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Posted

 

cantelopes-300x261.jpg

So the truck came with a set of Rickson wheels 19.5" and a set of tires that were less than a year old.  I liked the old forged-in-America wheels so I decided ot keep them on the truck.

 

I have never had one of these trucks befoer this one so I have no comparative baseline on how it "should" run and drive.  In LA these trucks are like hen's teeth and I have not found anyone near me that knows much abou them at all.  My local dodge dealer is a waste of real estate and every time I've gone there they turn up their nose at my old truck and try to sell me a new truck :-)  I couldn't even get a radiotor cap from that palce.

 

After studdying this issue of tire size, on this website, more closely I decided to take a closer look at my set up as believe there is a fly in the ointment.

 

Now for the more-fun-with-math part.

 

So according to Mopar1973Man the goal is to have a Final Drive Ratio that is between 3.55 & 3.73

 

My truck started its life with a final drive ration of 3.55 (Dana 80 in the rear and Data 60 in the front)

 

Stock tire size was 235/85-R16

Current tire size is  203 245/70-R19.5

 

So I have a lift of about .85"

https://tiresize.com/comparison/

 

image.png 

 

Upon running the calculation I now have a paultry effective final drive ratio of 3.41, so far so bad.

https://tiresize.com/gear-ratio-calculator/

image.png

 

 

Now the question is to should I lower the water or raise the bridge?

 

I could keep the wheels and change the gearing in the Axels or I can get a set of wheels and tires.

 

Either solution will cost about the same in the greater LA Area.

 

So let's say I decided to go the regearing route.

 

I believe Dana offers 3.73 and 4.1 gearing.

 

The question is this, if I went the re-gearing route which would be preferable (either 3.73 or 4.1) and why?

 

Also I have the NV5600 at (0.73:1) and I'm not exactly sure how to add that into my math here or that's even relevant.

 

Thanks @Mopar1973Man for this article this is super helpful in trying to sort this all out.

 

Edited by leety

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  • Doubletrouble
    Doubletrouble

    I was just making sure I was using that calculator correctly. I punched in my stock size in both fields and came up with 3:55 which is the ratio of both axles. So my final drive ratio is at 3:55-1 ?

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  • Author
On 10/15/2020 at 9:04 AM, Joe_Pool said:

Assuming that you were in 6th gear (.73:1).

 

Axle ratio = [(engine rpm) (tire diameter in inches)] / [(mph) (336) (transmission gear ratio)]

 

 

? = [(1825 rpm) (33.4")] / [(70 mph) (336) (.73)]

answer = 3.55 rear axle gear ratio

 

 

If you pull the diff cover you will find that Dana gears are marked on the ring gear like this.  At the top you will see 43X13, that is 43 teeth on the ring gear and 13 teeth on the pinion.  43/13=3.5384 or 3.54 gear ratio.

 

 

 

20190831_182343.jpg

Very cool thank you for the photograph.

 

I was thinking about that formula and wondering if you would want to put in the number for speed based on the speedometter, which will be innacurate with non-stock OD tires, or use the speed on a GPS (usually fairly precise) or manualy adjust the speed based on a different formula and the actual tires size if non-stock.

For speed adjustment:

 

(new tire diameter*/original tire diameter*) X speedometer reading = corrected speed

 

* can be mm/inch/feet... -- both must be the same units

 

235/85R16 = 31.7"            (235mm/25.4mm)" X (.85 X 2) + 16"  =  31.7"

245/70R19.5 = 33.0"         (245mm/25.4mm)" X (.70 X 2) + 19.5" = 33.0"

 

33.0/31.7 = 1.04        Multiply indicated speed by this number to get actual speed (+4%)

Edited by Joe_Pool
To add information

  • Author
2 minutes ago, Joe_Pool said:

For speed adjustment:

 

(new tire diameter*/original tire diameter*) X speedometer reading = corrected speed

 

* can be mm/inch/feet... -- both must be the same units

 

235/85R16 = 31.7"            (235/25.4)" X (.85 X 2) + 16"  =  31.7"

245/70R19.5 = 33.0"         (245/25.4)" X (.70 X 2) + 19.5" = 33.0"

 

33.0/31.7 = 1.04        Multiply indicated speed by this number to get actual speed (+4%)

This is exceelent!!!  More fun with formulas.  Thank you!!!

  • Owner

As for stashing a Quadzilla that is so simple. Since there is no display in the cab no one would know it was there. Now for the module and hook up hook up the same just hide your wiring with factory stuff. Hide the module like inside the fender skins I'm pretty sure there is a enough reach. 

  • Author
2 minutes ago, Mopar1973Man said:

As for stashing a Quadzilla that is so simple. Since there is no display in the cab no one would know it was there. Now for the module and hook up hook up the same just hide your wiring with factory stuff. Hide the module like inside the fender skins I'm pretty sure there is a enough reach. 

What they can’t see won’t hurt me ;-)

  • Owner

Being the display is your phone then just turn off your iQuad App. Nothing to see folks... Just a stock truck needing a smog check. Even @Me78569 master the Quadzilla enough to be able to run the Quadzilla and pass his smog check. You could like many just set a lower power limit for Valet Mode and that all the fuel they would get period. Hence all most look for is how dark if any smoke is produced. Same rule is Ada County, Idaho. 

  • Author
8 minutes ago, Mopar1973Man said:

Being the display is your phone then just turn off your iQuad App. Nothing to see folks... Just a stock truck needing a smog check. Even @Me78569 master the Quadzilla enough to be able to run the Quadzilla and pass his smog check. You could like many just set a lower power limit for Valet Mode and that all the fuel they would get period. Hence all most look for is how dark if any smoke is produced. Same rule is Ada County, Idaho. 

Some of the smog guys here will notice the box in the engine compartment so that’s the thing I will have to conceal somehow. The branding on the device will give it away. I could organize a 2nd cover for it over the fuse box to sweep it under the rug.

  • Author
6 minutes ago, Mopar1973Man said:

Some have extended the wiring all inside under the dash so there is nothing to see. 

Sounds like a hassle lol.

 

I should be able to put a little costume over it on the fuse box lid. I could probably build an enclosure out of a spare fuse cover lid and attach it to the actual fuse cover.  I’ll try that first.  There are other ways around it as well.

 

I know a guy lol

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Welcome To Mopar1973Man.Com LLC

We are privately owned, with access to a professional Diesel Mechanic, who can provide additional support for Dodge Ram Cummins Diesel vehicles. Many detailed information is FREE and available to read. However, in order to interact directly with our Diesel Mechanic, Michael, by phone, via zoom, or as the web-based option, Subscription Plans are offered that will enable these and other features.  Go to the Subscription Page and Select a desired plan. At any time you wish to cancel the Subscription, click Subscription Page, select the 'Cancel' button, and it will be canceled. For your convenience, all subscriptions are on auto-renewal.