Misc. Impala SS mods

This is a "catch-all" for the mods that don't really involve a full page's worth of details.

Transmission

I installed a Transgo shiftkit in my tranmission at about 62,000 miles.  My goal was to firm-up and quicken thet upshifts, and hopefully improve the downshifts.  I was also looking for something that might make the 4L60E last a bit longer.

As far as I know, the Transgo addresses these problems:

- Prevents fluid bypass in Overdrive.  The stock tranny bypasses the torque convertor when in OD in an attempt to minimize pump drag and therefore increase fuel economy.  Since the convertor would normally be locked-up in OD, there's very little heat built up in the convertor and there's no harm in not feeding fresh, cool ATF to it.  If you tow in OD, however, there's a very good chance that you'll be using enough throttle to unlock the convertor.  If this happens, the convertor can start to build up heat (due to slip), and that causes some major problems.  Eliminating the fluid bypass hurts fuel economy by about 0.5 MPG, but helps the tranny live a longer, happier life.
- Greatly lessens the time required for the tranny to shift from Reverse to Drive, especially when cold
- Increases transmission line pressure, which cannot be done by electronic (Hypertech, B&M "trans tricker") methods
- Quickens upshifts and downshifts
- Increases pressure to the 2-4 band, helping it live longer by reducing slippage

If anyone has any further info, please let me know!

I used two washers in the 1-2 accumulator.  It seems to be to be the ideal setup for a street car.  The car already chirps the tires on part- or full-throttle shifts (with stock tranny programming!), and anything more "violent" would just result in wheelspin with street tires.  Go with a single washer if you don't like firm shifts.

The stock torque convertor has been replaced with a 3100 RPM stall unit during the 396 install.

A T56 swap is planned during the winter of '01-02, which will bring with it a custom crossmember.  Stay tuned for a write-up with pictures!

Rear axle

I installed 3.73:1 rear-axle gears in my car.  This was to improve straight-line performance from a standing start, and to better accomidate the large camshaft that's going in the 396.  They're great around town and up to about 45 or so.  My biggest complaint isn't that they spin the motor too fast on the highway (although I'm now turning 2400 RPM at 70 MPH).  Nope, I miss the explosive 60-80 MPH performance that I got with the stock 3.08s.  You see, with the 3.08s, that 60-80 zone was the top of second gear.  The motor was right up in its powerband, and the car just tore right through that speed range.  It was particularly satisfying to hit highway entrance ramps.  Now, the tranny shifts from second to third at 65 MPH, and kinda sits down in a milder part of the rev range until 75 or so.  By that point, I'm getting ready to back off the gas and watch for Michigan State Police cars in the rear-view mirror.  With the 396 installed, the situation is much-improved - that motor makes power everywhere in the rev range, so all is good.
 

Interior

I added 2" Autometer oil-pressure and voltmeter gauges in the black trim panel, below the stock instrument cluster.  With the white-on-black graphics and black bezel, they look pretty stock.

I've also added 6-point harnesses to both front seats.  They greatly improve support during heavy cornering, such as autocrossing, and allow me to loosen up my deathgrip on the steering wheel.  As the passenger doesn't have anything to grip, it also makes life much easier for them.
 

That's all for now.  The only appearance mod that I've made to my car is the near-mandatory Red Bowtie in the grill, and a different shifter knob.  I think it's from a late-90s Pontiac Bonneville or Grand Prix.  I'll get a picture up at some point.

As always, feel free to contact me at eric@bryantperformance.com!