66' 230sl feels "jumpy" at highway speeds

[merrill]

hello
on my 66 230sl  auto,  manual steering,
a while back i had the tires rotated & balance and then took the car to the shop for an alignment. (now in spec per bbb for my car, see attached)

i noticed at high speed it feels "jumpy"  especially at 66 mph and higher.    i cant tell if its a tire balance or alignment thing.
the car tracks straight as far as i can tell, but something is just not right.

recent changes
new tires
replaced hanger klunk bushing a summer ago
new front caster rubber the fall before

its almost like the car is on rails but i can feel its jumpy or jittery at high speeds....

thanks in advance for any ideas matt

[stickandrudderman]

It's a bit of a vague description but one possibility is a failed steering damper.

[merrill]

hi
thanks for the reply, yes its hard to describe.   

i need to check the tire pressure, maybe when the tires were balanced and rotated the shop over inflated them.

at highway speeds the car seems like it is picking every road bump and in perfection and the entire car is almost vibrating....

its just odd, 

[Mike Hughes]

I'll second Stick's suggestion about the steering damper.  It and then the steering coupler at the base of the steering column were both replaced right after I acquired my 230SL back in 2003 and made a world of difference.  Even before doing the steering coupler I could tell the difference in how silky smooth the steering action became with a properly functioning steering damper.  The car was no longer "darty" at speed, but there was still some steering slop accompanied by a clicking noise emanating from down behind the pedals.  The new coupler took care of that.

[FresnoBob]

Or perhaps you should inspect your subframe mounts?  I also have a 1966 230 SL and changing my subframe mounts made the car feel considerably more "stiff", particularly at high speeds. 

[merrill]

hi
thanks for the replies,   what i find interesting is i did not experience this before the alignment.

i did replace the steering coupler , sub frame mounts and steering damper years ago, this car maybe gets 1k miles on it a year.

i'll start with the tire pressure and then inspect the rest of the suggestions.   

steering damper are not expensive, i may replace that since i know even though it has low mileage on it , it is 15 probably years old....

thanks again!
matt

[Pawel66]

merill, when you dismantle the steering damper, you can stretch it and compress by hand. My experience is, when they go bad, they are very easy to move in their middle part (where the center is). Otherwise they are quite tough to move, like shock absorbers.

[Shvegel]

I would have the front Toe checked again first.  Alignment machines are only as good as the person running it.  A little inattention on the setup can cause you to throw things off further down the line.

[merrill]

Shvegel
hi, thanks for the feedback,  I'll will take the car back in on Thursday.

After the alignment and test drive the tech did manually adjust both tie rods to straighten the steering wheel. 
i wonder if he accidentally threw off the toe in.

when i called to make the appt the service advisor first suggested to check the tire balance, however i had the tires balanced and rotated the week before the alignment just in case so that is out.

since the car did not have this issue when i took it in i am suspect the issue is the damper. Though i suppose it is possible with the cold weather here in Austin a failing damper symptom could show up...

back to the shop!

[merrill]

hi
taking the car in tomorrow to check the toe in.

in preparation for the visit i was going to make a steering box alignment bolt so we could make sure the steering was dead on,   low and behold
when i replaced the steering coupler years ago the box and steering column were not aligned.

so the question now is,   
do i just have the toe in checked and corrected
or
do i have the tech set the alignment correctly to the steering box and then deal with re aligning the steering column.


if i remember correctly it was a pain to replace the coupler.   (had to disconnect the tie rod and then unbolt the box from the car)


thoghts?
matt

[merrill]

well
took the car in and let the tech drive it,

he didn't think the toe in was off,   
his comment was when you get to highway speeds and let off the gas it seems as if the rear end is torqueing.
maybe the rear end is off or loose and causing the symptom. 
I also have the hankook tires that he said had soft sidewalls, he said that could also be part of the issue...

the car does track straight and is stable until about 66 mph.

we did find that the drivers rear drum brake was dragging, (hub cap was warm)

I'll re adjust the rear drums to have as little rotational resistance as possible and then test drive .   I have also checked that the trunk mount is tight, rear axle stabilizer is tight and the trailing arms are tight.

next to test drive and see if there are any changes.

if not there is a shop here in austin that specializes in older cars, i may just take it to them

best
matt

[Norm]

Hi Matt,

I have been following your efforts to identify your driving issue.  If it would help, you are welcome to drive my 66 230 (which also has Hankook tires) for comparison.  My front end has been recently rebuilt, replaced the steering box and recent alignment.  Seems pretty good to me, maybe a good reference point for you.

Drop me a PM with your phone number if you are interested.  If you are in Dripping Springs you can't be more than a half hour away from me in Wimberley.

Norm

[merrill]

norm
thanks for the offer,

i have had the hankook tires for a while now and this is a new issue (since the last alignment)

let me try the items i listed previously and go from there.

Best
matt

[merrill]

so this is interesting,

took the car for a drive after reducing all rear drum brake drag (drivers was hot this am after driving) and the jumpy feeling is basically gone.

i still may install a new steering damper to reduce steering feedback.

its interesting to drive the car after installing all new bushings, i can really "feel" the road thru the drivers seat.
the "klunk" bushing had been worn out for 40 years as well as the other rear suspension bushings so the car sagged in the rear.
now that she is standing tall and proper the driving experience is so much different.

thanks again - matt

[paults1]

What and where is this so called "Klunk" bushing?

[Mike Hughes]

we did find that the drivers rear drum brake was dragging, (hub cap was warm)

I'll re adjust the rear drums to have as little rotational resistance as possible and then test drive

so this is interesting,

took the car for a drive after reducing all rear drum brake drag (drivers was hot this am after driving) and the jumpy feeling is basically gone.

. . . as soon as I read that I knew backing off the adjuster a tad might end up being the cure for your problem.  I'm glad you dealt with it so soon as prolonged heating of that drum could have caused it to warp, and 230SL rear drums are not as easy to come by as the the brake discs for our Pagodas.

[merrill]

paults1
hi,
the "klunk" bushing is the circled item #151 in the attached diagram.    when this wears out the rear end of the car sags and when you accelerate or brake hard the movement causes a knocking sound.

Mike
hi,
yes, thanks,  i had not checked if the rear rims or hubcaps were hot as i adjusted them recently,  i guess i had them a tad tight.

i ordered a new steering damper today ,  i have a feeling the one that is installed on the car is 15 years old (low mileage)   replacing it may
further help smooth things out.

thanks again
matt

[paults1]

Thank You Merrill!

[450sl]

Merrill, you might want to look inside your trunk to see if the plastic cover 130 is lifted  ; then you rear mount rubber is kaputtt..

[merrill]

450sl,
hi, yes ,  before i crawled under the car i opened the trunk and removed the plastic cover to ensure that mount was still good and the bolt was tight!

[merrill]

Mike and Stick
good call on the steering damper,

installed a new one this am, what a difference!

the old one had no resistance in the middle / center.


thanks again!