Technical Why does my front end shake so much?!

Shock are most effective as shocks when perpendicular.
However mounting them further and further away from the wheel lessens there ability to control that wheel. A compromise is to mount as close to wheel as possible and angle them for clearance. The compensation for angle mount is to increase the dampening ratios or spring rate in coil overs. Mounting them at angle also creates diagonal stability and although they are adjustable they still provide because of dampening. Now a shock absorber just became more than it is in vertical.

If you are a fancy CAD guy -
Plot the levers and ratios in play on the OP's ride.
First the wheel to wish bone mount on the long axle.
The wishbone itself - frame mount to axle.
And put in the lower shock mount on the bone behind the axle.
How much does the wheel need move up before the shock compresses 1/8" (enough to take up the internal slop and bushings and compliance in the bone) and actually begin working as a shock Absorber.

 

As soon as one wheel rises on a beam axle, a perpendicular shock absorber is now on an obtuse angle, decreasing its effectiveness.

If you mount them on an acute angle, when one side of the beam rises, the shock moves TOWARD perpendicular, INCREASING its effectiveness.

 

Obviously you just want it fixed, but it you shotgun it and it works we won't know who gets to beat their chest.

And if it doesn't work take a video as mentioned above.

 

Air them up more and test it,it is free and helped my Buddys Hot Rod!

 

thats what i was trying to say. angled shocks will dampen side to side movement . all ive got is the old tried and true volkswagon bug steering dampner. i still believe its in the tires. borrow another set with rims and see what happens

 

Don't think a spring wedge will change the caster; either have to raise the rear mounting or pie cut and weld the wishbones.

 

What @ROADSTER1927 said. My roadster like 35 psi.

 

Wheel balance, toe in 1/8 In, caster 6 degrees, good shocks, kingpins and tierod ends new, steering box/pitman arm no play and steering stabilizer, and some leafs out of the spring. got to do all of this, any one of them can make the front end hop and bounce.

 

Most often,frontend bad action is a combo of things being off****,an at lest one*, being the one that starts messing up.
Just as a side note,tire psi can an often dose have a factor part of a prob.=Some facts you need;,the rate/speed and hight of bounce is controled by PSI for same bump,so higher or lower psi will bounce at def. timing. Trying only two settings is as good as not trying at all{ if there timing is close},the game is too find with any vib,a oscillating speed that dose not self generate side to side on axle.
I'm sure,like most frontends of all types,there is more then one thing off,trick being finding enough of them to make it behave.

 

I can tell you I had a channeled 29 roadster that had 16x4 steel wheels and 5.50-16 front tires , drove great, as a I ended up with some billet wheels and Bfg radial tires 15x6 with 225/70/ 15 I believe tires , I installed as a gag but wanted to see how much better the car would drive .

I drove around town ride seemed better slightly ,but felt wierd otherwise, went down the freeway and the things started bouncing violently like a ball similar to what you discribe , took them off immediately , never chased the problem as I didn’t want them on my car anyway

I had split bones , drop axle , pete Jakes shocks angled to the wishbone mount and a Eaton mono leaf spring, all standard stuff in the industry 7* caster 1/8” toe

 

^^^^^ Besides moving scrub line further out, a wheel that is further out of center line of wheel bearings plus further away from king pin can become leverage not taken into account for as well.

 

Running a stock A front end with the exception of reversed-eye Posie's and 600-16 bias tires.

Adjusted toe the best of my DIY ability...Henry sez 1/16"-1/8"...didn't feel right. Drove 20m. to the closest alignment rack. Very quick/simple, as they're just measuring front end. Turns out I'd set toe @ over 1/4". Adjusted to 1/8". Drove home MUCH more better. (26psi).

^^^Your front end looks REALLY wide, IMO...wudoino?

 

What is the latest

 

Shhhh , don't argue with the theorists ,they're having so much fun trying to baffle people with B.S..plus, you'll probably piss off the pope , ......or somebody .....

 

OK I am being silent now----forget I said anyth---

 

There's this guy here on the HAMB that's doing a thread on a coffin car.

 

Apart from the vertical shocks and too much caster, have you considered removing some leaves to soften the ride given that this is a very light car compared to a 1938 Ford. Reversing the main leaf eyes would maintain height at the front. Shock absorber efficiency is directly related to shock angle, the further out they mount and closer to the wheel, the more effective they are. Canted shocks will provide lateral stability to your front end. It's all a bit of a compromise. Ideally a shock will be at 1/3 downwards travel at rest. Perpendicular is 100% efficient (Stiff), mount them at 45 degrees and they are only 50% efficient (Soft). Are the shocks suited to your lighter car (Too much compression), lighter VW type shocks were popular and did the job nicely.
Personally I'd lay the shocks over more however that requires new frame and wishbone mounts. In the meantime reworking the front spring might assist in some small way.

 

^^^^^ What about the arc the axle has in regards to this tread? Just because shock is 90* of axle does not mean it's working at 100%. It's actually angled completely negative.

 

Yeah well it's not there anymore.

 

R.I.P.

 

Another thing to consider: measure the wheelbase on both sides of the car. 1/2" off can cause the problem described in the first post

 

I saw that but was distracted before I posted. It appears that the shock leans out at the top or is it my eyes? Put a magnetic base on the shock to get an accurate reading as it should be angled in at top rather than out. Also bones appear to have been bent at ends, are the spring mounts parallel to each other and the eyes on the spring, could be binding there?

Are the shock angles correct in relation to wishbones to work with suspension arc as per GIMPY's post (#62).
The laws of physics will always triumph. While you at it, check you wheelbase on both sides, centre to centre on axles as well as frame diagonals. Lots of things may be affect harmonics and shake.

 

I gave up.

 

Would it be worth taking a little test drive with the front shocks removed, to at least give you an idea of just how much or how little the shocks contribute to the ride condition? Might at least remove or confirm one area of suspicion.

 

UPDATE:
With 4 leaves removed I had to create a 2" spacer, then the racecar nose wouldn't fit. Added back 2 more leaves and made a 1" spacer. Now the nose fits. So 2 leaves have been removed and the front is rather springy. Remounted the shocks and it's just right. That was part of the problem.
My brake drums seemed to hang up a bit as the wheel rotated. I figured cheap offshore brake drums that are out of round. Down to the local frontend shop I go. I brought the '56 Ford truck hubs with me. First off, the drums weren't hub centric to the hubs. The drums are '66 F150 and the register hole was too big, as were the wheel stud holes so the drum was kinda floppin' around on the hubs. Remedied that by installing new wheel studs with a .160 shoulder on them. Still not hub centric but now stud centric so they're solidly mounted to the hubs.
Secondly, it turns out both hubs were slightly bent/warped! So.....the shop machined the hub face so they were true then reverse mounted the drums to the newly machined hubs and turned them. Now, both hubs and drums are machined true. Put it all back together and went for a ride today. Problem seems to be solved! Thanks HAMBers for all the replies and ideas!

 

TIRES TOO Big.....winner!!

 

Good that you got things worked out, but toss those $20 shocks and order a pair of Bilsteins.

 

I had the same problem with a 32 and stock -39 axel. Build by a friend, owned by next friend. We struggle to find the problem and at last find out the axel was not exact in middle.. The head of the center bult was not used... it was a allanbult like a v. don't remember the name.

 

I agree that a shock connection to the axle is ideally close to the wheel, ditto for the spring. To ponder it in the extreme, what if the the left and right side spring/shock were only separared by 6". To have any body roll resistance (or effective springing/damping action on single wheel bounce), the spring/shock rates would have to be enormous. Which would be pretty harsh for, say, a speed bump acting on both wheels simultaneously. Once having committed to an axle attachment location, inclination of the shock doesn't matter; if vertical is too stiff, get a softer shock. As for lateral stability, note that Ford used lever action shocks with vertical levers until the final year of the solid front axle. Also, in that final year, Ford provided Panhard link with the tubular shocks.

 

Thanks for posting the solution. Too many times we never hear from the OP and never know if there was a solution, or if fixed, what it was.