First off its my 1938 pickup with 59A flathead, 5spd, banjo rear end, open drive shaft and OT front end. Truck was running fine when I parked it but the next time I drove it there was a weird pulsing vibration that started around 50mph. It feels like the front end is going up and down. The vibration starts small and then builds up and then continues to cycle up and down until I slow below 50 mph. I have pulled and visually checked all the tires and then pulled them one at at time replacing them with the spare and it made no difference. Steering seems tight. Disc brakes seem fine. Engine seems to run fine. I have put it in neutral at speed and played with the clutch and no difference. Engine RPM's don't seem to make any difference as it happens at the same 50+ mph in 4th or overdrive. Possibly a bad wheel bearing??? Any suggestions on what to do next would be most welcome.
I had a similar issue with my ‘03 Silverado, around 45 it felt like an out of round tire, slower ok, faster ok. My issue was the strut, shock in to right front of the truck. Kind of a similar frontend, but something to take a look at?
What tires are you running?? What pressures are the tires? The rear tires should have less pressure than the front. I’ve run into this with my 34 pickup.
I would begin with moving tires around back to front,, left to right,, etc etc. Costs nothing and may eliminate or tell something
It would help to determine the frequency of the vibration. Wheel ends turn one speed while driveline parts turn between 3 or 4 times faster. In my experience, pulsing vibrations at high frequency tend to be driveline related. A pulsing vibration at lower frequency points toward wheel ends. The fact that you changed tires around and it didn't change sort of rules out tires (maybe). I have had stuck calipers cause odd vibrations at speed. It was a real problem on older Dodge vans. Does the vibration change while you are one a pull or coast?
Vibration is present over 50 mph under power or out of gear and coasting. Vibration seems to be at a lower frequency. The tires are big and littles so I can not reverse them front to back. The spare is in-between the front and rear size so I was able to use it to replace a tire at a time in my testing. I did look at the calipers. I'm beginning to think I may have to pull everything off the front end and go through it this winter.
Get the tires balance checked first thing. Missing balance weights are not unheard of, causing wheel tramp at certain speeds. Check the tires for out of round. Drive line vibrations are possible but my experience has been they are more constant rather than pulsating. Check the driveshaft for evidence of a missing balance weight. Not the most likely but possible that the clutch disc has thrown off a piece of the lining. I don't know what it is about these old Fords but they very often like to vibrate at around 50 MPH and I've never really figured out why. Vibrations when out of gear are most likely one of the things I have mentioned here. The only other thing I can think of is a slight wobble or shimmy in a front suspension part that often can't be felt at the steering wheel. The wheels on my '42 will throw wheel weights quickly if not installed in a very specific way. Very annoying.
Bounce the front to check the front shocks are working. Put the front on stands and check for wheel bearing or king pin play.
Sometimes I need to sleep on things to let them sink in. I assume your transmission is a T5. Check the bushing in the end of the tail shaft for any play. This vibration is obviously a drive line issue. Check the U-joints for play. Twist them back and forth and up and down. Use force. Check the pinion nut or whatever the drive shaft connection to the pinion shaft is for play or loose nuts and bolts. Check the drive shaft for any sign of excess run out. Bent or warped. There should be none. Check the welds at the ends of the shaft for cracks or other damage. I have gotten information from good drive line shops that there are some U-joints that are the cause of what you describe. One in Yuma asks where the U-joints were purchased before they do anything else. Imported junk, you know. Since it started this problem overnight, the drive line is the only thing that makes sense to me. Good luck.
This kinda reminds me of the 'ran when parked' statements made in some misleading adverts. There is no mention in this case that this problem occurred overnight, just when it came to be used again, with no mention of timescale. Some items will deteriorate over time, eg rubber bushes, and possibly moreso than had they been used over the same time frame. Could have a bearing. Chris
I had a C10 that I noticed the same issue. I only drove it once or twice a week at the time 20 mile commute, so I didn't think much of it. I figured it was the tires or shocks. I bought new tires, and lowered the truck with new leafs, and new coil springs, repacked all the bearings, replaced tie rods, made sure everything was nice and tight and what not. Of course after all that, the vibration was still present around 50mph. I said, "Ok, maybe its the driveshaft or carrier bearing, or U-joints, I'll check those out next week..." So, I ordered all new Spicer U-joints and carrier bearing assembly and was planning to do the job on the weekend. Heading home from work on a Wednesday, about 45mph about 2 miles from the office, I started hearing what sounded like metal pieces clinking off each other *ping, clink, ping". The truck was too low to really get a look at what was going on underneath, so I turned around slowly to make it back to work, trying not to give it any throttle to avoid being stuck on the side of the road. I got back to the office and jacked the truck up and found a U-joint cap had exploded and spit all of the needle bearings out (that's what I was hearing) Had to jump in the work truck, run home, get my parts and some tools, and head back to work to knock out the joints and bearing. After that the vibration was gone and it was smooth as butter with all new suspension, tires, etc.
I drive my truck often so I can not say the exact date it started shimmy but it was only a couple of days between driving fine and then not. This is why I was a little surprised when it happened "almost" overnight. PS: Twice I have personally experienced parking a running/driving vehicle that would not start after being parked a short time so as they say **it happens.
OK, handy to know! Another vote here for a uj. I had a problem with a u joint which I replaced several times. The shortest 'life' was no more than about 50 yards! I found out by complete fluke that the joints I was buying were incorrect (cap too small). Thats been fixed now for a long time, but when they were failing they made assorted noises. Same goes for wheel bearings which can be shot but show no apparent signs of wear. Have the bearings and u joints been routinely lubed up and checked for wear? Chris
You mentioned an open drive banjo... I'm assuming you used a kit like from speedway? I've seen Those get loose on the banjo coupler spines and cause a vibration... Also just a side note: when you convert to open drive with a banjo that uses a transverse spring and stock bones, a third link (think torque arm) needs to be added to make up for the torsional strength lost from removing the original torque tube... The stock bones can not handle it alone and will crack were they bolt to the axle. You may have already compensated for this, but if not I just wanted to make you aware. Best of luck!
Thanks. I used a HRW's open drive conversion and even added a 2nd "torque arm". Right now I'm pulling the front brakes and inspecting the front suspension (that by the way has always been well lubed). Pulling the drive shaft is next.
The Jalopy Journal
