Rev's Between Shifts Not Dropping
 

Over the last couple of weeks, I have noticed that the rev's on my SC are not dropping as normal between shifts. If I lift the throttle, give a momentary pause, then push in the clutch the revs drop as normal. This is the only issue and the car runs great otherwise.

Anyone have an idea where I should start my troubleshooting?

Check the throttle return springs both at the gearbox and at the throttle body itself.
If those are intact and not binding then check the area under the console where the clutch cable and throttle cables connect to the pedals.

One may be touching the other to cause the slow return.

If 1980 has a "Decel Valve", then perhaps it gave up.

Many unhook it anyway. If yours is still hooked up you can unhook, plug the line and see if the problem goes away. It's a pancake shape, on the passenger side of the airbox, above #5 and 6.


Also make sure something didn't change under the car near the trans to cause some binding with the accelerator/clutch cables.

Thanks guys. I appreciate the help.

I had this happen to me. It turned out to be the cruise control cable. It has a black plastic fitting where the cable attaches the throttle linkage. The little snap blades (can not think of a better term) broke and so when the throttle was released and returning to idle position, the black plastic fitting would get caught and would not allow the linkage to return to idle position.

I know that's probably clear as mud, but to see if you have the same issue: with the car not running, actuate the throttle linkage by hand and observe the cruise control cable. It will be fairly clear if you have the same problem or not.

Thanks, AlfonsoR. However the PO removed cruise from the car.

OK,

The accelerator linkage has these main parts, I'm going off memory and have not done this job my self. Maybe someone that has done the complete job can chime in:

1. pedal cluster: Pelican Technical Article: Pedal Cluster Rebuild

2. Linkage to transmission bell crank
3. transmission bell crank
4. linkage to engine bell crank
5. engine bell crank
6. linkage to throttle

Your problem has to be in one of these areas. The bushings in the pedal cluster are plastic so these wear down and can eventually cause the pedal to snag. Same thing for the bushings in the bell cranks, they can cause the linkage to snag.

There are bronze bushings you can purchase to replace the plastic, available through our host. You might want to start by eliminating each friction joint. Hope that helps.

Classic deceleration valve symptoms. Check this first and plug the hose. Don't think the linkage is binding or it would stick all the time.

Thanks for the help guys, it is very much appreciated.

Using basic trouble shooting, I went back to the last thing changed. At the November DE at VIR, my instructor didn't like the way I had setup the pedals and he changed the brake and gas pedal heights. So yesterday I went out and lengthened the accelerator rod to its original length. The issue immediately went away.

So, if I had to take a guess, one of the two ball joints wasn't fully engaged and when I reset the rod length, the reassembly was cleaner.

cool.

It's always great when it's an easy fix.

Fricke'n DE instructors, who do they think they are, anyway?