Throttle Linkage Improvements

[Captain Obvious]

Does anyone make an improved version of the throttle linkage between the firewall and the intake manifold? Here's the part that I'm talking about:

I'm chasing sticky, non positive throttle action and have found that my throttle linkage is sloppy and worn at the plastic pivot up by the firewall:

I know I could clean and lube it to fix the sticky part, but that won't do anything to fix the sloppy part.

Are there aftermarket options out there or am I looking at a custom repair?

[FastWoman]

Like you, I hate sloppy throttle linkages; however, I've never had problems adjusting my Z's linkage to get the slop out. I'm surprised just how durable the linkages are, including the plastic parts that miraculously don't break when you pop them off of the balls. I'd just try adjusting out all the slack and lubing the thing up. If that doesn't work well enough, find a used part. If it's like mine, it won't be worn out.

[ZCurves]

If you are looking for a replacement, remember that you could source a part from ANY L28 powered Datsun since they all had the same linkage. I wonder what the latest 810 (Maxima/Bluebird) linkage would fit my '78 ?? Also I have found that when lubing the Ball and Socket assy, you can clean the tiny hole in the socket piece with a Brad Nail and then fill with White Lithium. When you pop it back on the excess will squeeze out of the tiny hole, which tends to leave an adequate amount in the socket.

[olzed]

I seem to remember there was a linkage made that went some way to fixing the jerky feel of the 240 throttle .

I think it altered the ratio somehow.

Does anyone know of this.

[Zed Head]

I've had the same problem with sudden throttle opening from idle, on my 76 280Z with EFI. I cleaned the throttle body, got a softer return spring and lubed up all of the various joints, but still had it.

I fixed it by adjusting the linkage so that the bell cranks go less "over-center". Pretty sure that I lengthened the linkage rod that is parallel to the the firewall and shortened another. Or vice-versa. You can tell just by looking which way to adjust. The problem was that the bellcrank would go over center when the throttle was closed, then take a lot of effort to get it to go back over the top when giving some gas, then once over the top you got sudden movement and a jerky throttle response.

It made a big difference and I have smooth off-idle throttle control now. Just pop the rods off with a twist of a wide blade screwdriver, loosen the set nut and turn it out. I turned one all the way out.

18 in this picture is one of the two that I adjusted. The other is close to the throttle body (Edit - actually I might have adjusted the one that comes through the firewall also - I just kept adjusting until all of the bellcranks were sitting at about 90 degrees). http://www.carpartsmanual.com/datsunS30/DatsunZIndex/Engine280Z/Accelerator/tabid/1624/Default.aspx

After adjusting you'll probably have to re-set the gas pedal stop under the pedal to either avoid bending the linkage or to make sure you get full throttle.

Edited April 16, 2012 by Zed Head

[Captain Obvious]

Thanks for the tips guys.

This whole thing started with a hunt for an issue where my throttle would sometimes hang up just a little bit and I would have to blip it to get it to return to the low end idle stop. I started at the front end with the throttle body and have been working my way towards the pedal and have found and fixed lots of problems. I have also figured out what's going on... All of the issues I've found stem from the root issue that my previous owner got overzealous with the bead blaster and hit everything. The car sure was clean when I bought it, and now I've begun to understand why! :mad:

So I had glass beads in my throttle body and TPS making the throttle shaft movement grainy. I had glass beads making all of the ball and socket joints sticky. I had glass beads in the sleeve bearings where the throttle linkage mounts onto the intake manifold. I had glass beads grinding away inside that plastic spherical bearing.

Anyway, everything else has cleaned up pretty well and doesn't seem to be badly worn with the exception of that spherical bearing at the firewall. I guess I'll clean that part up as well and put it back on and see what happens.

On a related note, I figured out why I wasn't getting full advance on my distributor. Yup... glass beads mucking up both centrip and vacuum advance mechanisms.

[Travel'n Man]

You can always get the LOKAR throttle cable - it works great and get rid of the throttle surge and all slop or you can do this:

http://www.classiczcars.com/forums/showthread.php?30584-Accelerator-linkage-fix-questions&highlight=throttle+linkage

[240260280z]

about the bead blasting... weird.

My throttle linkage was horrible until I took it all apart, cleaned and lubed.

When I reassembled it, I made sure there was no play on the "pulling" direction when pressing the gas pedal. I figured, the slop in the return direction would be handled by the return springs. It made the car so much more drive-able.

[Captain Obvious]

about the bead blasting... weird.

Haha! Weird isn't the word I would use... :stupid:

So far things are going pretty well. This whole thing started with me removing that extra throttle return spring you noticed. Once I took off that extra spring, I discovered that the throttle would not always return to min. So it seems the previous owner put on that extra spring to fix the return problem, but in fact it was a band-aid and didn't address the root problem. He added more force but didn't fix the real problem in that it should not NEED more force.

After cleaning out all the grit, my throttle body movement is smooth and with the stock return springs, I get a good positive "clink" onto the idle stop each and every time. The linkage from the throttle body to the firewall is smooth and free turning as well.

Now that it doesn't take excessive force to close the throttle plate, I will take your advice on adjusting out all the slop in the pulling direction. My return springs now be able to do what they are supposed to.

[240dkw]

I seem to remember there was a linkage made that went some way to fixing the jerky feel of the 240 throttle .

I think it altered the ratio somehow.

Does anyone know of this.

This might be it, http://www.zhome.com/ZCMnL/tech/AccelLinkage.htm

Here is a photo of what I tried. I cut the main tube in half and the welded it back together at the new angle.

[Captain Obvious]

I like it. I'll probably do that once I work out the simple bugs.

Nice broken exhaust manifold bolt.

[240dkw]

I finally got a chance to plate the arm. Here is a photo of the modified arm(right) next to a stock one (left).