speedo calibrations

86capriasc · Post by **86capriasc** » Tue Apr 25, 2006 4:08 pm

Does anyone know if these coupes were recalibrated for the smaller diameter tires(225/50/15) or were they left stock for the 225/60/15. I have had to change my tires and rims do to dry rot. Funds are short right know so that was my only option. I have put on a set from my 83 RS that are 1 inch larger in diameter than the stock wheels. I found that these have 50 revs less per mile than the stock ones. I am just wanting to know how far off my speed will be with these tire.
Thanks, Mike.

Post by **negusm** » Tue Apr 25, 2006 5:56 pm

My speedo has ALWAYS been off.

I know my rear gears were stock as we had to pull the rear end apart to replace them once.

Until now, I have never had the 225/50/15 tires so I am hoping it gets back in line.

If it's like my car, you will experience something like a 7MPH difference at about when the speedo shows 60MPH (meaning you will in reality be going 67MPH).

So in short, yes, they were recalibrated by asc.

-Mike

ASCMCLRN · Post by **ASCMCLRN** » Tue Apr 25, 2006 9:05 pm

I have aftermarket 17" Cobra wheels on my car atm (car still in shop will need to check exact demensions), I was wondering if anyone had a site that can distinguish the difference in wheel height/ speedo accuracy? Thanks.

Nicholas

Post by **negusm** » Wed Apr 26, 2006 12:25 am

Yes,

http://www.miata.net/garage/tirecalc.html

ASCMCLRN · Post by **ASCMCLRN** » Wed Apr 26, 2006 1:01 am

negusm wrote:Yes,

http://www.miata.net/garage/tirecalc.html

Sweet thanks!

86capriasc · Post by **86capriasc** » Wed Apr 26, 2006 1:02 am

Yes, thank you for that site, it has helped alot.
Mike

tfs2121 · Post by **tfs2121** » Thu Apr 27, 2006 10:42 pm

i have never had my rearend apart yet but i have always had the right 225/50R15 on my car and i can tell you my speedo has ALWAYS been off its off about 5mph at 60mph

86capriasc · Post by **86capriasc** » Fri Apr 28, 2006 12:18 am

Is that 5mph slow or fast?

Sandy · Post by **Sandy** » Fri Apr 28, 2006 12:30 am

Regarding the dry rot ~

My '86 wears its OEM tires (50 series) B.F. Goodrich Comp T/A (s) ~ Absolutely no dry rot. Every OTHER (even years) I (using a medium-small paint brush, I "paint" my sidewalls with Armor All.) Now, I don't like Armor All for daily driver use, as it turns an ikky brown color, but sitting indoors it doesn't. Armor All has one heck of alot of oil in it, and I credit that for no dry rot. (Ditto the twin 1990's)

tfs2121 · Post by **tfs2121** » Fri Apr 28, 2006 10:55 pm

86capriasc wrote:Is that 5mph slow or fast?

speedo will say 65 but you will bedoing 70

Post by **negusm** » Sat Apr 29, 2006 12:50 am

Sandy wrote:Regarding the dry rot ~

My '86 wears its OEM tires (50 series) B.F. Goodrich Comp T/A (s) ~ Absolutely no dry rot. Every OTHER (even years) I (using a medium-small paint brush, I "paint" my sidewalls with Armor All.) Now, I don't like Armor All for daily driver use, as it turns an ikky brown color, but sitting indoors it doesn't. Armor All has one heck of alot of oil in it, and I credit that for no dry rot. (Ditto the twin 1990's)

What kind of Armor All?

The Armor All Vinyl (interior) has petro chemicals and silicone oil in it. These pull the oils out of rubber/plastic/vinyl and and breaks them down which causes cracking.

The fact that you have kept your tires in a climate controled environment probably is the trick. Changes in temperature and pollution can cause the cracking in the rubber. The Armor all you put on every other year probably doesn't really do much.

But what do I know? Seems like you have gotten the car this far in 20 years...I don't know if I would change the way you're doing it now.

For years I was told by different people that armor all was junk. The vinyl top guy who put the top on my Cougar forbid me to use the stuff. I never did and the top is still in great shape 15 years later. Here is a thread with some good info in it and a reference to a good product that would be better to use I think.

http://www.foureyedpride.com/phpBB2/vie ... ht=303+spf

One thing I did to my T5 shift boot was to "soak" it overnight in Meguiars Vinyl cleaner/protectant which is much better stuff. If really started to soften up the underside which had been pretty stiff.

-Mike

Sandy · Post by **Sandy** » Sat Apr 29, 2006 1:15 am

I went & looked. WTF do I know what the Heck I use? I know what the container looks like! I use Eagle-One Tire & Rubber Restorer that says that it keeps rubber flexable and restores the natural oils in rubber. I don't own any Armor All. I looked. To me, it's sorta like saying Jello, or Scotch Tape, no matter what the brand is. I do know that I use "No. 7" THE best car wash soap out there, and I use Souverne by Pinnacle for wax and Eagle-One Wheel Cleaner and now that I looked, I also use Safe-T-Kleen to remove bird-bomb stains in the clearcoat. I use MOPAR Super-Clean for tar removal, and No. 7 for stubborn stains. Window Cleaner is Detailer's Choice from Florida Mail Order, best in the world, I have to hide it from wifey. $16.00 @ bottle. I've got loads more, a whole closet full of "treats" ~ I have no Armor All. For shows I use liquiid shoe polish (black) LIGHTLY on the brake & gas pedals, and then spary a quick fine mist of hair spray over them so that when it (should it) rain and shoes get wet, the shoe polish is sealed in. A trick taught to me at a show.

Bob Lyons on here, stopped over recently and met my COUPE. Ask him how it looks! Don't take MY word, for it.

Post by **negusm** » Sat Apr 29, 2006 2:43 am

Oh, you said you used Armor All on your tires. I'm sure the Eagle One is good stuff. Carry on then

-Mike

Post by **negusm** » Sat Apr 29, 2006 2:56 am

Oh, and Sandy, everytime I hear you talk about what you do to your car, I write it down. I remembered the Eagle One Tire stuff you have to order and the buffed out vaseline you use to keep rust away.

Sounds like you have many many more tricks up your sleeve.

-Mike

Sandy · Post by **Sandy** » Sat Apr 29, 2006 2:57 am

'Ya, I know ~ somtimes I just throw out names, without much attention to detail. THAT is WHY I went & looked at my supply cabinet see what it is I really use. Oh, & I Goofed. It's NOT Detailer's Choice window cleaner, it's Detailer's PRIDE window cleaner. When used, it make the windows go away, >> all I know....

I'll be more careful in the future with "naming-names"