Got my Gryphon, Got Cpl Q's

[tg150]

We'll the day has come.. I got my Gryphon I'm so excited. i can harldy contain myself and its going to be a loong night before i can finally program it tomorrow. But i do have some questions and could use some advice..

My truck is an 04 Lariat, it has 373 gears. Originally it came with 18" wheels but i changed them out with the newer oem 20" wheels& tires, size 275x55x20 with pirelli scorpion tires.

My question is: during the initial programming after choosing the "Power Programming level" should i automatically choose "create a custom file" to enter my gear size and tire size? Or should i choose no and do it afterwards? Or not do it at all? Is there a default setting for the gears?

Also i did the equation for my wheels and tires and came up with 2546, is this correct?.. I did read something from Jack about a 7% squish factor but dont quite understand it or how to do it. I havent had the time to download pegasus yet and probably wont till tomorrow night. Can someone figure it out for me or if you have oem 20's what is yours set at.

Sorry if im asking to many questions.. Ty for any help and all reply's. Cant wait till tomorrow

[JWBFX4]

Someone will correct me if I am wrong, but I think I read it is not best to create a custom file during the first intial program. But yes I would say you would need to change it, because it is being read from what is wrote on your pcm (which is what it came with stock).

[88Racing]

To get the corrected measurement for the tire size goto peagasus and it has the tire size calculator. Compare the 18" and the 20" if you have not gone radical on the sizes it should not make a difference the only reason I wrote this is that I have that 20" wheel and tire size from the factory, but here's the kicker my spare is a 18" wheel. If I remember right the numbers for both tires were equally the same. I'll post my 18" tire size tomorrow.

When you start the custom file process the gryphon puts in a bogus number for the tire size and defalts to 3.73 gears. This is about what I know about the custom file option.

Jack could probably tell you more.

Lars

[Jackpine]

They have such faith in me, don't they, tg150? :o Hope it's not misplaced.

Yes, I would go ahead and enter whatever program you decide on and bypass the "Custom Options" choice at first. Why? To be honest, I really don't know. But, it seems to be the way to go.

When you do this, your factory gear ratio AND factory tires will be loaded into the appropriate areas of the PCM.

As I understand your post, the factory gears are 3.73, so, you can leave them alone. The tires, though may need to be changed, but, Lars could be correct - the net effect may be a wash.

I'd do it anyway.

So, once you've programmed your PCM, you can start all over again. Go ahead and select the SAME tune Level, but this time say "Yes" to "Custom Options". When you get that menu open, scroll down till you find "Load Previous Settings". Hit <Enter> there to make that happen. Now, scroll to the "Gear" setting, hit <Enter> to open it. It should be 3.73 - if so, hit <Enter> to confirm it. (If not of course, change it to 3.73 and hit <Enter>).

Now scroll to the "Tire Size" and hit <Enter>. You should be seeing the "factory tire size" if I understand the way this works now. I'd be interested to know what you see at this point, so please make a note of it and let us know.

I've looked at Bill's calculator and I come up with a value of 2479 mm for your new tires with a 7% rubber "squish" (the "flattening" of the tire that reduces the effective radius when there's weight on it). Your number, 2546, was absolutely correct by the way! But that's the distance your tire rolls in one revolution when it is not "flattened". This "squish" correction is just a guess though, and it's what worked for me. Anyway, I'd try 2479 at first. Confirm somehow, with a GPS or radar sign if the Gryphon speedo is correct. If it is, your dash speedo will be 1-2mph faster, but your odometer will be correct.

If your speed on the Gryphon is slower than you are really going, you need to increase the circumference value that you enter next time. If it is faster, reduce the circumference value still more. You can do this by trial and error, or, if you can determine the percentage speed error, simply change the tire circumference by that percentage.

Remember to "Load Previous Settings" as the first step from now on in the Custom Options menu, so that you reload any other changes you made.

Make sure also, that you hit <Enter> at each setting you reset or accept to same them, and then, scroll to the "Done" selection and hit <Enter> there to start the actual programming process.

Sorry, I know all this sounds a bit complicated, but I can do it in my sleep now. I't really not that bad once you get the hang of it.

Have fun!

- Jack

[tg150]

JWBFX4, Lars and Jack ty very much for your help.. I cant wait to try it out if only the sun would come up..


Jack,
When you say--- So, once you've programmed your PCM, you can start all over again. Go ahead and select the SAME tune Level, but this time say "Yes" to "Custom Options".

Do you mean after the PCM is programmed turn the truck off then turn the key back to on possition and start over or can i make the changes while the truck is running and it will prompt me to turn the key off when im done? Hope that made sence.. Thanks Again Jack and Everyone...

-Tony

[Sburn]

Originally Posted by tg150

.....can i make the changes while the truck is running and it will prompt me to turn the key off when im done?
-Tony

No you can't program while the engine is running. Start with the key ON but NOT running. Follow the prompts shown on the Gryphon. When it's done and returns to the gauges display then you can start the engine.

[88Racing]

Calculations I got with out "squish".

Stock
275/55R20-2546mm

Spare
275/65R18-2559mm

Difference tells me spare has 1/2" more tire in circumfrance. The post I did earlier this thread about being about equal is not true. The spare should only be ran as a spare(temporary) unless you change all 4 wheels to that size or get a 20" spare.

Lars

[Jackpine]

Originally Posted by 88Racing

Calculations I got with out "squish".

Stock
275/55R20-2546mm

Spare
275/65R18-2559mm

Difference tells me spare has 1/2" more tire in circumfrance. The post I did earlier this thread about being about equal is not true. The spare should only be ran as a spare(temporary) unless you change all 4 wheels to that size or get a 20" spare.

Lars

Interesting, Lars. TG150 (Tony) and I have had several back and forth's by PM this morning. For everyone's information, he loaded Level 2 without doing anything with "Custom Options" and his Gryphon speed exactly matches the speed shown on his GPS (and, of course, the truck's dashboard speedo reads 1-2 mph faster). I suggested he leave well enough alone and not mess with the tire size.

Lars, I don't think he ever said what his stock tires were, but the new tires are different than yours. So, it's quite possible they have the same rolling circumference.

I'd be quite cautious in any case if the stock spare were put on either of your trucks. I'd sure keep the speed below 55 (like when using a space saver spare) and try to get the road tire back on as soon as possible.

- Jack

[88Racing]

Jack

Tg150 said that he had a set of stock oem wheels and tires 20".
From what info and comparrison I did this morning that's why I posted the calculations.
I have the exact set wheels and size tires as he is running.
After doing the calcs w/o squish I found it interesting that there was that 1/2" difference between the 18" and 20" wheels/tires. I do think with the squish factor that it may actually be the same circumfrence. The 18" having a taller sidewall and the 20" having a shorter one.

Lars

[Jackpine]

Originally Posted by 88Racing

Jack

Tg150 said that he had a set of stock oem wheels and tires 20".
From what info and comparrison I did this morning that's why I posted the calculations.
I have the exact set wheels and size tires as he is running.
After doing the calcs w/o squish I found it interesting that there was that 1/2" difference between the 18" and 20" wheels/tires. I do think with the squish factor that it may actually be the same circumfrence. The 18" having a taller sidewall and the 20" having a shorter one.

Lars

You could be absolutely right about the "squish" effect. I may have misunderstood something in his first post.

- Jack