Severe front end shake? Shackles?

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TBones12
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Severe front end shake? Shackles?

Post by TBones12 » Sat Nov 26, 2022 8:41 pm

Is the cause of severe front end wobble because of bad shackles, or probably shackles or maybe shackles? Any other reason?

The wobbles oddly is not consistent as to when it happens. But when it has, the speed was only as it was shifted from low to high going up a small hill.

Thank you in advanced!


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Re: Severe front end shake? Shackles?

Post by Allan » Sat Nov 26, 2022 8:59 pm

The death wobble is not uncommon in a used T. Shackles may need replacing, and may fix it, but more likely you need to check everything in the front end and make sure all is up to snuff. The list includes king pins and bushes, shackles and bushes, tie rod end pins and bushes, tie rod ball and pitman arm ball, and drag link caps. if that does not fix it, checking the toe in and caster of the front axle should.

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Re: Severe front end shake? Shackles?

Post by John kuehn » Sat Nov 26, 2022 9:19 pm

The bushings throughout the front end need replacing. Also the tie rod end ball and the wishbone joint under the engine pan needs to be looked at. If your T hasn’t had the front end assembly gone through it might be time to do it. When the front axle assembly is rebuilt you will think your driving A different T. It really does make a difference.

Jack the front end off the ground and place two Jack stands near the front of the frame.

Slowly turn the steering wheel and you’ll find out where the loose tie rod bushings, tie rod ends or king pin slack is. It may not be much but it doesn’t take a lot for the wobble to start.

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Re: Severe front end shake? Shackles?

Post by Pep C Strebeck » Sat Nov 26, 2022 9:42 pm

Allan wrote:
Sat Nov 26, 2022 8:59 pm
The death wobble is not uncommon in a used T. Shackles may need replacing, and may fix it, but more likely you need to check everything in the front end and make sure all is up to snuff. The list includes king pins and bushes, shackles and bushes, tie rod end pins and bushes, tie rod ball and pitman arm ball, and drag link caps. if that does not fix it, checking the toe in and caster of the front axle should.

Have fun. Allan from down under.

I think that statement from Allan sums it up pretty well, especially the highlighted part. Having some slop/play/wear in any one given part is always an issue, but a little bit of wear in all of the parts can add up pretty quick to a lot of wear. Check it all.


Not an issue for the Model T but when I got my first Model A back in the 50's everything was tight and it drove and handled well. However, sometimes when you would go out for a drive the front end would start bouncing around like it wanted to come off the car, not the normal Model A death wobble (worn steering arm balls), rather something far worse. It drove me nuts trying to figure it out, because everything in the steering and suspension was tight, almost factory fresh. After about a month or so I switched from the original 21" wheels and tires to a set of free later V-8 wheels and tires, not trying to see if it fixed the problem, they were just free and rode better going into work. Surprise, the shaking problem went away. I started to break down the tires and wheels and the problem became quite clear, it sounded like the wheels/rims had a bunch of rice rolling around in them. The hollow rolled edges/beads for the rim were rusting from the inside and the loose rust had just been building up and was just rolling around on the inside. For no rhyme or reason it would all work to one spot from time to time and throw one or both of the wheels out of balance, HORRIBLY out of balance. I drilled some holes and cleaned out the rust and used a brush for cleaning boiler tubes to get anything that was loose and then patched the holes back up, never had the problem again. Again, not a Model T problem but that problem still reminds me to check everything.
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Re: Severe front end shake? Shackles?

Post by Nv Bob » Sat Nov 26, 2022 11:57 pm

Allan forgot the steering case at the steering wheel needs to be tight in the column
Also if this is a new to me car make sure front axle in right according to the perch boss to rear of the car just fixed a T with them in backwards


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Re: Severe front end shake? Shackles?

Post by DickC » Sun Nov 27, 2022 4:23 am

Everything that has been said should fix the problem. I had these issues with my 12 hack and applied all the fixes. They worked except sometimes when I crossed a railroad track at an angle I would get the T death dance. Having gone through all the fixes I resorted to the accessory shock absorber that attaches to the axle. I know what the purists are saying about this fix but it worked.

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Re: Severe front end shake? Shackles?

Post by TWrenn » Sun Nov 27, 2022 8:52 am

Unless I missed reading it above, one other thing to check that is often overlooked, is the condition of the top hole and bottom thread of the spindle yokes on the axle. All part of the puzzle that can cause the wobble. Pull your spindles, then put only the bolt back into the yoke all the way and yank on it. It should NOT move one iota! I've had 3 axles rebuilt with the "Stevens system" now and wow what a difference in how the cars handle.

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Re: Severe front end shake? Shackles?

Post by Mark Nunn » Sun Nov 27, 2022 9:51 am

I had one spring perch twisted slightly out of alignment. It would bind after I installed new shackles. That made the whole axle shift to the right when hitting a bump and wobble occurred.


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Re: Severe front end shake? Shackles?

Post by TXGOAT2 » Sun Nov 27, 2022 10:05 am

Wheels and tires out of balance or out of round will make even a new car shake and wobble.

@@@ Does your car have any free play at the steering wheel?@@@@


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Re: Severe front end shake? Shackles?

Post by Altair » Sun Nov 27, 2022 11:47 am

As mentioned above the shackles could be in backwards the left side has the odd number and the right has the even number. You can check the parts book for the correct numbers. You can't tell by looking at them. The easiest fix is to turn the axle around.


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Re: Severe front end shake? Shackles?

Post by jab35 » Sun Nov 27, 2022 12:28 pm

I agree with Allan, check everything for wear first, and correct it all. Then verify/correct Camber and Caster and adjust toe in, and if not done already, balance wheels and do a test drive

I don't understand how shackles could possibly be "reversed"? They can go in two ways but function the same either way? Perches, yes but correct/incorrect installation is easily identified by observing the location of the centering divots in the top of each perch. ymmv, jb

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Re: Severe front end shake? Shackles?

Post by Steve Jelf » Sun Nov 27, 2022 12:30 pm

I think David means perches backwards, not shackles. Yes, you can tell right from left by looking at them.

IMG_2605 copy 2.jpg
The casting boss (see arrow) should be toward the rear.


Several people have mentioned shackles as possibly being the problem. Specifically, a stuck shackle can cause the death wobble. Other parts of the steering system being worn loose can also be part of the problem. One worn part may not do it, but several can add up to trouble.
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Re: Severe front end shake? Shackles?

Post by Dan Haynes » Sun Nov 27, 2022 1:08 pm

Not that there's anything wrong with having the front end in tip-top shape, but what people rarely consider is the number of totally worn-out front axle assemblies that do NOT shimmy. Clearly a front axle doesn't need to be in like-new condition to not shimmy.

That said, once I chased a shimmy on a car through every imaginable cause and even some imaginary ones. When everything was snug as a bug, it still shimmied and the cause finally proved to be a mostly-missing (it was worn and compressed to paper thinness) spring pad inside the front cross member.
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Re: Severe front end shake? Shackles?

Post by TBones12 » Sun Nov 27, 2022 1:57 pm

Thank you! It all makes sense. The wobble occurred on it's first time on the road as a test run after putting it together.
I'll do as described above.


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Re: Severe front end shake? Shackles?

Post by Original Smith » Mon Nov 28, 2022 12:13 pm

I owned a T that the front end shimmied. I re-bushed everything, and never had a problem again.


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Re: Severe front end shake? Shackles?

Post by TXGOAT2 » Mon Nov 28, 2022 12:26 pm

Some worn out cars won't shimmy if you quit oiling the steering parts. That's not a good idea. There are a number of things that can contibute to shimmy, with worn parts being the primary cause. Out of round/out of balance wheels/tires are a close second. Too much toe-in can cause shimmy, as can too little caster, uneven caster, or uneven or incorrect camber. Bent steering parts can also cause shimmy. Loose steering system fasteners can cause it. Flat spotted tires can cause it. A worn steering system will often shimmy from various causes. A steering system that is in good condition and good adjustment will resist shimmy under all ordinary conditions, including minor wheel/tire issues. Running tires at the lower end of recommended pressure ranges can prevent shimmy and give a better ride in a car that is not heavily loaded. Always maintain minimum recommended pressures. A Model T in good condition does not need any of the spring type contraptions that used to be marketed to correct steering issues. An exception might be a car that, for some reason, is driven in reverse a lot.


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Re: Severe front end shake? Shackles?

Post by Norman Kling » Mon Nov 28, 2022 12:59 pm

A wheel severly out of balance will usually wobble all the time, where a loose part will not wobble until you hit a bump of something causes a vibration. Then ryhmic vibrations will keep on until you stop the car. when you start out again it will not vibrate until you hit something which starts it again. It can be a loose pitman arm at the bottom of the steering column or any loose bushing or spindle bolt or ball joint or any nut holding on one of the steering arms or pitman arm. Even possibly loose gears in the steering box. So you have to check for all loose parts, stuck parts or alignment problems. Even loose wheel bearings could be a cause.
Norm

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Re: Severe front end shake? Shackles?

Post by TRDxB2 » Mon Nov 28, 2022 2:40 pm

TBones12 wrote:
Sun Nov 27, 2022 1:57 pm
Thank you! It all makes sense. The wobble occurred on it's first time on the road as a test run after putting it together.
I'll do as described above.
Which vehicle of yours are you referring to? What kind of wheels?
Why/what did you take it apart?
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Re: Severe front end shake? Shackles?

Post by CraneJon » Mon Nov 28, 2022 2:57 pm

When you think you have the front end all fixed, invite two knowledgable T Club members to come inspect it at two different times, independent inspections. You do not want to ever go over center with an improperly assembled front end. Don't ask me how I know this!
Jon Crane


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Re: Severe front end shake? Shackles?

Post by Chris Barker » Tue Nov 29, 2022 11:27 am

The shimmy that is most often encountered happens at about 12mph. No credible level of imbalance will cause shimmy at that speed with 30" diameter wheels. Out-of-round might precipitate it but what has not been mentioned in any of the above - though there are clues - is damping or, a simpler word, friction.

Shimmy was a very common problem in the 1920s. itr took some while to understand it but it's an unstable oscillatory motion. The reed of a clarinet or saxophone, a blade of grass blown while held between your thumbs, aircraft wing 'flutter' the 1940 Tacoma Narrows Bridge and the 'tank slapper' oscillation dreaded by motorcyclists are other examples of unstable oscillations. The latter example explains the existence of steering dampers on some bikes.

On my own car, and those of several friends which exhibited shimmy at about 12 mph, the cure has been to nip up the spindle bolts slightly (the stub axle has to be a snug fit in the axle) to add just a little friction. When people claim that bringing everything up to 'as new' standard has cured shimmy, I suspect that the new tight-fitting parts have fixed it through adding some friction. I'm not advocating driving around with badly worn parts - and certainly not negative castor, but a lot of time and effort spent chasing the problem can be avoided quite simply.
I suggest that the 'nipping up' be done with both wheels off the ground so you can judge the friction at the steering wheel. Only a fraction of a turn should be needed.


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Re: Severe front end shake? Shackles?

Post by Norman Kling » Tue Nov 29, 2022 12:21 pm

One thing not mentioned above, is loose wood spokes. If you have a wood spoke wheel, especially the older ones with the wood felloes, things can get loose and cause the wheel to wobble. However, it is usually accompanied by a creaking or clicking sound as you drive along. Someone following you can also see the wheels wobble. This can easily be found by taking hold of the top of the wheel and trying to move back and forth with the bottom on the ground. loose spindle bolts or wheel bearings can also be found in this way and is a good test to make before every time you take the car out while you are doing your oiling and tire pressure testing. Any or all of the wheels can have this problem and the best fix is to find a wheel wright to rebuild the wheels with new spokes. Use hickory spokes. They are the strongest and most durable.
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Re: Severe front end shake? Shackles?

Post by Jerry VanOoteghem » Tue Nov 29, 2022 2:52 pm

Chris Barker wrote:
Tue Nov 29, 2022 11:27 am

On my own car, and those of several friends which exhibited shimmy at about 12 mph, the cure has been to nip up the spindle bolts slightly (the stub axle has to be a snug fit in the axle) to add just a little friction.

I suggest that the 'nipping up' be done with both wheels off the ground so you can judge the friction at the steering wheel. Only a fraction of a turn should be needed.
I've done that. It works, but it's a temporary fix.


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Re: Severe front end shake? Shackles?

Post by Dan Haynes » Tue Nov 29, 2022 5:08 pm

Chris makes an excellent point about out-of-balance wheels not being a credible cause of shimmy. A lot of cars begin to shimmy just past the shift point. I've seen a few cars that begin to shimmy while still in low, but they are not the majority. The thing is, *NONE* of those cars will start to shimmy at 30. Not a single one. Out of balance wheels will bounce vertically and they will make a steering wheel shake in your hands, but that is not the front end shimmy that goes by several names here (death wobble, etc.).
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Re: Severe front end shake? Shackles?

Post by TXGOAT2 » Tue Nov 29, 2022 8:09 pm

If you have a worn out steering system, a number of things, as mentioned above, can cause shimmy at almost any speed. The more wear, the more likely the car is to have steering problems, including shimmy, tramp, pulling, wander, excess road shock, excess noise, free play, etc. A tight steering system that is properly adjusted can tolerate some imbalance and other issues with wheels and tires and is much more stable on poor road surfaces, in cross winds, etc. Every part of a Model T chassis makes some contribution to steering stability, including motor mounts and the rear axle/spring.


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Re: Severe front end shake? Shackles?

Post by nicklm » Tue Nov 29, 2022 8:48 pm

Most all have good suggestions but here may be another place to look. We recently had the king pins replaced at a club meet, as they had some play. The car still had a shimmy when driven. Continued to look. The Universal tires on the two front wheels were replaced a while ago. Thinking that they may have been out of round, we checked by spinning. One of the wheels had an area that is about 4 to 6 inches long smaller than the rest of the wheel causing an indentation from fully round. As the wheel turned when driving it would cause a shimmy in the front. I will try replacing it and using as a spare or call the supplier for a solution.
Another place to look?
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Re: Severe front end shake? Shackles?

Post by TXGOAT2 » Tue Nov 29, 2022 9:52 pm

Round wheels give the best results. Most automobile wheels are not perfect. Neither are most tires. "Match mounting" wheels and tires can improve performance. In the case of demountable rims, selecting the combination of parts that runs true-est will give the best results.

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