Front End SHIMY after rebuild

BFS57 · January 16, 2012, 06:59:06 PM

Hello;
Just did the front end on my 57 chevy, upper and lower arms (Tubular) all new bushings and ends on the centerlink although these were made off shore the source "swears" by them.
The front end has a slight pull to the right. Today, leaving work, I was doing about 35 or so and the steering wheel started to "shimmy" I slowed down and it went away but when I reached the same speed again, it came back. I have noticed, since doing the work that sometimes when I break from around 50 to 60 that I get a Shimmy also.
The front end guy that aligned it said he needed to look at why it is pulling to the right but this shimmy is something new.
Does anyone happen to know what may be the cause of this problem and how I might bring about a cure??
I was hoping to improve the drivability of my car adding these expensive A arms but so far, I;m not impressed.

Bruce

unklian · January 16, 2012, 08:43:18 PM

If it pulls after alignment,

I'd be looking for another alignment shop.

Shimmy under braking can be caused by brakes.
I had one new rotor that shook real bad, braking at speed.

More likely, is play in the steering.

wayne petty · January 16, 2012, 11:47:31 PM

a few things....

pulls....

tire air pressure check.
jack up each wheel and check for dragging brakes..
run hand around outside of tire .. check tires for belt separation..
check for wheel bearing play.. wobble in and out at the top of the front tires.. up and down for the rears...
~~~~~~~~~~~~~~~~~~~~~

death wobbles...

drivers window down..
standing beside drivers door.. reach in and rock the steering wheel back and forth.. how much play in the steering wheel rotation do you have before the wheels react...

if you get play in the steering wheel.. before the wheels start turning..

continue with somebody rocking the wheel back and forth to the limit of the play while you examine the various components under the front end..

BFS57 · January 17, 2012, 06:00:33 AM

Hello;
Thanks for the Information. I will do some look seeing today. The guy told me, he thought my steering box was worn but I just wanted to drive the car. This modification is step one, step two comes when I replace the steering box with a new CPP 500 power box (famous term) I now have laying under my work bench.
Before I do that, I have to move the radiator back, ad a pulley to my harmonic balancer, move the fan with a spacer, mount the PS pump I have, and re mount my electric fan on the front of my condenser (shew!)
Keep any suggestions coming in this situation, the more the better.
Thanks guys!

Bruce

PeterR · January 17, 2012, 07:05:59 AM

When the guy did the alignment, did he use the original factory specs for castor. If he did and you have radials fitted, there will not be enough castor and that can lead to shimmy.

kb426 · January 17, 2012, 06:18:10 PM

Because of all the work to install the ps, have you considered one of the electric units? My exp. with shimmy usually ended up with something loose or really out of balance. I haven't had that exp. since I left the farm which had mud on the wheels and worn kingpins.

32coupe · January 18, 2012, 06:13:18 PM

The shimmy you discribe is usually caused by an out of balance or buckled rim.

BFS57 · January 18, 2012, 08:17:32 PM

HELLO;
Gremlins!, I say, Gremlins!! Darn thing hasn't done it since!! I still have to jack up the front end and check for any bad tires
Just put the rims on about 6 months ago new 17" TT 2 rims! Although I did scrimp a bit on the tires. They were balanced but that doesn't stop the weights from falling off!!
I'll check it out this Saturday!

Bruce

1800guy · January 18, 2012, 10:27:06 PM

A little trick on weights that I figured out the hard way - chasing a shimmy: I use a paint pen or a felt marker and put a line around all edges of the stick-on weights. If one or more come off you can see the blank space right away, and fix it on the spot if you carry a few pieces with you.

jaybee · January 20, 2012, 10:25:10 PM

My money is on a combination of play in the steering coupled with not enough castor. Modern tires like a whole bunch of castor...enough that it's sometimes difficult to get enough on these old girls, though a lot of the tubular control arms are built with extra castor.

BFS57 · January 21, 2012, 12:13:03 PM

Quote from: "jaybee"My money is on a combination of play in the steering coupled with not enough castor. Modern tires like a whole bunch of castor...enough that it's sometimes difficult to get enough on these old girls, though a lot of the tubular control arms are built with extra castor.

I Got the tubular A arms that have an extra 5 degrese of castor built in!
The guy told me, that the steering box was worn bretty good! Next, Power Steering box!

Bruce

jaybee · January 21, 2012, 06:05:05 PM

Quote from: "BFS57"I Got the tubular A arms that have an extra 5 degrese of castor built in!
The guy told me, that the steering box was worn bretty good! Next, Power Steering box!

Bruce

Are you running a stock steering box? Power steering?

BFS57 · January 22, 2012, 07:49:51 AM

Bruce[/quote]

Are you running a stock steering box? Power steering?[/quote]

Hello;
At present, the stock 57 chevy steering box. I thought it would be better (as I drive the car daily) to replace the suspension and rebuild the Centerlink and associated hardware first, then do the box because there is so much to do to ad the power steering box. I even upgraded my Idler arm to ball bearings! (as well as a whole new Idler arm assembly)
What are your thoughts?
It still hasn't done the shimmy since that day!? Gremlins?!
In my case to ad the power steering box, I have to remove the radiator, ad another pulley to the front of the engine, put a spacer behind my fan, Then go inside the car, remove the Steering wheel, and the dash area, then back outside where I have to cut the steering shaft at the stock box, remove the pitman, remove the box, remove the steering column, with shift, mount the new 500 box, install the pre shortened steering collum, attatch the rag joint, mount the pump, run the hoses, and replace the radiator behind the core support (in front now) The list goes on! I need about 4 days to (as Larry the Cable Guy would say) "Get Er Done"

Bruce

jaybee · January 22, 2012, 05:34:45 PM

A sound approach, I'd say. Here's what I see:
-There isn't any place left to have excess slack other than the steering box, because you've already rebuilt everything else. Have you checked the box to see if it needs the slack adjusted out, or is maybe worn out?

-Do you know what specs the alignment shop used? Sometimes they'll insist on using stock original specs without taking into account that those are meant for bias ply tires.

-I wondered if the car maybe had a 605 conversion, which can be over-assisted with minimal caster and relatively small tires.

-The roller bearing idler arm really appeals to me. It just makes sense to me that having that one point mounted in rubber when everything else is a strong mechanical linkage has to make the steering more vague.

BFS57 · January 23, 2012, 06:18:01 AM

Hello;
I don't know what the front end guy used as his measurements but he did comment on the wheel and tite package I had (16" TT2 with low profile tires. Anyway, he has to do another alignment because of the pulling to the right I have. I will ask him about that when he gets around to it.
BTW, The guy is a mobile front end shop. he has everything eithor at his house or in his van and trailer.

Bruce