VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 What's that thump???

Hi... fishing for ideas of what to look for.. I am getting a thump in the front end of my 46 Stylemaster that I can feel through the steering wheel... It happens when I brake a bit hard... I checked underneath and nothing appears loose... I thought it may be my sway bar bushings but they don't make any sound when I bounce the front end... Brakes are new... Sway bar links new... no major looseness in steering... Any ideas??? Thanks...

Was the "thump" there before the new brakes and the new sway bar links were installed?

Apparently something moves when a front brake is applied. Suspension bushing? Loose spindle bolts? Have several of you friends thy to move the car forward and back with the service brakes applied. One of them might pinpoint the noise location.

yes it was... it just does it when i brake hard and the nose dives a little... that is why i thought it might have to do with suspension..

Check your king pins.

It could be the lower control arm inner bushings, the outer upper pivot pins or lower pivot pins. See shop manual.
All of these locations are threaded metal to metsl bushings that require greasing every 1000 miles to prevent them from wearing out. a good front end shop should do an inspection for you and for saftey.

I think everyone has given you sound advice so far.

I suggest that in addition of the things mentioned being checked out, that you pull the drum and check out the brake innards. May be that a spring broke.

Good luck,
Charlie

Thanks everyone... will put car on hoist this weekend and check things out... Here is what I think might be wrong but it is pretty hard to check out by myself... all of the undercarriage is great except for the right frame brace near the transmission cross-member... (see in red circle in attached picture)... when I bought the car in 1997, the domed stamped portion (lower portion) had held water over many years and it was all rotten through... I grinded the domed portion off leaving the flat portion (upper portion) only... the blue circle shows the un-modified left frame brace... this is my question... could it be that braking makes this flat portion pop up and down since I have removed the domed portion, leaving it weaker and sucesptible to flexing (or poping) up and down under the stress of braking??? would braking cause enough stress in that part of the frame for this to happen??? I hope i will be able to include the photo in this post... if not, it will take me a few more minutes... thanks everyone...

https://www.pinterest.com/pin/357051076691807192/

Marellan,

Thanks a lot! for that there link right there. The medics had to use their paddles on me. I'm OK now.

Charlie

What would be the symptoms of bad king pins??? Looseness??? Not sure what to look for... Thanks.

Not sure how to interprete that paddle post... did the link work??? havent posted photos before...

Not sure how to interprete that paddle comment... Did the link work??? did the photo come out ok??? first time posting a picture... thanks.

The photo link did not load without creating a Pinterest account.

To inspect your suspension you should have the front tires off the ground or hoist, then you can put one hand on the top of a tire and the other on the bottom and try to rock the tire up and down. Do the same with one hand on the front right side and the other on the left of the tire, and try rocking the tire. A lot of movement means the king pins are bad. You can also spin the tire and hear if something is dragging. A loose or bad front bearing will also cause the the rocking motion. This is also a good time to check the tightness of all the suspension parts for obvious looseness.

I don't think your frame could be flexing do to your rusted out bottom cross member but I would be looking for a new one. I have had a couple of frames (3) that had a lot of rust through on the bracing for the transmission. The braces fill with mud, etc. and should be cleaned out. Likewise, the entire frame needs to be cleaned out after a normal 10-30 years of non city driving. I replaced my 41 frame with one I found on ebay. It was from Oklahoma and in excellent condition. The guy was Hot Rodding the car.

I would also check my motor mounts both front and back, and the transmission mount.

Good luck, Mike

P.S. I rationalized changing frames by assuming I was putting a lot of time and money into a car with a bad frame. This did not make good sense?

41 Cross member replacement

Check out the second picture Painting frames and suspension

Marcellin,

Re emergency medical service paddles. When I open the a tachment my eyeballs instantly locked on to the picture of a couple of old-timey babes, upsides down with their stepins a-showing. That was enough to send me in cardiac arrest, etc. I have now somewhat recovered and almost up to 100 percent. When I get there I plan on opening the site again but only risk one eye this next time. Only half a shock should serve nicely.

As to the thump, I can't understand something causing a thump unless whatever is causing it is stressed beyond the point of holding back and the stress/pressure must then be realeasd thus causing the thump. Some things that would cause this is lsuspension, steering, brakes parts or bearings. Seems that loose kingpins would go to the forward "thump" positiion immediately upon initial braking. Maybe other parts as well. The sudden "release" at hard braking is the puzzling part of the dilemma.

Good luck finding the cause,
Charlie