The Ball-Spline Drive System Has Racers Going Faster

(Reprinted with permission from an article by Jim Armbruster for Dirt Late Model Magazine)

Bert says its latest innovation is the best thing to come along since their transmission revolutionized dirt Late Model racing drive trains nearly 20 years ago. And Raciní John Mason adds, "The response weíve gotten from other racers is better than anything Iíve ever worked with before."

That's some pretty big stuff, coming from two of the most respected mechanical minds in Late Model racing. Remember that Mason's list of contributions to the technical aspect of our sport goes on and on, including -- among others -- most of the stuff you bolt on to the back of your motor. And Bert, well, all you have to do is pick up one of his catalogs and you can see that this guy's mechanical aptitude is somewhere above the genius plateau.

So, when these guys speak of their newest venture, which they say is going to help dirt Late Model racers gain speed, it's like the old Merrill Lynch commercial: People Listen!

"The guys who figure out how to use this thing are going to have an advantage," Mason stated.

We're listening! We're listening!

What the former Dirt Track World Champion is talking about is the new ball-spline drive system from Bert Transmissions. It replaces the output shaft you are currently using on your Bert transmission with a mechanism that has 12 ball-bearings and allows the yoke to roll in and out of the transmission instead of drag on the splines. This permits you to accomplish 5" of yoke travel without damaging your seals, making your race car go faster, sometimes much faster.

"I think there's a lot more happening here than we originally thought when we first got into this project," Mason said. "Even though the system is carefully balanced, (Bert holds tolerances to with .002) there is more to it than that, it eliminates the spline chatter. Gary Stuhler told me that he could feel the bind with the older style output shaft. I had never really thought about it, but you can feel that chatter or bind in it when the drive shaft slides. That means there's a lot of bind in there. The new ball-spline system relieves that."

"One of the biggest improvements is that the car becomes so much smoother to drive," Mason continued, "You'll notice the car rolls over on the right side a lot more. Friction at the yoke is reduced by 12 times and since there is less bind, the rear end is more free to come forward, giving you a greater push on your radius rods. You get more shock extension with the possibility of five-inches of yoke travel. This allows you to move the suspension further. You can really feel the car become more free when you get into the corners."

"I thought the first thing that would happen was that the fifth coil would move more, and that has happened. But it wasn't the only thing," the Millersburg, Ohio driver admitted. "I never thought that getting into the corner would be the ball-spline's greatest advantage, but maybe it is."

Mason has seen to it that some of dirt Late Model's biggest names had access to the new component, looking forward to the feed-back he'd receive. "BIll Frye said that you can accelerate and turn the car better. On a heavy track, you can run a groove lower because it lets you turn the car better," Mason noted. "C. J. Rayburn really liked it. He said it lets his whole race car work."

"Of course, I'm a common sense racer, or a common sense engineer," Rayburn stated. "I can see that it's going to be better. It looks good. I don't know about other guys' cars, but my rear end rolls so much and the drive shaft moves in and out a whole lot that I feel it's (the ball-spline drive system) really necessary there." Mason continued, "Billy Moyer said that it was sometimes hard to feel the difference, but on the clock he was consistently faster, so he's stayed with it. Early this season, Rick Eckert was winning with the thing. He was at East Bay and there you get a little push getting into turn one. You have to get into the turn just right to make a quick corner. Rick told me the ball-spline idea really helped him get into that corner. On tracks that are heavy, it makes the car more driveable, It takes the push out of the car."

Mason compared, " I believe the advantage would be greater on a heavy track than a slick track. But as guys run it more, they seem to like it as a slick track item. You know, anytime you can get even a small advantage on a slick track, it means a lot. I haven't got to run it on a really slick track yet, but we've found that in the past, when a track slicks up, it's harder to get weight transfer. The ball-spline, since it helps the weight to transfer, will help on the slick tracks, too."

If this information doesn't have you wanting to find out more about the Bert ball-drive system, the new piece possesses a safety feature also. You see, it locks the drive shaft yoke inside the tail housing. If you've ever seen a car vault end over end or know anyone who has been ripped up when a drive shaft came through their interior, you can appreciate this positive safety aspect.

"Shannon Babb tried one at Waycross (Ga.) and he really liked it," Mason contributed. "That place can get just like asphalt and Babb runs Rayburn cars. With all that bite, Babb broke his pull rod. The stop in the back of the tail housing kept the drive shaft from pulling out. Shannon ran seven or eight laps like that. I wouldn't recommend racing this way, but this time the ball-spline system saved Shannon Babb."

Let's say you call Mason Racin' and purchase the new Bert ball-drive system. "You can buy the complete transmission ready to bolt in or you can just buy the kit that includes a new tail housing. Bert had to shorten the tail housing an inch so that it takes the same length drive shaft and allows for the extra travel. " Mason explained. The complete transmission with the magnesium casing costs $2050. The complete transmission with aluminum casing sells for $1900. If you already have a Bert tranny, you can buy the conversion kit which includes a new tail housing and everything you need to swap over for $750. You'll also need to know what kind of chassis changes you'll need to make once the ball-spline system arrives.

"With a four-link car, you'll want to take some rod angle out of it," Mason said. "because it rolls up so hard. That was one of the first things we noticed. And from what we know right now, you'll need to stiffen the fifth, especially on a heavy racetrack. I'm not so sure you couldn't stiffen the right rear, too, and get more side bite that way."

"The first time we tested the ball-spline system on our test track out back, we knocked off three-tenths," Mason concluded, "But, I don't really like to tell people that, I do know, though, that it's worth a good, solid one-tenth."