Accelerator Rod

[Wayne P.]

Would anyone know the thread size on a 1964 accelerator rod ?
would it be 1/4 x 28 or a finer thread ? Thanks need to get a die to go over threads.

[Joe L.]

Re: Accelerator Rod

Would anyone know the thread size on a 1964 accelerator rod ?
would it be 1/4 x 28 or a finer thread ? Thanks need to get a die to go over threads.

Wayne-----


I'm virtually certain it was 1/4-28. However, whatever size it was it was a standard thread size and not some "oddball" special thread. So, it was either 1/4-28 or 5/16-24 and I'm pretty sure it was the former.

[Wayne P.]

Re: Accelerator Rod

I checked the thread at work seems odd 1/4 x 36 fine.
Must be a special thread not on any chart I can find.
Thanks

[Rich G.]

Re: Accelerator Rod

Wayne

Yup, 1/4 36.

That's the conclusion I came to, also. Tough to find a die for that. I'm sitting on a new rod I can't install because I have to extend the threads and cut the rod because I've apparently got the wrong arm in the car.

I haven't done anything because the set up in the car works and I am not ready to dive into changing all the parts, but continuing the non standard set up by modifying the new rod bothers me.

[Bruce B.]

Re: Accelerator Rod

On my 57 FI car the throttle linkage was either 1/4 32 or 1/4 36.
Dies are available but are usually special order.
Tapsndies.com has a 1/4 80, now thats a fine thread.

[David L.]

Re: Accelerator Rod

The 1964 Corvette uses rod # 3825203 (UPC 6, sheet D2.00 in the AIM) and the 1966 Corvette uses rod # 3880168 but they both use the same swivel, GM # 3758592.
I counted 36 threads per inch on the 3880168 rod and it measures 1/4" in dia.

Dave

[Bruce B.]

Re: Accelerator Rod

Dave,

1/4 36 seems to be the standard for old GM accelerator rod threads.
Probably needed to get the "fine" tune.

[Michael H.]

Re: Accelerator Rod

And while we're on the subject, what was the first year that the throttle rod swivel changed from zincad (silver) plated with no grooves, to black plated with two grooves?
I know it wasn't 63,64 or 65 but I don't remember if 66 and later had the new style black with grooves.

Also, I agree, the thread was something around 32 or 36 threads per inch, as mentioned.

[John H.]

Re: Accelerator Rod

And while we're on the subject, what was the first year that the throttle rod swivel changed from zincad (silver) plated with no grooves, to black plated with two grooves?
I know it wasn't 63,64 or 65 but I don't remember if 66 and later had the new style black with grooves.

Also, I agree, the thread was something around 32 or 36 threads per inch, as mentioned.

Michael -

My '67 has the dark plated swivel with two circumferential grooves. The rod and swivel threads are 1/4"-36.

[Joe L.]

Re: Accelerator Rod

I checked the thread at work seems odd 1/4 x 36 fine.
Must be a special thread not on any chart I can find.
Thanks

Wayne-----


Well, I guess I learn something every day. I am amazed that such a thread pitch was used for this application but I suppose they had a reason. I don't recall ever encountering such an "oddball" thread size on a Corvette but it's been so long since I had any involvement with these throttle rod-equipped Corvettes, I'd likely have forgotten by now.

Addendum

McMaster-Carr has a 1/4-36 die available but only in the round style die (requires special die holder) and it costs about 45 bucks.

[Stuart F.]

Re: Accelerator Rod

While we're on the subject, how do you guy's set your throttle adjustment? I, back in the day, had a lot of buddies with heavy right foots. I would have them mash the throttle to the floor, then turn the swival until I had to just force it into the hole. Now days, the best I can do is have the wife or a neighborhood kid put their whipy foot to the floor, then add a few turns of correction for my masher. Just pulling the lever forward will never get it there to account for carpeting and floor mats, etc.

Stu Fox

[John D.]

Re: Accelerator Rod

The repro accelerator rods have been a problem child for many years. Seems manufacturers don't have enough pride to use the proper thread. I have seen 57 and up FI accelerator rods with 1/4-28, 1/4-32, etc. Problem comes when you try to screw an original 1/4-36 swivel onto one of these critters. As Joe Lucia said McMaster-Carr sells the die.
Just about any industrial tool supply should have the die. Also you might as well buy the tap to go with it. JD

[Rich G.]

Re: Accelerator Rod

The rod I got from LICS has the correct 1/4 X 36 thread.

[John D.]

Re: Accelerator Rod

Go on ebay and type 1/4-36 RH die. See a bunch of them available from China for 5.99 buy it now-or best offer. Includes free shipping to USA.
Would be good enough for limited use.

You didn't ask but the 63 to 65 FI accelerator rod from LI is right on the money. Thread, configuration and even has the MW stamp on it. Hard to tell from NOS.

[Timothy B.]

Re: Accelerator Rod

While we're on the subject, how do you guy's set your throttle adjustment? I, back in the day, had a lot of buddies with heavy right foots. I would have them mash the throttle to the floor, then turn the swival until I had to just force it into the hole. Now days, the best I can do is have the wife or a neighborhood kid put their whipy foot to the floor, then add a few turns of correction for my masher. Just pulling the lever forward will never get it there to account for carpeting and floor mats, etc.

Stu Fox

Stu,

I have always had a problem with my 63 adjusting the WOT position by the book. I am not sure if I have a incorrect lever but I can't get the bump on the lever to hit the firewall like the manual say's and as a result my pedal feels high when you sit in the car. The lever seems to hit the firewall at the bend before the bump would hit.

I wish other 63 owners would chime in and let me know if this is another early 63 thing or not.. My 67 (very original car) adjusts just like the book states.