Machinist friends, I need some help!

[Matt Harwood]

I am sure there is a proper term for this, but I'm afraid I don't know what it is. I have a small stud that's 9/16" OD and a sleeve that fits over it that should be 9/16" ID. Unfortunately, either the stud is undersized or the sleeve is oversized by a few thousandths, enough that it wiggles a bit. I'm looking for a way to secure the sleeve on the stud to eliminate any movement so it doesn't rattle.

The application is the rear shock links of my '41 Buick. The NOS factory links I installed last summer have failed and since it's a Limited, replacements are all but non-existent (and will likely fail again). Instead of going that route, I decided to use heim joints (AKA spherical rod ends) instead. The mounting studs for the original shock links have a conical taper that holds them firmly in place in both the shock arm and the control arm of the suspension, and is secured with a nut. The original shock link has rubber bushings that are pressed onto these studs. The studs are still in place and I am using them as my mounting points for the new heim joints. Measured with a caliper, they're right around .5625, which is 9/16". 

 

Heim joints to replace original rubber bushings.

 

 
Original mounting studs have conical seats where they fit in the shock arms and suspension
control arm, so I would like to use them instead of a regular bolt.

 

I discovered that 9/16" heim joints exist, but they're $50 each because they're for the suspension arms on off-road trucks. However, 5/8" heim joints are $8. So I ordered four 5/8" hiem joints and four 3/4" spacer sleeves with a 9/16" ID and a 5/8" OD. They're from the same manufacturer as the hiem joints, so they fit perfectly in the bearing. Obviously, the issue is that the Buick parts are not quite 9/16, so the spacers are a little loose on the mounting studs and will clunk around when the rear suspension moves up and down. 

 

  
Spacer (red arrow) is a little loose on the mounting stud but fits perfectly inside the spherical bearing. Undersized stud is the problem.

 

You can see here how the link connects the control arm to the
shock absorber arm. Both ends are a little loose and
the total slop in the assembly is enough to create an

audible clunk/rattle when the suspension moves.

 

Question: Short of making new, slightly larger mounting studs with the proper conical seats to fit in the shock arm and control arm, how can I secure the spacer sleeve to the stud to eliminate the movement? Accuracy isn't critical, but it has to be durable.

 

Option 1: Epoxy, the hack mechanic's best friend. Smear some JBWeld on the shaft and inside the spacer, press it on, let it set up. Should eliminate movement, but will it survive the forces involved with managing the shock absorber and 5200 pounds of limousine?

 

Option 2: Solder. Sweat the spacer on like sweating a pipe. Will that work? Is solder strong enough? Can you even solder steel? 

 

Option 3: Skip the spacer and see if I can find some rubber, wrap it around the mounting stud, stretch it thin, install the heim joint, then release the rubber and hopefully it takes up the slack and provides some sound insulation.

 

Option 4: Something I haven't thought of yet...

 

Any suggestions would be very much appreciated. Thanks!

 

 

[Ronnie]

Silver solder might work for option 2 if you can get both surfaces perfectly clean. Regular solder probably won't work. 

 

Option 4 might be put the shaft in a lathe and knurl the surface to increase it's diameter so the spacer will be a light press fit on the shaft. It would have to be done with care to avoid increasing the O.D. of the spacer when you press it on.

[JV Puleo]

I'm not sure I understand the question perfectly but can you remove the part (center photo above) and ream the hole for a bronze bushing?

Failing that, I would use solder - probably the old fashion 50/50 lead/tin stuff and acid flux. That will stick just fine to mild steel. I had no problem soldering the hardened inserts into my valve adjusters.

 

Edit...I'd use "high impact" bushings - they have iron in the alloy. McMaster has them. I use them where there is relatively little turning but high pressure or repetitive motion.

Edited June 22, 2019 by JV Puleo (see edit history)

[Jim Bourque]

Making an adapter sleeve to fit the ID of the Heim joint and the OD of the stud would be a simple lathe project. Or look into a stud and bearing mount product if your clearance is only 10-20 thousandths. 

 

My question would be, how do you keep the heim joint/sleeve on the stud ?

 

Can you remove the stud from the frame?

Is there enough stud length beyond the heim joint /adapter to thread for a nut and washer? Drill and tap for bolt/washer? Cross drill, washer and split pin?

 

Jim

[Bhigdog]

Twer it me I would make new shouldered 5/8 studs that were a light press fit into the Heim ends, with a 9/16-18 threaded end to secure the Heim against the shoulder with a nut/washer. I'm afraid most any thing else is a jury rig at best. Not an especially difficult job but won't be cheap unless you have a very good machinist friend or can barter....................Bob

Edited June 22, 2019 by Bhigdog (see edit history)

[Matt Harwood]

New studs would be great but perhaps too expensive for a project like this--probably as much as another $200 set of links that will wear out in a few hundred miles. The conical seat is the problem--it's complicated but necessary. The heim joint setup will work as long as there's no slop in the assembly.

 

There's really only 2-3 thousandths clearance between the stud and the spacer; it isn't that loose, just enough to [maybe] clunk as the suspension moves. It's not 1/16" or anything like that. Just enough that there's a slight wiggle when the entire assembly is in place. That's all I need to eliminate. That's why I was thinking brazing or soldering, just to get some solid filler in there to take up the slack. Remember that the shock moves, so while the spacer is under stress it's not like it's solid and will be subject to massive impact forces. It just can't rattle or clunk.

 

For retaining the heim joints on the studs, my original plan was to simply weld a washer on the end of the stud (since it's ostensibly removable from the other end), but perhaps I'll drill and tap the center of the stud instead and use a washer and a bolt. There's not much lateral movement on the link, it would just be to keep it positively located on the stud.

 

I'll figure it out. Thanks for all the advice!

[Bhigdog]

If you're going to drill and tap for a retaining bolt use a wrap or two of shim stock to take up the slop. McMaster has shim stock or even use .001 or .002 feeler gage for shim. Jerry rigged but likely serve you for "Limited" use................Bob

[Stude17]

2 hours ago, Matt Harwood said:

New studs would be great but perhaps too expensive for a project like this--probably as much as another $200 set of links that will wear out in a few hundred miles. The conical seat is the problem--it's complicated but necessary. The heim joint setup will work as long as there's no slop in the assembly.

 

There's really only 2-3 thousandths clearance between the stud and the spacer; it isn't that loose, just enough to [maybe] clunk as the suspension moves. It's not 1/16" or anything like that. Just enough that there's a slight wiggle when the entire assembly is in place. That's all I need to eliminate. That's why I was thinking brazing or soldering, just to get some solid filler in there to take up the slack. Remember that the shock moves, so while the spacer is under stress it's not like it's solid and will be subject to massive impact forces. It just can't rattle or clunk.

 

For retaining the heim joints on the studs, my original plan was to simply weld a washer on the end of the stud (since it's ostensibly removable from the other end), but perhaps I'll drill and tap the center of the stud instead and use a washer and a bolt. There's not much lateral movement on the link, it would just be to keep it positively located on the stud.

 

I'll figure it out. Thanks for all the advice!

 

In the circumstances you describe it is as simple as using Loctite retaining compound.  A more than acceptable and adequate repair.

[Matt Harwood]

1 hour ago, Stude17 said:

 

In the circumstances you describe it is as simple as using Loctite retaining compound.  A more than acceptable and adequate repair.

 

Nice! I'll have some Loctite 680 in my hands tomorrow and we'll start there. If it works, great. If not, then I can braze it/make studs/something else. Good place to start. Thank you!

[PFitz]

I had a similar problem with shaft and sleeve worn too loose. . My bearing house recommended Loctite "Quick-Metal. 660. It's high strength, thicker and has better gap filling properties than the more liquid type locking liquids. It's solved many a loose fit problem.

 

Paul 

[Spinneyhill]

A clock maker would fettle the taper(s) to fit, either in a lathe or with a file. If the stud is then too small, a shim wrap (or a thicker bush like you have already) would work. Are all those Heim fittings the same taper on the stud? On re-examining, you could file or ream the Buick arm you are mounting the link to, to fit your Heim stud. The taper on the Heim stud is also longer than the original, so you will need a hefty washer under the nut.

 

As PFitz says, a chemical with gap filling properties is required. Loctite 680 fills gaps to 0.25 mm or about 0.010" and is for cylindrical fits, not tapers where the tapers don't match. Loctite 660 fills gaps up to twice that amount. These products are for cylindrical fits. I am not sure how they would work on a non-fitting taper. The other thing is that 660, for eg., is less than 1/10 the strength of the steel. I am not sure these products are suitable for this type of fitting problem but could be worth a try if you are able to clean them off so you can try another fix method later.

 

The taper on these fittings is typical of those on tie rod end studs and drag link studs, for example. For your 1941 Buick, the tie rod end studs (1314778L) are 0.703 to 0.609 over 3/4" (as for all 1938-42 Buick cars). Maybe your shock absorber links are a similar taper?

Edited June 22, 2019 by Spinneyhill (see edit history)

[Bhigdog]

Most bearing bedding compounds are used to correct a loose fitting bearing race that is not subject to shock type loads. Worth a try but likely to fail at some point.........Bob

[Matt Harwood]

The taper is on the mounting side, not the link side, which is ostensibly why the studs are permanently locked in the shock arm and lower control arm. The studs onto which the link mounts are straight. They're a little under 9/16 so I have the spacer that fits with .002 or .003 clearance, which hopefully the Loctite 680 retaining compound can fill. If not, I may try to braze it, which can definitely handle the load.

 

in the meantime, I was at the auto parts store and spotted some high-durometer rubber bushings for shock absorber mounts, so I bought a set and used my drill press to whittle them down to about the right size to press into the original shock links. Then I drilled out the center of the bushing from  about 3/8 to 15/32, and pressed them onto the studs in the car using a C-clamp. To prevent the links from sliding off the studs again, I drilled and tapped the center of the studs for #10-24 screws, used a 1-inch washer and a lock washer, and screwed them into place. Voila! Original shock links working and hopefully durable enough to survive another few years.

 

 

 

 

 

However, I did order the Loctite 680, which I'll have next week, and if the links fail, I have all the parts I need to install the modern links. I feel kind of bummed I didn't get to use the new stuff, but at the same time, the original stuff is probably a better choice. 

 

Thank you for the help, if I go with the heim joints in the future, I'll report back on the results. Thanks!

[Spinneyhill]

Good stuff. I hope it works.

 

I was imaging that the parallel side end of the studs was integral in the link, perhaps rivetted over a washer or similar to hold the rubber bush in. The tapered bolt part would then be bolted into the shock absorber arm or the bottom mounting? That would mean the shock arm and the bottom mounting hole would be tapered to fit the taper on the bolt fitted permanently to the link?

 

If this is the case, the shock arm and bottom mounting taper could be changed to suit the Heim links if necessary later.

[Stude17]

Replacing the rubber bushings in the original links is a great fix and should be as good as the NOS originals and perhaps better depending on the quality of the rubber.  I would have liked to see a larger bolt to retain the link but there should not be too much lateral load on it.  With respect to using Loctite do not underestimate its strength and with a 2-3 thou gap it would be the perfect option to retain the bushes.  Machining tolerances are declining with the use of Loctite no doubt to decrease costs. 

[PFitz]

13 hours ago, Bhigdog said:

Most bearing bedding compounds are used to correct a loose fitting bearing race that is not subject to shock type loads. Worth a try but likely to fail at some point.........Bob

 I tried to get a Quick-Metal repair undone. Trying to press and then hammer the parts apart didn't work. I had to heat the parts with a torch before the bond would release. Really holds even with shock loads.

 

Paul

Edited June 23, 2019 by PFitz (see edit history)