack!
Did you go to Freddy's or use one you picked up from Nigel's?

What's up with the T-5 get the 351w in yet?

 

[bnickel]

i think they may be a bit confused and thinking of the 9-3/8" center section into a 9" housing, that can be done with a little notching of the housing where the ring gear sits. not a very popular swap for obvious reasons though

 

[latamud]

Latmud


Hijack!
Did you go to Freddy's or use one you picked up from Nigel's?

What's up with the T-5 get the 351w in yet?

Haha I just found this old post Lew. I didn't do the mod to my rear end. It was yours I was talking about. Freddy(Clyde) tore up the Bronco rear end I got at Nigel's, I ended up putting it in the Cuda. Funny thing, the 65 fastback I picked up has a 9" rear with small bearing axles and tapered tubes in it. I wonder if it was a modded 8" to 9" or if that was how the 9"s came back then?

 

[bnickel]

Haha I just found this old post Lew. I didn't do the mod to my rear end. It was yours I was talking about. Freddy(Clyde) tore up the Bronco rear end I got at Nigel's, I ended up putting it in the Cuda. Funny thing, the 65 fastback I picked up has a 9" rear with small bearing axles and tapered tubes in it. I wonder if it was a modded 8" to 9" or if that was how the 9"s came back then?

that is how the 9" rears came back then, but it could also be one the 9" housing and 8" tube swaps still

 

[Edbert]

I have been assured by multiple shops that there are indeed 9 inch third members that will bolt in to my 8 inch housing and work from there.

I would smile, say thank you, walk out the front door of that shop and then run screaming all the way home. Amazing how stupid some "professional" mechanics are these days.

The bolt pattern on the carrier is different, and the ring gear wont even come close to fitting. Some 9s have bulges on the back to make room for the ring.