GM Trans. TV cable adjustment

[DJ]

Anybody know how to adjust the TV (throttle valve) cable on a GM THM 250 transmission?<br /><br />This is a rear drive car.

 

[DaleT]

Re: GM Trans. TV cable adjustment

Djohns, this site might help you some I'm not sure but I ran across it once looking for info for the same style trans.<br /> web page

 

[SlowlySinking]

Re: GM Trans. TV cable adjustment

On a similar note and for what it's worth, the GM 250 is a great tranny when used with the proper engine, when some genius at GM coupled this to the 1970's V-8 diesel car engines, it quickly earned the nickname, Terrible-250. The 350 and 400 trannys used real machined steel parts, the 250 used stamped sheet metal parts, with the diesel's torque I made a lot of bucks replacing these cheap gear trains, most customers opted for a 350 or 400 tranny.

 

[Skinnywater]

Re: GM Trans. TV cable adjustment

djohns, having done tons of AT work but not necessarily the THM250. Most all control pressure cables have the same adjustment.<br /><br />At closed throttle position there should be "no play, no load". Meaning no slack in the cable and just at the point where the cable is being pulled.<br /><br />Slight (only) or minor adjustments can be made from that point to change shift points. Slack is a lower shift point but greater pedal travel for a downshift.<br />A greater preload on the cable the later the upshift.<br />However, bare in mind that the cable isn't meant as a means to adjust shiftpoints substantialy. That task is governor pressure. Control pressure shouldn't be made to adjust for faulty governor pressure.<br /><br />Since were here.<br />The other pressure is modulator pressure. This controls shift quality, a softer or firmer shift.<br /><br />If someone is more experienced here with GM, by all means go with thier suggestions.

 

[DJ]

Re: GM Trans. TV cable adjustment

Thanks everyone.<br /><br />The trans. is behind a 229 V-6. That engine couldn't tear up anything. <br /><br />I think I'm getting a handle on what does what.