C1 upper inner control arm shaft / bushing fit

[Joe P.]

Interference.jpg

i have ordered 3 sets of bushing now, and either they are far to loose as shown in the video link below or cause a large interference fit.


https://youtu.be/_vU3N0HLQ6w

[Dan B.]

Re: C1 upper inner control arm shaft / bushing fit

I would not attempt to re thread the shaft, you will ruin it. If you can get a good tight interference fit I would not worry about the exact differences. Once the shaft is threaded in it should be locked in place. Find a bushing that will give you an interference fit for the front (which you are replacing), weld it in and crank the shaft in to place. As long as the shaft can't turn easily in the tower, you should be good.

[Joe P.]

Re: C1 upper inner control arm shaft / bushing fit

I would not attempt to re thread the shaft, you will ruin it. If you can get a good tight interference fit I would not worry about the exact differences. Once the shaft is threaded in it should be locked in place. Find a bushing that will give you an interference fit for the front (which you are replacing), weld it in and crank the shaft in to place. As long as the shaft can't turn easily in the tower, you should be good.

Thanks, Dan.
The reason i am in this mess, is that i had to replace one of the shafts. Understanding that it had to be a tight fit, i followed the advice and posts of Tom Parsons, but i didnt check the actual interfernce fit.. When i started to thread it on the the bushing everything was going well until i heard the metal coming apart from the spot welds and actualy crack around one weld. The interference was to great and i broke the welds. This time around i want to make sure this doesnt happen again. Hence my question on what is the best way accomodate an appropriate interference fit.. IMG_8453.jpg

[Dan B.]

Re: C1 upper inner control arm shaft / bushing fit

Joe, You may have just been unlucky and had a weak original weld break. I would grind it smooth, weld in a new bushing, and crank in the replacement shaft. You or your welder can go beyond the factory spot welds and add a few more, it won't come loose if done properly. Good luck.

[Joe P.]

Re: C1 upper inner control arm shaft / bushing fit

Joe, You may have just been unlucky and had a weak original weld break. I would grind it smooth, weld in a new bushing, and crank in the replacement shaft. You or your welder can go beyond the factory spot welds and add a few more, it won't come loose if done properly. Good luck.

Thanks Dan, so the interference of .027" should not be an issue then? I cant seem to get it started on the one side and I was worried about pulling the one side bushing off again.. I would get the bushing tig welded around the entire bushing..

[Dan B.]

Re: C1 upper inner control arm shaft / bushing fit

I was hoping Tom Parsons would chime in (he's the expert), but I'll give you my experience with having done a few. From your picture in post 1, small end of shaft should pass through the front larger bushing without cutting the threads (loosely) and when the larger back end of the shaft meets the front bushing (larger one) you start the shaft EVENLY into both bushings at the same time. You will have to crank it in and it takes some force as that portion of the shaft that is in contact with the bushing is cutting it's threads in 2 places while tightening. I can't speak about specific clearances as I never saw the need to measure since the fit was tight. You can use a little heat if you need it to make things easier. Just to be clear, you would NOT install the end bushings before the shaft was first fully installed in it's final position in the tower.

In general, I don't recommend removing the original shafts if they are not damaged, usually its just the bushings that wear.

Make sure the surface is perfectly flat and parallel the other one before welding in the new insert.

[Gary C.]

Re: C1 upper inner control arm shaft / bushing fit

Joe,

Send Tom Parson's an email. Tom has written many excellent posts on C1's front suspensions. Tom's listed in the Member's List.

Gary
....

[Joe P.]

Re: C1 upper inner control arm shaft / bushing fit

Joe,

Send Tom Parson's an email. Tom has written many excellent posts on C1's front suspensions. Tom's listed in the Member's List.

Gary
....

Gary, I have been emailing Tom, during the entire rebuild of my front end. Just sent me a second email on this.. hope to hear from him soon...
While I was waiting on different size bushing deliveries, i was able to rebuild my steering and T-10 Transmission, this bushing / shaft is the only thing holding me from rebuilding the entire suspension..

thanks for the help
Joe

[Joe P.]

Re: C1 upper inner control arm shaft / bushing fit

Got a reply from Tom, he says:

IF, IF, IF, the shaft will bite into the bushing, Then it can probably be screwed in all the way. BUUUUUUUUUUUUUUT, yes, those bushings need to be solidly welded all the way around. Just a few tack welds will not hold the bushing.
If you have an additional LOWER-OUTER bushing, screw it TIGHT onto the other end of the shaft threads. Use it as a method to assist getting the shaft to screw into the new bushings. As you attempt to screw the new shaft into the bushings, then tighten the heck out of the outer-lower bushing on the other side of the shaft, then screw the shaft a little more, then tighten -----------REAL TIGHT---------- the bushing on the other side. Once the shaft takes a good bite into the threads of the bushings, it should finish screwing the rest of the way. Once the shaft is fully installed, it should essentially be seized into the spring tower!
Once, and if, you get the shaft to screw into the bushings, start taking measurements of the protruding threads on each side of the spring tower and MAKE ABSOLUTELY SURE THAT THE PROTRUDING THREADS ARE EQUAL on each side, as pictured.

100_1207.jpg


I will give it a try...

[Joseph L.]

Re: C1 upper inner control arm shaft / bushing fit

What does it take to get the shaft to screw in?
I stood and jumped on my 1/2" breaker bar to get the final amount of the shaft in, so that the protruding threads were even. That was an assembled '57.
It is a lot more than you will expect!

Joe

[Jake M.]

Re: C1 upper inner control arm shaft / bushing fit

I have the same questions and issues. The inserts/bushings easily thread onto the shaft just like OP's youtube video, etc

[Joe P.]

Re: C1 upper inner control arm shaft / bushing fit

I went through 3 sets of bushing and two sets or shafts i still had issues, Talked to THE vendor and they indicated the supplier made the bushings to the large end of ID spec. And they were expecting the next shipments would be better. However, Got very lucky that i got one of the bushing from another member that gave me a good fit.. in the end i ended up tack welding the rod to the bushing to make sure there was no play.. IF I every do this again, i know what i am in for.. Not planning on having to redo this job!

[Tom P.]

Re: C1 upper inner control arm shaft / bushing fit

Let me try to add a little information which may be helpful.
First, FROM THE FACTORY, the upper-inner shaft was an ULTRA, SUPER TIGHT FIT in the threaded inserts which were spot welded into the spring tower.
UNFORTUNATELY, because of not being lubricated regularly, the bushings, and threads on the ends of the upper-outer shaft, became worn excessively and they needed to be replaced. Back during prehistoric times, when GOOD QUALITY replacement shafts/bushings were available (GM, MOOG, TRW, etc), the inboard threads (which screw into the inserts) were GENERALLY about .008in over size, and it required an Arnold Schwarzenegger type person to screw in a new replacement shaft. And that's how they should fit--------------virtually seized into the threaded inserts in the spring tower.
And sometimes, even worse, BECAUSE OF NOT BEING REGULARLY LUBRICATED, the shaft finally became loose in the inserts which were welded to the spring tower. The BEST threaded inserts I've found were several years ago from Paragon (attached). As can be seen, the inserts attached have a straight surface where they fit into the hole in the spring tower. Whereas the ones that Jake has acquired have a radius. They should be straight so that they go into the hole and fit flush, as the original inserts did.
I have NO CLUE about the source for thise present day shafts/bushings/inserts. BUT ABSOLUTELY, FOR SURE, THE SHAFTS SHOULD BE ULTRA TIGHT ON THE SHAFTS. Thus, when a new shaft is installed properly, it should virtually be seized in the spring tower. The ONLY thing which should move is the bushings which are installed in the upper A-frame and screw onto the ends of the shaft.

LAST, I CANNOT EMPHASIZE THIS ENOUGH -------------------------- THESE PRIMITIVE FRONT SUSPENSIONS WILL OUTLAST US IF THEY ARE REGULARLY GREASED!!!!!!!!!!!!!!! YES, of course, I know it is messy. Just have plenty of rags available. And make sure when greasing each joint, there is grease squeezing out all around. Sometimes, there is a joint that does not want to take grease, so it may be necessary to let the car down on the wheels and jounce the car up and down a few times to assure grease goes completely through the joint-------------then grease it again.
Keep in mind, ALLLLLLLLLLLLL the joints in these early suspensions are metal-to-metal, and the ONLY cushion in the joints is the grease.
If you don't keep them greased, you are going to have fun like Jake and Joe.

[Tom P.]

Re: C1 upper inner control arm shaft / bushing fit

If a new shaft and threaded inserts cannot be located which fit ULTRA SUPER TIGHT, then about the only thing I can suggest is to reach inside the spring pocket and weld the shaft to the inserts. If the shaft is welded from the outside to the inserts, it MUST be a very small thin bead so that when the A-frame bushings are screwed onto the ends of the shaft, they do not bottom against the weld.

[Tom P.]

Re: C1 upper inner control arm shaft / bushing fit

Now, with all of the above said, there is also one more option.
The 49-54 Chevys used virtually the exact same front cross member/suspension.
If a 49-54 car cross member can be located, AND IF IT HAS TIGHT UPPER-INNER SHAFTs, even if the outer threads are badly worn, it can be directly swapped on a 53-62 Corvette and new shafts installed into the car cross member. Some additional holes will need to be drilled in the car cross member, but that is a non-issue.