I have been perusing copious articles regarding the function and adjustment of said "Downshift / TV cable " that is attached to the throttle body butterfly shaft assembly. I have read about the RPM, spring valve and governor function in managing shift points while driving and understand their use in regulating pressure to ensure efficient shifting relative to speeds and RPMs.

My question is, if I disconnect the "TV cable" at the throttle shaft assembly and manually shift my car, will doing so damage the transmission. I have read that small changes in the crimp and cable adjustment affect pressures that can increase or decrease pressures in the trans. If, with the cable disconnected, are the pressures regulated by RPM, spring valves and governor adequate for proper operation of the trans without damaging it by shifting manually?

My reasoning for the question is that the accelerator cable does not operate smoothly with the downshift cable attached. I am trying to get it where it is a smooth transition from idle to WOT. I look forward to your response. Thank you in advance.

 

My $.002.
If your acceleration is nice and smooth with the TV cable disconnected, the fault maybe with the TV cable.
I am not sure whether the governor alone will control your line pressure to facilitate the required shift points.
My recommendation (based on what you stated) will be to replace the TV cable.
I had a stiff accelerator pedal and found one strand of the cable broken and it was catching on the cable housing.
Replaced the 30 year old cable and now it is as smooth as silk.

 

Sanchez,
I have already removed the TV cable and the car will not shift through the gears. This is okay for me. I am a retired truck driver and prefer shifting the trans manually. I am looking to find out if driving without the TV cable will harm the trans.

Thanks for your input.

 

What transmission do you have?

 

Sorry, didn't put particulars. 1987 XJ6 S.III, BW66. I know the BW65 used a downshift switch, rather than a cable. Not sure how the BW65 managed oil pressure like the BW66 cable.

 

If it is not shifting with the TV cable disconnected, I would assume that it is staying in 1st gear.
Questions:
If you select #1 = 1st gear ?
If you select #2 = ??
If you select D = 1st gear ??
With the TV cable disconnected, the tranny is not able to increase/ decrease the line pressure required for the gear shifts based on engine RPM.
The BW 66 requires both the TV cable and the governor working properly for upshifts/downshifts.

 

That cable is essential to the operation of the gearbox ! it is not just a downshift cable, sometimes called a kick-down cable here in the UK . So if its stiff, check why and if necessary replace it.

 

Thanks guys. Appreciate the responses.

Just an FYI.
When the TV cable is disconnected, and the selector is in "D" the BW66 will start in 3rd. You can manually shift the trans, starting in "1" and it will move in first gear, but not upshift. You then can move the selector to "2" and the trans will shift to second, but not upshift to 3rd. You must move the selector to "D" to get into 3rd. There is no upshifting or downshifting with the cable disconnected. The trans actually acts like a manual. All shifting requires input from the selector. Not sure what the internal pressures are and whether they affect the trans adversely. That would best be answered by a trans tech familiar with band surface wear and pressurized clutch mechanisms.

Thank again.