Apparently some one swapped the rear end out on my car to a drum brake rear end. The only reason I can think for some one to do this is for whatever is in this rear end.

I believe the ring and pinion are a 4.10 set up, is this just a normal 4.10 set up slapped on a posi and stuck in a drum rear end? I can't seem to figure out if it is a factory rear end or not, It has drum brakes (formula 350 ws6), but should have come with a disc brake rear setup. Would having a drum brake rear in a disc car cause proportioning issues?

 

I'm not sure, I know the disc rears came with a different proportioning valve then drum brakes did. Tomorrow I can provide a picture of what a drum brake proportioning valve from one of these cars looks like.
I also think the gear ratio is stamped somewhere on the carrier although I was never the one to go near the rear other then to change fluids.

 

From what I've read, some WS6 packages did come with drums (a shortage or something. I search will no doubt provide more info on that). That said, note paragraph three concerning the Gov-Loc.

While the disc/drum and disc/disc combination valves are different internally, they look exactly the same. For best braking performance, the correct valve should be used.

There are several ways to confirm gears and limited slips--Yours looks like a Gov-Loc, by the way, which I'd think makes the rear something from the early 80's if it's from a thirdgen. Anyway, check the following FAQ:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

The infamous grenade-lock. That and most likely the ring & pinion came out of a truck.

RBob.

 

Wow. This thing went through my 350, my cammed 383, and now a cammed LSx...Never even changed the fluid till last night. Thing is more stout than most give it credit for.

 

Probably broken and not engaging. I've never seen one that was not coated in magic metal dust.

 

It certainly locks well, I still get both tires roasting at about ~50mph. Feels a bit odd around corners compared to my old posi though.

 

Read through the threads on the gov-lock. That is NOT a posi you want engaging going around a corner with any power.

 

I've driven the car 3 years like this, I'm used to it. It just likes to push outward in turns. My posi felt like it was on rails in turns, this locker just kind of "slides" the rear end around corners. Definitely more of a straight line car with it.

 

Exactly. That posi does not have any kind of transition between lock and unlock. Because it locks so suddenly it causes tremendous stress on the drivetrain and the gov-lock itself is usually the weakest link.

If no one has mentioned it, the ratio should be stamped on the ring gear, expressed as a fraction of whole numbers: 41:15 would be 41/15=2.73333.

 

My speedo is set for 3.73 and reads 5mph fast for any given rpm/speed. So I believe they are ~4.10 ring and pinion.

 

I've got time for a little fun.

Your speedo is off by 5 mph for any speed? So at rest (0 mph) it's reading 5 mph?

If the speedo gears are set for 3.73 and you have a 4.10 gear the speedo would be off by 4.10/3.73, or 1.099. At 50 mph (actual speed) it would read 50 x 1.099 = 54.95 mph. At 10 mph it would read 10.99 mph. At 0....you get the picture.

 

Re-read your post, that is what I mean. It's a percentage, not a solid 5mph all the way around. At lower speeds it nearly dead on, but at highway speeds it's about 5-7mph off.

 

Well considering what I've read, I am really surprised this rear end hasn't grenaded all over the street, and now I know why it takes a bit of "skill" to drive it. No wonder no one likes driving my car. It will be going to the track this friday as is. Hopefully I make it back with all the pieces - I will post results.

 

Well???

 

It grenaded, even on street tires it was just too rough. Spun hard through the 1/8th mile the first time and ran a 13.9. Second time I tried to launch it from 2000-2200rpm but it blew the tires off so bad I aborted the run.

Seems like I might need a bit of suspension work LOL

 

and the GOVLOC lives up to its true nature lol i decided to go with a torsen unit out of a fourth gen

and instead of speculating you could count the teeth of the ring and the pinion, driven over drive = ratio

your math sounds right tho its probably 4.10's but it never hurts to check