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My original, rust free subframe was accidentally
scrapped by a good friend who was storing it for me at the time.
We rushed to the scrap yard later that day but it must've been shredded
by then. Having detailed all of the subframe components, I only
needed a bare frame. Several months of searching led me to
Fabulous Firebirds.
In January 2004 my patient family let me make a weekend trip out of picking up the subframe
so we spent time in St. Louis. Larry Cooper let me pick the best
'67 frame he had, but it still needed the mounts fixed. |
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All four mounts were repaired to look as
original. The underside dents were also removed. See my
Sub frame Tech section for more pictures. |
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The finished subframe has
Hotchkis coils and sway bar, Moog
rubber bushings and ball joints, polyurethane biscuits for mounting to the body.
Correct 4-piston caliper flex hoses may be purchased at
Ames. |
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The rear axel is ready to install - 3.55
gears and Detroit Locker center section. I already had the locker
or would've gone with something more streetable. I used 1968 brake
lines because they are bent for the u-bolts. The brakes are Master
Power Brakes' big drum conversion. I went with these after seeing
how much trouble folks were having with disc conversions. These
drums are HEAVY and if I had to do it again, I'd probably go with discs
or stock drums. I'll reserve final judgement until I'm able to
drive it. |
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An interesting thing about '67 Firebird 400
4 speeds is that they come with two of these I-beam radius rods
(traction bars as some may call them) designed by the factory to limit
wheel hop. While Chevy introduced a similar device after the start
of the model year for the high performance Camaros, it was a single
hollow tube design. Failures were high and the Camaro radius rod
design was changed to a beefier square tube. Pontiac completely
avoided any issues by using this solid I-beam design and going with two
rods on higher horsepower, manual transmission cars. The good
thing about the Camaro design is that it uses the same bushings-now
available through PST.
Steele Rubber was good enough
to reproduce the snubber pad (not shown) for me. The part number
is 70-2293-35. |
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6/8/2006: I bought Bilstein shocks
valved to Hotchkis' specifications to go with my Hotchkis springs.
Unfortunately, Hotchkis didn't know that the '67 rear shocks mount
differently from the '68-69 shocks. I had to make a bushing (upper
left) to use a through bolt in place of the '68-69 stud (lower left).
I also had to use smaller rubber bushings (top middle) for the top rear
instead of the bushings supplied (lower middle). Bilstein's tech
support was great in identifying an appropriate service kit and sending
me the bushings (at a cost). The kit is for Corvette C2/C3 front
shocks. |
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01/01/07 (New Years Day): Pictured top
is the new '68-69 DSE multi-leaf shock mount plate, reproduction parking
brake cable bracket and assorted hardware. Pictured bottom is the
original '67 mono-leaf shock plate and assorted hardware. The DSE
plates come in left and right versions (unlike the originals) for use on
non-staggered shock cars. These plates would've allowed me to
avoid the problems above with the lower shock mount hardware.
Upper mounts would've still required the Corvette install kit.
I replaced the mono-leafs with Hotchkis 1.5"
drop multi-leafs. I removed the spacer plate and replaced the
spring bolt with a carriage bolt so the head wouldn't interfere with the
mono-spring perch. I honestly don't know why Hotchkis doesn't do
this for us '67 owners because all of us have to do this mod.
The pictures at the bottom show the before,
during and after pictures. Ironically, the 1.5" drop gave me an
almost identical ride height as the worn mono-springs. The ride is
noticeably firmer in the rear now. |
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3/18/07: At about 10" of vacuum my
factory booster was not functioning well and the brake pedal had a dead
feel to it. After looking at numerous options (vacuum reservoir,
vacuum pumps, etc...) I opted for a hydraboost system from Paul at
Hydratech Braking Systems.
Their service and products are tops. I also took this opportunity
to replace the Chevy style power steering pump reservoir that aimed the
return hose into the upper a-arm. I purchased the polished
aluminum housing (top left) from
Speedway Motors.
Braking assist is excellent! |
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3/18/07: I picked up a full set of LS1
rear discs from a local junkyard for $100. These came on '98-02
F-bodies and are essentially the same brakes as used on the C5
Corvettes. The shoe in disc parking brake setup makes for a very
clean looking install. With non-staggered shocks, I'm okay
with a left and right by just switching sides from the stock positions.
After much research, I intend to go with front and rear '98-02 F-body
discs to improve stopping ability. Unfortunately, the popular C5
or C4/C5 hybrid setups will not fit my 17" fat lip rims. |
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4/14/07: I scored a set of front '98-02
F-body brakes for $35. The rotors are 12" just like the rears and
use a caliper that is similar to the C5 except that the piston bores are
larger and the caliper casting is not as strong. Nonetheless, it
will be a big improvement over the factory four-piston brakes that stop
very well, but are leaking even after stainless steel sleeving. |
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4/15/07: I mocked up a bracket from 1/2"
thick poplar after taking careful measurements of the spindle and
caliper bracket (abutment). I want to run a hub with 5/16" greater
offset than the standard drum hub to match the track width of the
factory discs. These will actually move the wheels outboard
between 1/16" and 1/8".
2010 Update: Here is a link to a drawing
of the front disc brackets:
Front Bracket Drawing
(AutoCad)
At bottom is a picture of the taller hub
(left) compared to a standard Camaro/Firebird hub (right). The
taller hub is found on some Firebirds, perhaps with a heavy duty drum
option. They are much more common on late '60s and early '70s
Lemans and GTOs.
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5/5/07: Here's my hand holding a paper
mock up of the rear bracket. This will act as both a spacer and
parking brake bracket. I must've had 30 iterations before I got it
to where the cable passed by the shock and spring without binding.
2010 Update: Here is a link to the
bracket pattern: Rear Parking
Brake Bracket (AutoCad), the gusset:
PB Bracket Gusset (AutoCad),
and bearing retainer:
Bearing Retainer (AutoCad). If you have a c-clip rear, you
should be able to just open the hole in the retainer up to the same
diameter as the bracket. I would also reduce the thickness from 12
ga. to 16 ga. because it will simply be a spacer on the c-clip rear and
that should center of the caliper better. |
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5/12/07: I had parts from my front
(left) and rear (right) brackets laser cut from 12 ga. steel, the
original thickness of the drum backing plates. It's pretty amazing to
hand the laser house an undimensioned CAD drawing and get a high precision part
back. The fronts require some additional machining and the rears
need bent up and welded. The rears incorporate a cable mount and
bearing retainer. |
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9/13/07: Here is the machined and power
coated front bracket mounted on a factory drum spindle with the
Lemans/Tempest hub that has been turned down to fit into the 4th gen
rotor. |
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11/18/07: Finally got around to
installing my custom LS1 brake kit.
The 12 inch rotors are black zinc chromate
plated and are dimpled and slotted instead of drilled and slotted to
reduce stress risers. These are made by
EBC Brakes and were
purchased from the WS6 Store along
with Hawk HP+ pads.
I replaced the disc front lines and brackets for drum versions, mostly
to increase the value of my original disc parts if I sell them but they
also aim the hose down which is a better angle for attaching to the
caliper. Longer studs were purchased from NAPA.
I saved about 7 pounds off each side in the
front (44.2 versus 37.4)!
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11/24/07: These pictures show how my
self designed parking brake cable bracket and spacer fit the rear.
The stud holes were laser cut and no grinding was required to slide it
on! |
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11/24/07: The top picture shows the LS1
backing plate loosely installed and the axle bearing before pressing
into the housing. The bearing is about 1/4" proud of the
bracket/spacer in the picture.
Below is the bearing retainer I made. It
will slide between the LS1 backing plate and bracket/spacer. I
found some F@rd T-bolts that are long enough
to bolt the entire assembly together. |
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11/24/07: The top shows the rear of the
backing plate after being bolted down. The parking brake lever can
be seen in the lower right of the picture. By swapping the brake
assemblies from right to left and vise-a-versa, I was able to eliminate
shock to caliper interference and also convert the parking brake to
front pull. The rear rotors are also 12" diameter and I saved
XXXXX |
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Coming: Stay tuned for my 4-wheel disc conversion! |