Cascade Crew

townaj · Posted: Sat Dec 13, 2008 5:38 pm Post subject: Weird transmission thing

Ok so my 700r4 is acting kinda weird. When I accelerate hard the transmission will shift out of gear but won't shift up into the next gear. So it stays between gears for a while and the rpm's shoot way up into 5k and sometimes higher. I'm thinking this can't be good for the engine. Anybody have an idea as too what is happening? And maybe a fix? I'm putting in a t56 soon hopefully, but I need this tranny to last till then.

Aj

izcain · Posted: Sat Dec 13, 2008 6:05 pm Post subject:

Could be many things, What condition is the fluid in? smell burnt, ect? TV cable sometimes can do that as well as low fluid level or a burned band. Does it only do it in a certain gear or every gear or what?

townaj · Posted: Sat Dec 13, 2008 6:09 pm Post subject:

Well I just put on a new carb so I adjusted the cable. But I'll double check that and the fluid tomorrow if its not too crappy out. It does it in one gear pretty badly, the others do it too but not to the same extent.

chevymad · Posted: Sat Dec 13, 2008 6:13 pm Post subject:

What kind of carb and do you have the proper brackets for it? Transmissions with TV cables instead of kickdown cables need to have a very exact geometry for the bracketry. Otherwise you'll burn the transmission up in a hurry. When I put a holley carb on, I bought Holleys 700r4 tv cable brackets.. Transmission did NOT work right at all! The geometry of those brackets is waaay off. I ended up buying a very expensive bracket set from bowtie overdrives. The tv made easy kit. Made it work perfectly.

Anyway, make sure you have the right brackets and the cable is adjusted properly. If thats not it, since you're going to change the trans soon anyway, I'd try some magic in a can. Like transtune or lucas tranmission tune.

townaj · Posted: Sat Dec 13, 2008 6:22 pm Post subject:

Ok. And I think I have the kickdown not the TV, but I'm not sure. I'm pretty new to this stuff, I'm used to the Model A. I'm just not sure when I can get the new one in so I don't know if I should totally fix this or not. I still need parts for the t56 so who knows when I can get it. The carb is a Holley 4175 and it should have the right stuff.

chevymad · Posted: Sat Dec 13, 2008 6:47 pm Post subject:

700r4 is a TV system. th350/400 would be kickdown system.

Here's a link about the tv system and its geometry.

http://www.tvmadeez.com/article/index.php

There are other sites that will show you exactly what radius the attachment point has to be from the throttle valve rod, and how many degrees forward of the pivot point it has to be etc. That all has to be exact. Not only does the the tv cable control all the shift points, it also controls the hydraulic pressure in the transmission. If its set wrong, the transmission will slip and burn up. Makes changing carberators not such an easy deal.

townaj · Posted: Sat Dec 13, 2008 7:14 pm Post subject:

Oh ok. I think I understand it now. So I'm going to be getting rid of that cable when I switch to a manual right? If so then I won't need to mess with the geometry of the bracket correct?

Dewey316 · Posted: Sat Dec 13, 2008 7:26 pm Post subject:

That cable won't be there in a manual. If you are going to run the automatic for a while though, you need to make sure that TV is set up correctly.

townaj · Posted: Sat Dec 13, 2008 7:49 pm Post subject:

Ya I'm gonna check it tomorrow. But I'm not supposed to be driving it so it won't be used much until March. I bet I'll have the swap done by then though. So basically just check the fluid and make sure its adjusted right? I'll move the Model A out of the garage for a while I guess so I can work in the dry.

Twilightoptics · Posted: Sat Dec 13, 2008 10:33 pm Post subject:

If you don't have TV bracket, you wont be able to get it adjusted properly to the transmission.

The cable is a "throttle valve" cable. It basically tells the trans where the throttle is and varies the line pressure accordingly. If it's not adjusted right, it can shift late cause it's not getting the right pressures.

townaj · Posted: Sat Dec 13, 2008 10:38 pm Post subject:

Its not really shifting late, the shift points are fine. But it has a lag when shifting I guess. Like in a manual car, if you forget to let of the gas when you push in the clutch and the engine races. It's like its searching for the right gear. It's weird, I don't know how else to describe it. You'd have to ride in it I guess.

Twilightoptics · Posted: Sun Dec 14, 2008 12:55 am Post subject:

That's a late shift. :O)

townaj · Posted: Sun Dec 14, 2008 12:09 pm Post subject:

Isn't a late shift just when it lets the rpm's get too high before it shifts? That doesn't really seem like what its doing to me.

Twilightoptics · Posted: Sun Dec 14, 2008 12:53 pm Post subject:

Well you can think of it as late in terms of RPM... shifts too high in the RPMS.

Or late as in you're at that RPM but you're waiting for it to shift.

townaj · Posted: Sun Dec 14, 2008 12:56 pm Post subject:

Yea thats not really what its doing. It shifts out of gear at the right rpm, but it won't go back into a gear. Like its in neutral between gears or it can't find the next gear up.

chevymad · Posted: Sun Dec 14, 2008 1:06 pm Post subject:

Make sure about that tv cable.. hopefully you havent allready burned up the trans. Then add some magic in a can.. hope something is stuck in the valve body. I'm thinking the trans is probably over allready.

townaj · Posted: Sun Dec 14, 2008 1:13 pm Post subject:

Ya I checked the cable and it move a little bit further but not much. If the trans. is done its no big deal I guess. Ever since I got the car it has always shifted kinda jerky. Like going from reverse to park. Or park to drive. Or reverse to drive. Not while I'm driving though, its when I go between different gears with the shifter when I'm stopped. Is that normal?

chevymad · Posted: Sun Dec 14, 2008 1:15 pm Post subject:

Sounds fairly normal.. especially for a carbed car.. and maybe a higher idle then normal.

townaj · Posted: Sun Dec 14, 2008 1:23 pm Post subject:

Ok that's good. I set the idle at about 700 rpm. I figured that was a good speed. Sometimes it dips below that if its cold and I take it off of high idle too soon.

aaron_sK · Posted: Sun Dec 14, 2008 5:31 pm Post subject: