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Plenum and TV adjustment

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turbov6joe

Signal 1 J-12
Joined
May 22, 2002
Messages
2,220
I remember reading somehwere on this board that the larger Precision plenums can cause problems with the TV adjustment....something to do with where the TV bracket is located with the aftermarket plenum. Can someone please shed some detailed light on this matter? I did a search and could not find the info I need. I currently have a precision 70mm plenum and am having problems with line pressure and am wondering if this plenum has anything to do with it:confused: TIA
 
Just got a tranny from Brian Hoffer, he says "You will need to slot the 2 small mounting holes to move the bracket forward, as well as slightly bend the linkage bracket forward".

I've got mine almost back together, but still have to do this.
 
This is interesting. I have a Precision plenum and can't seem to get my TV adjusted right. I've had to move the cable toward the firewall almost as far as it will go, which would imply that if I had moved the bracket forward it would have accomplished the same thing.

Jim
 
This is interesting. I have a Precision plenum and can't seem to get my TV adjusted right. I've had to move the cable toward the firewall almost as far as it will go, which would imply that if I had moved the bracket forward it would have accomplished the same thing.

Jim

Same idea. I had my TV cable in as far as it would go and the shift was still soft. Even at WOT it would not ratchet out like most would. In the case of the Precision plenum I guess the position of the mounting amplifies the problem.
 
Just got a tranny from Brian Hoffer, he says "You will need to slot the 2 small mounting holes to move the bracket forward, as well as slightly bend the linkage bracket forward".

I've got mine almost back together, but still have to do this.

How much did BH say you would have to slot the bracket? What I'm going to do is drop the pan and watch to see if the TV valve seats fluch with the valve body. If it doesn't then I'll slot the bracket as much as it needs to get the valve all the way in as far as it can go.
 
No, sorry, never mentioned how much to slot the mounting holes. Maybe he'll see the post?
 
I pm'd Brian this afternoon about this problem and just noticed this thread. Guess I'm not the only one having this problem.
 
Scot W did some testing for me on this.
After devoloping a flare after a complete engine swap, he did the slotting and moved the bracket forward, and cured the flaring issue. With the different larger T-B and plenum combos, the trans has been left out in the cold. The geometry on the throttle arm has changed, leaving the cable to reset itself at WOT. Typically, the amount is 2 clicks of TV adjustment (that it resets). So, you are looking at approximatly 1/8 of an inch of slotting. Also, I slightly bend the throttle bracket forward with some pliers.

Kevin Mellander (inventor of the stage right brake) used to modify the linkage. But, for the life of me, I can not remember exactly what he did. But, it worked.

Maybe we can get Scot to post a pic for us.
 
Scot W did some testing for me on this.
After devoloping a flare after a complete engine swap, he did the slotting and moved the bracket forward, and cured the flaring issue. With the different larger T-B and plenum combos, the trans has been left out in the cold. The geometry on the throttle arm has changed, leaving the cable to reset itself at WOT. Typically, the amount is 2 clicks of TV adjustment (that it resets). So, you are looking at approximatly 1/8 of an inch of slotting. Also, I slightly bend the throttle bracket forward with some pliers.

Kevin Mellander (inventor of the stage right brake) used to modify the linkage. But, for the life of me, I can not remember exactly what he did. But, it worked.

Maybe we can get Scot to post a pic for us.


After all of this time chasing a 2-3 flair since the motor rebuild (plenum change as well) I'll be mighty pleased if this is the cure. I just dropped off my tranny last week to find out that all gears but 4th were toasted after just 17 track passes and a few hundred street miles:mad: I did notice that I had the TV adjuster all the way into the firewall and it stayed there even at WOT...makes me believe that this could be my problem. I should have the tranny back in a few more days. I'm going to put it back in with the TV set just the way it was, drop the pan, and take a look at the TV valve to see just how far it is pushed in.
 
As I think about it, I don't think I had any trouble when I first put that plenum on. I've had recent problems with lock-up, and now problems getting the shift points right, but I'm not ready to blame the TV bracket yet.
It does make sense that the thicker plenum would change the geometry, and in theory so would an RJC power plate. I have both installed.

I did notice that the cable would not 'self adjust' and that I had to hold in the tab and work the throttle in order for it to pull out. As a result, I don't think the cable is resetting itself at WOT. But now I'm wondering if the TV cable might be limiting throttle travel? I had to shorten the cable substantially by moving it back toward the firewall. I have it to where it's shifting okay but downshifts are funny. I'm going start a separate thread on that so as not to hijack this one.

Jim
 
As I think about it, I don't think I had any trouble when I first put that plenum on. I've had recent problems with lock-up, and now problems getting the shift points right, but I'm not ready to blame the TV bracket yet.
It does make sense that the thicker plenum would change the geometry, and in theory so would an RJC power plate. I have both installed.

I did notice that the cable would not 'self adjust' and that I had to hold in the tab and work the throttle in order for it to pull out. As a result, I don't think the cable is resetting itself at WOT. But now I'm wondering if the TV cable might be limiting throttle travel? I had to shorten the cable substantially by moving it back toward the firewall. I have it to where it's shifting okay but downshifts are funny. I'm going start a separate thread on that so as not to hijack this one.

Jim

Feel free to keep it going here as it applies to me as well. I'd like to know what all findings come as a result of this thread.
 
Feel free to keep it going here as it applies to me as well. I'd like to know what all findings come as a result of this thread.

Thanks.

I didn't put up another post because a quick search actually confirmed my suspicions. I have the cable too tight. The pressure is too high so downshifts happen too late and it is reluctant to drop to first.

I was goofing around with it last night. I don't know if it's the changed geometry or what but no matter how hard I pull on the throttle it will not self-adjust. It was limiting throttle travel the way I had it adjusted. I pushed it forward a few clicks and that seemed to fix it. It's amazing the difference just a click or two makes. Finding the right combination of shift firmness and shift points is like finding a needle in a haystack.

TCI makes a universal bracket for TV cables that might be easier to use than trying to tweak the stock bracket. They also have some good, clear instructions explaining how to set their adjustable cable (the principle applies to trying to set a modified cable arrangement). There are PDF versions of the information on their web site.

Jim
 
I got the tranny in today and immediately dropped the pan after the TV cable was hooked up to see what the deal was. At WOT with the TV adjuster where I normally keep it the TV piston was flush against the valve body like it should be. I pushed the adjuster all the way to the fire wall and went WOT...it self adjusted like it should to the position where I normall had it. I then buttoned it all up and went for a ride. I just started using syn fluid for the first time and immediately noticed that the tranny seems to operate smoother. The shifts, although quick and snappy are not violent like they once were. The WOT 2-3 flair I had is gone and the gear changes are quick like they should be....so far I'm happy...now lets see if this sucker holds up at the track:confused:
 
I went ahead and modified the bracket mounting holes and moved the bracket forward. Now the cable self adjusts to the right spot and the shifts are nice and crisp, and my 2-3 flair is gone. The cable ends up being about 1/8 inch out towards the radiator. Hope this helps.:)
 
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