9" rear
 

Hey everyone,
A friend of mine told me that the Ford 9" in my 1970 Mach 1 is either a 14 spline or a twenty spline. He said that with the motor I am putting in it, I will rip it apart (I am putting in a custom built 514 Stroker CJ with approx 950 hp). Is my rear end really only a 14 or 20, and if it is, should I change it to a 37-spline?

I hope I can clear up a little confusion that your friend is causing.

The 9in. is either a 28 spline or 31, this is the number of splines on the two axles where they connect to the center section. Your motor might be a little strong for the 28 spline and the 31 would be better, but Ford's 9in. is one of the strongest ever built with or without the 31 spline. You can check with alot of chevy racing guys they know this rearend can't be beat and they have them installed in their cars.

Thanks Clark,
That is what I told my friend. I wasn't sure about the numbers of splines, but I knew that the 9" was the strongest. Two of my slomaro friends have them in their cars, but this other friend was insistant that mine would not hold. Thank you for replying; I am going to show my friend this posting.

31 spline is still a bit on the weak side. I just tore mine up at the 700 horse level after one season and stepped up to a 35 spline setup from Dutchman. Fully assembled with a gear set, axles, carrier, shortened and backbraced tube and maybe a spool expect to spend up to about $2000.00 to $2500.00 Would definitely need a backbrace on the tube, and a good nodular carrier. Never heard of a 37 spline...35 or 40 maybe. I would also be very concerned about the chassis at that level, and how to plant that much power. Back halving the car, ladder bars, subframes, 10 point to stiffen the body.

Ron

950 hp? No place for a stock rear end. I'm with ron1 on this one. That rear end sounds like a bargin conpared to the cost of making 950 hp. Another option, Call Currie and ask what they would recomend for your application.

What did you use?
 

What did you use to make a 514 Stroker CJ Motor with that much Horsepower?

The Ford MS 514 makes 600 HP out of the box. With a minor cam change and some head work, I have seen them creep up to about 725 horse. With some added N2O could get 950, but the other problems that creates are going to cost a fortune. With a calculated loss of 15% thru the drivetrain, that is still 808 at the rear wheels. Based on my calculator, estimating 3400 pounds, that is a 9.30/9.40 at 145/150 MPH. When you do the rear end, have them weld on the wheelie bar brackets as well, and someplace to mount the chute. 150 MPH is the cutoff. Are you going C6 or are you thinking a PG?

Ron

To make the estimated 950 hp, I am using a forged 514 stroker crank with a .060" overbore, brand new custom ported CJ aluminum heads, roller everything with radical cam, and port matched wiend tunnel ram with 2x4 750cfm Speed Demons. Later I will add a small 150hp nitrous shot. The horse power estimates were made by the motor sports company that is helping get the specialized, not to mention expensive, parts that I am getting. Once I finish the motor, I will go on to suspension - not sure yet, but probably 4-link, subframes, etc... As goes for the tranny, I want to get one of my C6's rebuilt to hold the horse, but, since I don't know transmissions, if that is too expensive, then I will just buy a new hi perf tranny. If anybody has any questions or suggestions, please write. Thanks everyone. Josh

Couple of suggestions maybe...I own a 514 equipped 68 FB. If I was to do it over I would definitely go with motor plates. It will make the exhaust fit a lot easier. I might have even done a front clip. As far as the trans is concerned, if you go C6 there is only one vendor I would go to. JPT in Eaton Falls, MI. They specialize in high HP ford transmissions, and convert the trannies to full rollers (less loss thru the drive train), with their own custom planetaries. Your other option is to buy all the hard parts from JPT and find a local guy to assemble it. I would never recommend a four link to anyone, unless they had a lot of background in drag racing. Ladder bars and coil overs would be my first choice. Once set, they work great.
Another question of course is who is backhalving the car?

Ron

9'' REAR
 

Good point you guys but also remember that very few 9'' rears with 28 or 31 spline axles came with HARDENED SPLINES. People tend to forget this point. Get some good hardened aftermarket axles and you should be fine. 900 hp is way to much for a street car though.

Not one to disagree, but there is not a snowmans chance in you know where, that by merely going to some hardened aftermarket axles it will solve the problem. That 9 inch will grenade the first time out of the box. 35 spline, 1 1/2 inch dia. 1/2 inch dia. wheel studs instead of 7/16. Nodular case and, not to repeat myself, but a back braced tube. Look at Currie, Dutchman Motorsport, Strange, Morrison and Mark Williams.

If he is running 800 at the rear wheels, with 750 lb/ft of torque, you have to have the best money can buy, or close to it.

http://www.markwilliams.com/technical/faq.html

Ron

RDRZ...found a great informational link for you..try here..
http://66.96.130.106/archives/2002/0...ch/index.shtml
while you are there, I noticed they also have a 460 based 1000 HP buildup.

Ron

Thanks
 

Thanks everyone for all your help and suggestions. Now I know what I need to get and how much to spend. Ron1 - thanks for the link, I will check it out once I get back home (I am on vacation). Thanks again everyone for all the information. It will help a lot in getting the Mach on the road faster.