theiceman

Okay here is the scenario.

twice now I have gone over small rises in the road with a dip right after. Not at a horrific speed by any means ut certainly cliping along. As the car goes down into the dip BANG ... or should I say GRIND. My car bottoms out on the road. It has never been lowered the fenders sit at around 25" and I have brand new Bilstein sports on ... Is this normal for this car and I was just being too agressive ? I have never had any car bottom out like this before. I did notice that the rear of the car pan is lower than the front .. I also was going down hill into a right hander later in the day and heard a diferent scrape, that turned out to be the front left tow ring hitting the ground WTF !!!! ?????

should I be looking at upgrading parts or is something just wrong with my car !!

Gary R.

Iceman - I would look more to your springs being shot, how many miles on them? You can either stay with stock ride height or go with H&R/Eibach progressive rate springs with the Bilstein's you already have. I highly doubt that the shocks aren't doing their job if they are new but their job isn't to keep the car from bottoming over semi-major bumps either way, it's a function of the spring/shock combo. I have used both of the above mentioned PR springs and have never bottomed out my cars.. and they absolutely handle better with PR "lowering" springs IMO..

GT-three

you may just need a rear suspension adjustment or your torsion bars are shot.have a mechanic put it on a lift to get a better idea.

Gary R.

Hehe.. jut realized I was in the 911 Forum, not the 964 Forum!

Peter Zimmermann

The problem is... Hey Ice, by your side pic from another thread it looks like your car is Euro ride height, perhaps just a tad lower than that in the rear. I have never had a 911 bottom out on me, but I've had plenty of them make a scrape noise, usually a too-wide left front tire/wheel that just touches the fender lip. If you're touching a front tow hook that usually happens going in/out of driveways. Going through a dip, in my mind's eye, would leave the belly of the car with more clearance, not less, but depending on the road angle would leave the very front and rear of the car susceptible to touching/damage. Just a thought, are your two muffler clamp bolts in the correct place (pointing up, on the engine side of the muffler - not at the bottom of the muffler)? I've seen a number of cars with ground down muffler bolts come into the shop for first-time service. We would loosen/replace them, and put them at the approximate 4:00 o'clock position looking from the right side of the car along the front of the muffler. We took care of some cars with wiped out front tow hooks and muffler bottoms, but most of that damage was from steep driveways, fairly common in SoCal. It sounds like your problem occurs when you unload, then immediately load, the suspension - you might be expecting a little too much from the car. I don't know how Sport shocks interact with stock torsion bars, other than their valving might be too firm. I guess that it's possible that, when you experience the problem, that the shock and torsion bar are fighting each other, rather than working together, especially during compression. It doesn't sound like anything is actually wrong with the car, but that it's expected to handle a situation that it's not capable of handling.
Pete

Gary R.

Pete - you must be getting old (I am obviously already there from MY response to him!) because it's his FLOOR panel that is grinding away on the road (put the glasses on, look at his pictures.. ...).

BTW, did you see that the 964 motor in N.C. sold for $4200 on Ebay? And it was a later 3.6 with head gaskets apparently..

Away I go!

theiceman

Actually I was thinking that it may have something to do with the unloading and loading of the suspension also , That is why I thought it may not be broke" . I will actually measure my ride height and repost. I actually had two seperate incidents, the one in the pic when I went over the rise and into the dip ( actually did not see the dip for the rise and went in a little quickly I guess). The front scrape was on a downward hill right hander at the bottom . My 944 would take it no problem at speed without any scraping but the 911 definitely scraped. But I will recheck the location.
when I put the Bilstein sports on the front should I have added any external bump stops like were on my boges ? I just removed the ones on my Boges and didn't put any new ones in. If I am expecting too much from the car and this was just a learning experience fair enough, just wanted to make sure i didn't miss anything.

Thanks guys ..

Gary R.

Wish I could offer more Ice, but I have both a 78SC and a 93 964, both driven VERY hard on/off the track and I can't imagime my floor panel whacking the road like your picture shows. I guess it's possible that without bump stops on the shocks you can get the 8" of travel down but can't decisively say. My SC has a custom Bilstein front end put in by the racing shop and 31mm/23mm torsion bars so it ain't stock...

theiceman

Gary

Thanks for the input . I iwll keep digging and repost if I gather more data.

ice

DGaunt

I think it's his gas tank thatis hitting...if so, not a good thing at all.

Peter Zimmermann

Gary: LOL! Excuse me a moment, I must comb what's left of my very gray hair! Regarding your secondary note, I wish that they would have told me that engine was headed for eBay, I would have made him an offer. Oh well... Yeah, I saw the damaged floor, but it didn't look like scrapes done by hurtling across bad pavement.

ice: Are your front Bilsteins inside Boge struts, or did you buy new struts?
Pete

theiceman

Hi guys here is the info

Pete you were right on as usual .. I jacked up the car crawled riht underneath and looked right under the tow hook .. rusty .. just could not have hit here. that thing was flat from something but it was not recent. Then I inspected the tire ... uh oh .... I guess these wheels have the wrong offset and will not t ck under the fender. Closer inspection revealed the tire had actually unpeeled the fender which a little coaxing fixed ... I have atached a pic of the tire. So now I know the car was dipping into the right hander and the left front tire hit the fender and cut up the tire. The rise and dip caused the underside of the body to hit the ground. Now waht .. is there anything I can do other than drive much more conservatively? I like the look of the wheels on that car and they would have to be replaced with a different offset.

Pete I put bilsteins into a Boge insert, chucked away the old bump stops as they would not fit and put the spacer back .

it would make sense that only the left side is showing this as I only heard the sound on the left side. and I guess there is more weight there .. ( 170lbs )

Here are my newly shaved tires..

Peter Zimmermann

ice: Nice lookin' tire - I've seen that before! If you do a really good job rolling your fender lip you should be able to use your present tire/wheel combo. You can also dial in another 1/2 degree negative camber on the front wheels, but don't do that unless you're still getting a little touch. You're OK with your bump stop situation, but you're going to have to loosen the top of your struts and get those spacers out of there! Those things are only intended for USA ride height with 5 mph bumpers, not the height that your car is at. I doubt that you hurt your new shocks but remove the spacers ASAP.
Cheers!
Pete

theiceman

Thanks Pete I now have a project for the weekend.. at least taking the spacers out. But I alwys thought without the spacers beteen the top of the strut and the body the car would be lower.... never did understand that stuff....

Peter Zimmermann

ice: Every shock has a design range in which to work, our front shocks were designed for Euro ride height.
When Porsche had to produce the ridiculously high cars to accomodate 5 mph bumper requirements, rather than design a new shock they simply added a spacer, which kept the shock safely inside its working range.
Pete