Thread: Project "Left Overs"

Tweet

Originally Posted by sfort

You know guys "looking old is becoming cool". Sounds like a win/win. Us and the cars!!

That's right, I want people to look at me driving this one and say "I bet he's the original owner!"

Don

Don, I just discovered this thread. I was wondering when you'd get back to this one. I better get back to work on my roadster or you'll be done before me...

Dan and I were just talking about you a few weeks ago, Jim. Dan asked if you ever got the track T done and I told him you had gotten sidelined with some honey-do's, and stuff like that. Tell you what, you push me to get mine done and I'll keep on you.

Don

It's a deal! I'm almost done moving stuff around in the new garage. Then I'll have no excuse...

And Jim we have missed your input around here as you have been absent for too long.

Thanks, Whip. I haven't been completely absent, though, just quiet...

Today I scored the rear end for the project. A guy advertised a 2000 S10 rear from a 4 cyl 5 speed truck for $ 275.00 on Craigslist. I called and asked about the condition, said it was from a 50,000 mile truck and it was a posi. When we got there it was a 3:73 ratio, but not a posi. So I offered him $150.00 and after some hesitation he took it. A one wheeler if fine with me, that is what I ran under my 23 and it held up great.

When I got it home I pulled the back cover off and everything looks good inside, with no slop in the gears. It has 11-41 stamped on the ring gear, and after doing some dividing I confirmed that is a 3:73. I really like these S10 rears, nice and narrow, parts are cheap to rebuild the brakes, and only two spring pads to cut off before you weld what brackets you need to make it work for your application.

I also got the other front frame rail tapered, so now I can start cutting the rails for under the body. While I was doing all of that Dan was starting to install the wiring kit on his rpu. He got the dash gauges all done, and is only waiting for some disconnect plugs to arrive before he can start doing the rest of it.

Not huge progress for either of us, but progress nonetheless.

Don

Good stuff Don, any progress is good

Originally Posted by Itoldyouso

Not huge progress for either of us, but progress nonetheless.

Don

Any progress is better than no progress (like me)...

S-10 rear ends are good ones. As you said, plentiful, strong, and not too wide. (Another good rear is Toyota truck - they are also plentiful, came in a bunch of different gear ratios, many of them are posi, and they have a Ford bolt pattern - 5 on 4 1/2.) I have an eight-inch Ford "one wheeler" under my coupe, but it digs with both wheels when I nail it anyway. It has a lot to do with weight distribution and the type of rear suspension.

This should be a fun thread. You are at the part of the build I like best - chassis fabrication.

Thanks Steve and JIm. I know the S10 rear won't fit into the overall old look I am shooting for, but it won't be seen. I plan on putting the radiator and gas tank in the bed and putting a louvered tonneau cover over it, so no one will know what kind of rear I am running. The 3:73's should be good cruising gears, especially with the torque of the Olds engine. I ran 3:70's in my 27 for years and now wish I hadn't put the 4:30's in there.........and to think I was actuallly considering ordering 4:56's. How did we put up with 4:88's and 5:13's in some of the cars we used to have?

Don

I for one, and I'm sure many others would agree, would be very happy to never see your rearend.

The TREMEC book has an easy formula for calculating cruise RPM and shift points: RPM = (mph x Differential Gear Ratio x 336 x OD Ratio)/Tire Diameter in Inches

The "336" is just a unit factor. For example, my '33 at (70mph x 4.11 x 336 x 0.64)/31 yields 1996 RPM. For shift points put in your individual tranny gear ratios in place of the OD ratio, like my shift points at 3000RPM are 23, 36, 53, 67 and it'll hit 105 in 5th. I built a little Excel spreadsheet when I was chasing my ratios - I can e-mail it to anyone that wants it, or there are lots of calculators on the web (forum does not allow Excel file attachments).

Hmmmm... I have to take issue with the TREMEC book. I can't figure out where they got the 336 figure. Using more conventional math methods with the numbers above (wheel diameter X pi, converted to feet per minute X gear ratio, etc, etc.) I come up with 3119 rpm @ 70 mph. When I figure it back the other way (1996 rpm/ 4.11 X tire circumference, etc, etc.) it comes out 44.8 mph.

I can post the rather lengthy process I used if anybody is interested. Meantime, can somebody else do the calculations and see which is correct?

Originally Posted by J. Robinson

Hmmmm... I have to take issue with the TREMEC book. I can't figure out where they got the 336 figure. Using more conventional math methods with the numbers above (wheel diameter X pi, converted to feet per minute X gear ratio, etc, etc.) I come up with 3119 rpm @ 70 mph. When I figure it back the other way (1996 rpm/ 4.11 X tire circumference, etc, etc.) it comes out 44.8 mph.

I can post the rather lengthy process I used if anybody is interested. Meantime, can somebody else do the calculations and see which is correct?

Multiply and divide the numbers as written - 70x4.11x336x.64 = 61,867.008 divided by 31 equals1,995.7 . The 336 figure takes pi plus all of the conversions of miles, feet, minutes, seconds, etc into account, and the numbers prove out by seat of the pants in the car. Trust me, I ran the dimensions and confirmed the 336 number before I used it....

The 336 comes from (5280ft/mi x 1hr/60min x 12in/ft) divided by pi to get the dimensions into RPM. Your 44.8 MPH is right, but neglects the final OD ratio of 0.64 - when you divide 44.8 by 0.64 you get 70MPH.

Here is a site I have used in the past and it makes it very simple to figure out your rpms. All you do is plug in your gear ratio (no periods or colons), your tire size and your intended speed, and it gives you the rpms for an automatic, aod, manual, and 5 speed transmission. It is very accurate, my tires on the 27 are about 29 inches tall and it pegged my rpms at 2984 and change. On the road I was turning 3,000 at 60 mph on the gps.

http://www.reiderracing.com/rtech-engine-rpm.php

Try this with your cars info and see how it compares.


I have been considering changing to Hurst brand slicks this time on the rpu, but they are a little short, only 28.75 tall, and the Firestones I had on my 23 were 30. That 1.25 makes a little difference, and also looks better IMO.

Don