4020 final gear ratio March 08, 2016 02:10PM
Have been pulling a 4020 with a stock transmission with 4010 planetaries. We have been pulling in 7th gear.
The transmission let go so we have decided to get a 3 speed.

I am having trouble figuring what final ratio I have right now. How is this figured?

Thanks for the help!!
Reply Quote

Re: 4020 final gear ratio March 08, 2016 03:12PM
Does 25:1 sound right????
Reply Quote

Re: 4020 final gear ratio March 08, 2016 08:52PM
7th gear in a 4020 with 4010 planetaries would be 31.2:
Reply Quote

Re: 4020 final gear ratio March 09, 2016 02:55AM
J&R Thanks for the help.

Can you show me how to figure this? I'm doing something wrong.

What would the ratio be if I put the 4020 finals back on???

I am planning on pulling in our 3000 rpm pro field class this year with 20.8x38 151's uncut.

What ratio do most pullers in this type of class run?
Reply Quote

Re: 4020 final gear ratio March 09, 2016 06:26AM
The tooth counts for a 4020 in 7th gear would be as follows

high range pinion on top shaft 23
counter shaft 28
7th gear on pinion shaft 33


ring and pinion 9 and 47

ratio of 4010 planetaries 4.167:1

So to figure the ratio you need to multiply all the driven gears together and then divide by all the drive gears.

The driven gears would be
countershaft gear, 7th gear on pinion, ring gear and the large number in the ratio of the planetaries

The drive gears would be
high range pinion on top shaft , countershaft gear , pinion shaft and the small number in the ratio of the planetaries(this number is a 1 so really you can disregard this number.


28 (countershaft gear) x 33(7th on pinion) x 47(ring gear) x 4.167(large number in planetary ratio) / 23(high range pinion on top shaft) / 28(countershaft gear) / 9(pinion shaft)

28 X 33 x 47 x 4.167 / 23 / 28 / 9 = 31.22:1 ratio

Now you will notice that I used the 28 tooth countershaft gear as both a drive gear and a driven gear.7th gear is the only gear that this happens. I could have disregarded this gear since we were figuring the ratio of 7th gear but 5th 0r 8th gear would require including this gear in the calculations but then it would only be used as a driven gear.



Edited 6 time(s). Last edit at 03/09/2016 09:40AM by J&R Machine.
Reply Quote

Re: 4020 final gear ratio March 09, 2016 06:35AM
the ratios with 4020 planetaries would be

28 X 33 x 47 x 4.8 / 23 / 28 / 9 = 35.97:1

Notice the ratio of the 4010 planetary is 4.167:1 and the 4020 planetary is 4.8:1
Reply Quote

Re: 4020 final gear ratio March 09, 2016 09:50AM
Thanks J&R!!!
I can see how to figure it now.

I was only counting one of the two 28 tooth gears for 7th. This what was throwing me off .
Reply Quote

Re: 4020 final gear ratio March 09, 2016 10:08AM
Yes like I said in the calculation of 7th gear ratios, the 28 tooth gear could be left out of both the driven and drive gears. That gear is a driven gear when the power goes from the top shaft to the counter shaft but then it is a drive gear when it drives the gear on the pinion shaft. So basically in 7th gear it is only an idler but in the other gears it is a driven gear when the power comes from the top shaft. then the power is transferred to one of the other countershaft gears which then drives the corresponding pinion gear.
Reply Quote

Re: 4020 final gear ratio March 09, 2016 10:22AM
what do you have for a motor, turbo and pump
Reply Quote

Re: 4020 final gear ratio March 10, 2016 04:04AM
466 cid
S-366 turbo- 2.66
cam
P-pump with 4-28 dual feed injectors
simpson water injection
Reply Quote

Re: 4020 final gear ratio March 10, 2016 04:11AM
I would think you should be able to run almost stock road gear. With a 4020 that would be about 22:1. With your 4010 planetaries that would put it up to 19.1:1. The problem with these is that if you have enough power to run road gear, it probably wouldn't hold up.
Reply Quote

Re: 4020 final gear ratio March 10, 2016 05:17AM
We generally pull the sled @ 20 mph or just a little more according to the sled with 20.8x38. This is at 3000rpm.
With 18.4x42 we go a little faster because they are bigger around. Regardless we could use a little higher gear.
I post a video tonight so you see what it runs like.
Reply Quote

Re: 4020 final gear ratio March 10, 2016 02:47PM
[youtu.be]

Last run before we broke.
Reply Quote

Newer Topic Older Topic

Author:

Your Email:


Subject:
Spam prevention:
Please, enter the code that you see below in the input field. This is for blocking bots that try to post this form automatically. If the code is hard to read, then just try to guess it right. If you enter the wrong code, a new image is created and you get another chance to enter it right.
Message:
Website Statistics
Global: Topics: 38,771, Posts: 229,938, Members: 3,338.
This forum: Topics: 37,096, Posts: 226,027.

Our newest member Jacklovik2009