I did a search and didnt really find an answer to my question, i have a T-5 but i dont know if it's a world class t-5 or not, what years got them and what years didnt, and what advantages do they have over the basic t-5???

 

I believe the so-called WC-T5 was used from 88-92. Supposedly, they're a bit stronger. If you find one from a TPI car, the 5th gear is a little better .73, instead of .63--I see you have the L03, which would be the .63.

JamesC

 

Supposedly is correct. I broke 3 of those suckers on a TPI car with bolt-ons!

 

The world class gearbox is mainly a better shifting more efficient tranny. Has needle bearings on the main shaft gears that reduce friction and make for a smoother shift. Other improvements too but these bearings are the main thing.

 

How in the world is .73 better? .63 is more of an overdrive. Who in their right mind wouldnt want that??

 

Exactly. Me, crazy or not.
By the way, I believe the L69 with T-5 had the .73 fifth gear as did the LB9, that is the hotter of the 305's.

JamesC

 

http://www.5speeds.com/t5/index.html

 

I remember reading somewhere that said that the WC T-5 has straight cut gears instead of the typical angle cut gears, making it stronger..... That would be a "minor" diff also....

 

Could be the different (lower) overdrive ratios work with a higher rear gear with the higher torque engines? Have to be a reason for this.

 

No, the 2nd design T-5 does not have straight-cut gears. They're just like the 1st design gears.

The reason the .73 5th gear ratio is better, is because with that, you have 2 gears that are close enough in ratio, that you're not "missing" a gear in between. Like the 6-cyl T-5s.... the spacing between gears is SO WIDE, that you will often find yourself in a situation where one gear is too low but the next is too high, and you don't really have the "right" gear. The engine goes from "scream" in one gear to "lug" in the next. A car with some weak LG4 or L03 motor, 3.08 gears, and a .63 5th, will have trouble pulling itself up a hill in 5th, especially below 60 mph or so; but when you shift down to 4th, the engine RPM is up above its power band, so it won't pull in that gear either. It'll cruise down the straight and level just fine (which is what the EPA's fuel economy ratings are based on) though.

That's why they put the crappy ratio in the gas-mileage sacrifical lambs, and the good ratio in the performance cars..... because people who buy the low-perf cars aren't looking for performance anyway, and won't really miss the better tuning of the ratios, otherwise they'd be buying a performance car instead of a LG4 or L03 car in the first place.

 

I have an S10 with the small V6 and five speed, and what you're saying is exactly true. Not enough guts to pull a steep hill in fifth, but fourth has the engine roaring. (Good old truck though, 205K miles with no major repairs.) .

 

Yeah, I think the designers pushed that 5th gear ratio as high as they thought they could make it, without causing buyer complaints... I guess .63 was "perceived" as OK, but .62 (which would have eeeked up the gas mileage by another couple of inches per gallon) was "perceived" as too gutless.

It doesn't really sound like you're making a big change, going from .73 to .63. But, if you turn those numbers upside down, it makes the ratios easier to compare.... 1 : .73 is 1.37, which is about the same as the other "steps" between gears in the V8 T-5; whereas 1 : .63 is 1.59, which is a HUGE step. In fact it's almost exactly equal to the "steps" in the 6-cyl T-5s: 1.59 cubed equals 4.01, which is in fact the 1st gear ratio (three steps).

 

After just getting a "WC" in my current car I can say that there is a pretty big difference in shift quality than the "NWC". The "WC" tranny shifts a lot better, it switches gears smoother and powershifts a LOT better, like night and day, speed-wise. Cant say anything for the strength, Ive never broken either kind (cause 99% I drive like an old lady, heh).