Front end shimmy

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Model T Ford Forum: Forum 2015: Front end shimmy
Top of pagePrevious messageNext messageBottom of page Link to this message  By Butch Reif on Thursday, March 19, 2015 - 09:10 pm:

I posted something and got so excellent advice, so l m going to try it again. Got alittle front end shimmy in my car and everything seems tight on the front end and don't have any play in the steering wheel. Only does it on slow speed and on asphalt. I was thinking about getting a steering stabilizer from langs or macs. Is it really worth buying or has anyone had any experience with them?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Strange - Hillsboro, MO on Thursday, March 19, 2015 - 09:26 pm:

The steering stabilizer works, but you should be able to get rid of the shimmy without it.

Doublecheck your front end alignment (especially caster) versus the Ford specs. Here is an older thread that talks about how to check caster:

http://www.mtfca.com/discus/messages/179374/208098.html?1304700854

On my car, I have found that the slightest amount of slop in the drag link ends or tie rod ends can result in low speed shimmy. With the car sitting in the garage, get under the car and try to push and pull the drag link from side to side. Any "clicking" indicates slop that needs to be tightened up. If the tie rod checks good, grab the pitman arm and pull it from side to side to check for "clicking".

Also, check your front wheel bearings to make sure they are snug, but still allow the front wheels to turn freely.

If you find any slop, you can either file the ball caps, or use the shims that the vendors sell:

https://www.modeltford.com/item/2728SH.aspx


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Thursday, March 19, 2015 - 09:45 pm:

Check the king pins for play too


Top of pagePrevious messageNext messageBottom of page Link to this message  By Gary Tillstrom on Thursday, March 19, 2015 - 09:46 pm:

Butch

There is a lot to making you car track correctly and be able go down the road without a death grip on the wheel. In addition to what has already been mentioned as far as checking for wear, check the pitman arm to steering shaft to ensure there is no play there. Don't forget the bushings in that bracket can also allow the shaft to slop around.

When you make your toe in adjustment, here is how I do it with the reasoning behind it. First, when Ford gives the specs for toe in they are giving you a set number of degrees expressed in inches. Suppose for a moment you measure at the worst possible wheel position for error and it shows toe in perfect. It may in that case be zero or even toe out.

I use a shower curtain rod and mark each tire at the rear. Take your measurement with your shower curtain rod. Now rotate those same wheels 180 degrees and measure again. Compare that number to the spec Ford gives. Doing it this way you have eliminated runout error common especially in wood wheels.

If all checks out ok, make sure the front spring shackles are not too tight. They should allow for side to side movement freely.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Ken Todd, ............Red Deer, Alberta on Friday, March 20, 2015 - 11:19 am:

Also ensure that the front spring clips (U-bolts) are tight.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bill dugger on Friday, March 20, 2015 - 11:36 am:

Butch: I had that to happen to my '19 and I traced it to the fact that when I assembled the axle it tilted forward instead of backwards. Look at page 45 para 146 and check that . I changed the axle and the shimmy was gone. Just my opinion. It is worth checking.
Get it done and have fun with the "T"


Top of pagePrevious messageNext messageBottom of page Link to this message  By Chris Barker, Somerset, England on Friday, March 20, 2015 - 11:37 am:

Shimmy at about 12mph is an instability like airplane flutter, motorcycle 'tank slapper' or a clarinet reed. By all means check and fix caster, wear etc, but the only really significant factor is damping. This can be an add-on damper, but it's easier and cheaper just to add a bit of friction.
It's worked 100% on my '26 (the bigger balloon tyres are worse than beaded edge), and nothing else did work.
As long as the stub axles have only minimal up-and-down freedom in the axle, you can add friction just by tightening the spindle bolts A LITTLE. If you do have up-and-down play, add a shim washer to the spindle between the stub axle and the axle, at the bottom.
The best thing to do is to jack up the front axle and disconnect the track rod. Then, each wheel will steer on its own. Remove the spindle split pin and slacken the lock nut. Then tighten the top of the spindle while 'steering' the wheel. You need just-perceptible friction. When you re-tighten the lock nut, it may get tighter, so check and allow for this.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Friday, March 20, 2015 - 03:46 pm:

The last time I fixed a shimmy on one of my cars it was the spindle arm loose where it connects to the spindle. I tightened up the nut and re-installed the cotter pin. That was about 4 years ago and it hasn't shimmied since. Anything in the steering system can be loose causing the shimmy. Problem is that it kind of bounces. The system is built to self center when everything is in alignment. A bump movement tends to bounce. This can be a bump in the road or a wheel out of balance. So if it moves one way the self centering moves it the opposite direction but if something is loose, one wheel will go past center and bump in the other direction and so on. If everything is tight and in alignment, it goes along smoothly.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Alan George Long on Saturday, March 21, 2015 - 10:27 am:

My recent experience with shimmy on a 1927 Touring lead me to believe (in my case) that it is the tyres. We cured the shimmy 3 months back by simply swapping the front wheels left to right.

Three months on after being stored in the garage our first drive the shimmy was back. Suspect that there must be flat spots on the tyres. The trick will be drive it until the tyres get warm and see from there. It really is a violent shimmy and it can be clearly seen as the vehicle drives down the road. This is a vehicle that has never had shimmy until the engine was changed out. we went through all of the documented fixes and checks and now back to square one


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Saturday, March 21, 2015 - 11:42 am:

You can keep the tires from getting flat spots by jacking up the front axle and putting on stands while the car is parked for an extended period.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Miller, Sequim WA on Sunday, March 22, 2015 - 12:46 am:

Chris already picked up on this, it is no so uncommon to have these backwards. Make sure that your spring perches are not on the wrong sides, Also check you tire pressures.


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