Speedometer recalibration?

[vtach]

Anyone know if there is a way to recalibrate the speedometer for larger tires?

 

[dm22630]

I think that you need to get a different speedo cable.

 

[poppop]

I don't think its the cable itself. You have to change the drive gear that turns the cable, but I don't know if thats possible on these trucks.

 

[Barrman]

There is a little gear box on the t-case where the cable screws in. Each tire size 9.00 and 11.00 had a respective gear box.

I do not know about making the speedo correct with the really big tires though.

 

[vtach]

Actually, I am currently running 11.00x20 and that is the size that I need to calibrate for. Does anyone know where i can get the part/parts needed?
I suppose being that the stock 9.00 are 39", and the 11.00 are 43" so when my speedometer reads 50mph, I am really going 55mph. It would still be nice to just have a corrected speedometer.

 

[tm america]

get a speedo adapter from a five ton boyce has em my speedo is dead on with the 15.5s

 

[tm america]

you can get a speedo adapter from a m34 but they are hard to find that would put your speedo right since they had 11.oos on em stock

 

[KsM715]

you can get a speedo adapter from a m34 but they are hard to find that would put your speedo right since they had 11.oos on em stock

Forgive me cause I dont know what a M34 is, but does it have the same gear ratio in the axles as a m35 because that would affect the speedo to.

 

[tm america]

its a deuce that came with single 11.oos on it same gear ratio they only made one axle ratio for the deuce 6.72 to 1 the speedo adapter has a different ratio for the 11.00s which are almost three inches taller than the 9.00s

 

[SasquatchSanta]

I think Stewart Warner makes little adapter gear boxes the fits on the back of the speedo. It screws into the speedo and the cable screws into it. I also think they are a series 666 or 777 --- not sure which one.

I've been meaning to look into this with me Car Quest dealer. With the 395X85R20s my speedo of off about 15%.

 

[tm america]

call boyce tell em what youre running they have the ratios for the different adapters i have one from a five ton my speedo is right with the 15.5s they are the same height as the 395s easy fix on the transfer case in place of the stock speedo adapter

 

[FreightTrain]

Saturn has them for $28.50 each.Page 5 of the M35 list.5 ton speedo adapter.

Edit-Just placed an order for one.Lets see if it is the right one!

 

[cranetruck]

References from your friendly -20P TM:

 

[dabtl]

I got 14 new 11:00x20 NDCC for V V A 920 to put on their deuce. I figured the five ton drive would work to recalibrate the speedo. Thanks for the confirmation Bjorn!

Now, where you come up with all these parts lists is still a mystery to me, but you readily share your knowledge with us.

 

[vtach]

Great, I will order a 5T for my deuce Monday. I did not want to order one until I knew if it would work or not.
Thanks.

 

[cranetruck]

Double check the NSNs, the 5-tonners have different axle ratios.

 

[vtach]

Will the NSN tell me if it will work or not?

 

[tm america]

call boyce to find out the one you need before ordering it from saturn cuz there are different ones for the 5 ton there are different tires sizes and gear ratios i think they came with a 6.44 or a 6.17 11.00s or 14.00s so boyce has the ratios tell em what you have they will let you know what you need then you can price shop once you have the part number

 

[tm america]

i dont think the nsn gives a ratio its on the part itself the one i needed over drives the speedo by 15% over stock boyce can tell you the ratio of the different one availible the you can figure out which one you need just figure out what % bigger the tire is that you are running that is the % you will need to overdrive the speedo

 

[dabtl]

Double check the NSNs, the 5-tonners have different axle ratios.

You make me feel so glad that all I have to worry about are three deuces.