Steering "BUMP" in reverse: TADTS!

"They all do that, sir" (TADTS) That's what the service writer at Porsche told us.:crazy: Here is the symptoms: A cold day in the morning. Backing up and turning the steering wheel to the "stop" slowly and a disturbing "thump" or two occurs on the steering wheel and the front wheel. The cars are bone stock. The rest of the day is fine. This happens on my wife's '07 Cayman S tip AND my ' 06 Cayman S 6 speed. Is it TADTS? Do YOU experience this too?? --Hal & Terry

Ummm Mine 2. Only when its < about 35F. If I don't turn to the stop, or let the car warm up, it's fine. Larry

This 'bump' is normal when you're first starting out.

http://www.planet-9.com/cayman-boxster-complaints/9838-mechanical-binding-when-backing-up.html

Same thing with my '08 C. Happens when temp falls below 40 F. I didn't notice this last winter (less cold days). When it first happened, I thought I had run over something, like a rock.

I believe the bump is due to the differential path between the inside and outside of the tire in a slow turn. I think it is the inside or outside "letting go" to equalize. I have backed my car around an entire circle and it will keep doing it all the way around. Also, when I back out of my drive, it occurs nearly every time at the same place on the driveway where there is an expansion joint and an increase in slope that would reduce the vertical load on the inner part of the tire, allowing it to release. I have also induced the feeling by turning the wheel with the vehicle fully stopped (something I avoid just to keep from scrubbing my tires). I do not believe it is symptomatic of any steering abnormality other than wide tires.

If I reverse, with the wheel turned (backing onto street), down a steep driveway with foot on the brake, I get a grinding sensation in the brakes. Feels like ABS. Anyone get that?

Have experienced the same "ker-clunk" or thump first thing on cool/cold mornings. I wonder if the wider 18" front 235s on the S models make this worse? It seems odd but harmless along with many other Porsche problems.

I get the same bump on my '99 Boxster with 17" wheels when it's cold. Glad you posted this because this is the first winter I've owned the car and it just started when it got cold. I though something major was going wrong with the front suspension.:dance:

Happens on my 08 cayman S and my girlfriends 08 Boxster S ..... Dealer told us it was normal as well.

My Cayman S does it, my 993 did it. MacPherson struts, suspension geometry, cold tires. It is alarming the first time you hear it, sounds like something broke, so it is pretty smart to check out if it is 'normal'. Chuck

Yeah like others mentioned its normal in cold temps. Scared me the first time I heard it too.

I presume th OP is running warm season tires like the PS2s my '07 came with. I bet if you switch to Winter or even all-seasons you won't experience the problem - at least not as much.

Ditto...scared the heck out of me...

On another note, does ur steering wheel make a clunk noise in the column when turned to the stop as if there is metal on metal contact. Most other cars when you turn the steering wheel to the stop there is a dampening. Is this normal on the CS?

I can't say I've experienced that. How hard are you turning the wheel? -Moto

Yeah I meant to say when u turn the steering wheel fast and hard like when making a u-turn...when the steering wheel hits the stop its kinda hard. On my Acura and Lexus when u turn the steering fast and hard to the stop there is a dampening and tension as u approach the stop. But on the CS the steering wheel seems so free and easy to turn to the stop. I can't say I've experienced that. How hard are you turning the wheel?

Oh! Yes, has happened to me several times in the cold. I kept thinking "odd that I keep backing out over rocks".

so if everyone's having this "bump", yet we're not experiencing it in any other cars we own(ed), what does that say to the design of the steering on the 987?

@kehr: What is this "winter" you speak of?

i think the bump while backing up and hitting the steering "stop" you are expriencing might be the precurser of "sudden acceleration syndrome (SAS)" where your Porsche speeds up to 100 mph without touching the pedal. Porsche, better start figuring out a solution! We are driving Porsches, NOT Toyotas! Although, my Cayman S accelerates toward 100 mph every open, deserted straight-away in the road.:banana: Is this recall material? --Hal

Yes !!!!!! '07 Cayman S - my first year with the car. 6000 miles. I noticed this in the fall when the temps dropped. It's happened several times, but only when the temp is around 35 or below. One or two times it happened going forward with the steering wheel cocked all the way. I garaged the car for much of the winter and just started driving it again. Temps around 50...and no bump. My local dealer suspects that the power steering fluid contracts in colder temps, leading to the slip - I don't fully understand the explanation and figure they're FOS It's comforting to know others have it too, and it appears to be benign and strictly temperature related.

Happens to mine as well.

He's right. They all do that. When at the stop the two front wheels are actually aimed differently. As you move you will drag one a bit sideways. If you are in doubt, turn the wheel to the stop then stop the car and get out. Look at where each front wheel is pointing. It's obvious that they are not pointing exactly in the same direction. The reason you don't feel this in many other cars is for 2 reasons: 1) Other cars, especially FWD carws don't allow you to turn the wheels as far as the 987. 2) Porsche uses a lot of caster in the front end. That way they can make a McPherson strut suspension handle the way it does. BMW does the same thing and their cars do a little hop at full lock too. But since there is less weight on the front end of the 987 you notice it more.