Couldn't pass it up....

[graphicjunki]

Well....I don't know what to say. Aside from taking apart the diff... The documentation says I've got 3:08's.... LOL...

Once the 6" of snow melts again...I'll get out there with my GPS and get a speed reading. And verify the actual RPM that it's at running 60.

[OldVetteFan]

Originally Posted by graphicjunki

Well....I don't know what to say. Aside from taking apart the diff... The documentation says I've got 3:08's.... LOL...

Once the 6" of snow melts again...I'll get out there with my GPS and get a speed reading. And verify the actual RPM that it's at running 60.

No need to wait for all that - just get the back of the car off the ground, put a mark on the drive shaft, and a mark on a tire, and count the number of times the drive shaft moves for a full revolution of the tire. You don't need an exact measurement - it will be readily apparent that the drive shaft has moved either just over three turns, or very nearly four turns.

Enquiring minds want to know!!!

Steven

[Sly Vette]

Just a small hijack,please....For those of you that aren't as mathematically challenged as I am....
I am sure I have a 3.08 gear and with my WC T-5 I turn just a hair over 2100 rpm's at 70 mph. GPS verified. I have always assumed that my o.d was .84. Does this sound about right. I have 255-60 15 Eagle GT's. Trans didn't come with a I.D tag so I threw it in,after a good inspection, hoping for the best and all is fine,it's more of a cruiser with what some might consider a R.V. cam,than a speed car....Just curious.
Thank you and now back to your regular programing...

[diehrd]

Here is a link to find out RPM just enter your facts and your done it does it all for you,

http://www.chevellestuff.com/tools/rpm_calculator.htm

[Sly Vette]

Originally Posted by diehrd

Here is a link to find out RPM just enter your facts and your done it does it all for you,

http://www.chevellestuff.com/tools/rpm_calculator.htm

Thanks...Looks like my o.d is right near .70.
I never checked the rpm's/speed in any of the other gears. I think I will do that next Spring when I get the car back from paint.

[graphicjunki]

Well...failure.

I jacked up the car, marked the tire right next to the side pipe.
Marked the drive shaft on the u-joint behind the transmission.
Started to rotate it and there was a LOT of tension. Made sure I had it in N not D/3...and it was in N. Hmmm...

Realized that when jacked up in the air, the rear spring rubs the inside of the tires. I only got maybe 1/2 a rotation of the tire before I couldn't turn it any more, and by then I was focused on the friction not the count. This freaked me out, so I started to inspect the tires to make sure I wasn't rubbing while driving. There are no other marks besides what I just 'drug out'. WHEW! Seems that I need to have it on rollers to test this. Guess I need to install that Dyno with the service tunnel in my garage.

But seriously, I don't know of any other way to lift it without this happening. Obviously can't put the jack stands on the rear 'axle'... There isn't enough suspension material to connect a cross beam to. I could remove both rear wheels I guess...that shouldn't mess up the geometry of the measurement. Just makes it harder to turn.

...Why is it that when you've been laid up sick for a week, the wife gives you nasty looks for heading out to the shop?

[OldVetteFan]

Originally Posted by Sly Vette

Just a small hijack,please....For those of you that aren't as mathematically challenged as I am....
I am sure I have a 3.08 gear and with my WC T-5 I turn just a hair over 2100 rpm's at 70 mph. GPS verified. I have always assumed that my o.d was .84. Does this sound about right. I have 255-60 15 Eagle GT's. Trans didn't come with a I.D tag so I threw it in,after a good inspection, hoping for the best and all is fine,it's more of a cruiser with what some might consider a R.V. cam,than a speed car....Just curious.
Thank you and now back to your regular programing...

I calculate an OD ratio of 0.73:1 with the given information.

The chevelle llink isn't right - I checked with some of my known data, found it to be off about 300RPM, then did the calculation an entirely different way - still get 0.73:1 for your OD ratio.

That matches up with a T5 gear ratio table I found.

Steven

[Sly Vette]

Originally Posted by graphicjunki

Well...failure.

I jacked up the car, marked the tire right next to the side pipe.
Marked the drive shaft on the u-joint behind the transmission.
Started to rotate it and there was a LOT of tension. Made sure I had it in N not D/3...and it was in N. Hmmm...

Realized that when jacked up in the air, the rear spring rubs the inside of the tires. I only got maybe 1/2 a rotation of the tire before I couldn't turn it any more, and by then I was focused on the friction not the count. This freaked me out, so I started to inspect the tires to make sure I wasn't rubbing while driving. There are no other marks besides what I just 'drug out'. WHEW! Seems that I need to have it on rollers to test this. Guess I need to install that Dyno with the service tunnel in my garage.

But seriously, I don't know of any other way to lift it without this happening. Obviously can't put the jack stands on the rear 'axle'... There isn't enough suspension material to connect a cross beam to. I could remove both rear wheels I guess...that shouldn't mess up the geometry of the measurement. Just makes it harder to turn.

...Why is it that when you've been laid up sick for a week, the wife gives you nasty looks for heading out to the shop?

Couldn't you lift the rear and then position jack stands under the shock mounts? Then lower it so it's at it's approx ride height. That should allow you to rotate the tires just like as if it was on the ground.
When I need either or both ends of my car raised for clearance I put a jack stand under each shock and it provides for a very stable platform. It also prevents the half shafts from binding in the rear and reduces stress on the frame.
Having the spring making contact with the tire when the shock is fully extended would make me a bit nervous even though my car would never see that much extension of any of the shocks...Front or rear. Some that like to get some air under their tires from time to time would have more to worry about!

[diehrd]

Cant ya drive the car ? note 60mph rpm .. and go from there.

[OldVetteFan]

Originally Posted by diehrd

Cant ya drive the car ? note 60mph rpm .. and go from there.

He's in Colorado, and presumably, has a bunch of salty snow on the road.

Steven

[graphicjunki]

Yea, we got about 6" of snow the other day...plus I've had the flu....not very easy to get out there....

[graphicjunki]

Took it back out on the highway today. Little scary since the roads are kind of patchy....and these tires suck the big'n on anything other than dry. LOL...

Took it up to 60.... tack'd out at 27-2800. So no, not quite an actual 3K...but very close.

I don't think it's the speedo.. The transmission still shifts funny... I tried to video it on my phone and you can't make out crap... But basically to make it simple, 1 & 3 match. But 1 won't do a kick down shift. So maybe the torque converter is toast. Maybe it's not locking up at all. I don't know.

[diehrd]

I guessed you run a 255/60/15

if so that means your gears are 3.73 not 3.08 which is a great gear with the O/D tranny if you go to it

[tektrans]

Even if converter isnt locking up it still would only be 100 or so rpm less.

[diehrd]

He cant have a lock up with a th400 .. my post of his gearing should be spot on