Afternoon everyone!

Just had a new clutch installed and had my mechanic service the differential in my 86 Firebird with LG4.

Found a broken washer and a lot of sideplay in the diff, so looks like time for arebuild.

HOWEVER, my friend has an already setup 3:73 posi from a slightly laterCamaro (88 I think), but it's BRAND NEW gears and posi unit, never run, andready to bolt right in. Oh by the way, I can get it CHEAP (like less than thecost of the gears)

So this leads me to two questions

First, in going from stock 2:73, to 3:73, is going to be quite a jump. Myplan is to drive this car A LOT, and while I don't mind gas mileage I don'twant excessive wear on the motor. Currently, the car is surprisingly peppyaround town and I know 3:73 would be a hoot, but does my motor have the torqueto take advantage of the low gears or am I just going to lug the car?

Second – how available are speedo gears for a T5 and are those replicablelike an older transmission? I want my speedo properly calibrated and I’m notyet super familiar with the T5’s.

Thanks!

 

For the T5 it is tough to find the blue gear that goes inside the transmission.

The red 21tooth is easy.

These guys seem to be able to get the blue gears but charge 4x more then regular so about $40

http://www.transmissioncenter.net/

 

I just bought an 86 iroc z28 that has stock lg4, t-5 and 3.73 gears factory (g92 option)
You're right about it being a hoot, sure makes 155hp feel like a lot more.....

 

3:73s in a manual boy that is a LOT of shifting. Which is not ideal for a daily driver. The gears won't wear on your engine but it will be putting more load on your t5 and your rear diff. The diff will wear out much faster; because it spins more over a period of time than 2:73s. It all depends on what you want in the long haul.

 

3.73 works fine on a T5

Not bad at all for a daily driver, No one says you have to go through all the gears and once you get over 40 just use 5th

 

I was under the impression that the T5 has a very short 1st gear as it is and a 3.73 would make it practically non existent.

 

Running 3.73 gears with a T5 myself and glad I made the swap. I originally had 3.42's so it wasnt as big a difference as you'll see, but it was definitely noticeable.

As mentioned above, the 1st gear is pretty short, so you shift out of it pretty quickly. But I just start out in 2nd if I'm not on a hill. If its wet though, I use 2nd to start on a hill cause otherwise it just spins the tires, even with posi.

I'll second what midias said about not needing to hit all the gears. I frequently skip 3rd or 4th, depending on how I'm driving and traffic/road conditions.

 

With a V6 trans yes

A t5 will hit 40 at about 5500 rpm in 1st

No issues here, my car came factory 3.73 and T5

 

My car also came with the T-5/3.73 combo.

Worked fine.

HOWEVER, it was NOT the bottom-of-the-line LG4. That motor is pretty much maxed out at 3.23.

You need some other motor, with some sort of RPM capability, to use that much gear effectively. It will force the RPMs up into a range where the LG4 is utterly gutless and futile.

That said, if the price is right, try it; if you don't like it, it'd probably be pretty eeeeeeeezy to find someone that would LOVE to take it off your hands.

 

Master bearing kit = $90.00

Axle bearings and seals = $30.00

Installation/labor= $300.00 (estimate)

Total= $420.00

Posi/carrier and ring and pinion you mentioned = ?

Not too bad.
Did he happen to mention what posi. unit it has ?

 

The problem I have seen with running higher than stock numerical rear gears is that the stock motor doesn't have the high RPM power to support the revs the lower gearing will want. This doesn't make the car undrivable, it just means that you will go through gears much faster and may end up feeling like your engine is winding out at highway speed. Your LG4 runs out of steam at about 4,800rpm. This will make your gears seem very short.

 

Exactly:

What you can all too eeeeezily end up with, is one of those deals where it has all this phenomenal out-of-the-hole JUMP, but that's IT. Can't even pass a semi on a 2-lane road if you're going over 55 mph.

I have a little brother who bought a 84 Z28, LG4/auto. In about 86 or 7 I guess it was, we came across a wrecked 84 HO 5-spd car at the local buzzard's. He put the 3.73 in his car, I snagged the hyd clutch setup for mine. So it's safe to say I've had experience with the situation at hand. And I'm describing EXACTLY what his car was like.

 

I have a T5 with 3.73 gears and a L69.

Puts a smile on my face every time. You will go thru 1st gear much quicker, and that is ok