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08/16/07

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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.

All four mounts were repaired to look as original.  The underside dents were also removed.  See my Sub frame Tech section for more pictures.

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

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.

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 PSTSteele Rubber was good enough to reproduce the snubber pad (not shown) for me.  The part number is 70-2293-35.

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. 

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.

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!

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.

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.

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". 

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.

 

5/12/07:  I had parts from my front (left) and rear (right) brackets laser cut.  It's pretty amazing to hand them 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.

   

Coming:  Stay tuned for my 4-wheel disc conversion!

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This site was last updated 08/16/07