GMT400 History

Discussion in 'Engine Performance + Maintenance' started by Greg, Mar 16, 2010.

  1. Greg

    Greg Über Mod Staff Member

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    Here is my condensed history of the 88-98 GMT400 trucks. This is a basic history of the C/K line of trucks. I posted this in the engine performance + maintenance section as there really is no other place on the forum for it...
    (Links: 1 2 3 4 5) Also included, is information provided by members of this forum who have responded within the pages of this history and discussion.



    GMT400s were introduced in April, 1987 as 1988 models. They started production in Fort Wayne, Ind., Pontiac Mich., and Oshawa, Ontario, Canada.

    These trucks featured large doors extending into the roofline and down almost to the bottom of the rocker. With a low step-up height and high headroom, it made for easy entry and exit.
    The trucks featured flush side glass, a modular-assembled bonded-flush windshield, single-piece door frames, hidden roof pillars and built-in drip rails.

    Trim levels included:
    Cheyenne: value standard full-size work truck
    Scottsdale: "a big step up in a sensible blend of function and form"
    Silverado: top of the line.


    Wheelbase:

    RCSB: 117.5 in
    RCLB: 131.5 in
    ECSB:131.5 in
    ECLB: 155.5 in
    CCLB: 159.5 in


    For total frame dimensions check this link: Frame Dimensions PDF

    Quick page reference
    Pg 81 RCSB C1-3500 Frame
    Pg 82 RCSB K1-3500 Frame
    Pg 83 ECSB C1-3500 Frame
    Pg 84 ECSB K1-3500 Frame
    Pg 85 ECLB C1-3500 Frame
    Pg 86 ECLB K1-3500 Frame
    Pg 87 CCLB C1-3500 Frame
    Pg 88 CCLB K1-3500 Frame


    Exterior was 3.5 in narrower than 73-87 trucks, but intrior had more leg and shoulder room and seat travel. Fleetside boxes measured 49.15in between the wheel wells and 63.8in between the side panels. At midyear, Chevy introduced a new K1500 Sportside model on the 117.5-in. wheelbase. It had a 6.5-foot sportside box with fiberglass fenders with steps built in.

    2WD trucks used independent coil spring front suspension in all weight classes. 1500/2500s used a semi-floating rear axle and 3500s used a full-floating axle. 4WD had a new IFS with a hypoid driving axle and torsion bars. It utilized a wire-form design for upper control arms with lighter, stronger parts. The torsion bar springs and jounce bumpers were connected to the lower control arms. The torsion bars were computer selected to match a truck’s GVWR and balance with the rear springs. The 4x4 frame had an additional cross member under the transmission. Their new "Shift-On-The-Fly Instra-Trac" system allowed shifts from 4x2 to 4x4 high and back, without stopping, at any speed. The front axle disconnect system locked the front hubs automatically when a lever operating the 4x4 system was pulled back. The shifter connected directly to the transfer case. In 4x2 mode, the front-axle disconnect allowed the front wheels to turn freely. In 4x4 mode, the transfer case split the power equally to the front and rear wheels. The K1500 had off-road option with a front differential carrier, engine and transfer case shields, front stabilizer bar, gas shocks and heavier jounce bumpers.
     
    Last edited: Nov 6, 2010
  2. Greg

    Greg Über Mod Staff Member

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    1989:
    Complementing the Sportside 4x4 was a new Fleetside Sport with a 6.5-foot box. The 4x4 Sports featured blackout wheel flares, bumpers, mirrors, a front air dam and tow hooks. Extensive changes took place in the brake system. The parking brake cable was protected by revised routing and a new shield. To cut noise, a molded, semi-metallic brake lining was used. A new 28MT starter motor and revised engine dipstick lettering were used on 6.2-liter diesel engine-equipped models.

    A new Borg-Warner 1370 transfer case with electrically actuated synchronizer was offered for dual rear wheel K3500s, allowing dual rear wheels to be ordered on 1-ton R/Vs and Chassis-Cab models. This increased GVWRs.



    1990:
    The 454SS was a new high-performance C1500 regular-cab 4x2. Its content included a potent 7.4-liter EFI V8, three-speed automatic, performance handling package and 3.73:1 axle. The 454SS delivered 230 hp at 3600 rpm and 385 lb.-ft. of torque at 1600 rpm. Also standard were a heavy-duty radiator, engine oil and transmission oil coolers and a locking rear differential. It came with bucket seats, a console, a Sport appearance package, air conditioning, AM/FM stereo with cassette, a sliding window, a tilt steering wheel, power door locks and windows, electronic speed control and auxiliary lighting.

    The interior was tweaked in 1990 with slightly different "half-moon" gauges, and touched up door panels,

    1990 introduced the Work Truck model. (W/T) It was available only as a cheyenne, but featured a different grille and body-color filler panel, charcoal bumper, and W/T ID.
    GVWR: 5600
    Payloads -
    4x2: 1711 lbs
    4x4: 1331 lbs
     
    Last edited: Mar 17, 2010
  3. Greg

    Greg Über Mod Staff Member

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    1991:
    Mid-Year updates included new needle gauges to replace the "half-moon" gauges from 1988 to the beginning of 1991.

    The new 4L80-E heavy-duty electronic control four-speed automatic overdrive transmission was available for all models rated at or above 8,600-pound GVWRs. It had enhanced shifting precision and smoothness.

    A new TBI system was used on the 4.3-liter V6 and 5.0-, 5.7-l and 7.4-liter V8s. It had longer throttle shaft bearings, new return springs and improved fuel mixtures. The 4.3-liter V6 was improved by the use of a revised air cleaner system and processing changes in manufacturing spark plugs. Both the 5.0-liter and 5.7-liter V8s were upgraded with heavy-duty intake valves, powdered metal camshaft sprockets and improved oil pan baffling on the heavy-duty 5.7-liter V8.

    The 1991 Work Truck included a new 4-spoke steering wheel and larger outside mirrors. Below-eye-line exterior mirrors became standard on all C/Ks. The standard AM/FM stereo radios were improved with more signal sensitivity and less interference and signal tracking. Air conditioning for C/Ks was improved.

    The 454SS option included a Sport steering wheel, black moldings, power locks and windows, tilt steering, cruise, Sport Handling, analog gauges, a tach, a 7.4-liter EFI V8 and a four-speed overdrive automatic transmission.



    1992:
    The 1992 C/K3500 Crew-Cab was the last Chevy pickup to use the styling first seen in 1988. The all-new Crew-Cab had a four-inch longer wheelbase, seven inches more rear-seat legroom and more front leg and shoulder room. It got antilock brakes. Standard engine was a 5.7-liter V8 linked to a five-speed heavy-duty manual transmission with "deep low" and overdrive.
     
    Last edited: Mar 17, 2010
  4. Greg

    Greg Über Mod Staff Member

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    1993:
    For 1993, the 4.3-liter Vortec V6 got a new balance shaft, revised heads, TBI revisions, a new quiet fan, a new thermostat, a revised oil filter and a new dual-stud air cleaner. Both the 5.0- and 5.7-liter V-8s were improved in the same areas. The 5.0-liter had new low-tension piston pins. A modified version of the 5.7-liter V8 could be converted to CNG, propane or dual-fuel capability.

    A new 1500 regular-cab Sportside Sport included Silverado trim, Sport decals, a body-color Dura-Grille, a Sportside box, cast aluminum wheels, painted mirrors and color-keyed bumpers. All trucks had a new "Leading Edge" anti-chip coating applied to the hood, roof and A-pillars. 1993 was the only year in which factory dual exhaust was an option.



    1994:
    New in 1994 was the Sportside Sport with a "step-side" short-box design. It came in just three colors: Oynx Black, Teal Green Metallic or Victory Red and included matching bumpers and mirrors, a new grille and aluminum wheel finish.

    In December 1994, Chevy settled a controversy over older C/K pickup trucks with the U.S. Government. The government dropped its efforts to force a recall of older C/Ks in exchange for a multi-million dollar commitment, from GM, towards future auto safety.
    (Article on Safety from the Wall Street Journal)
     
    Last edited: Mar 17, 2010
  5. Greg

    Greg Über Mod Staff Member

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    1995:
    The interior in all C/K models is updated to a newer refreshing design. New gauges, an updated radio, new seats and door panels round off the interior redesign. New for the exterior were new mirrors with plastic surround and mounting brackets.
    1995 is also considered the "odd-ball" of the 88-98 GM C/K trucks as the wiring harness, HVAC controls, and bell housing are not compatible with other years.


    1996:
    The Extended Cab models gained a third door on the passenger side as an option. On the alloy wheels the center caps were updated from having fake lug nuts to being smooth with no lug nuts exposed. The exhaust tip was reworked with a slight notch.

    The V6 and V8 engines were improved with Vortec technology for greater fuel economy, added performance and longer maintenance intervals. Spark plug life and coolant life were extended to 100,000 miles. The Vortec 5700 V8 that was standard or optional on full-size models gained 50 hp over the 5.7-liter.

    New:
    Daytime Running Lamps (DRL)
    Clutch
    Electronic Transfer Case


    1997:
    While the 2-door Tahoe would continue, the 2-door Yukon was discontinued.

    The interior gets update once more with the passenger side gaining bulk and losing cupholders with new passenger side airbags.
    The 4L60-E got a more sophisticated engine / transmission computer for greater fuel economy and smoother shifts. The steering was updated with a new EVO steering valve/sensor.



    1998:
    An updated airbag system was used on the steering wheel.
    PassLock is introduced to deter vehicle theft.
    Rear A/C was introduced in 4 door Tahoes and Yukons.


    1999:
    Remaining 1998 models are badged as 1999 models to sell off remaining stock in C/K 1500s.
    Last model year for most GMT- 400 Tahoes, Suburbans, and Yukons. (Replaced by GMT-800 series.)


    2000:
    Last model year for C/K 2500 and 3500 Trucks.

    Remaining GMT-400 Tahoes were badged as the Limited and the Z71.
    - Limiteds were 2WD and only available in black with a two-tone gray leather interior.
    - Z71s were 4WD and available in Victory Red, Indigo Blue, Light Pewter, and Emerald Green.
    They had painted bumpers and grilles, as well as fog lights and specific 16" alloy wheels.
    (These two models shared suspension, brakes, and several other mechanical pieces with the Police Package Tahoe)


    2002:
    Last model year for C/K 3500 HD trucks featuring the new 8.1L.
     
    Last edited: Dec 16, 2010
  6. Greg

    Greg Über Mod Staff Member

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    Exterior Badges:
    88-91: EFI sticker on lower right corner of tailgate.


    GMC:
    88-91: Large GMC letters on the center of the tailgate, tailgate width chrome bar was also used to mount the GMC letters to the back of the tailgate.
    92-97: GMCTruck in the lower right corner of the tailgate with chrome letters and charcoal surround. Sierra was badged on the lower left corner of the tailgate, also with chrome letters and a charcoal surround.
    98-00: GMC in lower right corner of tailgate with chrome letters and charcoal surround. Sierra badged on lower left corner of tailgate, again, with chrome letters and charcoal surround.
    88-96: C-Pillar badge is square.
    97-00: C-Pillar badge is square with rounded edges.


    Chevy:
    88-97: Chevrolet on tailgate width chrome bar.
    98-00: Chevrolet Silverado badge on lower right corner of the tailgate.
    88-97: C-Pillar badge is square.
    98-00: C-Pillar badge is square with rounded edges.






    Engines:
    Six engines were used between 1988-1998.
    The 4.3, the 5.0, the 5.7, the 7.4, the 6.2, and the 6.5.
    (6.2 and 6.5 were diesels with the latter having a turbo option)


    I will illustrate the history of the 5.7L here as it is the most common among GMT400 enthusiasts and owners.


    The LO5 was introduced in 1987 for use in GMT400 and still continued older body style K5 Blazers and Suburbans. The Bore and Stroke of the LO5 was 4.000 in x 3.48 in.

    Its factory applications included:
    1992/1993 Buick Roadmaster
    1990-1992 Cadillac Brougham (opt)
    1993 Cadillac Fleetwood
    1992/1993 Chevy Caprice Wagon (opt)
    1993 Chevy Caprice LTZ
    1992 Olds Custom Cruiser Wagon

    The LO5 was replaced by the GM LT1 after 1993 in B-Body cars until LO5 production ceased in 1996.

    The Vortec 5700 L31 is the last production Gen I small-block from Chevrolet (GM). The cylinder heads feature combustion chambers similiar to those of the LT1, but with reverse flow cooling. The L31 heads are compatible with older small-blocks. Vortec heads however use four bolts attaching the intake manifold as opposed to the older and traditional six bolts per head. 2005 model year was the final year for the L31, used in the Kodiak and TopKick, whose small block origins date back to 1955. The Bore and Stroke of the L31 was 4.000 in x 3.48 in.


    The L31 produces 255 horsepower and 330 ft lbs of torque.

    Its factory applications include:
    1996-2003 Chevy Express / GMC Savana
    1996-1999 GMT400s (C/K, Suburban, Tahoe-Yukon)

    The L31 used TBI in its G-Series vans in 1996.
    (also used in Isuzu Box Trucks)

    F44 package. Factory 14b 9.5 rear with 1500 Badging but Higher GVW and Bigger rear brakes. And + 1 more leaf spring in the pack. Pretty sure this was available from 88-98 in GMt400 trucks but 88-94 they were badged as 2500's but Still 6 lug just with the F44 package.

    95+ F44 trucks were badged as 1500 but were identically equipped to 88-94 trucks.
     
    Last edited: Nov 6, 2010
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  7. MIHELA

    MIHELA Nooo! Noooooo

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    The entire interior changed in 95.
     
  8. Cajun4x4

    Cajun4x4 The Green Seal

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    werd... aslo third doror came in 96 not 97, 97 also got the dash reconfigured with a passenger side airbag for 1500 models, 97s where also the first year of the EVO steering valve/sensor, 98 was the first year of pass lock

    just off the top of my head
     
  9. Bigg G

    Bigg G I'm Awesome

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    x 2 on the entire interior change in 1995 and adding that 1995 is noted as being the **odd ball year** because there was some other slight changes such as the HVAC controls that looked identical but will not interchange with any other years. l
     
  10. 99z28monster

    99z28monster I'm Awesome

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    I thought the 95s have the 4l60e that wont swap into any of the other trucks?
     

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