Vibration

L

lhancoc

Junior Member
I just finished rerassemblying a 29 Roadster Pickup. I do not have the shocks on yet, but wanted to drive it around the neighborhood. There is a terrible bounce in the rear wheel area. I thought it might be a wheel out of round, but I have tried different wheels. Would there not being shocks on yet cause this problem. It is worst at about 25 mph.does anyone have a suggestion? The streets are smooth in the neighborhood.
 
You say you have tried different wheels. Did you also try different tires? If the streets are smooth the car should ride nice at 25 MPH.

I don't have shocks on my 28 yet, but the ride is pretty good, unless I hit bumps while rounding a corner, then it wants to skip sideways a bit.

Are your springs, clean, smooth and well greased? Or, at a minimum squirt a bunch of oil on the springs until you can take them apart and lube them with grease and graphite. Spring covers are nice to keeps the grease in and the dirt out.
 
A car with good springs and no shocks is a nightmare to drive much above 25 MPH. I drove my 30 fordor without shocks, once. Was busy putting together shocks that night. I was afraid I was going to loose control at about 30. With shocks I ran it all around at 55+ MPH and it just seemed happy to run that fast.

A light weight pickup, no shocks and good springs I think would be all over the place. Just plain scary to think about.

Since you have the wheels off the truck check them to be sure. No need guessing.

Put a front hub on a spindle C clamped to your bench. Lightly oil the bearings and mount the tires. Spin them and look across the top, does the tire seem round?
Let them find the heavy spot. Does the wheel rapidly find the spot indicating a heavy imbalance?
Try breaking the bead and rotating the tire on the rim and see if you can get a heavy imbalance to reduce if you have a fast rotating wheel while balancing.

The A axle is very heavy. The very heavy unsprung weight tends to hide/ prevent imbalance and out of round conditions.

You could always put 10 guys in the bed and see if the load helps (I am just kidding on this one).
 
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is the rear spring centered with the square bolt head firmly inside the hole in the crossmember? If not, the wheels will be mis-aligned.
 
No shocks on my 30 ccpu and it was all over the place! You could not throw it into a curve she was just too loose. After I installed a set of Shocks by "Pete" (hes nolonger with us) the truck will go anywhere you put her with ease. Running Lester tires with 35lbs air.
Wick
 
Question;

Do you have Float A Motor motor mounts installed?

If yes, do you also have the ****** support installed?

I had FAMs in my 30 Coupe without the ****** mount and there was a very noticeable vibration at around 30 - 35 mph. I installed the ****** support and the vibration went away. It felt like the rear wheels were square.

Dick
 
usually an out of round tire or rim would be felt on a smooth road even coasting slow in neutral you would feel a wobble or thump. if it coasts smoothly at 5-10 mph i would look elsewhere
 
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You should not be getting bounce on a smooth road,shocks or not.The shocks may cover up a problem that needs to be fixed first.You could have a bent axle,or you could have pushed the axle key on too far when installing the drum.Then the drum will ride up a little to high on one side of the axle,and just a slight bit off will result in a little wobble,and a big hop.I have driven more A's with either bad shocks or no shocks than with working ones.I built a 28 RPU a few years ago,and I drove it for a year while scouting up parts for a set of shocks.I kind of forgot all about them as it performed fine.The current owner drives it like a little hot rod..125 over,BF head,3.54 gears.I did build a good set of springs,using a roadster spring in the rear.It was never going to haul anything heavy ever again anyway.I used to maintain a 29 pickup for an old fellow.His springs ware wrapped in canvas,leather bound,with grease fittings at points along the sides.Those had to have been installed when the truck was new or close to it.That truck rode like a baby buggy,just a little too bouncy with bad shocks.He decided to buy a pair at a time,I bought the first pair from Bert's,they had real nice smooth and even action.Real happy with them.I put them on the rear and he came back asking me to take them off.No matter how we adjusted them the ride in the rear was too stiff for him.I put them on the front and he said the truck handled like a dream.He never had me put any back on the rear.He had a bad hop in the rear that turned out to be a bent axle.
 
MikeK said:
Quick and dirty: Put the rear axle up on two jack stands, ****** in gear and let it idle. See if things run true or not.
Click to expand...

to add to this i would check it at the end of the axle where the axle nut is. if that runs true your wheels and tires should run true also
 
Where do I find the "vechicle identification number" on a 1929 Model A Ford, standard four door sedan ? (other than the engine number) Thanks, EAV8
 
If you are looking for a hell lot of work ( to find the frame number ) just lift the body off the frame and you will find the number on the drivers side of the frame close to the front door pillar. Good luck,
 
I just went through the same thing. The rear wheels would hop, with shocks or without shocks, but at a little faster speed than what yours is. I rebalanced wheels, checked axles and driveshaft for straightness, which of course is a pain with a A rear. Ended up having my wheels RFV balanced. It stands for Road Force Variance. I had mine done at a local Discount Tires store, cured my problem. I was pulling my hair out trying to figure out what was wrong. Rides smooth as glass at all speeds. Hope this helps.
 
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