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Re-Calibrating VSSB due to tire upsize

I know solder is not meant for connector, but as a holder of connections, but If i just run a piece of solder through the pin holes, and melt it from the backside, that should be fine for this low current/volt application? Make this job 100x easier.
 
buddy said:
Perhaps the makers of the DRAC/VSSB took into account the deflection of the tires and theoretical values for tires, because you should use a higher circumference to make the speedo read faster.

So perhaps you should use 101.5" which is the theoretical circumference of a 235/85R16= 32.2" tall, or at least something close to that, like 100" because most specs I have looked at show somewhere around 31.5" tall which would sill only be 99" circumference.
Click to expand...


Glad your on today buddy. This stuff seems to be your fortee. On the link it says match exact with chalk method. I'll try that when daughter takes nap (right now) and try again using my solder as connector method. Just can't test drive as wifey left for a little while...

I did notice my exact is alot less than all the tire calc websites, even though they vary from one to another itself.

I'll post back shortly with exact measured on ground method and take it from there...

30 minute jobs always turn into projects for me, lol. The dipswitch method is highly recommend for anyone PLANNING to do this btw. On memorial day Sunday weekend I'm determined to finish now, and I can't get dippies.
 
Matt Bachand said:
94.836828230242 Seems to be my circumference, not 96.something I was using before.

The thing that bugs me now, is that if I calculated it larger than actual, i would think my speedo would be reading faster, not slower.

This is making me think that my paperclip solder/joint isn't making contact?? although its stuck there good with solder, so it must be. Unless its a non conductive material....
Click to expand...


Funny how actual recorded with line on road is just about 97. Which is close to what I started with originally. Makes no sense as 30 3/16 x pi is around 95. Seems small error makes large differences.

I'll try it at 100. See what that does for me.
 
0.854980 1 0 0 1 1 1 0
0.864746 1 0 0 1 1 0 1
0.874512 1 0 0 1 1 0 0


The middle one again is closest to my math answer.

Now this numbe (input ratio) is smaller than my last result.

Does that make sense? Larger tire size = smaller input ratio? Gonna solder her up now, and when wifey gets back i'll Test drive....
 
Lower ratio makes sense, I see now that they say to take off the tire, thats where the differnce is, when its on the truck it has that deflection/sag when loaded down.

This is also on the site
Compare both results. They may vary depending on rim width, tread wear, and the fact that the circumference increases at higher speeds.

I have a feeling that the theoretical height might be closer to what it is at speed.

And if using 100" circumference you should be at 0.812
 
Damn, just finished soldering it up to .846.... Oh well, i'll Test drive it in a few and see wehre i'm at.

Thanks buddy. On a side note, i'm getting good with soldering....
 
I bought some dip switches online and plan to do mine soon, was going to grab a VSSB out of a junkyard truck, never seem to find the time when the junkyard is open though.

I think when you did the math you used 120K, instead of 128K in the denomenator.
 
buddy said:
I bought some dip switches online and plan to do mine soon, was going to grab a VSSB out of a junkyard truck, never seem to find the time when the junkyard is open though.

I think when you did the math you used 120K, instead of 128K in the denomenator.
Click to expand...

Whatever I did wrong, it must have countered out the oversized circumference I put in because my speedo is dead nuts on to my GPS!!!

Operation=perfect success.

Buddy if you're afraid of ruining your current VSS don't be. I'm not into doing small electronics or anything of that sort, and I modified mine twice, once with a paper clip, and the other time with a length of solder as the connector.

My soldering gun doesn't have a sharp point, and couldn't even melt the PC-board's old solder joints. Its too big for this type of work and it all came out good in the end.

I appreciate your time to double-check my math, and it was you're suggestion to use 100 that got me my perfect result with my error!!

BTW, i couldn't remove the old pins, so i just cut them with some tiny wire snips i had.
 
To anyone else going to takle this with or without dipswitch's, make sure you have a good soldering iron with a sharp point.

A large soldering guntype is too big and clumsy to melt the existing pcboard's solder it seems.
 
Dave Barbieri said:
Glad the operation was a success!!
Click to expand...

Thank you too for your help DB.

Indeed, i was aiming for a little over, but I'll settle at perfect.... Now to try to mount the little bugger back in its place.

As mentioned earlier, getting that thing out isn't the easiest.

It's located directly under the PCM. Comes in a white case.

I had to use a large screwdriver to pop the plastic clip i could't see. Don't be afraid you'll break it, the worst thing you'll do is crack the clip on the plastic case the VSSB sits inside of.
 
When I replaced my dash last summer, the white box wound up lying under the glove box ledge. Now it's really simple to reach - just remove four screws and pull the glove box. My soldering job wasn't great - couldn't find my pencil tip iron and got impatient to finish it. Next time around, I'll get the right iron and take my time. I'll also take the time to install a dip switch. Never know what future gear train mod I might come up with! ):h
 
I realized your original math was off too, so you had originally changed it to a circumference of less than 91" and the correct number for 96.63" circumference would have been .84, and if you used .864 for the last mod then that would translate to a 94" circumference.

You modded it for 0.864 right? Which would mean it matches up to your actual measured tire height really well, 30 3/16" x Pi = 94.84" circumference.

So by increasing the circumference you lowered the ratio and it did bring the speed on the speedo up, and it works pretty close to actual measured height, because if you went by the 97" chalk method you would have been at .837.
 
buddy said:
I realized your original math was off too, so you had originally changed it to a circumference of less than 91" and the correct number for 96.63" circumference would have been .84, and if you used .864 for the last mod then that would translate to a 94" circumference.

You modded it for 0.864 right? Which would mean it matches up to your actual measured tire height really well, 30 3/16" x Pi = 94.84" circumference.

So by increasing the circumference you lowered the ratio and it did bring the speed on the speedo up, and it works pretty close to actual measured height, because if you went by the 97" chalk method you would have been at .837.
Click to expand...

I did mod it for .864.

Someone recently said to me.

"Doing it once slow is better than twice fast, ask any woman".

Good advice...:)
 
Matt you have learned many lessons for the rest of us :)

To summarize was your tire measurement done with it loaded on the truck? where you got 30 3/16"

How fast have you gone with it right on?

Maybe I'll do mine tomorrow, need to find my fine tip.
 
buddy said:
Matt you have learned many lessons for the rest of us :)

To summarize was your tire measurement done with it loaded on the truck? where you got 30 3/16"

How fast have you gone with it right on?

Maybe I'll do mine tomorrow, need to find my fine tip.
Click to expand...

tire size measured loaded, on hind sight a tire has a flat spot on the bottom, That wouldn't effect the circumference marked on the ground though.

30 3/16" was measured tires on truck loaded.

Not sure where my math errors came, but its all behind me now.

Total cost, zero.
 
buddy said:
Thanks, funny how all the math was wrong but it worked out for you.
Click to expand...

I just double checked all my math and it was all wrong... lol...

I see my notes and I did u se 120,000 as the lower denomenator too, as you mentioned... Oh well. To summarize my math should have been closer to this.

(63360) (4.10) (40)

________________

(97) (128,000)


=


10391040
________

12416000

=

0.8369072

The slight variance between that value and the .864 is probably the fact that my circumference isn't exactly 97, but very close.
 
Matt Bachand said:
tire size measured loaded, on hind sight a tire has a flat spot on the bottom, That wouldn't effect the circumference marked on the ground though.

30 3/16" was measured tires on truck loaded.

Not sure where my math errors came, but its all behind me now.

Total cost, zero.
Click to expand...
The 'flat spot' thing had me stumped, too. I wasn't sure where to measure on the tire to make up for that. I mean, did the flat spot cause the other parts of the tire to bulge a bit? Would rpm cause the tire to 'grow' like a dragster tire does? Finally just decided to go with the chalk mark thing. It rolls what it rolls. Don't remember what the measurement was - I've slept since then. But it got me within one mph, so I'll probably do it again next month when I install the new ring & pinion.
 
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