As we’ve all seen in print and even online, lowering the front end of early Chevy passenger cars (’37-54) can be as easy as unbolting the old and bolting in the new. When you factor in the aid of additional modern technology, the frontal ride height can be drastically reduced. However, to do so on the opposite end with an equal drop takes a little more effort than simply busting out your basic hand tools; bolt-on leaf kits are limited to the space between the bottom of the top-hat frame rail and the rear end axle tube.
Even with a decent C-notch, leaf spring-based rear suspensions have their pre-determined limits, thus adding a similar type of adjustable component as the frontend (i.e., airbags) ultimately defeats the inherent function of the leaf to begin with. For many, including myself once or twice in the past, the solution was to remove individual leaves from the spring pack. With a dually-convoluted air spring, which acts as a coil, it’s not so bad―but when using a sleeve-type airbag, that’s where the mechanical issues arise. Leaf springs were simply not designed to act as adjustable locators for your car’s rear end.
There are options, but unfortunately, they’re not as inexpensive as the aforementioned bolt-on kits, nor are they as straight forward installation-wise. If your goal is to go as low (or lower) than your front end, you’ll want to consider going with either a parallel or triangulated four-link, or a truck arm style two-link. Four-links are almost as popular as Mustang IIs these days, and because of that, there’s a good variety out there to choose from. (If this is the direction you decide to go, definitely go the triangulated route.) However, the two-links are gaining more and more popularity as of late, and you’re about to see why.
With a properly designed two-link (or trailing arm) setup, you have a rear suspension with no compromised components; everything works in unison, giving you ample adjustability and great ride quality. You also end up with a more user-friendly geometry of parts that offer both better ease of installation as well as the room needed to route your forthcoming exhaust once all is said and done. These upgrade possibilities inspired Jimenez Bros. Customs (JBC) to come up with their own two-link kit.
The setup JBC offers has plenty of flexibility fitment wise, so its application goes well beyond the ’37-54 Chevy you’re about to see it installed on. In fact, at the time this was done, they were fitting one to a ’50 ‘Merc, which didn’t need the step notch due to its high arcing rear rails. JBC’s two-link consists of square-tube trailing arms with bolt-on/adjustable rear end mount, adjustable forward link mount crossmember, four-piece step notch kit, tubular upper shock mounts, shocks, a Panhard bar, and airbags (which we sourced from RideTech along with a two-way RidePro setup).
Before we could incorporate everything, we needed to do something about the rearend. This is also something many of you will be faced with, especially those of you still running the stock closed driveline. Due to the fact that we wanted to go the Chevy route rather than the usual Ford 9-inch, we went to Moser Engineering and asked them what they recommended. As it turned out, they suggested a little of both; 12-bolt housing with 9-inch style ends and 30-spline axles―with one of their Muscle Pak complete rear end kits. And by “kit,” they mean drum-to-drum, chrome diff cover to pinion yoke, and even E-brake cables and hardware.
Once the new rear end arrived from Indiana, Jimenez Bros. had their first prototype two-link ready to install―that is, once the ’47 Fleetline body had been removed from the chassis and all the factory obtructsions rid of..
1. Having already been equipped with a Heidts front
end (currently outfitted with coilovers, which will soon
make way for ShockWaves), the rear suspension on my
Fleetline needed to be addressed in a major way. I won’t
have a custom with its nose lower to the ground than
its rear, period.
2. The solution; Jimenez Bros. Customs’ new adjustable
two-link kit, complete with RideTech airbags, on a
Moser Engineering Muscle Pak 12-bolt rearend with a
two-piece driveshaft from Inland Empire Driveline. The
kit provides form (lowness) and function all in one shot.
3-4. JBC’s two-link comes compete with square-tube
trailing arms with bolt-on/adjustable rear end mount,
adjustable forward link mount crossmember, four-piece
step notch kit, tubular upper shock mounts, shocks, a
Panhard bar, and airbags (from RideTech along with a
two-way RidePro setup).
5. If at all possible, removal of the body allows for
substantially less “overhead” work and gives you a
much better vantage point for plotting out and installing
components, although the kit does not require it
for installation purposes. Once we pretty much had
everything stripped from the trans-crossmember back,
the frame was leveled on jackstands.
6. Beginning with the step notch portion, using the
stock wheelbase gave us a great starting point. Since
the rear wheels on the ’42-48 Chevy two-door Aerosedans
(Fleetline) are exactly centered, we made the
necessary adjustments to ensure they would be the
perfect kick-off, especially at ride height. Preparation
means not having to rely on fender skirts to conceal an
error that can easily be avoided during this initial stage.
7. Once the side plates are squared up and placedwhere
they’re supposed to be (in relation to the wheelbase),
they’re welded to the frame. The metal thickness on
the main portion of these frames is rather thin and
fragile, so short weld sections were made to prevent
any damage from excess heat.
8. Next, the flat plate top sections are welded in place.
Starting from top center (with the plates themselves
centered), they’re tacked in sections then bent accordingly
as you work your way down to the frame rail.
9. Now, with the sides and tops welded up and the
frame supported from both sides of the notch; the portion
of framerail can be removed from the notch section
using either a plasma cutter or a Saws-all.
10-11. The final component of the notch, the inner
hoop, will tie everything together and re-establish the
integrity of the framerail.
12. The inner plates are supplied slightly longer than
may be necessary just trim off the excess as needed.
13. The three holes on each side of the boxing plates
are not only used for welding purposes, but to indicate
front (two holes) and rear (one holes) positioning.
14-15. Now we were able to turn our focus toward
the actual suspension, beginning with the Moser
Muscle Pak rear end. Since this is a 12-bolt, having had
its ring and pinion already setup by Moser, it remained
in place, but the axles/brakes would not. Fortunately,
the external-flanged axle housing made it much easier
to do so, rather than having to remove any C-clips from
16. Basically, we’ll bolt all the components together,
from the forward-mount crossmember to the twolink
U-bolt mounts on the rear end, before welding
anything in place.
17-18. The blocks that mate the trailing arms to
the rear end’s axle tubes actually bolt to the arms,
making it much easier to assemble everything with
just two hands, as shown.
19-20. The front crossmember for the trailing
arms has sliding frame mounts, allowing for any
adjustment if needed. Ultimately, the ends will get
welded to the crossmember as well as to the frame
21-22. With the links installed onto the rear end
first, they’re simply lifted up and installed on the
crossmember. Having the rearend positioned on a
floor jack will help in positioning everything when
determining and setting the desired wheelbase.
23. The pinion angle can be set simply by loosening
the U-bolts to allow the rearend to rotate. When all
is said and done, we’ll most likely weld the blocks
to the axle tubes, but considering the amount of
horsepower/torque the car “won’t” have, that may
not be totally necessary.
24. Now for the upper airbag mounts. These will
be supplied as shown on the right—pre-drilled but
flat with slots for bending the side gussets (as illustrated
on the left in the vise).
25. At this point, both the bag mount and the upper
shock mount have been tacked in place simply by
installing the ‘bag/shock on the lower mounts and
cycling the rear end through its range of travel of
estimated travel. No real science there, but still
plenty of room for error.
26. Only after we were 99.9 percent certain that
the mounts were in the proper locations, at the
proper angle and range, did we proceed with the
final welding duties.
27. The last item to be welded onto the frame was
the Panhard bar mount, which uses a flat plate base
welded to the frame with attached tabs, making for
a stronger piece with less stress on the thin rail.