Me and the next door neighbor have been building a 29 roadster. The car is built and we are having problems with the front end. At approx. 60mph the front wheels start wobbling, they are not jumping up and down, they are wobbling. So far we changed the front end from a tube type to a brand new super bell axle, new kingpins, everything is new on the front end. It has made no difference. We have 1/8" toe in, 5 degrees angle on the axle to the rear. We have moved toe in from 0 to 1/4" and it makes no difference. We have moved the axle angle from 5 degrees to 10 degrees and no difference. The wheels are brand new, tires are new whitewalls and they have been balanced. We ruled this out by changing tires and wheels that did not shake, and put them on the car and it made no difference. The only thing not new is the Model A spring and frame. The frame is boxed. The last time I drove it tonight, the wheels and tires were wobbling so bad, they were chirping on the road. It does not matter how fast you drive, they still wobble. I have had some shakes that you can power on through on other cars and once you get through it, it is fine. This one , it does not matter. As long as you are under 50-55mph it drives like a brand new one. What in the hell are we missing????
] What kind of brakes are you running ? The reason I ask is ive had trouble with aftermarket kits and wheel bearings. Is seems some of the castle nuts you get along with the spacers and such to use after market discs dont adjust well. I now load up my bearings back the nut off to the first space for the cotter key then check to see how loose the bearing is. If I have any play (or too much Play)I put a shim bteween the center of the bearing and the washer then try again. I had one that was so loose after backing off the nut to install the keyway that it was nasty over 65 and deadly when I hit a bump. Just a little sumpin for you to check and I hope it helps Dave
Dave, we have disc brakes and rotors from Speedway on the front. We have checked the bearings, steering and everything else we can think of and have come up side a brick wall. This is not the first car we have built, between the two of us, we have built 10-15 cars and never had this problem. The car has a little bit of bump steer, but this should not be the problem, as my modified has 10 times as much bump steer and it does not shake like this one. My whole front end was pieced together out of junk and it handles way better than the one we are working on now.
If you can rule out anything loose, then the next thing would be to check the tires. A broken belt in one of the tires can cause a hop, bounce, or wobble. Had it happen to me a couple of times over the years.
What are you using to locate the axle? What type of tires/wheels are you using? On the tires, have you checked for flat spots or out of roundness?
My guess would be that you will have to install a steering dampner. If your running dics brakes, tighten the bearing snug and then go at least to next key slot.DO Not back the nut off as you would for the early drum brakes. Just some thoughts--Paul
Rej, I fought the same issue about 15 years ago on my old A, I ended up having to run about 1/8th-1/4" toe-OUT and it drove great....AND there was no strange tire wear out of the norm on a straight axle car. Glenn
Good idea. Sometimes swapping the nuts from side to side will get you where you want to go. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Where are you measuring the caster from? Comparing it to the frame or to a level floor? Caster is compared to a flat floor. If rake is severe enough that can pull 2-3 degrees out of the caster equation. One thing that I think helps on the solid axle cars is a panhard bar. Ch***is bracket on the same side as the steering wheel is. Make the bar as long as possible. If something is causing the axle to swing back and forth on the shackles the panhard will put a stop to it. Here's a pic of my 31's panhard axle bracket. It bolts up against the batwing. It's hard to see, but it's a flat plate of 3/16" CR with 3/16" CR tabs welded on. The batwing bolts hold it to the batwing. The pic of the 32's panhard bracket where it attaches to a 63 Chevy type bolt-on shock mount with the mount side sawn off and welded to a SuperBell tubular axle.
Couple of things to check: 1. Is the Ackermann correct? If you draw a line from the center of each kingpin to the center of the rear axle does the line p*** through the tie rod pivot point? 2. Is the front cross member square to the frame centerline? Is the frame square? Hope these help.
C9, I think you hit the nail on the head! I noticed that when the wobbling starts, it looks like the front spring is moving from side to side. I thought it was from the wobbling, but maybe that is the whole problem. I will not have time to put a panhard bar on it before I leave for the drags, but definitely will when I return. Thanks for all the suggestions and help, it is greatly appreciated.
Putting more caster in is the wrong thing to do. Try to take some out like down to 3 degrees.You didn't say if you are using cross steer or drag link style. If it is cross steer, you for sure will want to install a panhard bar. If all else fails, you can install a steering stabilizer available from So-Cal.
Try this simple test..... Get a buddy to sit in the car and steer it right to left/back and forth...observe and notice if the axle shifts/moves in the shackles..that will tell the tale.
It`s been my experience over the years that shocks play a big roll.Having done front end work for 30 years I have found that a wobble in the front end at speed could be shocks.
"Get a buddy to sit in the car and steer it right to left/back and forth...observe and notice if the axle shifts/moves in the shackles..that will tell the tale." ChopRods is correct, that is why I build my cars with a dead perch on the drivers side.
Hi , just got on to see what's going on and read the post. I think you left out a little important info on the type of steering setup you have. side steer or cross steer. Go back to your original settings 1/8 in, --5-7*, as you have established this as a base line, air the tires to 26 lbs. Drive the car at 10 mph increments until the vibration just starts. Determine if this is vibration is causing the steering wheel to move or the car just picks up a harmonic and the wheel is straight as an arrow. Most problems are caused by balance or movement and it is necessary to establish which. Since you changed wheels and this did not solve the problem. The next question is, did the steering wheel have movement. If it did, this is a tracking problem, if it didn't it is necessary to still check the balance. lets do one scenario at a time, Since the effect was the same with other wheels, remove the wheels and put a straight edge against the edge of the brake rotor and spin it to check round. If these are redrilled hubs or offshore units, line up a screw driver blade on the outside edge of one of the studs and slowly rotate the hub slowly to make sure that the hub is drilled on center correctly. If everthing is ok, Now swap tires side to side and repeat. If it is there and the steering wheel doesnt move the next test gets a little more complicated by using a spin balancer on the car. This will check the balance of the rotors. Hopefully you wont have to go this far, Scenario two, in the beginning, it was asked if the steering wheel moves, If you have a side steer car usually any spring movement is not immediately noticable, however in a cross steer car with out a panard rod the steering box becomes the locating rod and tracking problems begin. This is evidenced by a shimmy as the front end tries to continally center itself. This is not as noticable at low speeds as the sidewall flex of the tires masks the movement until the tire spin takes over, Some side steer applications, where the drag link is at an angle to the tie rod it acts similar to a panard rod but when you have both drag link and tie rod parallel the front end tends to want to locate it self and then the problems start. so before this turns out to be a book more info is needed from you on your front end setup. **** still ther
****, the steering setup is side steer. We have checked the rotors, hubs and wheels for straightness. Everything is straight. The wobble starts at 55mph and the steering wheel is shaking with the wheels. Although I mentioned it in the previous post, the wheels are not shaking(as in unbalance) they are actually wobbling from side to side. We have jacked up the front end and spun the wheels up to 60 mph(one at a time) and they do not wobble, it is only when the weight of the car is on them. As I also mentioned in the post to C9, it looks like the front spring is trying to move from side to side. I though it was from the wobble, but now am begining to think that this is what is causing the problem. As of right now, we are running the car with no shocks on the front and this could also be letting the spring and ch***is move back and forth. After the drags are over, we will install shocks and then a panhard bar and see what happens. As to eliminate tires and wheels, we have changed wheels and tires on both the front and rear, with tires and wheels that have run over 100mph, and it has made no difference, the front end still wobbled. Thanks for all the replies, we will get it figured out and I will post the results of the shocks and panhard bar.
Can I suggest you do one at a time and test, Just to find out if it's the shocks or the panhard bar? Pete
Pete, that is exactly what we plan on doing. We are going to add the shocks and see what happens and then go on to the panhard bar.
Getting back to front end situation. Lots more info from your last post really helps. Since you have eliminated potential unbalance situations, the failure to run shock absorbers on the car may be a major part of the problem. An uncontroled spring occillation will create the same feel as an out of balance tire. If your test road has been very smooth, shock dampening is minor and side to side movement indicates a tracking problem. In a process of elimination lets start with the fact that you have no shocks. Since most roads have a series of expansion joints, patches or bumps the harmonic starts when the spring deflects and returns to position. Now with deflection comes rebound. The spring does not return to neutral, it deflects past static and then returns. Sort of back-n forth until the energy is gone, a shock is need to control this compression and rebound or it continues to a vibration. Once this vibration starts it becomes hard to control and is magnified by higher speeds. Usually heavy braking or a slow down will cause this to go away and indicates a shock failure. You description seems to mirror this, so at this time I am leaning to agree with the other poster who is keying in on shocks. Since you don't have any, might be the next issue to address. Good luck let us know your results.
Modifieddriver, the reason there are no shocks on the front of this car, is that the one I am currently driving, I drove without shocks for two years and had no problems. This front end was out of a field where it had been sitting for God knows how many years. I put shocks on it two years ago and have not noticed anything different, the shocks were off a 41 Ford pu. We are going to use regular oil filled shocks on the front of this one.
The suggestion of adding a steering dampner may help. Usually front wheel wobble is the result of something loose or worn. Check king pins and bushings, tierod ends, steering gear, etc. Once you have made sure that everything is tight the only other thing that can cause wheel wobble is out of round or out of balance tires. It's not rocket science, there is something basic that you have missed so go back and check it all again. Good luck.
jumping from 5 degrees to 10 degrees is a big jump in changing caster. if the front end is really bouncing around you'll be constantly changing the caster as well. You could always try and tighten your shackle bolts tighter to limit the movement in the mean time to see if a panhard would help.
Coupla other things: On the shocks and difference from your modified, the dif may actually be in the spring--a new, slick spring (teflon in there?) will REALLY need shocks, and an old crusty one may have a sort of crude friction shock effect built in from the friction between leaves--self-damping by crud! On the side movement at spring (sway), look at your shackles--many dearched springs are too long, resulting in vertical shackles and hammock-like sway. Shackles need to be around 45 degrees or so, and this will build in considerable resistance to sway. Shorter main leaf may be only way to get there. And really look at all the concentricity and correct manufacture tests called for above--you have lots of new parts, some of which may be from parts of the planet where the lathes don't move in actual circles... C9, does anyone still make the olde acessory store "educated nut" for the bearings?? My '48 has those...the actual nut has no castellations for the cotter, and it has a socketed cover with 12 notches for the nut and numerous cotter notches to allow very fine adjustment.
**** Spadaro- I like to read your posts, but as a hi school dropout -I- even have trouble reading them... Please put in some punctuation and Capital letters at the front of the sentences..... I used to be the worst at that ,NOW YOU ARE CHAMP..... seriously tho-ALL IN GOOD FUN NOW!
Yes and no. I haven't seen them in parts houses for quite a while, but they are commonly found on later Fords. My 88 Mustang GT w/5.0 liter had them. I just finished installing pads and packing the wheel bearings on my bought new 2002 F-150 SuperCrew with 5.4 liter. It had the "educated nut." (The nut proper wasn't too large and probably about the same size as the one on the Mustang was.) I'd say take your 48 nut to a Ford dealer and see what the parts guy can do for you. Even the Dorman bolt nut dept. at a for-real parts house may have them in stock.
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