Does anyone know where to get upgraded axles for our 8" rearends? Also, did any broncos or trucks or other 70's fords come with a 8" rearend and hardened axles? Thanks, Jamie
i believe currie makes an aftermarket 8" axle. but i don't know if it's any better than stock. what do you intend to use it for. the 8" axles are pretty tough.
All 70's Broncos and Ford Trucks came with 9 inch rears. From what I have read, the 8 inch axel is just as strong as a 9 inch axel. With an 8 inch, I think you would break something else before breaking an axel.
8" axles are just 28 spline 9" axles. The differential and gears themselves are the weak points in an 8". Dave
Never under estimate the little 8in rear. If you are running an auto trans, they will hold up just fine up to 450HP. Std. trans and dumping the clutch is another story, may want to go to 9in and 31/35 spline axles such as Moser or Strange. Our Mav ran 8in, C4 with 9in slicks for years with no failures. Even with 10.5 slicks, it performed great with a 302 @ 400+HP. When we needed more gear ratio, I shortned a 9in and still used the 8in axles, still use this rear in my Fairmont with the 331 alky motor. The Mav now has 408+ci and 14in wide slicks, which made for the addition of Moser axles for durability and safety. Biggest problem with 8in is the rear pinion support bearing and, in some cases, the size of the gears themselves (depending on ratio). If you look at both the 8 and 9in pinions on the bench, you will see that the 8 has a very small diameter bearing shaft on the end. It is about 1/2 in, the 9 is approx. 3/4, bearing and case sizes are corresponding to each. Make your decision based on use and power etc. The 8in axles I refer to are from Mavericks, others may not be as strong. As an after thought on this subject, when installing deeper gears in the 9in case, like 4.86 etc, sometimes have to grind some material off the rear pinion bearing support case, for the thicker ring gears to clear. Be very gentle doing this so as not to weaken the case, lots of pressure on this area when dumping the clutch or applying lots of torque and HP at launch as the gears try to climb over each other. JMO
Good info guys. As far as setup - I have a .030 over 351W that should be making 400 HP and same torque or a little better. I plan to run a 4.11 gear and a 2800 stall, which is what I fear will cause me issues. There are a couple of guys selling 8" center pumpkins on ebay and otherwise that can handle ~ 450-500 HP so I just wanted to get the axles up to snuff if I go this route. I can't remember where, but I read on some web page that there were some factory hardened axles, and the author even went into how you could verify by scrathing the axle... if you could scratch it is wasn't the harder axles. Just wondering if anyone knew of this and exactly which vehicles the donor axles came from, and yes they could come from a 28 spline 9" i.e. a bronco or truck. Maybe I didn't really read that and just wish I had . I have also read that the 8" turns easier than the 9"(HP savings) and weighs a little less. I don't plan on upgrading the engine for many years if ever, so if I could stick with the 8" for this combo I would prefer that route for the weight/HP/ and the fact that it is in the car already!
I have not heard of any factory hardened axles, but not to say there aren't any. You can use the scratch method on the 26 spline C4 input shaft, which a few were hardened. 4:11 and 2800 stall should be no problem for the stock axles. What size and type tires are you going to run? Is it a auto or std. trans? If you are really that concerned for safety etc, you can get axles made for less than 450.00 from Moser. This is a kit with new bearings and retainers included, I don't think they will warranty 28 spline though. If it were me, I would get the stock axles magnafluxed or magnaglowed and install them with new bearings and such. Then hammer on it and not to worry, pull them for inspection every so often and check to see if the splines have started to twist etc. JMO
I was planning to run standard 28" radial tires on the street/highway (or whatever will fit) and 26" ETs or slicks at the track to get the better effective gear ratio. How much do you think the magnaflux/magnaglow and bearing job would cost?
