Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 13, 2025 ...

Transmission Speed

March 31, 2024, 03:01:29 pm

I have noticed on my Silverleaf that driving at 65mph that the transmission speed is showing about three bars into the amber zone you have to slow down to 62 or less to get it back into the green band. This does not seem normal to me. Any experience with this from others? I was going to call Allison and ask their opinion on this.
Thanks

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Re: Transmission Speed

Reply #1 – April 01, 2024, 04:17:21 pm

By Silverleaf, do you mean something that was installed by FT originally, or the VMSpc add on?

I have the VMSpc and all the gauges are editable.  I can set where I want the gauge to change colors, etc.  Maybe yours is this way too.

Also, 62mph is the slowest speed the trans will upshift into 6th in my coach, so I can't see how that would be into any "caution" range.

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Re: Transmission Speed

Reply #2 – April 01, 2024, 04:47:32 pm

It's not the add on. It's installed in the dash.  Next time I'll take a picture.

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Re: Transmission Speed

Reply #3 – April 03, 2024, 10:37:16 pm

This is at 65 mph. That doesn't seem right.

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Re: Transmission Speed

Reply #4 – April 03, 2024, 11:31:27 pm

777, I have an aftermarket SilverLeaf VMS645 11" dash in my older coach.  I did not know Transmission Speed (TS) was even a measured parameter until your post.  I cannot display TS on the home screen, and have never driven with scan mode...only Drive mode. TS display option for the scan mode was even "hidden" in my setup menu.

I'm parked until July, so can't do a test run to compare data.  If I do get unhooked for a fuel run before then I'll do a data check and let you know what I see. 

Transmission Temp is what is displayed on my home screen, has been my go-to for transmission load and health.  Since it seems almost no one else is even aware what TS means, I would ignore or even hide the info and drive on unless Allison can expound on what are the parameter specifications and limitations.  Try driving in one of the Drive mode pages...a lot of timely, useful info there.

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Re: Transmission Speed

Reply #5 – April 04, 2024, 11:42:35 am

That is my Home Screen in drive mode. I normally keep boost pressure there. But you can take the black knob and scroll through all the parameters. I plan on contacting Allison about this. It just seems unusual. Maybe it's normal or acceptable. But in the world I came from the amber band is not normal or a place you want to stay in for long. I'll post their response.

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Re: Transmission Speed

Reply #6 – April 05, 2024, 08:57:08 pm

The coloring of the gauge might not pertain to anything Allison setup and might just be what the programmer doing the display thought should be there. I'm guessing the first yellow bar is somewhere around 2100 rpm? That might be the rated speed for the engine so the programmer might be thinking that's the upper limit of how fast it would go. I'm guessing transmission speed is output shaft speed? Which when you are in overdrive will be higher than engine speed. So it could just be what someone one thought would be a good place to turn yellow.

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Re: Transmission Speed

Reply #7 – April 05, 2024, 09:23:00 pm

Well that's an interesting thought. I'll be curious to see Allison's thought on this is.

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Re: Transmission Speed

Reply #8 – April 06, 2024, 01:50:36 pm

I think Allison is going to say "Bring it in" and nothing more.

I believe that reading is the RPM input to the transmission.  The transmission has a maximum rated RPM input and it's saying you are close (if not) exceeding it.  But it must be incorrect since I doubt your engine is turning 2316 RPM (closer to 1500 right?).
I don't know if it's before or after the torque converter but it should be exactly the engine RPM if the converter is locked up and a little slower than the engine if not locked up.  If the speed really was exceeding the rated maximum I would think the transmission ECU would throw a "transmission" warning light on the dash and a code.  Can you read any codes on the Silverleaf?

I see two possibilities:
1. The actual speed sensor on the transmission is bad.
2. The Silverleaf is interpreting the data incorrectly.  I don't see how that might have changed but I don't know that system.

IF you take it to Allison they can verify the input sensor is ok or not.  They have a reader that will see the same data stream that the Silverleaf pulls from.

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