Hey I need some help I have an 1989 dodge 318 tbi with the 904 with over drive when I put it in deive and floor it it shifts at about 3500rpm I won't it to shift about 5000rpm what do I need to ajust or get to do this any help is appreciated thx
Need help with shift point
- Thread starter Terryp
- Start date
85crewcabbie
Well-Known Member
You need to adjust the throttle pressure linkage. There is usually a threaded part in the system for doing this or there is a slider type holder on the transmission throttle pressure arm. Since you have TBI, your throttle pressure actuator is probably a cable that will have to moved in it's bracket. You want to lengthen the linkage to increase the shift point. Find the linkage/cable that is attached at the carb and goes down to the trans directly above where your shifter lever attaches. There are two arms where I'm referring you to on the topside of the left front corner of the transpan. The lower arm is the shift selector arm and the upper, which is usually shorter is the throttle pressure arm. If the throttle pressure is controlled by the computer you may be out of luck.
7mopar
Well-Known Member
The adjustment is at the governor fork linkage attachment. Should look something like this. Will be just above the shift lever on the transmission. Adding tension to the spring should increase shift point rpms.
85crewcabbie
Well-Known Member
In the upper picture posted of the cables/linkages at the throttle body, the mechanical linkage on the far right with the flat, slotted bar, the U shaped pivot, and the additional linkage arm from the pivot down to one of the levers on the transmission are your throttle pressure linkage system in total.
Very easy to identify the throttle pressure rod at the transmission by simply trying to move the two rods, preferably with vehicle not running and in park and the E brake applied. The throttle pressure rod will move easily when pushed toward the rear of the vehicle and snap back to it's original position when you let go due to its spring loading. The gear selector rod will likely be immovable unless key in in the ignition and turned to on position. And if it moves it clicks because it has detents throughout its range of travel at each gear selection point.
In the bottom picture posted I can't tell which of the two arms are the throttle pressure linkage coming from the throttle body. If it is the linkage piece with the single bolt and spring on it, simply loosen the bolt and move the rod, in the clamp with the spring, forward so that less of the rod is sticking out of the back of the clamp. There is a limit on this adjustment at this point because there must be enough of the rod in the clamp for the bolt to tighten down on for proper holding. If it is the other rod/lever on the transmission there is no adjustment at the trans and you will have to follow the linkage up, toward the throttle body, to find/ locate another adjustment point in the linkage system. Mechanical throttle pressure linkage is always adjustable somewhere in the system. It will likely take a couple of tries to find the sweet spot your looking for as there is no magical formula like extending rod length 1/8" equals 1000 RPM shift delay.
Hope this helps.
Very easy to identify the throttle pressure rod at the transmission by simply trying to move the two rods, preferably with vehicle not running and in park and the E brake applied. The throttle pressure rod will move easily when pushed toward the rear of the vehicle and snap back to it's original position when you let go due to its spring loading. The gear selector rod will likely be immovable unless key in in the ignition and turned to on position. And if it moves it clicks because it has detents throughout its range of travel at each gear selection point.
In the bottom picture posted I can't tell which of the two arms are the throttle pressure linkage coming from the throttle body. If it is the linkage piece with the single bolt and spring on it, simply loosen the bolt and move the rod, in the clamp with the spring, forward so that less of the rod is sticking out of the back of the clamp. There is a limit on this adjustment at this point because there must be enough of the rod in the clamp for the bolt to tighten down on for proper holding. If it is the other rod/lever on the transmission there is no adjustment at the trans and you will have to follow the linkage up, toward the throttle body, to find/ locate another adjustment point in the linkage system. Mechanical throttle pressure linkage is always adjustable somewhere in the system. It will likely take a couple of tries to find the sweet spot your looking for as there is no magical formula like extending rod length 1/8" equals 1000 RPM shift delay.
Hope this helps.
85crewcabbie
Well-Known Member
PS - If I understood what 7mopar wrote I disagree (key word if). While his confirmation of the clamped rod with the spring as the throttle pressure rod should help you. Increasing the tension on this spring, to me, means compressing it, or inserting the rod farther into the clamp increasing the amount of the rod sticking out of the back of the clamp. This actually lowers the shift point RPM's and my understanding was you wanted to raise them.
Also understand that you have to decide between I want a full throttle, floored accelerator pedal, shift at 5000 RPM (what I assumed you wanted) and I'll live with the increased/lengthened shift points at part throttle while in traffic. OR I want certain shift points while cruising in traffic and I'll live with the shift point at full throttle, whatever it is. You can't have both.
Also understand that you have to decide between I want a full throttle, floored accelerator pedal, shift at 5000 RPM (what I assumed you wanted) and I'll live with the increased/lengthened shift points at part throttle while in traffic. OR I want certain shift points while cruising in traffic and I'll live with the shift point at full throttle, whatever it is. You can't have both.
7mopar
Well-Known Member
Lenghten it to far and the throttle body will not open up all the way. That will defeat increased shift points. Higher rpm shift points will also keep it from down shifting under load. Would be more practical to just manually shift when higher shift points are wanted.
85crewcabbie
Well-Known Member
I agree with 7mopar. You can only adjust it within a preset range. To much throttle pressure, as he suggests, and it won't upshift under pedal down, full throttle condition. You'll actually have to lift off the accelerator pedal for the trans to upshift. A clear sign you've gone to far with your adjustment.
Thx for all the help loving the adjustments I did struggled with them at first then figured out I was missing the spring that hold the kick down rod forward now adjusting it is working got the 1 /2 shift perfect but the 2/3 3/4 shift has a dead zone and takes a few seconds to down shift
85crewcabbie
Well-Known Member
Not that I'm aware of. If it were possible it would likely require removing and reworking the valve body inside the transmission. Even then I don't think it's possible but others likely know far more.