TH350 Pedal Mounted Detent Cable??

[TravisB]

I am working toward doing an LQ4 swap into my 78 C10 and had planned to keep the TH350 I have for the time being or for a long time if it lasts. Anyway, long story short, I would like to figure out a way to keep the passing gear cable and wondered if running it off the accelerator pedal would be a better solution that rigging something up under the hood. I believe some cars had it setup this way originally but I don't know which. Is there any ready made solution to this problem available or will I have to get creative? I have a drive by wire throttle body but I am not sold on using it. If I used it, there would be no throttle cable at all and I would have to do without or connect it to the pedal.

 

[AuroraGirl]

I am working toward doing an LQ4 swap into my 78 C10 and had planned to keep the TH350 I have for the time being or for a long time if it lasts. Anyway, long story short, I would like to figure out a way to keep the passing gear cable and wondered if running it off the accelerator pedal would be a better solution that rigging something up under the hood. I believe some cars had it setup this way originally but I don't know which. Is there any ready made solution to this problem available or will I have to get creative? I have a drive by wire throttle body but I am not sold on using it. If I used it, there would be no throttle cable at all and I would have to do without or connect it to the pedal.

you just need a bracket for .. wait.. how could it .. im not sure

 

[SirRobyn0]

I am working toward doing an LQ4 swap into my 78 C10 and had planned to keep the TH350 I have for the time being or for a long time if it lasts. Anyway, long story short, I would like to figure out a way to keep the passing gear cable and wondered if running it off the accelerator pedal would be a better solution that rigging something up under the hood. I believe some cars had it setup this way originally but I don't know which. Is there any ready made solution to this problem available or will I have to get creative? I have a drive by wire throttle body but I am not sold on using it. If I used it, there would be no throttle cable at all and I would have to do without or connect it to the pedal.

I'm not really sure I have a good answer for you. The TH400's used an electric switch for passing gear, but to my knowledge a cable off the accelerator pedal has never been done from the factory. I really have no idea how you'd hook that to throttle body, but I really think that would be the way to go. Hopefully someone that has been in your shoes will give some better info than I can.

 

[GXPWeasel]

Not what you asked, but if you're updating the engine, why keep the TH350 (other than cost savings)?

 

[Bextreme04]

Obviously the best drivability option with a DBW setup would be to run the correct 4L65e or 4L80e that would have come attached to that LQ4 originally. My vote would be for a takeout junkyard 4L80e. The only issue with that will be with the speedometer since neither one of those has a decent mechanical output option. The other option would be to hack together some kind of bracket and mounting solution from the old kickdown cable mounting hardware. You will have to make changes regardless for a whole new gas pedal anyways to use the DBW setup, so you should be able to make something that connects the kickdown as well. The only ones I've actually seen pictures of are brackets to adapt the DBC throttle body setups to use the kickdown cable. I did find lots of people that just didn't connect the kickdown and said it was fine without.

 

[bucket]

My '73 Chevelle has a pedal mounted detent cable for it's TH350. I didn't realize GM did such a thing until I got my car. Apparently '71-'76 B-bodies used a similar setup.

 

[TravisB]

Not what you asked, but if you're updating the engine, why keep the TH350 (other than cost savings)?

The LQ4 is in a 4x4 and my truck is not. I may upgrade the transmission later but I don't have one to use for now.

For now I am still in the brainstorming phase. Going back to the yard Friday to get the LQ4. I wanted to get this thread going in case someone else out there in square land has solved this one that I could copy their success.

 

[Matt69olds]

I think all the 69-72 GM A bodies used a kickdown cable that goes thru the firewall and is activated by the throttle pedal. The proper A body kickdown cables have only recently become available in the aftermarket. They are much more expensive than normal kickdown cables.

Technically, a TH350 does t have to have a kickdown cable connected. Unlike a 700, it has zero effect on line pressure.

The only issue of not running a kickdown cable is the trans will want to “short shift” at wot.

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Watch this video at around the 7:20 point, Richard discusses how to “trick” the valve body into thinking the kickdown cable is there. This won’t give you full throttle downshifts like a fully functional kickdown would, but for the cost of a pan gaskets it’s worth a try.

 

[TravisB]

Well, I have been working on figuring out how to convert the 4x4 4l80 in that truck the motor is in to 2wd and that might be the best option. It gives me an overdrive gear and would be more beef than the TH350.

I called the local trans shop and they offered to check it over and switch it for $350 and I am seriously considering that. There will be enough else to sort out and letting the experts handle that might be my best bet.

 

[Bextreme04]

Well, I have been working on figuring out how to convert the 4x4 4l80 in that truck the motor is in to 2wd and that might be the best option. It gives me an overdrive gear and would be more beef than the TH350.

I called the local trans shop and they offered to check it over and switch it for $350 and I am seriously considering that. There will be enough else to sort out and letting the experts handle that might be my best bet.

switching a 4wd 4l80 to 2wd is very simple if they already have it apart for an inspection. You have to disassemble the entire trans to get to the rear output shaft. The 2wd slip-yoke shaft can be had for $10(i bought one for my 4wd 4L80e to adapt to the NP205) and you can get the 2wd tailshaft housing for about $100. You will also need to use the 2wd rear lube plug with an orifice instead of the solid plug used in the 4wd units. Having a shop do all this for $350 seems like money well spent if you don't feel comfortable doing it yourself. Although a 2wd 4L80e core form junkyard should only cost about $2-300 depending on where you are.

 

[Matt69olds]

Not all 4WD have the tone wheel for the speed sensor. I found this out during my first 4WD to 2wd conversion years ago.


In addition to the output shaft, you need to make sure the tone wheel is on the rear planetary gearset. Otherwise the speedo won’t work, a d most likely the trans won’t shift right either. Pull the rear dummy speed sensor plug, if you see the stepped teeth, the gearset in the trans will work.

 

[TravisB]

Well, I guess we’ll figure it out. I’ll probably get the neighbor who runs a trans shop fix me up but it did look fairly easy on YouTube lol

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[Bextreme04]

Well, I guess we’ll figure it out. I’ll probably get the neighbor who runs a trans shop fix me up but it did look fairly easy on YouTube lol

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Oh man, was that thing in a fire?!?!? That engine looks terrible... I hope you got a great deal on it, because you are going to need to source a whole lot of other parts for it to replace the burned up stuff.

 

[TravisB]

Yep, been in a fire and I got a pretty good deal on it. The accessories should be easy to come up with in the junkyard.