Hi guys,

A little help. Getting the carb dialed in for the engine rebuild and the I need the gear ratio. i jacked the car up blocked one wheel (driver side) marked the tire and the yoke. Spun the tire 10 times. the yoke spun almost 14 times. I doubled that number to 28 so I figure it is a 2.78 ratio. Does that sound correct? It sounds tall to me. 68, 400, auto, convertible.

Thanks,

Craig

 

Sounds like your 442 was/is a Turnpike Cruiser, very mild gear, 290 hp 2bbl. auto. Though it may be a 2.56:1. This is what my buddies was, upgraded to cast 4 bbl intake, 3:23's, and a cam.

 

Mine has 2:78s going to 3:31s.

 

The standard ratio for '68 was 3.08 if you didn't order a specific ratio as an option.

 

It's not a turnpike cruiser, I thought they only came with 2 barrels. Maybe it is a 3:08.

Thanks for the info!

Craig

 

If your axle tube is not rusty, you should be able to find a two letter code on the pass. side of the axle tube. Usually stamped upside down.

 

I also was under the impression a 3.08 was the standard rear axle ratio.
If you can find the axle stamping on the axle tube this would be a way to confirm your ratio, as long as a previous owner did not swap it out.

Other way would be to count the teeth on the ring gear and pinion gear and divide to get the ratio.
Good Luck

 

Crawled under to look at the axle tube, didn't see anything (didn't look to hard) I really think it is a 3:08, makes sense. It is all for the carb specs, probably not that critical right now.

Thanks!

Craig

 

You will need a wire brush to find the stamping. The letters/numbers are about 1/4" to 3/8" tall. I found mine on the forward side of the passenger axle tube about 12-14" from the backing plate. Hope that helps.

 

Stop beating yourself to death and just raise the rear end, find a spot on the tire, turn it twice and count how many times the driveshaft turns and that is the gear in the housing, I just did it last weekend.

 

He did the turn count already.
If that's not good enough, then pull the cover and read the numbers and do the math.

I think it's important to know the final drive ratio, and should be done. What a great excuse to change the fluid too.

 

Thanks guys,

I'm restoring the drivetrain but am still at the front end. I will eventually get to the rear, just don't want a garage sale in the garage! I will try to locate the marks on the axel tubes this weekend.

Craig