VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Sign of a Bad Kingpin?

Noticed a possible problem while rebuilding my brakes and putting in new brake lines.

Grabbing my left front wheel by the top and bottom while the car is jacked up, I can rock the top and bottom of the wheel in and out. I can't do this with the other wheel.

I seem to remember reading somewhere that this is a sign of a bad kingpin but I can't find where I read that (searched all over these forums).

The car (41 Special Deluxe sedan) does shimmy somewhat at above 40mph - haven't driven it faster than that yet.

So, is this a sign of a bad kingpin or something else, like a tie rod?

Thanks!

Check the wheel bearing adjustment and if still the same then it does indicate a loose kingpin.

Rocking the wheel like that checks for clearance in 2 places, king pins and wheel bearings. Get a friend to rock the wheel as you have while you watch form under the car you will see what is moving, if the top and bottom of the spindle moves it is generally king pin but if only the brake drum moves a second test is to try rocking the wheel with hands front and rear of the wheel, this shows play in wheel bearings and steering linkage / tie rod ends.
This is part of the roadworthy inspection for every registered vehicle more than 3 years old down here.
Tony

I have the tires off the car and can see the bottom of the spindle shifting a lot when I rock the drum on the top and bottom. Neither drum rocks from side to side.


So that seems to nail it - the tie rods and steering are OK but the left kingpin is bad, which means I should probably replace both. More fun!

Why would you feel the need to replace both? They are individual parts and wear differently. A bad (clogged) grease zerk can cause it to not get enough grease, and over time, it wears more than the other one that is getting greased enough. Just replace parts that are bad. And when greasing your car, pump until you see clean grease coming out; then wipe off all old grease. If you are not getting grease out, you are not getting it in; check the zerk.

You also could have a worn uppper pivot pin. That is at the top of the king pin support where it connects to the upper arm of the shock absorber.
You should haave a proessional check the front suspension including the pitman arm bushings, tie rod ends, king pins upper pivot pins and lower control arm cross shafts.

When I rock the drum from the top and bottom, I can clearly see the bottom of the spindle shifting back and forth as though the bushings or whatever should be holding it firmly is totally not doing its job.

I ordered a kingpin set from the Filling Station - comes with kingpins, seals, etc. for both sides. I go by the assumption that if you have two of something and one the wears out, it's only a matter of time before the other wears out, too. After all, the car is 77 years old. So, as long as I'm doing one kingpin, I might as well do the other, too.

I'll also be checking into new tie-rods, etc. for the front suspension. This wasn't on my list to do right away but the rocking of the wheel caught my eye and explained the front-end shimmy I was ocassionally experiencing.

Bottom of the spindle would be the lower control arm pin. t is a treaded pin or shaft that fits into a threaded outter housing. The threads wear due to lack of lubrication. The grease fittings were to be "greased" every 1000 miles.

Pretty sure nothing was greased on this car for at least 100,000 miles (can't tell because the speedometer was broken long ago).

Will the kingpin kit I ordered from the Filling Station fix this or did I just waste $70?

Either way if it were mine I would replave the king pins. could steer easier if nothing else.

It has been my experience that front end shimmy is caused by looseness- usually in the tie rod and/or drag link ends. The king pins definitely sound like they need replacing and I think you are on the right track by checking the rest of the steering parts. The tie rod and drag link ends I believe are adjustable.

The tie rod ends are of the ball and socket type and arn not adjstable and a 1941 does not have a drag link....how ever the pitman arm is two pieces bolted together with four hard rubber insulators for absorbing shoch. The insulators are usually junk causing slop in the arm and play in the steering linkage. See shop manual.

Looking at the illustration of the front suspension in the parts catalog and identifying where I see the movement, I would lay money on it being a bad kingpin bushing or, as Gene said, the lock pin. The way the lower part of the kingpin shifts, it's almost as if there is nothing at the bottom of the kingpin to stabilize it.

I'll get all the packed dirt and grime cleaned out from under there to find all the grease zerks, replace the kingpin assembly and then grease everything before diagnosing if anything else needs replaced. All of this, of course, after getting those darn brake lines to quit leaking. Still have the leaf springs in the rear to replace (they are perfectly flat and at least one leaf is broken in the left one) and put new gaskets in the rear shock absorbers - they seem to work fine after re-filing them but can see that they are slowly leaking through the rear gaskets.

As always, thanks to everyone for all the advice and help! I'll keep you posted on how it goes.

BJ
I am surprised you can see the actual king pin, there is usually a shallow cover (like a freeze plug) top and bottom.
I was thinking you had a solid axle therefore had not thought of the knee action joints, movement in these joints is checked in the same manor as king pins but are much easier to replace.
Tony

I can't actually see the kingpin itself but I know it's in there under the cover.

Hopefully, from the procedure I've read in the shop manual, these should be "somewhat easy" to replace, meaning I won't have to buy any new tools to accomplish it.

Yes, shop manual process works well for this.

It was not hard but I recall using my heaviest jack stands, having to buy a much larger ball peen hammer (fist side head or larger) and having to pound very hard with very little movement in the beginning..I also bought some cheap sockets to use as sacrificial "punches" and beat the heck out of them and they worked great. It was all about force in the correct direction.

Yes, kingpins can be difficult to remove. I have only done them on straight axles. For 2 of the 3 we had to remove the axle and take it to a machine shop so they could press them out.

One limitation we had was that without a lift we could not get the vehicle high enough to really get a good hammer swing to try to drive the pin up. As Tim noted one trick is to get it moving both ways.

The problem is caused by the fact that the kingpin is locked to the spindle support by the lock bolt. There is no motion between those parts and grease never gets there. So over time they just rust and grow together.

Your suspension has multiple pivot points so as Gene suggested you need to check them for wear.

Ahhh...I had my front sheet metal off so I could get full baseball style swings with the hammer without a problem.

YEP! Good to replace all three hoses if they look at all compromised. I was backing my '40 off a trailer and hit the brakes only to have the pedal hit the floor and the rear bumper hit a power pole with enough give to cave in the trunk lid... Since it had been sitting for about 30 years, I also flushed out the system and rebuilt the master cylinder and all four wheel cylinders. :-( Could also be cracks in the metal tubing.

Richard, yep, I've replaced all the hoses and lines along with a complete rebuild of all four drum brakes (new shoes, springs and cylinders). Flushed all of the old fluid out. Have a rebuild kit for the master but I'm leaving it alone for now as it seems to be working fine. Will probably rebuild it later but I've got enough other problems to tackle now (including rear suspension and kingpins) without creating more work for myself.

But I have another thread out there on the brakes and the problems I'm having with stainless steel lines seating correctly into the junction blocks. Hopefully, I'll have a positive update on that tomorrow.

On the bright side, I picked up my new white wall tires mounted and balanced on my newly-painted rims today! And I've discovered that tinfoil, a stiff vinyl brush and Brasso work wonders on old hub caps (amazingly, this car came with all four hub caps).

A few years ago I replaced a set of king pins in a truck, 14lb sledge hammer took several over the shoulder swings to shift them.
Tony

BJ,

I hope you have a manual.

Things to remember:

a. The bushings do not need to be reamed. They come properly sized.

b. The bushings go in a certain way so that the zets is aimed at the slot in the bushings.

c. Getting the plugs out of the bottom and top is a pain. The lock is not so bad. Try not to destroy. New ones may come with the kit.

d. A good long reach punch is needed to drive out the KP. Drive it out from bottom to top. Insert new one the same way.

e. Make sure you put the bearing in the right order. It is easy to get it on the wrong side of the support. Use the shim if you need it.

f. Drive out the lock pin carefully. Use a brass hammer or a loose nut so you don't brad the threads. Make sure the proper side of the KP is so that the lock ping goes in properl

g. Use some grease on the KP to help it slip in. Hammering in will be a littlel easier.

I just replaced the ones on my project car. A real pain in the axx. And I had the front sheet meatel off.

Good luck and keep at it. I wouldn't replace but one side. The bad one. No use fixing something that ain't broke. Just clean up the passenger side and lube it good.

Charlie

BTW: Just remember that installing a king-pin is not as simple as it may seem. Put it together right the first time oe you may have to backtrack. Not good.

The bushings are full floating............in other wors are free to spin on either side and are not pressed in.

Gee, but the shop manual makes it sound so easy!

I have the online manuals and I usually just print the pages I need off as I need them. Maybe I'll have to break down and find a printed one, though, so I can get it covered with greasy fingerprints.

Anyway, yeah, I'm thinking I'll probably remove the front fender before tackling it. Still fighting with the brake lines for now, though, and then I need to do the rear suspension so it may be awhile before I finally get to it.

Thanks all!

The king pins may drive out easier than you think. Do not remove any fenders at this point.