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View Full Version : 80 series speedometer correction...


corsair23
11-09-2009, 04:46 PM
Looking for advice on what is the best unit out there to get? I know there are simple gear swaps (don't think they will work with 4.88s and 285s or 315s though) and then there are boxes...Seems like those that have the Truspeed think it is the shizz and those that have the Mark's box think it is the shizz :hill:

Looking for something that I can use with my 285s now and then change when I move up to 315s. I knew I would have to do something but after my drive this morning I figured it will have to be sooner than later...Based on GPS readings and using my scangauge to adjust it looks like my speedo is running 14% faster with 285s and 4.88s...Before I was reading 3% under.

So what are you guys using for correction? Any pros/cons or "if I could do it over I would have..." statements? :)

Tch2fly
11-09-2009, 04:57 PM
redneck speedo correction - I drive with the speedo indicating 10% faster than the speed limit (for 4:88s and 315s) then I THINK I'm getting there quicker but I'm still only doing the speed limit :hill::hill:


I keep thinking about adding a box but if I fix it I'm liable to continue to drive 10% over and end up with a ticket :homer:

FJBRADY
11-09-2009, 05:03 PM
Looking for advice on what is the best unit out there to get? I know there are simple gear swaps (don't think they will work with 4.88s and 285s or 315s though) and then there are boxes...Seems like those that have the Truspeed think it is the shizz and those that have the Mark's box think it is the shizz :hill:

Looking for something that I can use with my 285s now and then change when I move up to 315s. I knew I would have to do something but after my drive this morning I figured it will have to be sooner than later...Based on GPS readings and using my scangauge to adjust it looks like my speedo is running 14% faster with 285s and 4.88s...Before I was reading 3% under.

So what are you guys using for correction? Any pros/cons or "if I could do it over I would have..." statements? :)


GPS on the dash of the 40 or add 9 miles or so to the actual speedo reading. As always, I hope I have helped!

Romer
11-09-2009, 05:05 PM
I use the "yellow Box" it has dip switches you can change easily and at any time. There is a thread on Mud, they have two versions and you have to order the right one.

nakman
11-09-2009, 05:06 PM
redneck speedo correction - I drive with the speedo indicating 10% faster than the speed limit (for 4:88s and 315s) then I THINK I'm getting there quicker but I'm still only doing the speed limit :hill::hill:


I keep thinking about adding a box but if I fix it I'm liable to continue to drive 10% over and end up with a ticket :homer:

Same here... no correction, wouldn't want it any other way. :o:hill:

corsair23
11-09-2009, 05:14 PM
I use the "yellow Box" it has dip switches you can change easily and at any time. There is a thread on Mud, they have two versions and you have to order the right one.

Found your thread from 2006...

To the folks that use GPS or just know they are over...For me it is more about putting more miles on the LX than it is really seeing :hill: - I didn't mind so much when it was the other way around but I was only off by 3% so after 100K on the odometer I would have really driven 103K...Now though after 100K the odometer will read 114K :eek:. Even at my measly 8K miles or so per year the odometer will show I'm putting 1K+ more miles on the LX than I really am. Right now I figure the odometer is only off by 600 miles or so from actual so maybe I'll wait for 6 months to do the correction so it closer to spot on :rolleyes:

The other reason is I've read about correcting the speedometer helps with shift points but maybe that was a bigger concern when under vs over :confused:

Corbet
11-09-2009, 08:00 PM
I'd get the programable one as you plan to change tire size next time. Why do a speedo gear change to only have to do it again. And yes I'd want to change it out asap too if I was adding that many extra miles for no reason.

corsair23
11-10-2009, 04:22 PM
Looks like 4 options...

1. New speedo gear (couldn't find one that would correct for 285s and 4.88s and as Corbet mentions, I would need to change the gear again when I install the 315s)

2. Yellow Box (http://www.bluegauges.com/prod_yellow_box.htm) - $100, one tire setting (can be adjusted), requires splicing into the speedo signal behind the glove box

3. Superlift's TruSpeed (http://www.superlift.com/accessories/truspeed.asp) - $215 ish, offers two settings to run two sets of tires, requires splicing into the speedo signal behind the glove box

4. Mark's 4WD Speedo Conversion Box (http://www.sleeoffroad.com/products/products_speedo.htm) - $200, offers two settings to run two sets of tires, and from what I can tell is a true plug-n-play box requiring no splicing

I like the price of the Yellow Box but not real excited about splicing into the wires...Don't like the price nor the splicing aspect of the TruSpeed box.

That leaves the Mark's 4WD box. Not super excited about the price but I do like the plug-n-play aspect (if true) and Slee seems to be the sole distributor of the units in the US so I'd get to support Christo with more lunch money :hill:

Looks like aside from Romer the rest of you 80s owners are just winging it with the speedo huh? If anyone has the Mark's box and would like to chime in on installation ease (big bonus for me :D) and how you like the box that would be great.

Romer
11-10-2009, 07:47 PM
Where do you get the oine setting on th yellow box? Not true. With the dip switches, all you do is change the setting and it works with any combination

corsair23
11-10-2009, 08:35 PM
Where do you get the one setting on the yellow box? Not true. With the dip switches, all you do is change the setting and it works with any combination

Probably bad choice of words on my part...Only stating that you only have one setting/ratio at a time vs the other options have a switch that you can alternate between two different ratios for two different tire sizes. Yes it is true that you can easily change the dip switches on the yellow box should you change tire size.

Honestly having the ability to flip a switch to change the ratios isn't a big seller for me...Once I make the switch to 315s the other time the 285s will go back on is for emissions testing...I'm drawn more to the plug-n-play over the splicing...Electrical work and I don't always get along well :o

I do like the size of the yellow box though and it would be an install and forget it thing based on my understanding of where it goes.

Romer
11-10-2009, 09:18 PM
I went to the emissions station near Highlands ranch with 35's and no issues

You can also drive by the Rapid test stations multiple times prior to 2 months before your due. I am going to try that for next time

Old40Dog
11-10-2009, 10:27 PM
Just a suggestion...when you see the equipment on the ramp, get up a good head of speed and drift past the sensors on idle, you should PASS with flying colors. This has worked for me on two different vehicles that I did not expect to pass even with help from God. I got the renewals in the mail marked that I had passed the roadside emmisions...Thank you very much...:beer:

Tch2fly
11-11-2009, 07:25 AM
That leaves the Mark's 4WD box. Not super excited about the price but I do like the plug-n-play aspect (if true) and Slee seems to be the sole distributor of the units in the US so I'd get to support Christo with more lunch money :hill:

Looks like aside from Romer the rest of you 80s owners are just winging it with the speedo huh? If anyone has the Mark's box and would like to chime in on installation ease (big bonus for me :D) and how you like the box that would be great.

If I decide I really need an accurate correction I will purchase the Mark's box.

PM Bikeman, he has done a Mark's box install on his truck.

Corbet
11-11-2009, 07:55 AM
Looks like aside from Romer the rest of you 80s owners are just winging it with the speedo huh? If anyone has the Mark's box and would like to chime in on installation ease (big bonus for me :D) and how you like the box that would be great.

I'm winging it as long as I'm putting less actual miles on the odometer, but I'm only off 6% with my 295's.

When I goto 4.88 or 5.29's then I'll pony up for the Mark's unit. More money but I prefer not to splice into the OEM harness when ever possible. Having the ability to run two different tire sizes is cool too but unless I decide I need 37" tires for the trail I'll most likely just have two sets of 35's summer/winter or DD/trail tires.

Bikeman
11-22-2009, 09:58 AM
Sorry for coming into this thread late. I've been in AZ for 2 weeks on vacation.

I have the Mark's box I bought from Slee. It is totally plug 'n play and it works as advertised. it is easy to calibrate with a GPS. No wires to splice or anything unusual.

Jeff, you could come by and see it in the cruiser.

corsair23
02-02-2010, 12:34 AM
Forgot to post up after the fact :hill:

I decided to go with the Mark's 4WD Speedo Correction Box, purchased from Slee :thumb: - Completed this back in December...

On a scale of 1-10 this is a 1 banana install job but 10 bananas on the PITA scale IMO.

Maybe I missed something but threading the cable through the grommet and down to where it needs to be connected was simple...Disconnecting the OEM plug, plugging in the connectors from the box, and zip tying everthing up out of the way was a royal PITA. I STRONGLY recommend anyone that is regearing to go ahead and install the box and run the connectors while your front driveshaft is out...I seriously considered dropping my front shaft because it was nearly impossible to get my hand, let alone both hands, up to where the connector is.

If you are familiar with Toyota connectors, they can be a PITA to get apart when you can get two hands on them...Trying to do so with one hand and a pair of long angled needle nose pliers was frustrating to say the least. Then trying to do the one handed zip tie installation was :rant:....I envy the guys on MUD that completed this in 30 mins or less...

I'm still trying to figure out where to permanently mount the box...I was hoping it would be small enough to sort of sit above and toward the DS of the hole but it is too big. I need to find a spot where it won't get kicked by feet or other stuff crammed down in the PS floorboard.

The other thing I've noticed is that it takes about a 1/2 block or so before the speedometer starts working? At first I thought I had fubarred something during the install but everytime I start up the truck it takes about a 1/2 block or so before the speedometer comes to life :confused: - Anyone else with the box notice this?

All in all I'm happy with it...I had figured out via GPS that my speedo was showing about 14% over what was actual so I set the box at 86 and the speedo is pretty much spot on now.

Pics.

Bikeman
02-02-2010, 09:23 AM
With my box, the speedo works quickly, but the needle does "jump" when the rig starts rolling. You might ask Christo or Joe, since I first got a bad box. My box is mounted at the end of the shifter console vertically. My wife has only kicked the switch up to the other position once. I know immediately then, because the speedo is like 10 mph off. You could see my install if I make it to the meeting.