73 Mav. I have a new (reman) C4 tranny that will not shift when in drive. When manually placed in 1st it runs in first. When manually shifted to 2nd it shifts to second. When placed from 2nd into drive, it slips and goes into 1st. When I start in drive. it stays in 1st. Reverse works fine. This reman does not have a vacumn line. I had initially used a B&M cable shifter that I accidently clamped over what I believe to be the kick down linkage. I removed it and now am using the standard linkage. Any ideas as to what I should try next. Otherwise my 250 to 302 conversion went well. Tom
Tom, if it runs well in reverse then it is not going into second it is going from 1st to high. The intermediate band needs to be adjusted. If this is a stock transmission the loosen the locknut on the front band, tighten the adjusting screw to ten foot pounds and then back it out (loosen) it three turns. Tighten the locknut while you hold the adjusting screw to keep it from moving. If you can't adjust the band then it may be broken or it may have dropped a strut. Yiou will need to pull the pan and valve body to fix it if it is a strut - you will find the strut in the pan when you remove it. If it is broken then I suggest that you take it back to the rebuilder and have him install a new band. You might want to drive the car to the rebuilder so that he can test drive it so he knows what is wrong.
I am going to back up a bit here... Is the C4 a reman performance C4 or a stock build? If it is stock it has to have a vacuum modulator and a vacuum line to it. The vacuum line is a 3/16 or 1/4" metal line that is connected to the intake manifold vacuum and connected to the transmission at the vacuum modulator with a short piece of hose. (you shouldn't use a rubber hose all the way as it will collapse from the vacuum and cause more problems. With the vacuum modulator disconnected it will not shift from low until you are going between 30 and 58 mph (depending on the rear gears that you have) all the other gears 1,2 and R will work manually with the modulator disconnected. When in drive it will go to the lowest gear that is supported at WOT or when the manifold vacuum is below 1 in of mercury. be sure that you have filled the tranny by checking it's level with the engine running in Park.
Paul This was a Reman from Advance Auto Parts. There is a modulator at the rear of the Transmission but the modulator did not have vacumn lines. The Old transmission did have vacumn lines. It is a stock Transmission. I currently do not have the Kick down installed. I do plan on getting a kickdown cable once I get the thing to shift properly. So, If I was to take the modulator off the old transmission do I take the vacumn off the Carb or intake. Tom
PaulS Nevermind the question on the vacumn. I noticed in your post you mentioned the Intake. Thanks. Still a question on the old modulator working. I assume this is a late model C-4 transmission. Tom
PaulS I replaced the modulator with the old modulator and connected both line to intake. Still no shift. Any thoughts. Tom
Tom, The modulators with two connectors sticking out the side is for smog motors and make it shift at slower speeds than it should for best transmission function. You should put the new modulator back on - the vacuum conection is at the back of the modulator and is recessed into the modulator body. When you took the modulator out did a small rod come out with it? Did you put it back in when you put the modulator back in. The modulator rod MUST be in place between the valve and the modulator for it to work. If you don't see one then make one from a nail that is 1/8" in diameter and cut it 1.6" long. Use the bigger vacuum line that has vacuum all the time and block the other one off at the EGR valve or where-ever it connects.(probably a fitting tree) Check to see that the kick-down lever is working - I know you don't have it connected but check to see that the lever pushes down about 1 1/4" and then returns by itself under spring pressure. If it doesn't move then the tranny is defective and you need to either take it back for another one or remove the pan and valve body to check the plunger. If it works OK then the valve body was installed wrong and when you install it you need to make sure that the manual valve and the kick-down lever are working properly as you install it. It can be a little tricky but you can do it. If the lever is working then there are no problems in the linkage. If you checked the fluid level, linkage, get the vacuum line to the modulator and the rod is in place, then it should operate normally. If it doesn't then you have a defective tranny and you need to contact Advance and get it replaced. If they won't honor the warranty then call the Attorney General, Better Business Bureau, and the district manager of the store chain. Even if it doesn't resolve your problem it may keep someone else from getting burned in the future. You can contact me through email (just click on my name and then send an email) and I will do what I can to get you running.
PaulS- Right on. When I closed one of the ports, I had a T at the intake side so I wasn't getting vacumn. I put the new one on and connected to the intake. Transmission now shifts. Seemed to shift high when I first started but then shifted earlier when it warmed up. I ran out of Type F so I have to get another quart. Thanks for all your help with this. I am driving it to work for the first time tomorrow. Next project is to get the PS to work again. With my dynomax headers, I removed the PS and will need to reroute the hoses. Thanks again and also thanks to 71gold Tom
Tom, Good job! glad you stuck with it long enough to get it right. The next step you will want to do is put some insurance on it and a shift kit. The insurance is cheap - get a 20000 lb cooler and run it after your radiator cooler. That will make your tranny last twice as long. Then you can put in a TransGo 40-2 kit and then you will love your tranny. If you ever want one for a 400 HP engine let me know.... ever been to Seattle? It might be fun to travel to Colorado again. (jk)
