quote:

Hi Bill,

Please place these photos in the Barthmobile site with the below info.







The other day I had cleaned the tires on the Barth and then used sun protector spray on them. As I got to the right rear wheels,
I sat down on the ground to use the protector and noticed something hanging by the wires next to the transmission.
It apparently had vibrated loose from the top right hand side of the tranny.
I managed to bolt it back in place by using needle nose vice grips (not the best way). I could not find a wrench thin enough or with
an angle to allow it to fit on the nut.

My question, what is it for and could something else be missing from inside of it.
I thought this is why I lost my speedometer but it still isn't working.
Has this anything to do with the tranny temp gauge?

One larger wire in it seems it ought to touch a contact on the tranny, however as I said I don't know if a spring or something
else was inside and was lost.

I was thinking of driving to Fort Myers to the Allison shop but thought maybe someone could advise me on this and save me a
trip.


Thanks,

Jim

1985 Barth 35ft Regency MCC
Detroit Diesel 225HP - Allison 4 speed

My answer: You have 2 sensors there - a VSS or Vehicle Speed Sensor and a Hall Effect Sensor.

Both are in series and will control a speedometer. There is a small shaft in there turning a gear drive. You need to make sure it is not broken.

Anyone else want a stab as to why there are two of these?

Could this be the Speedometer Ratio Adaptor and the 2 "mini-gens" (generators) that are stacked on top of it?

If so, the Speedometer Ratio Adaptor is a thingy that threads into a port in the transmission. It has some gears and a couple of shafts inside.

Everything in that area of the tranny sits at weird angles and it is tough to get any type of tool near it.

On top of the Speedometer Ratio Adaptor are 2 thingys called mini-gens.

To the best of my knowledge, one sends a signal to your speedometer and one sends a signal to your cruise control.

This may answer why your cruise isn't working.

-OR-

I
...possibly I have no idea what I'm talking-about...

Thanks Bill & Mac.

I never thought of it, but I did lose my cruise control at the same time I lost the speedometer.

I could not tell if something was missing from inside of it, however I just have a feeling there was.
Does anyone have pictures of what would be inside of it?
Would be best to drive it down to Allison and have them check it or at least show me what could be missing. I don't think I want to tackle getting it back off and putting it back on.

Thanks again,
Jim

3 years ago, this June, I had a failing Speedometer Ratio Adapter [SRA].

The SRA plugs into the Speedometer Drive Opening on the transmission and is in a precarious location.

It does not look "precarious" until you actually get your hands up in there or attempt to find a layman's tool that will fit into that space and allow-you to turn the nut.

I removed the SRA and took it apart. I think it had 5 gears and 2 little shafts in it. Some of the gears looked pretty chewed-up.

There were no identifiable numbers on this unit.

My diesel mechanic was able to find, what he thought, was a match to this unit and installed-it.

I had a call in to him at the time to provide a part number, but he never got back to me and I was traveling at the time and forgot to get back to him.

If you search on ebay, you will find these SRAs. My coach is a 1990 and yours is a 1985. Your SRA looks different than mine, but both types are listed on ebay with photos.

The confusing part, is there must be a specific RATIO that you need to know to get the right thing. This is why I have no idea how my mechanic knew which one to get.

I would imagine it has to do with the type of transmission and *maybe* your tire size in order for your speedometer and odometer to be accurate.

My speedo and odo ARE NOT accurate according to GPS.

My tires are currently Goodyears and the originals were Michelins. The Michelins were a taller tire.

So, now I question whether or not I have the correct SRA in there since the repair.

Then the 2 devices attached to the SRA are called Mini-Gen Signal Generators. I think a company called Woodward makes these.

They have a shaft running thru them, which, in-turn, spins a little signal generator that sends an electronic signal to your speedo and cruise.

One stacks on top of the other and the shafts spin thru them.

To me, it is a somewhat precarious design and smells of failure; with so many little devices connected together and sticking out of the side/top of the transmission.

In your photos, it looks like the end of the mini-gen is packed with grease and you might be able to see the end of the shaft right in the middle.

If you do go to Alison to have this investigated, be sure to get all the numbers and information you can, as I did not do a very good job of this while mine was being repaired.

Look on-line at a few of these devices and you will find exploded views.

It's basically a shaft to shaft to shaft, mechanical operated system.

...and you might want to verify all of this, as I am only speaking from what I saw and what appears to be a fairly simple concept...

It also seems to me that there was a bracket that held/supported those mini-gens, but I don't remember from 3 years ago.

My coach is at my other house and I might be there for a while today before work.

If so, I will crawl underneath and have a quick look.

Otherwise, I will be there tomorrow.

Mac,

Thanks for the additional info.
In reference to the tires I did the same thing,
I went from Michelins to Goodyears.

I have HHT (vein disorder) and it is becoming more difficult (as I get older) to crawl under my Barth without having pressure in my head which causes nose bleeds. Most of the time I have to put something under my head/neck area to hold it up. With that said I still do it but slowly and is the only reason I may just take it down to the Allison shop. I try not taking it into shops as it is just getting so costly. Beside it is interesting to learn what all these things do.

Jim

Here is the OLD Speedometer Ratio Adaptor that was failing and removed/replaced 3 years ago.

It does have some embossed information on it:

SS White [Company] - 700 Series

The gears within also have some alpha/numeric identifiers on them as well.

Maybe Jim will become the expert on this subject an be able to enlighten-us on what some of this stuff means and how to determine what SRA goes with what transmission/tire confirguration.

I will get some photos posted from underneath the vehicle, but we have been getting some major rain here in Minnesota the past few days, so I have been delayed in that plight.

Mac,
Thanks for the additional info and photos.

I have an appointment with Allison shop in Fort Myers Monday morning.

When I put it back on I recall that both sections seemed to be loose. I would have had to take it back off to fix that.

I will post what they find and any numbers or codes.

Jim

quote:

Originally posted by Jim & Barb:
I have an appointment with Allison shop in Fort Myers Monday morning.

I will post what they find and any numbers or codes.

Received this from Jim

quote:

Bill,

Would you please insert this into my post - Hall Effect sensor- vss sensor-speedometer ratio adapter.

Today I went to the Allison transmission shop. They found that the drive pin which goes into the transmission and the other end into the speedometer and speed/cruise control was sheared off.
The had to drill part of it out. They advised that the speedometer and cruise control unit appears to be ok.
However the problem is they were unable to find a matching replacement pin. They even went into a box of very old stock and did some calling around and could not find a match.
They gave me two pins to take to a machinist to see if he could turn down the X part of pin (B) to match the correct end of pin (A). They have alot of pins but none matched mine.

Pin (A) the correct end fits into the control unit and pin (B) the correct end (square drive) fits into the transmission. The big problem, both of the correct ends have to be on the same pin.

Any ideas or suggestions where I could find one beside taking it to a machine shop.

Thanks,
Jim

eBay: Speedometer Gear Ratio Adapter. Small Part Kit - Auction 1 At this time, 9 are left

eBay: Speedometer Gear Ratio Adapter. Small Part Kit - Auction 2 At this time, 15 are left

The one on the right "Looks Like" it might work. For $9.00, it might be worth the trouble of ordering to see if it's the one. Maybe get 2 kits?

quote:

Pin (A) the correct end fits into the control unit and pin (B) the correct end (square drive) fits into the transmission. The big problem, both of the correct ends have to be on the same pin

It seems to me that the wrong end of pin A could be filed square like the right end of pin B.

Thanks Bill,

I think I'll give it a try for $9 ,would be a lot cheaper than having one turned down. If they are the wrong ones I could do like Dick Dubbs suggested and try filing a square end on one.
The one on the right in the picture you sent sure looks close.
The trouble is that so many of them at the Allison shop looked like they would fit but were just too large.

Thanks again guys for the help,

Jim

My question is where did they have to drill? Was it is the sensor or transmission? If it was stuck that badly there may be more to this than just replacing the pin.

Did they check to make sure the sensor was free turning? Something caused that pin to break. Maybe it was just because the unit came loose and got jammed but I would suspect there may be other causes.

Ed,

The part that had to be drilled out was in the drive section located on top of the tranny.
The sensor is free turning and all appears to be ok.
It is suspected that it sheared as the whole assembly vibrated loose from the tranny. Then just fell off suspended by the wires.

Just got off e-bay and ordered the kit. Now it is wait and hope it's the right one.

Jim

Just a quick update...

The pins arrived today, however as close as the one appeared, it did not fit. The square end was ok the other end just a "tad" too big.

I think I will be trying a dremel tool and keep taking off a little at a time (trying to keep in round)until it fits. Or try what Dick suggested and take the one pin and file a square pin on one end.

I just wonder what the purpose was to make so many different ones---OH YES- to drive me nuts.

Jim