R-Model rear axles

[mlplunkett]

Were the axles in the 9" R-Model rear end any different than the 28 spline axles used in a regular v8 8" axle?

[The Going Thing]

Yes. They were 31 spline axes. The ends of them look different than the 28 spline as well. My 31 spline are solid on the flange end where the 28 spline are concaved.

[gt350hr]

    Sorry Keith ,
      R model axles were standard "manual trans" 28 spline axles , not 31 spline . 31 spline '65-66 axles were used in A/FX Mustangs ONLY and were not sold over the counter at your Ford dealer. They use an XW part number and only available through Holman Moody "in the day" There were two versions. Yes the hub end looked the same as the '67-70 31 spline axles. BTW R models did not use nodular cases or Daytona pinion retainers. The manual trans axles were a different forging that the automatic axle forging that was phased out for '66.
   Randy

[The Going Thing]

Randy: I worked on a '65 GT350 that was 31 spline axles. I assumed they were being my 67 500 is. Thanks for the enlightenment.

[shelbydoug]

I doubt anyone racers a very original race car.

Certainly in their day, they were run very hard and I'd be surprised if any of the R's or T/A's retained the 28 spline build components.

[acman63]

I doubt anyone racers a very original race car.

Certainly in their day, they were run very hard and I'd be surprised if any of the R's or T/A's retained the 28 spline build components.

Doug:  i know a couple guys that vintage raced the stock axles for 15 + years and I now own the axles  and they have no issues with splines  and straightness

[The Going Thing]

I doubt anyone racers a very original race car.

Certainly in their day, they were run very hard and I'd be surprised if any of the R's or T/A's retained the 28 spline build components.

Doug:  i know a couple guys that vintage raced the stock axles for 15 + years and I now own the axles  and they have no issues with splines  and straightness

Jim: Small block cars never put out 550lbs of torque then. I could see them live forever in a 306HP 289 car.

[mlplunkett]

Thanks for the info. How can I tell if my axles are standard or auto trans axles?

[acman63]

I doubt anyone racers a very original race car.

Certainly in their day, they were run very hard and I'd be surprised if any of the R's or T/A's retained the 28 spline build components.

Doug:  i know a couple guys that vintage raced the stock axles for 15 + years and I now own the axles  and they have no issues with splines  and straightness

Jim: Small block cars never put out 550lbs of torque then. I could see them live forever in a 306HP 289 car.

it wasn't in the 60s   , it was in the 90s when they started running big cube engines

[The Going Thing]

Big cube small blocks didn't exist in the 60's, 70's or 80's. I was stating they would survive even with a high-winding 289. With a 428 in stock-form you're looking at 420 lbs of torque which is why the 31 spline axles were used 1967 up.  You start pushing 500+ lbs of torque on 28 spline axles they twist or even snap at the splines beyond that.

[shelbydoug]

Big cube small blocks didn't exist in the 60's, 70's or 80's. I was stating they would survive even with a high-winding 289. With a 428 in stock-form you're looking at 420 lbs of torque which is why the 31 spline axles were used 1967 up.  You start pushing 500+ lbs of torque on 28 spline axles they twist or even snap at the splines beyond that.

It's difficult to do a scientific study of original racers at this point. Even so, it was so difficult to talk to anyone about specific information back then, that it comes down to what one person thought they heard from another. People got hostile.

As I recall, 28 spline axles were an issue from day 1 on race cars even WITH 289's. Can I prove that scientifically? No. Does it matter? No.

Racers changed what they broke to something they considered better. Was the better unbreakable? No. Everything is.

ONE of the larger changes made to beef up these cars from the original product was the rear. There are quite a few parts in the assembly that were beefed up.

The cars as built by Ford just started as 28 spine assemblies. Things just naturally evolved into 31 splines as they became available. 35 splines with spools for drag racing.

Personally my cars have forged Strange axles rather then the Ford. It's just safest to acknowledge that some guys can break anything.

[gt350hr]

Thanks for the info. How can I tell if my axles are standard or auto trans axles?

     The "automatic" axles were smaller in diameter (bordering on spindly) and had a rough finish. Most often had a forging number ( on the end) of C2OW. Manual axles had a larger much smoother , consistent diameter , finish to them and had a C4OW forging number on the end. These numbers were not always legible. Both have the "oval" shaped depression in the hub. 31 spline axles were first available in '64 for drag race Galaxies and Fairlane Thunderbolts. Fairlane axles would work in the '65-66 Mustang housing and it is entirely possible that they were changed . Bottom line is the R Models were "produced" and shipped with 28 spline axles on day 1.
   Randy

[gt350hr]

  It takes about 500 hp to compromise the driver's side 28 spline axle at the end of the splines ( guess how I know). The longer passenger side rarely , if ever, breaks. Really hard cornering with sticky tires increases the load on the axle causing it to flex at the wheel bearing. This "has" been known to cause cracks on the axle at that point. The smaller "original" axle bearing limits the diameter of the axle and a switch to the "big bearing" allows a larger diameter ( and additional spline count Doug mentioned) axle to be used. Many road racers have gone to the far safer "floating axle" design for maximum safety.
   Randy