I tried to get on the Chevy forum but I guess its not working right as it will not let me log on. My 1940 Chevy truck has a problem with its steering. It wants to follow every crack or bump in the road. It like every component in the steering system is ready to fall out. Catch is, Everything seem tight. I cant find any play in anything. Even the King pins seem tight. What am I missing? It basically has closely same steering system as the Model T. What am I missing?
It has lost its castor.
The first thing I would check is the alignment. It sounds like you have toe-out on your wheel alignment.
How much steering wheel play before truck responds ?
your caster angle is off
Is caster readily adjustable with this axle? Will in the original post notes it's similar to the Model T so I am assuming caster is not readily adjustable much like Ford's Twin I beam that required bending to adjust caster and camber.
The easiest adjustment to check is for toe out.
Also, has anything been done to the factory ride height of this vehicle?
my 46 2 ton does that as well i think it is in the steering box. post it over on the stovebolt web site.
Tom, To my knowledge the front end is original. I can find the alignment spec's for 1940 cars but nothing for trucks. I guess it should be the same for cars and trucks.
I used to own a very nice 1941. The steering gear is a recirculating ball and worm. Very easy to steer, but I don't think a 1940 has that. A good thing to have is the shop manual for 1940. It covers the cars and trucks.
It COULD be dry, worn out box, but you can easily test that by seeing how hard it is to turn and how smoothly it travels through its range while standing still.
These trucks have a a solid axle so you are limited to cranking (twisting) the beam, or, because the springs run parallel to the frame, you can try placing shims under the rear or front of the mounting pad that locates the spring to the axle.
You may also be able to cure bad caster angle by getting your springs re-arched or replaced with new ones.
After a little more research I found out that the front end spec's for a car is different for a truck. For what ever reason, I still can not get into vintage chevy or vintage chevy truck forum. Maybe I need to be approved before logging on. There just dosen't seem to be any information on the web for the 40 kc truck
It's probably just toed out. Easiest thing to check and easiest thing to correct. If that's the case it will try to follow every little ripple or crack in the road. They need to be toed in just a little bit.
What do your tires look like?
It turns out I have a shop manual after all. After digging through boxes of shop manuals I found I have one. Any time I'm at a flea market I tend to buy up any and all shop manuals and then forget what I have. I think this one might have come from a forum member.
Just in case someone else needs the spec's>
those front tires look better than the ones on my 2014 truck!
I think youre going to have to find an alignment shop that isnt afraid of 20th century cars.
Dale, The tread does look good but sides are badly weathered
A GOOD alignment shop should be able to fix your problem. Caster is corrected by bending the axle. KGB
Question: after a turn does the wheel spin back to straight ahead by itself? If it doesn't it could indicate a change if the front end OR something so tight it's affecting the steering. Like tight (or lacking lube) king pins or a dry tight box..
Charlie, The wheel will come back on its own. Everything is well lubricated and as it should be as far as front end parts. I was amazed at how tight all the front end components were. There is almost no free play between the steering wheel and the tires. I think somewhere in its past someone must have rebuilt the front end. I have to wonder maybe who ever did the job used car spec's instead of the specs for a truck. As mentioned, The truck wants to dance toward any crack or divot in the road. I drive it rather slow to be able to correct the action the wheel is taking me. She's a 78 year old truck. I expect it to not be perfit but I would like it to go down the road straight! There's been a couple of times that it down right scared me. I have an appointment at a place for the alignment. He just needs to convert whats in the book to what he can plug into his computer. I would had preferred an old school alignment but that dosen't exist any longer.
Check all the specs to know what way to go. Chevrolet in 1940 would have some form of independent front suspension on the cars, but all trucks (including pickups) would still have a solid front axle just like most cars of the '20s.
Proper way to correct both caster and camber (after making sure all springs, shackles, and bushings are good and proper), is by bending the axle itself into proper spec. These days, this must be done by a truck alignment shop. No common car alignment shop is likely to have a clue how to get it right, even if they did have the means. There are no real cheats on camber. However, Caster can be corrected by putting wedges between the spring and the axle. They used to make steel wedges for this purpose, and they could have been bought in any decent auto parts store. These days, you may be able to find some on line, or make your own.
Besides everything else that's been said...Looking at a '37 Chevy manual, the steering gear box in a truck has the same worm end adjustment as out '53 Chevy which we had to adjust. The instructions are in there and it is doable if you have a big enough wrench. The box may also be loose from the frame, some have a spacer in-between. You may also check to see if the driver's front spring is worn more than the right side. Bounce the truck up and down to see if it starts to sway. If you have spring loaded connecting rods, check for a broken spring (we had that too). But a slightly twisted axle is more likely.
I would have to ask my self a few questions before diving in #1 has this done this right along or have you just bought this truck #2 have you changed any parts or tires and noticed the problem. Changing a tire and putting on a radial on 1 side will have the truck act up.#3 when you jacked the truck up did you put it on stands (2) one on each end of the axle to check for looseness and have a helper hold one tire still when you grab the other looking for loose parts. #4 do you have a soft or flat inside dual tire on the rear? The caster on a stake rack truck is more forgiving than on a short wheelbase car. I am sure it did not come into this world acting up. #5 Does it act up empty or loaded.
1- The truck came to me with this problem.
2- I have not changed any parts.
3-It has same size bias tires all around
4-I jacked it up and put it on two jack stands
5- Its a KC 3100 1/2 ton pick up, No duels
6- Iv never put a load in the truck other than the one from my pants the first time it tried to cross the road on me.
What about suspension? Broken spring? Anything that will let the axle shift around side-to-side? Bad king pins? Loose wheel bearings? Haunted by ghosts?
I would suggest to have front axel on jack stands, disconnect steering linkage from gear case, and then move linkage and check for movement. If acceptable, I would look for proper bearing adjustment and lubrication of the steering case.
Getting frustrated won't help.
It's possible that the forces from the truck that generate the problem are bigger than the energy used in diagnosing the culprit.
Our left spring was sagging more than the right. However the right spring had way more travel. We ended up replacing both sides and the problem went away.
If you are sure there is nothing mechanical wrong and suspect the tires, then just rotate them and try again.
Just thought of something else. If there is a worn spot in the gear box (worm or follower), it will only show up when the steering wheel is in that position, allowing the front wheels free roam.
You know Will can you please try to give us a better description about what the truck is doing besides "it follows every crack in the road"? You say the wheel spins back to forward as it should after a turn so what is it actually doing?
The truck looks like it may have been restored get printout of current alignment specs. it might have the front axle turned around so the designed positive caster may now be negative. also the "kingpin inclination angle" needs to be similar left and right if not that would indicate something bent!
I would check the front end over and look at the king pins and tie rod ends. Has the front end just been greased? Sometimes that can loosen things up a bit for a while. Also tires can aggravate the problem. Have a friend with a vintage car that would follow any and all cracks in the road. He had the tires siped and the issue went away. Tire siping puts horizontal cuts across the tread that makes old style tread look more like modern tires.
Jerry, The king pins and all other front end parts feel tight. I cleaned and repacked the front wheel bearings also. I don't think any of the spring are broken but I will look into it closer. If not an exorcism may be in the future. I might have to call the ghostbusters.
Bob, Iv learned it does no good to get frustrated, I thrown to many good tools and have learned that getting mad only makes me buy new tools.
George, I like your idea of possibly the axle might have been installed backwards. I'm going to look into that possibility.
Vern, I have an appointment for an alignment on Monday. I'm hoping that maybe a fresh set of eyes might see something Iv missed.
Bill, All the front end components appear tight with no slop. I was told that possibility the bias tires could be the problem, I'm not sure as I drove many years on bias tires before the invention of radials. If all else fails I will switch over to radials.
Charlie, Pretend your chasing a rabbit and your following every move the rabbit makes. That whats going on with the truck.No matter how hard you try you cant get the truck to stop following that rabbit.
Good point you mentioned... similar to a Model T problem...
" might have the front axle turned around so the designed positive caster may now be negative. also the "kingpin inclination angle" needs to be similar left and right if not that would indicate something bent! "
Bob, I agree. Giving the almost new parts in the front end makes sense that maybe who ever installed the parts may have switched the axle end for end. Iv got to much on my plate today to devote any time to the 40 so I will address it tomorrow.
If the guy who rebuilt the front end removed the axle, that may just be the problem.
Luckily, its an easy fix. Just raise the truck, drop the axle, the turn the truck 180 degrees and lower it back onto the axle- simple!
Dale, that how I swap my front tires and when I do the rear two, I have to remember to use "R" instead of "D".
I still would have it put on a alignment rack verify all the angles prior to changing anything, no use creating a bigger problem. After being in the automotive industry about 51 years. No one printed a manual for concerns created by someone else. Get a printout of the angles including the "KIA"
Often on straight axles supported by two semi-elliptical leaf springs, caster angle is adjusted by placing steel wedges between the leaf spring and axle. Camber on the other hand, can be a pain in the A-- to adjust. Typically it involves bending the axle.
Update on the steering issue on the 40 Chevy, The alignment shop says the alignment is perfit and all the steering components are in new condition. The problem is all in those old bias tires. Coker says they can fix the problem for just $241 per tire plus shipping for black wall tires or $265 for white wall tires. These are bias ply looking radials. The guy at Coker did mention that I may still have a slight issue due to the tire being so thin. So, I guess if I'm going to shell out big bucks I might as well go for the white wall tires. Now to just find the $1060.00 plus shipping. Would anyone like to buy an arm or leg?
Hey Will, tires are still cheaper than a new radiator. All kidding aside happy that the Mechanicals are okay and it's just the tires.
Didn't Coker have regular bias ply tires for your truck? Hopefully they would be a little less than the radials they are trying to sell you
Bob, I was talking to my local tire shop and they told me a 215-70-16 radial is real close to the old 600.16. I can buy 4 of them for about $100 each. All I got to do is throw a tube in the mix. I'm thinking about going that route. Is not like I'm going to drive the old girl to Texas and back.
Will: Ask if they have a tire in the 80 series that will fit. Mostly will resemble original .
Thanks Bob, I will look into them.