SYTYSOGT BUYERS GUIDE

More than thirty years ago, GMC Truck Division launched the production of the Syclone, Typhoon, and Sonoma GT, introducing the world to the fastest production trucks of their time. These trucks were known for their track times faster than a Ferrari and their impressive 0-60 acceleration. However, their time in the immediate spotlight was short-lived.

While some trucks went lovingly into collector status mode and carefully stored away, others were enjoyed on the weekends with the occasional spirited drive and car show, and of course, lots were busy chalking up hard mileage down the track and looking for that unknowing victim at the next stop light on the streets.

The market today is full of trucks with varying histories and conditions. While it's still possible to find low-mile gems, most trucks on the market show signs of age, mileage, and modifications. Potential buyers need to understand that these trucks require a unique level of maintenance specific to the SyTySoGT. Although many parts are shared with the S-series platform on which they were built, these trucks also use specific parts that are only found on the Syclone, Typhoon, or Sonoma GT.

This SyTySoGT buyers guide is designed to cover both the common areas of the Sonoma/Jimmy platform but also focus on the unique features of the Syclone, Typhoon, and Sonoma GT and what should be considered when looking to purchase one of these Sportmachine trucks.

BEFORE YOU BEGIN

Please take some time to research these trucks and consider if this vehicle is worth your time and money. The SyTys (excluding the SoGT) are trucks that require a high level of maintenance to run at peak performance, whether they are in stock or modified form. If you are not mechanically inclined, be prepared to learn or make sure you have access to a certified and trustworthy mechanic who can work on your truck. Just as you wouldn't take a Ferrari to a Honda dealership, most mechanics today may not have the knowledge or ability to diagnose specific issues that are unique to SyTys.

“Many can afford to buy a Syclone or Typhoon, but many can’t afford to own a Syclone or Typhoon.”

If you can bring along a current owner or someone who has knowledge of these trucks when going to look at a potential truck to purchase, it is to your advantage. What an inexperienced eye might miss, one who has been around these trucks will quickly be able to point out both the positive and negatives.  You don’t know anyone? Join our forum or facebook group and ask. You’d be surprised how many people will offer to help or might already know the truck and be able to give you history on it. The SyTy community has been around since the mid 90s and many of our resources are spread out across many social media platforms.

Some helpful resources to ask questions or seek help:

• International SyTy Registry Facebook Group (the largest SyTy group on FB)
• International SyTy Registry Facebook Resource Page
• SyTy Registry Instagram Page
• SyTy Registry Forum (COMING SOON)

CLADDING

The cladding (body kit) on all SyTySoGTs is made of an injected plastic and held on by both rivets, screws, and brackets. Over time it becomes easily dried out and very brittle making it prone to cracking or breaking off of the mount tabs with little effort if not maintained. The SyTySoGT cladding is specific to the trucks, as no other S-Series received these pieces during production. While OEM pieces can sometimes be sourced through private sellers, certain pieces are becoming harder to source and can go for high dollar amounts depending on which cladding needs replacing. Today’s market has opened up to fiberglass alternatives.

• Check for broken, cracked, or missing cladding pieces. The more common pieces to break are fender arches, rear corners, and lower cab pieces.
• Factory Syclone cladding should appear as a matte black finish. The discussion has been brought up and has been revealed that the cladding was indeed painted with a matte finish using a flex agent from the factory. This was found out due to owners being able to peel what seems like a layer of paint off their aged cladding. If the cladding appears to be various shades of color (sun bleached), this is an indication of a truck that did not receive routine treatment with cleaners/plastic shine products and is usually in a very dried-out brittle condition.  ALL Typhoon cladding for 92 and 93 trucks are painted! Refer to the FAQ for the correct color breakdown on Typhoons/SonomaGTs.
• Sonoma GT cladding shares the same front and rear bumper as the SyTys while the rest of the pieces are unique only to the Sonoma GT. The front fender bumperettes are a common broken piece along with the rear bed corners. The SGTs have skirt cladding that flows underneath the cab and on the lower front quarter of the bed. The side skirt cladding uses C-clamps to mount the trucks.
• Look for cladding that is not properly riveted onto the truck. It is common for the front bumper to be misaligned to the front of the fender arches. This could be either from incorrect placement on the bumper hangers (which can be easily adjusted by 2 bolts), broken cladding tabs, or a possible sign of a past accident. Be sure to inspect this closely and ask questions. The front fender arches are known to be weak on the tabs around the fender and can easily break off resulting in a lost piece of cladding on the road. Giving a gentle pull on each piece of cladding can help indicate loose or broken pieces. We emphasize gentle. Lets not rip cladding off of a truck you may or may not purchase.

Are you painting or fixing your cladding and in the market for new rivets? Sportmachines carries a complete rivet kit for both the Syclone and Typhoon!

RUST

Do a typical inspection as you would for any vehicle for rust. This is more of a concern on trucks that are in areas that snow or near the coast due to salt exposure. It is not untypical to see light rust scale on the frames or suspension. Use your discretion for how much is too much. Other specific areas to look for rust:

• Check the bottom of the doors
• Check the bottom of the tailgate (opening the tailgate will expose the bottom side much easier)
• Rust is known to hide behind cladding, especially lower fender area by the doors. Make sure to reach up behind any panel possible.
• Typhoon – Check around the gasket seal of the rear side windows. This is a known area of rust for all S-Series.
• Typhoon – Check around the rear glass. This is a known area of rust for all S-Series.
• Check body mounts

PAINT

While many trucks still wear their original paint, after 25 years, many have also been repainted. Check for signs of paint work along any rubber trim or overspray on the wheel wells. If the truck has been repainted, ask if the cladding was removed when painted. A quality paint job should have had the cladding removed to paint the entire body. Cladding can also hide hidden secrets (see rust above).

1992 TYPHOONS

Check the SyTySoGT Paint Guide for color breakdown.

• Check if it’s a correct 92 color scheme. Other than Blk/Blk, Radar Blue, and Raspberry, all 92s should have painted gray cladding.
• Silver Typhoon decals (specific for 92)
• Two-tone grille:  Body color + gray headlight buckets and center portion. If the grille is all one color, suspect replacement or paintwork.
• Has door escutcheons (plastic pieces surrounding door handles)

1993 TYPHOONS

Check the SyTySoGT Paint Guide for color breakdown.

• Check if it’s a correct 93 color scheme.
• Gold Typhoon decals (specific for 93)
• Monotone grille: The grill is the same as the body color. NO gray headlight buckets or center portion.
• NO door escutcheons (plastic pieces surrounding door handles)

Know the interior differences between the 92 and 93 Typhoon by reading the full Typhoon differences page.

• Syclone & 92 Typhoon Seats – Check for the lumbar support bulb on the front part of the seat. This is a common part that breaks on trucks as the hose becomes hard and brittle and breaks off at the pump bulb. 93 Typhoon seats are electrically controlled! Test to ensure the seat electronics are properly working, including positioning.
• The emergency jack should be located behind the passenger seat for Syclones and with the spare tire on Typhoons.
• Check the center console lid. This is also a common area of wear and tear due to usage. The outer cover is known to peel up or the spring to the button will break and not allow the lid to latch and lock (can be opened without depressing the button).
• Check gauge cluster needles. The oil pressure needle has been known to flip over and become stuck on the lower needle stopper. The fix for this is to take part the gauge cluster and flip it back around by hand.  Some have added a 2nd stopper to not allow the needle to flip.
• Check for cracks in the dashboard. Common places are around the vents and speaker grilles. 1st generation dashboards are becoming increasingly hard to source and expensive to purchase when in good to mint condition.
• Check the passenger side carpet under the dash area for any sort of moisture or signs of wetness. Smell the carpet. A common problem with the trucks is the heater cores leaking. When this happens, coolant will dump onto the passenger floorboard. If you notice a coolant smell and the carpet is wet to the touch, changes are the heater core is leaking or possibly has been changed recently. The heater core can be replaced using this how-to article. 

The Typhoons are famous for having what is called “window squeak” which is due to the back window latch having worn out and rubbing on the release hook while driving. This is very common among all the platforms (Jimmy/Blazer/Typhoon) and is easily fixed with an aftermarket latch system from Sportmachines.

SUSPENSION & DRIVETRAIN

Many trucks today have been lowered using using rear drop blocks and then turning the torsion keys on the torsion bars to lower the front. Inspect that the rear blocks are properly installed. If the rear wheel seems to be off center of the wheel well, changes are setback plates where not used. Re-centering the rear wheel can be fixed easily with the installation of setback plates.  Many also go the route of lowered leaf springs for the rear.

Check all bushings and greased parts for signs of cracks or tears. This includes areas such as – upper/lower control arm bushings, tie rod ends, ball joints, idler arm, u-joints, and even CV axles.

Inspect the forward propshaft. Stock trucks use a booted propshaft that commonly get ripped or torn, therefore destroying the joints (think in the same manner as a CV shaft). There are stories of propshafts failing and denting/destroying the floorboard right under your feet. The stock propshaft is not serviceable.  Inspect the boot for any signs of rips and leakage. Many trucks have switched to an upgraded double cardon joint propshaft. These proshafts tend to be serviceable as well as much stronger than the stock propshaft. They range from $300-500.

The Typhoons came standard with a ride-leveling system in the rear. There is a pump located on the driver's side behind the rear wheel. This pump is hooked up to air shocks.  If enough weight is put on the rear of the truck to engage the system, you will hear the pump run, and the rear of the truck will slowly rise back up to the proper height. If the pump is in working order, you can usually make it engage by sitting on the tailgate. Many pumps no longer work or have been disengaged due to lowering the truck. Is it necessary to have? If you plan to haul heavy items in the truck regularly, yes, consider it. If not, there is no harm in not having it, and many have chosen to unplug it altogether. This is something to consider if you are looking at a lowered truck as well. If your shocks leak, you will notice the pump running on a regular occasion to keep up with the leak and level the truck. Inspect the shocks and air lines for leaks.

ENGINE MODIFICATIONS

Many trucks on the market today have some degree of modification under the hood. This can vary from minor reliability upgrades to heavily built and bolted on parts. Due to the range and degree of modifications, this list is an overview of more of the commonly known areas to focus when looking under the hood. This list mainly covers stock to mildly modded trucks with upgraded stock components or standard bolt on parts.

BLOW-BY

Blow-by occurs when the explosion that occurs in your engine’s combustion chamber causes fuel, air and moisture to be forced past the rings into the crankcase. This causes a loss in power and oil dilution. In short, a motor with blow-by means a definite rebuild coming soon.

Start the engine and unscrew the cap from the oil-filler neck. Look for smoke or vapors coming out of the oil filler. If there is a lot of smoke, the rings/valve guides are worn and the smoke you see is blow-by. If there is no smoke, hold your hand above the filler neck. If there is a lot of air coming out, it’s a sign of blow-by.

UPPER RADIATOR HOSE / ENGINE MOUNTS

Run your hand along the radiator hose, specifically nearest the area of where the alternator is. You are feeling for any cuts in the hose (always on outer ride side of the hose, facing the engine bay) caused by the alternator fan. This is a quick indicator of bad engine mounts due to when the engine torques over, the bad mount allows the alternator fan to touch the radiator hose and cut into it.  Motor mounts aren’t fun to do on the SyTy, so a quick “bandaid” fix is to install a torque strap which is typically bolted on around the alternator and down to the frame. Various style straps have been made using chains and hooks or billet brackets and turnbuckles. A worn or broken motor mount isn’t a deal breaker when buying a truck as solid mounts are readily available, but the work to install them is a bit demanding due to limited work space.

STOCK INTAKE TUBE

If the truck you are looking to purchase has the stock plastic intake tube, ask the owner if they could please take it off the truck to inspect. Yes, this sounds inconvenient, but you possibly could uncover a ticking time bomb or worse, a hidden issue that would have gone unnoticed. Check each end of the tube for cracks or if it's missing altogether.  The intake tubes are prone to cracking when the hose clamp on either end is over tightened. This has resulted in more than one incident of a piece of the intake cracking, breaking off, and feeding the turbo….thus destroying the turbo.  Which leads into….

TURBO

If you have the intake tube removed, take an opportunity to inspect the turbo and shaft. You may notice a small amount of oil sitting on the turbo inlet, this is normal. If there is an excessive pool of oil, this could be an issue with the turbo itself or the PCV system.  Reach into the turbo inlet and grab onto the intake wheel (the truck should not be running of course) and check the in/out and side/side play. The shaft should have little to no movement. If you can feel the shaft moving excessively around, the turbo is ready for a rebuild. Inspect the intake wheel for any damaged or bent blades. Pro-tip: use the camera on your smartphone!

COMMON MODS & UPGRADES

Here is an incomplete list of common modifications and upgrades you may find under the hood:

• Adjustable Fuel Pressure Regulator (AFPR)
• Intercooler lines changed from stock metal to 3/4″ hose (various methods to route)
• ABS Delete
• Stock intercooler replaced with “Air to Air” (A2A) intercooler system
• Intake elbow or aftermarket cold air box (replaces factory stock intake tube – see above)
• Electric fans (single or dual setups)
• Injectors (stock injectors have “red tops”)
• Battery relocated – Common places to relocate are bed, under the bed, back of truck (Typhoons) or lowered in the fender area
• Oil filter relocated to the block