[inquiring_mind2]

I have a 75 cj5 I use in mudd bogg competitions. I have a 427 bored 60 over. I am using dana 44 front and rear ends out of a 78 J10 truck. I have a turbo 350 with a reverse manual valve body and I am using the dana 300 transfer case. I also have 35 in boggers on it. my question is what gears should I put in it to get the maximum rpm range out of my motor. The cam is good up to 7200. I would like for it to be quicker off the line but I also need enough gear to keep the tires turning bout 6800 rpms because the track is 200 ft long.


Right now I have 410 gears in the front and the rear. in drive I am turning about 6000 rpm's in second gear I am running about 7000. I would like to keep it in drive if at all possible for less wear and tear on the tranny. Any help would be greatly appreciate.

[sqzbox]

4:56's should have you in third before you drop into the pit! Or, put it in 4/W low range.

[inquiring_mind2]

I have it in low range now. I would love to run high range but I tried that and it fell flat on its face

[sqzbox]

So what your saying is you want something between low and high, right?
4:56's! I think that 5:something would be the same as low range.

[inquiring_mind2]

yes that is right I would love to go to high range but I don't know what gears would go good with the turbo 350 and the dana 300 transfer case I have or I can stay in the low range and use different gears to get the most out of my motor. I am open for any options right now

[a1supersport]

http://www.rockcrawler.com/techrepor...omax/index.asp

From what I read here^^, low-gear in a Dana-300 is 2.62:1? Assuming high gear is 1:1, if you add 2.62 to your 4.10, will give you a final ratio of 6.72...which is what you'll need in the axles to get the same performance you're getting now...but running in high gear. Gears in the 6+ range is pretty high (low). What about changing to a higher stall converter to get your RPM up (was it 7000 you wanted?). That's definitely cheaper.

[inquiring_mind2]

I would like to be able to run around the 7000 rpm range. The stall I am using know is small its 3200. I know I need a bigger one but I understand what you are saying. So If I understand correctly I need something in the 6's to make it work correctly in high. Now will running it in high gear get me more wheel speed? with those gears?? I don't know if it would be cheaper to buy the gears or the converter. A good converter will set me back about 600 to 800 dollars.

[a1supersport]

Running a 6.72 gear (or something close), in Drive, with T-case in high...will get you pretty much the same performance as as your 4.10, 2nd-gear, with T-case in low. That's a lot of gear though...to get the same performance. Do they even make a gear that size for a Dana 44?

[inquiring_mind2]

I have no clue I would have to do some research on that

[inquiring_mind2]

ok I have another question to ask?? I was thinking about running high side on the transfer case and running maybe 1st or 2nd gear in the transmission. I also did some checking around the and tallest gear I can get for a Danna 44 is a 589. I didn't know if that would work or not. ALso would any one be willing to tell me how to figure all of this out?? I am always wanting to learn new things that way I can help others out

[matts37chev]

i would stick with low range in the transfer case
one thing to think about, is using a little higher gear ratio in the front axle
so it will pull you straight

[matts37chev]

Originally Posted by inquiring_mind2

I have a 75 cj5 I use in mudd bogg competitions. I have a 427 bored 60 over. I am using dana 44 front and rear ends out of a 78 J10 truck. I have a turbo 350 with a reverse manual valve body and I am using the dana 300 transfer case. I also have 35 in boggers on it. my question is what gears should I put in it to get the maximum rpm range out of my motor. The cam is good up to 7200. I would like for it to be quicker off the line but I also need enough gear to keep the tires turning bout 6800 rpms because the track is 200 ft long.


Right now I have 410 gears in the front and the rear. in drive I am turning about 6000 rpm's in second gear I am running about 7000. I would like to keep it in drive if at all possible for less wear and tear on the tranny. Any help would be greatly appreciate.

so you are looking to gain 1000 rpm so you can run in drive?
are only using 2nd now?

[big gear head]

Keep this in mind too. When you go to something like the 5.89 the pinion gear head is getting very small, and much weaker. With the tires you are running you are putting a lot of strain on the drivetrain.

What connecting rods do you have in that 427? Just because your cam is good to 7200 RPMs doesn't mean that the rest of your engine is. I've built a lot of big block Chevy engines and they have very heavy parts in them. The 3/8 rod bolts have a big job trying to keep everything together with those heavy rods and pistons, and the valve springs have some heavy valves to keep under controll. Be carefull when you spin a big block that fast.

[sqzbox]

Originally Posted by matts37chev

i would stick with low range in the transfer case
one thing to think about, is using a little higher gear ratio in the front axle
so it will pull you straight

Like mine? 4:09's in the front and 4:10's in the rear. I only have 31" M/T's
but in low range, 3rd gear is like first in high range.The secret to full pulls is wheel spin like seeing 70 mph on the speedo all the way through the pit.

[eloc431962]

Originally Posted by big gear head

Keep this in mind too. When you go to something like the 5.89 the pinion gear head is getting very small, and much weaker. With the tires you are running you are putting a lot of strain on the drivetrain.

What connecting rods do you have in that 427? Just because your cam is good to 7200 RPMs doesn't mean that the rest of your engine is. I've built a lot of big block Chevy engines and they have very heavy parts in them. The 3/8 rod bolts have a big job trying to keep everything together with those heavy rods and pistons, and the valve springs have some heavy valves to keep under controll. Be carefull when you spin a big block that fast.

This is some very good advice.


Cole