I'm in the process of deciding what rearend to put in my 51 F1. I've read the tech article on rear end options, but I'm looking for more information on the 8.8 inch rear end. The 9 inch is the preferred rearend, however, the 8.8 offers some advantages. Disc brakes, small wheel bolt pattern, locker etc. However, I'm unsure of it's reliability. I'll be using a 351W and a C4. Has anyone had any experience with this rearend and/or can you point me to some information?

 

for street use, the 8.8 should be plenty strong. Its used in mustangs, and explorers and trucks, amongst others.

 

The 8.8" in my Bronco crapt out after 150k, and at least in the 30k I owned, I haven't done anything that could've caused any excessive wear. Because of the ABS, sweapping it for a 9" rear is bit problematic for me.

 

The Explores with rear disk brakes uses a 8.8 with 31 spline axles. Most come with LS and 3.73s or 4.11s. With a C-clip eliminator they’re just as strong as a 9” and weight less. For the best axle, a 9” with after market components is best, but unless you’re racing, strongly consider a 8.8. Keep in mind though that the 8.8 pumpkin is very slightly offset to the right. Measure carefully.

 

I would probably go with the 9 inch first because they are the best to work on over the long haul. Though if I wanted disc brakes I would go with the 8.8. There really is not much strength difference between the two, except if you break an axle the 9" housing will retain the axle. I would worry more about the C-4 behind a 351w. I would upgrade that to a C-6. Every 351w I owned had a C-6 behind it from the factory.

 

Thanks for your input everyone. You've pretty much confirmed what I was thinking. The 8.8 should be fine. One thing I'm a little confused about was an item in the Ford racing catalog. The C-clip eliminator description said "not recommended for rear disc brakes". I want a rear disc brake rearend. Has anyone use the C-clip eliminator on a rear disc brake 8.8?
As far as the C4 goes, I've also got an FMX that I could use. It's a good trans but heavier that the C4. I'll also consider the C6.

 

Either way you cant go wrong. Although if your spending the money fixing up a 51, they do make rear disc brake kits for 9" axles. I think you can get them for under $600. Maybe even under $500. I think the deal is with the C-clip eliminators and the rear disc brakes on the 8.8 is the way the c clip eliminators work. I think they conflict with the flange and how the disc brakes are bolted on. I would also say that you would be just fine with the C4 transmission. Just have someone who knows what they are doing build it. I put a C6 in my V8 ranger and regret it due to the amount of power loss, and added wieght.

 

If it were mine I would stick with the C4 - it weighs less, has a LOT less internal power loss than the C6 (free horsepower) and can handle a 460 if built correctly. For a relatively mild 351W, the stock C4 will handle it easily, particularly if you have a late model pan fill. There is a great forum on C4s here - http://www.fordmuscle.com/phpBB/view...11&forum=13&47

 

I don’t know why Ford would say their C-clip eliminator kit shouldn’t work on a disk brake axle. Maybe the axle flanges will interfere with the brakes. Hopefully somebody that has done that swap will chime in. One interesting thing I’ve been told is that the disk brakes off a Mark VIIs 8.8 will bolt up to a later model 9”. Again I Haven’t done that swap (even though I’m planning on it with my Mustang II) so I don’t know for sure that it works. As for the transmission, the C4 is a lot more tougher trany than most people give it credit for. If it is built and cooled right it is amazing what they can do. The FMX is a stout transmission, but it is very heavy and complicating. Not every shop can build one right. On the other hand every transmission shop out there has built C4s and if you ask the racing crowd I bet you can find a good one around you. The C6 is on a whole other level. Stock it was offered in 1 ton Plus trucks. If you’re planning to work your F1or the Windsor is going to be really, hot then the C6 is the way to go. If you’re going to build a show truck, daily driver, or just something for fun the C4 will be fine with proper cooling and some after market help.

 

One more thing I forgot to say. Is that in reality a disk brake rear, that isn’t racing, shouldn’t need a C-clip eliminator. If the axles were to brake the calibers would keep the wheels on the truck. But why not spend the $150 for the piece of mind. I big truck with a hot small block I would like to have them.

 

C-clip eliminator - OK, I've researced it a little more. The 8.8 has axle tubes that extend past the axle flange. These need to be trimmed when using the C-clip eliminator bolts to the backing plate behind the axle flange. This was gleaned from "The official Ford Mustang 5.0L Technical Reference & Performance Handbook". The yolk on the 8.8 appears to be a little different. I'm still researching that. Anyone have any input on that?

C4 - I've always felt that a properly built C4 should handle a mild 351W easily. However, it's always prudent to investigate all alternatives, get multiple opinions based on experience and then make your best choice.

Mine will not be a race truck. However, it won't be show truck either. I plan to just rub out what paint is there and leave the "patina". I'll use it to cruise to car events (certainly not "show & shines").

Thanks for everyones input.