Here I Go Again

BULL · **Posted:** Sun Jun 08, 2008 8:04 pm

NITE wrote:

...Going to modify it from a .8:1 od to a .6:1 od.
Link that with 2.73 diffys,...

Is this a proven setup that you've seen elsewhere or is this an "experiment"?

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

Actually, Bull, it is a half experiment.
It already has 2.73 diffys.
With the SR4 tranny, which was 1:1 in fourth, I got about 32 mpg(imperial gallon)
With the T5 I am expecting, without mod, 40mpg, and with mods about 45 mpg(although my calculator says 53.
Regards,
NITE

BULL · **Posted:** Sun Jun 08, 2008 11:13 pm

NITE wrote:

Actually, Bull, it is a half experiment.
It already has 2.73 diffys.
With the SR4 tranny, which was 1:1 in fourth, I got about 32 mpg(imperial gallon)
With the T5 I am expecting, without mod, 40mpg, and with mods about 45 mpg(although my calculator says 53.
Regards,
NITE

Be careful that you don't go to far and fall over the other side of the torque curve. Do you happen to know what the rolling resistance is (factory published perhaps???). I'm sure the drag coefficient on that thing is like that of a brick... :nod:

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

That is a very good point, Bull.
Rolling resistance would be a 2 parter.
You can grab the front bumper and pull it with a lot less effort than you would think.
On the other hand, aerodynamics are not, shall we say, optimal.
The year or two after my particular CJ was made, they introduced the T5 that I am recieving w/ the .8
O/D, so I know the combo works.
Now, the unknown is if I step down to a .6 O/D, can the motor handle it?
The torque curve of the 258 is flat and broad as I have tuned it, and at low rpm.
If it fits in the torque curve, great, and awesome mileage.
If it skips slightly out, I can shift to fourth for the hills, and use fifth for those long straights, decent mileage.
If it totally bombs, I have the original .8 to fall back on, and all it has cost me is 140 bucks and some time, good mileage.
Interesting logic?

Regards,
NITE

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

Well a pic update.
Freshly treated frames are purty.
I will be chopping the last 2 inches off and sliding a new box over top and welding.
Following that, a nice new 3/16 rear bumper versus the 3/32 that was stock.

Here's the tranny that's going to help the mileage along.
Needs a bit of work but is a sound piece.

Bull, you made me think, and pull out my calculator again.
My O/D will be a high .6 to low .7, (there's a .73 gearset available)not that I am worried
about the torque curve, but to keep the rpm ratio in the same area.(.74 was the mathematical right)
Thanks, man, sometimes you need someone to put in a jog to your thinking.
Regards,
NITE

BULL · **Posted:** Sun Jun 22, 2008 8:02 pm

Did you do the frame yourself or some other shop? And is it paint or powder?

I'm glad I helped you rethink the tranny, I hope it didn't sound to negative, it was more of a "critical thinking" approach...

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

Bull, you never sounded negative.
At 43 years, I find the best wisdom is to listen to other people and see what they say, then formulate your own opinion.
Anyway, the frame was done by myself, and it is neither.
Paint is ok
Powdercoat is ok, but chips badly.
Neither will hold up under our NE BC roads and the wonderful calcium.
It is coated with asphalt and butyl rubber undercoat.
Regards,
NITE

Scorpiuscat · **Posted:** Mon Jun 23, 2008 4:22 pm

Very cool, I love seeing the process you are undertaking.

How is the writing going?

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

Sorry, Scorp, the writing is on hold till bad weather or winter.
However, this project has given me ideas, if you get my drift.
Anyway, here's today.

A rotten rear bumper/crossmember.
What do I do?
A replacement is 45 bucks plus shipping.
For 25 bucks I buy better metal, and build a replacement.

A small sideshot to show the difference,

This is getting fun.
Regards,
NITE

BULL · **Posted:** Sat Jun 28, 2008 10:24 pm

Do you have your own brake and shear? What gauges can you work with? Most people that do have them are typically limited to fairly light duty stuff... (lighter than what you appear to have used...)

In any case, nice work. I really miss having my Fadal 5020A VMC, I couldn't do sheetmetal, but I could throw some damn chips with that machine... :cry:

BULL · **Posted:** Sat Jun 28, 2008 10:26 pm

PS, watch your weight with things like that, it'll add up quickly...

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

Well, here's today.
Reboxed the rear of the frame.

To answer your query, Bull, I have no brake or shear.
The original was made of 3/32 flat that was bent.
My replacement is made of 3 inch channel, cut to the right length.
I then relieved the top 4 inches each end, and the 45 with a cutting wheel.
From there, I mig welded a 3 x 3/16 x 6 plate on each end.
Then, mighty drill press took over.
Total increase in weight, about 15 pounds.
Regards,
NITE

BULL · **Posted:** Sun Jun 29, 2008 8:19 pm

NITE wrote:

Well, here's today.
Reboxed the rear of the frame.

To answer your query, Bull, I have no brake or shear.
The original was made of 3/32 flat that was bent.
My replacement is made of 3 inch channel, cut to the right length.
I then relieved the top 4 inches each end, and the 45 with a cutting wheel.
From there, I mig welded a 3 x 3/16 x 6 plate on each end.
Then, mighty drill press took over.
Total increase in weight, about 15 pounds.
Regards,
NITE

Well then, excellent work!

NITE · **Joined:** Thu Jul 28, 2005 11:40 pm **Posts:** 247

Well, not a lot accomplished this weekend other than parts ordering
A/c unit on its way from Texas.
Tranny gears from Florida
Rebuild kit showed up.
Hey, Bull, settled on a stock .86 overdrive.
Would have required a massive change to do otherwise.
Still, my calculator says 40 mpg.
And a new twist.
Going to buy a pipe bender and rebuild the headers I had before.
Regards,
NITE

BULL · **Posted:** Sun Jul 06, 2008 10:07 pm

If you can, I would be interested to see the formula you're using for your mpg calculations? Is it something you can easily post?

Here I Go Again

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