Neutral position on speedometer on dodge t110

serge · #1 17-10-09, 21:01

Hello

CANADIAN DODGE T110 D60 L5 or CANADIAN DODGE T110 D60 L12 own a two speeds rear axle (the first with single rear wheels and the second with dual rear wheels).

During the restoration of it’s CANADIAN DODGE T110 D60 L5, my friend found a wire which began on the sihft used to engage the low speed on the rear EATON axle and ended to the speedometer.. On the DODGE T110 technical manual , in the chapter « rear axle », a method to adjust this strange system is described but we don’t have understood i’ts aim..
This system means that the speedometer has a neutral poistion !!!!

I suppose that when we drive the truck with the low speed engaged , the speed of the truck is very low and can cause damage to the speedometer due to the jitter of the arrow of the speedometer.
Is any body an explanation or had used this system?
The following pics show the technical manual copy, the system on the shift level and the hole and the wire on the front of the cab.

Regards to every

Grant Bowker · #2 17-10-09, 22:01

I have not seen or worked on the system you describe. My knowledge comes from manuals, not "hands on".

As I understand the system on these Dodge trucks, the speedometer takes its speed information from a gear at the rear of the transmission. If the speedometer did not have the adapter gearbox you describe it would indicate correctly in one of the two rear axle speeds, but be incorrect (by a factor of 1.391 which was the ratio between the two speeds in the rear axle) in the other one because the rear axle ratio changes after the point at which the speedometer gets its information.
They probably used the procedure shown of adjusting the cable with the axle and speedometer adapter both in neutral because both axle and speedometer adapter gear changes had a holding detent in neutral. Also using the middle neutral position will have less error in each gear than would result if the system were set up at one extreme of its travel and then moved to the other extreme.

serge · #3 18-10-09, 07:02

Hello Grant

Your answer would be right if the information was taken at the rear axle but on the DODGE T110 (all versions) the wire of speedometer starts from the gear box !!!
It's the reason for what we don't understand the system.
I thank you for your answer and we wait for other idea

Best regards

cliff · #4 18-10-09, 08:00

Quote:

Originally Posted by serge

Hello Grant

Your answer would be right if the information was taken at the rear axle but on the DODGE T110 (all versions) the wire of speedometer starts from the gear box !!!
It's the reason for what we don't understand the system.
I thank you for your answer and we wait for other idea

Best regards

The way I look at it is that because of the lower/higher axle ratio's the gearbox would spin at the same speed in either ratio, but the difference is that the forward/reverse speed of the vehicle would be greater in high ratio and slower in low ratio "for the same gearbox speed" so therefore the speedo needs to 'adapt' to the different vehicle speeds even though the gearbox gears are spinning at the same speed internally in the gearbox.

Hope that is understandable...well it is to me anyway

rob love · #5 18-10-09, 10:05

I think Grant's last sentence was bang on.

If I am reading this all right, the transmission turns the speedometer cable at a constant speed with relation to the output speed of the transmission. As such, it would only be correct in one of the two axle speeds.

There is a speedometer cable adapter, with a high speed output, a low speed output, and a slight neutral in between the two.

The adjustment is made with the axle shifter centered between high and low (it's neutral), and the speedometer adapter in neutral. The cable is slipped and adjusted to provide the proper length, so when the axle shift lever is in it's center of travel, the speedometer adapter is also in neutral.

This procedure will provide an adjustment that works off the center of the possible range of movement. Trying to adjust it from the high or low position could result in an adjustment from one extreme which may not result in complete engagement to the other extreme.

That's my 2 cents worth. I am not familiar with the particular truck you are working with. Am I to assume there is an inline two speed speedometer cable adapter or is the two speed adapter built into the speedometer?

serge · #6 18-10-09, 15:13

"IN FINE" I think that the explainations of ROB are right and the speedometer owns differents meshs (gear) . Inside the speedometer one group of mesh would be engaged when the truck is in high speed and the other group when the truck is in low speed.

Unfortunaly the truck of my friend is in BELGIUM and the pics showed at the begin of these thread had been shoted on and other truck which original speedometer has disapeared.

I will ask other information about the speedometer to my friend.

MLU forum is a wonderfull mean to understand what the old mechanics knew

Thank to all

Grant Bowker · #7 18-10-09, 16:40

Looking at the page Serge posted in the first message. it looks like the adapter is inline (possibly threaded to the input of the speedometer) rather than inside the speedometer.

Perhaps my first attempt at explaining what I though was designed here was not clear. I agree the information for the speedometer is taken from the rear of the transmission. The speedometer drive gear is clearly shown at the rear of the transmission in the maintenance manual. With the two speed axle being between the point that the speedometer gets its information and the tires, it is possible to have two different road speeds for one indicated speed. To correct for this the speedometer adapter would have two ratios (probably direct and 1.391:1 so that there is only one set of gears involved), different from each other by the same ratio as the two ratios in the axle.

Tony Smith · #8 18-10-09, 23:13

Quote:

Originally Posted by serge

Hello

CANADIAN DODGE T110 D60 L5 or CANADIAN DODGE T110 D60 L12 own a two speeds rear axle (the first with single rear wheels and the second with dual rear wheels).

During the restoration of it’s CANADIAN DODGE T110 D60 L5, my friend found a wire which began on the sihft used to engage the low speed on the rear EATON axle and ended to the speedometer.. On the DODGE T110 technical manual , in the chapter « rear axle », a method to adjust this strange system is described but we don’t have understood i’ts aim..

Is any body an explanation or had used this system?

Regards to every

There is a ratio adapter fitted to the rear of the Speedometer which changes the cable speed to match the selected diff ratio. In other respects, the speedo is standard.

See This thread

Grant's description above is correct.