Heim Joint Linkage...how to build drawings & details

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Heim Joint Linkage...how to build drawings & details

Postby JRGilbert » Sun Jan 14, 2018 2:32 pm

The attached link contains construction plans, list of materials and details on how to fabricate a Heim joint linkage for Weber IDF44 carburetors.
I hope this will be helpful to some of you.
It's an easy project and well worth the time to do.

Regards,
Jim

I Have removed the link from my Dropbox. See "Show off Photo Gallery for drawings.
Last edited by JRGilbert on Mon Mar 19, 2018 5:34 am, edited 2 times in total.
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Re: Heim Joint Linkage...how to build drawings & details

Postby Larry Jowdy » Mon Jan 15, 2018 1:23 pm

As many of you know, I"ve been modifying hex linkage for years. When I did the modification, I just cut off the stand that holds the ball that rides inside the hex bar. I smoother it out, drilled a hole in the base and inserted the heim joint. I then took a 5/16" bolt, cut off the hex head and rounded that end. I then drilled and tapped the inside of both ends of the hex bar and threaded the 5/16" bolt into the hex bar with loctite. I then used some fairly firm springs over the bolts and inserted the hex bar into the 5/16" heim joints. The springs kept the hex bar centered between the heim joints. This is an inexpensive way to ensure that your carburetors stay in sync.
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Re: Heim Joint Linkage...how to build drawings & details

Postby beck688 » Tue Jan 16, 2018 3:58 am

I did mine like Larry worked great.
Oh sh*t -- It was rocket science!
That's how my brain works. It's not a perfect organ.
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Re: Heim Joint Linkage...how to build drawings & details

Postby DannyP » Tue Jan 16, 2018 8:23 am

A California-based spyderclub member and I both did this same mod back in 2006. I can't remember if it was RS-60 Mark or if it was Spydermike. Hey it was eleven years ago. The funny thing is we did it simultaneously and without knowledge of each other! My hexbar was worn out after about 3000 miles.

I cut the ears off the CB carb bases and filed them flat as Larry explains above. I got 5/16" female rod ends, secured with a bolt from underneath. I used a piece of 5/16" hardened rod instead of a bolt in the ends of the hexbar. Often you can re-use your bar, but you can also purchase a longer one if needed. I bought one from CB I believe about 2" longer than what I originally had. I roughed up the one end of the 5/16" rod with sandpaper and then epoxied them into the hexbar.

You do need to make allowance for engine expansion. I left a 1/4" total gap engine cold and installed a spring between each rod-end and hexbar to accomodate the engine getting wider.

Almost 40,000 miles since then and virtually no wear. Great mod!

I did this mod on a buddy's Speedster which had steel baseplates. Used male heims and locknuts so we could adjust the height of the bar.

I don't think I have more than $20 in my modified linkage.
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Re: Heim Joint Linkage...how to build drawings & details

Postby danstern » Wed Jan 17, 2018 6:25 am

Larry did mine, so you know it works great!! Probably the best mechanical mod.
Best appearance mods are the aluminum half tonneau and the new rear clam.
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Re: Heim Joint Linkage...how to build drawings & details

Postby JRGilbert » Wed Jan 17, 2018 9:07 am

I've added some photos of the finished linkage. A picture is really worth a thousand words.
It's 10 degrees in Mississippi this morning...we're used to 56-60. Sorry for the quality.

https://www.dropbox.com/sh/4dnemmzloe33 ... 9pExa?dl=0
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Re: Heim Joint Linkage...how to build drawings & details

Postby RVosari » Wed Jan 17, 2018 1:48 pm

Hej Mr. Gilbert,

What is that spiffy looking chrome bug-catcher on your fan intake :)

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Re: Heim Joint Linkage...how to build drawings & details

Postby JRGilbert » Wed Jan 17, 2018 1:59 pm

The bug-catcher is available almost everywhere for about $13.
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Re: Heim Joint Linkage...how to build drawings & details

Postby SpyderMike » Wed Jan 17, 2018 10:03 pm

I wasn't me in 2006 DannyP...it is still on my to-do list some 11 years later. Great looking mod.
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Re: Heim Joint Linkage...how to build drawings & details

Postby RS-60 mark » Tue Jan 23, 2018 5:53 pm

It was me. Eleven years, they have flown by haven't they? I have about 25K miles since the heim mod. It is magic. Every year or so (actually I can't remember the last time) I stick the snail in the vents just as a matter of curiosity. I have never needed to touch the carb balance since making the mod unless I removed the linkage for some other mechanical reason. Even then, the balance was practically dead-on when the linkage was reinstalled.
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Re: Heim Joint Linkage...how to build drawings & details

Postby RandyM » Sun Feb 04, 2018 8:35 am

Hey guys,

I really need to get this modification done, but sadly my brain was not created with an engineering background.....Can someone send me a very layman version of either fix with some photo's ?

My car is "bucking" in second gear every time I hit a bump or other rough surface, it's so sensitive the slightest bump causes my foot to barely move and then my car turns into a wild horse.

I have the original setup from Vintage with the hexbar linkage. I know all the post state how easy this modification is but I have no idea were to even start, what to buy, what size, etc.......yep, carbs and linkage are not my thing.

Thanks for any help.

PS...Here's what I have now.
https://flic.kr/p/Hofi3Z
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Re: Heim Joint Linkage...how to build drawings & details

Postby Larry Jowdy » Sun Feb 04, 2018 9:01 am

what I've done for customers is to cut off the riser off the base of the air cleaner. It's the riser that holds the black ball stud. Once it's level with the rest of the air cleaner base I drill a 5/16" hole and in the center of the area that once occupied the riser. Then I drill and tap the ends of the hex bar to 5/16" Take a long 5/16" bolt and cut off the hex head and grind it smooth and loc tight it in place in the ends of the hex bar. Then install 5/16" heim joints into the holes you drilled in the air cleaner base. Insert the bolts into each end of the hex bar and place springs between the hex bar and heim joint. Once it's assembled re-sync your carbs and you're done. I've done several of these conversions for customers and all have been happy.
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Re: Heim Joint Linkage...how to build drawings & details

Postby DannyP » Thu Feb 08, 2018 4:36 pm

Larry explains it rather well, but I may have a picture tucked away from 2006. I know I posted them on here, but they may be too old to find in the archives.

Sorry, Mark, I forgot it was you. Getting older and forgetful...

Randy, loosen the throttle cable, mine bucked until I added some play. It's also possible your motor/trans mounts are shot.
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Re: Heim Joint Linkage...how to build drawings & details

Postby DannyP » Thu Feb 08, 2018 5:10 pm

I just searched for the original post and came up empty
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Re: Heim Joint Linkage...how to build drawings & details

Postby RS-60 mark » Fri Feb 09, 2018 11:41 am

My original pictures on spyderclub are long-gone too. So I just snapped one in the garage.

The way I went at it was first I made a bracket to bolt on with the existing holes in the aluminum carb bases' uprights. Next, as pictured, I mounted a 3/8" rod end (heim) on the bracket. Then, I then drilled and tapped the hex bar for 3/8-16 threads. I made the adjustable studs for the hexbar ends by cutting the hexhead off a 3/8-16 bolt, leaving about 1/2" of smooth bolt shank above the threads for bearing surface within the rod end. Next, I put a lock nut on each of the threaded studs and screwed them equally into each end of the hexbar until the end-to-end length to the tips of the studs was 1/8" less than the measurement between the heads of the top bolts on the rod end mounting bracket. Last, tighten the lock nuts on the stud against the hexbar.

In use, the hexbar free-floats between the heads of the top bolts on the rod end mounting bracket. Be aware that the dimension between these two bolts expands and contracts with engine temperature. In my case, I have always found my engine will "grow" when hot. Thus, I have set my free floating thrust to maybe as much as 1/16" when cold and rely on it to never be too tight because it can only "grow" with engine temp.

Initially, I was going to put a wave spring on each side between the lock nut and the rod end, but I found that the amount of side to side thrust travel of the hexbar was so small that I decided to simply let it free float without further methods to keep it centered.

Anyway, that's how I did it and it has completely eliminated what at the time was referred to as the "hexbar blues". It could have been made more simple by, instead of welding the mounting flange for the rod end in the middle of the bracket, just make the mounting bracket out of one piece of 1" 10ga with a 90* bend on top for mounting the rod end. Mount the rod end up-side-down so that the hexbar stud still bumps against the top bolt on the bracket.
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