GMC syclone

[greymack]

Hi guys I'm just curious if any one know why the GMC syclone is 4wd or was that a awd vehicle?

[Jordan White]

The Syclone and Typhoon used a full time AWD transfer case, similar to the Astro/Safari.

Edit: why? Probably to better transfer the power and low range wasn't needed.

Edited September 7, 2012 by Jordan White

[Fat Brian]

The problem with hot trucks has always been that there isn't any weight over the drive wheels so GM went with AWD to get the most performance out of the truck.

[Joe Handley]

Plus with the AWD in the Astro, Safari, and Bravada you could use it all the time without causing binding issues within the drivetrain when it wasn't snowy or muddy. The 4wd system used in most trucks is a part time, only for use in low traction condition system that can tear themselves apart in used when on dry or wet pavement for too long. Many of the newer "automatic" systems are just computer controled part time cases that use the ABS sensors to shift them in and out of 4wd as traction changes. The case used in this truck (as well as many Jeeps and I believe Rovers) have a small differential in them to allow for a varation in power between the front and rear diffs which keeps everything happy and in one piece.

[greymack]

Thanks for the info guys

[Longbox55]

Many of the newer "automatic" systems are just computer controled part time cases that use the ABS sensors to shift them in and out of 4wd as traction changes.

That's not exactly how they work, but it is how they tell the sales staff to explain in to customers. When they are in "automatic" mode, they are engages in full time 4 wheel drive, using a torque biasing differential to split the power, usually with a 20% F/80% R bias. I get people coming in the shop all the time wanting to know why their SUV/truck "hops" on turns. Every time it's the same thing, the 'case was in "automatic" mode. Put it back in 2wd, problem goes away.

[Joe Handley]

The Cyclone had the acceleration and braking abilities of a Corvette!

IIRC, It was quicker than the Vette, which usually means Chevy threw a tantrum and it had to be slowed down (Typhoon), then killed (Grand National anyone?)

That's not exactly how they work, but it is how they tell the sales staff to explain in to customers. When they are in "automatic" mode, they are engages in full time 4 wheel drive, using a torque biasing differential to split the power, usually with a 20% F/80% R bias. I get people coming in the shop all the time wanting to know why their SUV/truck "hops" on turns. Every time it's the same thing, the 'case was in "automatic" mode. Put it back in 2wd, problem goes away.

If it's hopping like that, then it isn't full time or at least if it is, the tire pressures are off causing a difference in tire diameter that can cause such issues or the vehicle needs u-joints or cv joints in a bad way. My Cherokee and the first gen Grand Cherokee I had both had a New Venture 242 which is a full time transfer case that uses a planetary diff to allow for the variances that arise as a vehicle turns on a high grip surface. It also has a part time feature to lock that diff so that the same amount of power goes to both axles all the time, which is good when you need traction, but at minimum can cause the "hop" you're talking about, bit that same loading can also strain and destroy transfer cases, differentials, and all of the u- and cv-joints.

[Longbox55]

No, there wasn't any tire presure problems, U joints and CV joints were all ok, no worn front end parts. But every time shifting it out of automatic mode corrected the problem. I've had GM, Ford, and even a few Jeeps come in for the same problem.

[Jared Roach]

IIRC, It was quicker than the Vette, which usually means Chevy threw a tantrum and it had to be slowed down (Typhoon), then killed (Grand National anyone?)

The typhoon was slower because it had more weight then the syclone (ie; the roof, electric mirrors, rear air-ride etc). And they killed it because it was poorly marketed and they didn't sell as many as they intended(still limited edition but about 15,000 a yr) and shortly after PAS(The aftermarket outfitter that also produced the 89 turbo trans am) went out of business after gm failed to renew the contract between the two.

BTW I love these trucks, absolute dream to own one someday. I already built one kit and plan on building many more sometime.

Edited September 8, 2012 by Jared Roach

[vwdave92]

The Cyclone had the acceleration and braking abilities of a Corvette!

A friend of mine owns one of these little rockets. The acceleration will blur your vision. It's 0-60 time is sub 5 secs and I don't have a problem at all believing that. Very cool rig.