JRB53 Posted July 9, 2017 Share Posted July 9, 2017 Picked up an MPC Jawbreaker (super cheap) and am very curious about the unusual design of the front axle. Tried "George Klass Remembers" for some reference photos but can't find a thing. What are those small couplers? why two steering links? Is it accurate? who started this type? was it modeled after a real racer? and what time period are we looking at? With those wild exhausts, I'd love to model a wingless version for early 60's, but will I have to redo the front end?I found FloridaBoy's post of April, 2015, but there's only a passing mention of the dropped front axle and the installation problems. Also, does his observation concerning the Late-model Hemi limit this build to post-1965 time period? If so, I could modify the valve covers and dig up an old-style Potvin blower to help backdate the motor. Or am I just going to run into more time-period problems with the tires, wheels and frame?Thanks for any help you may be able to provide. Usually I'm pretty good researching the Internet, but this dropped axle has me stumped.Jack Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted July 9, 2017 Share Posted July 9, 2017 (edited) I just don't have the patience today to do an exhaustive image search, but if THIS is the front axle assembly in question... It's a torsion-bar setup. The lower flat links connect the axle to a transverse torsion bar, while the upper two tubular links are essentially radius rods that keep the axle from twisting and maintain caster angle. There is NO steering link shown in the upper photo, but it would be a single long link running from the Pitman arm to the left front spindle, just like many other front axles...or a center-pivot setup like shown below on a similar front end... The shot below shows another similar front end with another more typical steering setup. Torsion bar front suspension on rail dragsters began appearing in the late 1950s. The early VW Bug front torsion bars were a natural for being used in this design, as they're stacked leaves and easily shortened and tuned for dragster applications. EDIT: If I remember correctly, Kent Fuller originated a torsion-bar setup for rail dragsters on Tommy Ivo's single-engined Buick powered car from 1958, and it appeared on many of Fuller's subsequent chassis. Edited July 9, 2017 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted July 9, 2017 Share Posted July 9, 2017 This is yet another torsion-bar front end setup that uses hairpin-style radius rods. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted July 9, 2017 Share Posted July 9, 2017 More... The "Jawbreaker" kit is said to be based on the earlier American Graffiti John Milner rail kit. Though I don't have either kit in stock to physically check, that car (and the kit) also have torsion bar front suspension. Quote Link to comment Share on other sites More sharing options...
Ace-Garageguy Posted July 9, 2017 Share Posted July 9, 2017 (edited) Yup...center-pivot steering, as shown in one of the photos above (but with a conventional tie-rod tying the two spindles together). And I don't know what the big fat round things molded to the tubular axle are, but I suspect they may be supposed to represent weights. Edited July 9, 2017 by Ace-Garageguy Quote Link to comment Share on other sites More sharing options...
D. Battista Posted July 9, 2017 Share Posted July 9, 2017 I just don't have the patience today to do an exhaustive image search, Wow.... with not having the patience you did an awesome explanation of the front end in question. I really appreciate this kind of info. Someone asked...... and I learned something new today.... Thanks for your time Bill...! Quote Link to comment Share on other sites More sharing options...
JRB53 Posted July 9, 2017 Author Share Posted July 9, 2017 Thank you for the great tutorial, Bill. Now I understand how that front end is supposed to work. Still have one question about the kit model. On Pg 9 of the above shown instructions, Part #120 has two large "bumps" (right beside the dark circle #1) near the center of the axle. All of the Real-life pictures I've seen show smooth, clean tubing in the center section. What is MPC trying to show? a three piece axle? They don't line up properly to be the attachment points for the radius rods.Thanks again, Jack Quote Link to comment Share on other sites More sharing options...
JRB53 Posted July 9, 2017 Author Share Posted July 9, 2017 Sorry, Bill, I re-read all your posts and saw where you have already answered the question about the mysterious bumps. Thanks again for all your help. Quote Link to comment Share on other sites More sharing options...
oldnslow Posted July 10, 2017 Share Posted July 10, 2017 Those "bumps" are weights bolted to the front axle . Quote Link to comment Share on other sites More sharing options...
Mark Posted July 10, 2017 Share Posted July 10, 2017 The More American Graffiti dragster is itself based on the Ramchargers dragster kit. Besides the Ramchargers, Milner, and Jawbreaker versions, it was also issued as the Carl Casper Galloping Ghost II. But the Ramchargers version was the first one issued. Quote Link to comment Share on other sites More sharing options...
JRB53 Posted July 12, 2017 Author Share Posted July 12, 2017 Thanks for the confirmation on the axle weights. And while we're on this interesting group of "MPC vehicles", why does the Milner dragster have two fuel tanks? Both in the movie and on the kit instructions above, it shows a tank directly in front of the motor and one further forward. Thank again for the help.Jack Quote Link to comment Share on other sites More sharing options...
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