NorthWet Posted December 15, 2004 Share Posted December 15, 2004 This might be better in OffRoad Forum, but thought I would try the general group first. How do people with taller-than-stock tires deal with the introduced speedometer error? I would like to go to larger diameter road wheels, with normal profile tires, to give better highway gearing. But I really would like my speedometer to be somewhat accurate. Anyone have a way of regearing the tranny, using an intermediate device between the tranny and the speedo head, or whatever, to compensate for the difference? Quote Link to comment Share on other sites More sharing options...
mtsmiths Posted December 15, 2004 Share Posted December 15, 2004 I don't think you can regear the speedo drive, or that anyone makes any aftermarket device. But I'm willing to be corrected. I think about all you can do is to figure out your 'new' speeds and either make a guage overlay or learn to recompute in your head as you drive. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted December 15, 2004 Share Posted December 15, 2004 extra addon gearboxes are available for a wide variety of tray/transfer case speedo drive's fnding one that has the correct gearing to compensate would prolly not be hard what might be hard is to adapt the in and out of it for suby btw they are used alot on modified 4wd's such as chevy' and such with large tires my 76 k5 blazer with 44"s had a speedo box in fact Quote Link to comment Share on other sites More sharing options...
idosubaru Posted December 15, 2004 Share Posted December 15, 2004 im' sure you know this, your taller tires may perform different than the shorter guys. i did this once on my XT6 thinking i wouldn't notice much difference, wrong. big difference. handled terrible with the taller tires. never tried that again. Quote Link to comment Share on other sites More sharing options...
the_bard Posted December 15, 2004 Share Posted December 15, 2004 There are programmable speedometers... check out http://www.sw-performance.com/Prods/30speed.html. Last time I looked at 'em, they were kind of expensive, though... $300 or so. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted December 16, 2004 Share Posted December 16, 2004 like everything else i would imagine tehre is a do it yourself solution to the expensive digital one lets see.. that saab 9k i had used a encoder type setup to drive the speedo.. no cable soo.. take the encoder <i kept including the dash in fact hmm saab dash in a suby...> build a small circuit <i supect northwet could do that ..> to read the encoder and some sorta display.. just a idea Quote Link to comment Share on other sites More sharing options...
diluded000 Posted December 16, 2004 Share Posted December 16, 2004 How do people with taller-than-stock tires deal with the introduced speedometer error? Some of the school zones around here have those radar signs that tell you how fast you are going, and then flash if it is too fast. I hold a steady speed the use the radar speed those signs display to estimate the percentage error in my speedometer. I did this when I put smaller snow tires on my truck. The Boulder County Sherriffs Department only charged me $75 to confirm that even though my speedometer said I was going 65 mph in a 45 mph, I was really only going 60 mph. - James B Quote Link to comment Share on other sites More sharing options...
NorthWet Posted December 17, 2004 Author Share Posted December 17, 2004 For years I did the "mental adjustment" to the speed in my Datsun (non-original tranny w/different speedo gear), but after about 200k miles this got old. (A matching diff solved that problem!!!) And I was the only driver of my Datsun. With my t-wagon, there is the possibility that my wife might drive it (since it used to be hers), and she would not appreciate the unnecessary calculations. Go figure. :-\ Well, I was hoping for a ready-made, adjustable converter, but that seems unlikely. I could make one, but that seems like too much work and not enough flash. I could go oddcomp's digital route, but I like analog and not video game... Grew out of "Oooh! Pretty lights!" some time ago; much prefer function. Maybe I'll look into building an encoder and use its massaged output to control a motor to drive the speedo cable. Anybody got a dead/unused speedo that I can cannibalize? Quote Link to comment Share on other sites More sharing options...
MorganM Posted December 17, 2004 Share Posted December 17, 2004 I really don't worry about it. Just go with the flow of traffic or slower and you are fine. Nobody on the road with you? Don't sweat it just watch for cops and follow your 'gut feeling'. I guess I'm not that worried about how fast im going /shrug Speedo hasnt worked since my 4WD conversion and I really don't intend to fix it :-p Quote Link to comment Share on other sites More sharing options...
NorthWet Posted December 17, 2004 Author Share Posted December 17, 2004 I really don't worry about it. Just go with the flow of traffic or slower and you are fine. Nobody on the road with you? Don't sweat it just watch for cops and follow See remark about my wife driving the car... Not married, are you? Quote Link to comment Share on other sites More sharing options...
monstaru Posted December 17, 2004 Share Posted December 17, 2004 if you wish you can try an educate her on this.it might set her at ease.here is a link with a calc.http://www.4lo.com/ it does not seem to be viable or economic to try and purchase some type of unit to fix this.so maybe you can at least set her at ease.i can see this coming up with my ol'lady as well. good luck and may the wind be at your back on this endeavor. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted December 17, 2004 Author Share Posted December 17, 2004 if you wish you can try an educate her on this.it might set her at ease.here is a link with a calc.http://www.4lo.com/ it does not seem to be viable or economic to try and purchase some type of unit to fix this.so maybe you can at least set her at ease.i can see this coming up with my ol'lady as well. good luck and may the wind be at your back on this endeavor. Hhhhmmmm... another young person, maybe? Uneducated in the ways of old marrieds??? You don't educate long-time wives, you say, "Yes, Dear." Not really a prob making something, but I would want to do it right and use real cable fittings. Computers, electronics and mechanics are right up my alley. Quote Link to comment Share on other sites More sharing options...
BobBrumby Posted December 17, 2004 Share Posted December 17, 2004 the easiest way would be to get a nikko, 2 mobile phones and mate with a newish car. get him to do a certain speed on a 4 lane road and mark when ur level with him. also could use a gps but wheres the fun it that? Quote Link to comment Share on other sites More sharing options...
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