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In our last issue, we initiated our look at Mark Williams Modular 9-inch “hot rod housings.” In that segment, we zoomed in on the cast, precision machined housing center. If you rewind, you’ll find that these streetable modular centers are engineered to accept a 9-inch Ford center section and can be set up to accept any number of bell and axle tube combinations to fit myriad combinations (and that’s exactly why the housings prove to be “modular”). This issue, we’ll take a closer look at the bells along with the axle tubes.
In the design of the 9-inch Modular Housing, M-W came up with a half dozen different side bell combinations. The bells overall widths include 3 11/16-inch, 4 3/16-inch, 4 11/16-inch (two different bearing sizes), 5 11/16-inch and 6 11/16-inch. These various bell widths allow the housing to fit various four link widths and combinations along with various axle tube configurations. The center casting is machined to incorporate a seal adjacent the side bell (seals are readily available).
The 3 inch steel tubes are manufactured from 4130 Chrome Moly steel and they can be built to any length and with any MW housing end. In our case, the overall housing width is 54 inches, axle-to-axle flange (typical for a first generation Camaro) and it has been fitted with small GM housing ends (again, typical first generation Camaro fare). We should point out all housings are engineered so they use a positive bearing retainer style of axle retention instead of c-clips. We’ll get to that in more detail in an upcoming segment. Williams notes that with this style of axle tube, “Suspension, wheelie bar, and spring mounts can be attached to the tubes at the discretion of the builder just as with a normal steel 9 inch housing.”
That’s not the end of it either. While our sample housing is fitted with bare tubes, it’s also possible to equip the housing with a high tech steel four link. According to Mark Williams: “Using steel end bells, 4-link housings can be built with MW laser cut 4-link brackets made from 3/16-inch thick steel plate. The 4-link attachment points on these brackets are similar to our aluminum brackets and accommodate 5/8-inch cross-hole rod end. Other mounting holes for the adjustable shock mounts and wheelie bar mounts are 3/8 inch diameter. 4 link centers can be as narrow as 21 inches. To add rigidity to the 4 link mounts, a 1-inch X 3-inch steel cross tube is used to tie the 4 link brackets to the bottom of the housing.” Williams also sells all of the steel four link brackets separately (including front chassis mounts). All are laser cut and CNC machined from 4130 Chrome Moly steel.
If an application has special suspension requirements, Mark Williams can also install customer-supplied ladder bar or 4 link brackets, shock mounts, wheelie bar mounts, spring pads and so on, on steel tube housings.
If that’s not enough, the modular can be fitted with a complete aluminum four link with dimensions typical for a modern Pro Stock or Top Sportsman style car. While beyond the scope of this series, it goes to show that you can configure and re-configure a modular to fit any number of different combinations.
Finally, these housings are definitely light. If you’ve ever had to bench press a bare Dana 60 housing into a car or muscle one around your shop, you’ll be pleasantly surprised at the weight of the Modular Housing. The 54-inch steel tube example shown in our accompanying photos tipped our scale at 57 pounds. That’s on par with (and in many cases, far lighter than) a number of sheet metal housings.
The attached photos and captions will provide you with further insight into the housing. But that’s the not the end of it either. Next issue, we’ll dig into a typical street-strip, street machine or street rod center section M-W offers in conjunction with the Modular 9-inch. Watch for it!
With an M-W modular setup such as this example, the side bells allow for the installation of steel axle tubes. That means it can be installed in any number of applications, such as leaf spring or coil over with a ladder bar or four link.
The key ingredients in the Modular “system” are these billet aluminum side bells. Mark Williams manufactures a broad range of side bells. The text offers detailed info.
As you can see, the side bells are engineered to allow for simple steel axle tube installation. Essentially, the whole setup is a bolt-in.
12 point aircraft quality hardware is used throughout. This photo shows the stud and nut arrangement used to install the axle tubes to the side bells.
M-W offers a full range of available housing ends for use on the 3-inch axle tubes fitted to the Modular 9-inch. This particular setup is for GM “small car” brakes (Camaro-Nova-Chevelle, etc.).
This housing end is designed to work with M-W’s Pro Street axle bearing. That bearing features a large I.D. and is unique in that it can take thrust in either direction.
This tapered roller bearing exceeds the radial capacity of common O.E.M. ball and roller bearings.
Backing up a bit, here’s a good look at the stud and aircraft lock nut setup M-W uses to install the third member into the modular case.
