My 924s has north of 330K likes on it and for the last 50 or so I have noticed that it has a lot of chaise flex. It creaks and makes noises. Hell it is an old car. What brought this to the for front was I got to drive another 87 924s but it only had 80k on the clock. It was amazing how little flex there was in it.

A little history on the car. From 87 to about 1990 it was a street car. From 1990 to about 2004 it was a track car driven hard and a lot (although never crash) It probably had close to 30K miles of track miles put on it in that 10 years (this is strictly a guess as the odometer stopped working at 54K). the car has three drivers were driving complete schedules in it for more than 10 years. In that 10 year period it also had another 80K of street milage put on it as it was the spae car that we shared when some ones car was in teh shop or what not. Since 2004 I have DD'd it constantly putting on average 30K per year on it. I have only made changes to the car to make it a bit more street able (like putting the radio back in it) It still has the track suspension in it.

Other than I have a very long history with this car there is nothing really special. I don't think it is a MO30 optioned 924s although it did have the proper options to be one however those were all pulled out of the car and replaced with racing parts back in the early 90's (by me). Ya I know but back then it was just a 924s

So what to do? Just face the inevitable and replace the car? Go find another 924s with low millage and swap over all the go fast bits? I really don't think seam welding the car is an option as it would require a complete teardown and then a complete stripping of the chaise as it has the gunk that Porsche put on the underside of all there cars.

What to do?

The car has new bushings in it the suspension is in excellent conditions. There is no mechanical issues with the car that would be contributing to the flex. It is just that the car has been driven hard for its whole life and now it is starting to ware out.

Are we talking Chassis? Or is there something with the 924's that I don't know/understand?

Weld-in roll cage or sell it and buy another.

It's sad but them's the breaks. My RX-7 is the same way, the thing is noodle-floppy but replacement cars have skyrocketed in value so I'm resigned to living with it. (Last CL troll had cars going from $2500-7000... ouch!)

In reply to Knurled:

nailed it, with age get a cage or stitch weld, but know that with stitch welding even a 5mph will likely wreck the chassis from the energy transfer trhough out twisting and bending it opposed to absorbing it at the point of impact.

I already have a bolt in bar and I really don't want to go full cadge as it really is a street car now. I can live with it but. .. . I know it is not rite. It feels floppy when taking off ramps and what not.

@ Bobzilla Yes Chassis sorry auto spelling correction changed it.

You mentioned the bushings had been replaced, but what about the ball joints?

captdownshift wrote: with stitch welding even a 5mph will likely wreck the chassis from the energy transfer trhough out twisting and bending it opposed to absorbing it at the point of impact.

The opposite is more true. An unstitched chassis can deform everywhere while a welded-up chassis tends to maintain its integrity. That's why people stitch weld chassis, after all.

In reply to Knurled:

i was referring to in an accident. in a stitch everything bends as it doesn't crumble. I've seen a few unstitched logbooked cars be fixable after 30mph offs and some stitched cars be toast after 10-15mph adventures that didn't look too damaging. of course individual results may vary. (especially if stittched in front of the front strut towers

I'm assuming that you only stitch the cabin and the area up to the strut towers. Everything outside the suspension is just there for looks, really.

Suspension bushings age out. After six years they are toast just from age. So while you may have replaced them in the 1990s, they may be ready for replacement again.

But yes, metal fatigues when stressed. The more it fatigues the more it flexes, and the more it fatigues.

I say replace the bushings and other warm suspension and enjoy it as a DD for another 330K.

David

+1 for cage, and add-on bracing. Seam/stitch welding is risky in that if you make a "design" mistake it can rapidly accelerate the wear on the chassis. I know that in stage rally, they sometimes knowingly turn the chassis of the car into a consumable item through "aggressive" seam welding, but they consider the stiffness gains to be worth it.

For stage rally, the car is a consumable because the car is a consumable. Even if you don't have an off decent enough to require a reshell, the floor gets a pounding from gravel.

I didn't believe it until I saw pictures of see-through flooring... just abraded away. Although I understand it took three or four seasons to get that bad.

That's from the floor coming to the gravel rather than the other way around...underbody armor could take care of it, but if you're running more armor than you need just to get through a stage, you're not seriously competing.

The frames made consumable through seam welding tear first.

When was the last time the shocks were replaced ?

Who is Chasie Waring, and why did someone let her out??

Unibody cars just tend to wear out. The design and build quality have a lot to do with it, but there are just some unibodies that will last darn near forever, and some were limp noodles that were unsafe from day one.

Its mostly a function of metal fatigue. A unibody car is a geometric assembly of welds, bends, triangulation, and sheet metal. A body-on-frame car is a relatively rigid ladder frame with a body bolted on to it.

Fixing rattles, squeaks, and flex in a body-on-frame car is usually much easier. Once a unibody car loses its rigidity, its time to either scrap it or cage it.

MadScientistMatt wrote: You mentioned the bushings had been replaced, but what about the ball joints?

Everything in the suspension has been replaced. Ball joints tie rod ends strut purchs swaybar busings. I even replaced the bushings on the rear torque tube (that was fun ) in the last couple of years. I have the luxury of being able to put the car on a lift when ever I want to so it gets inspected with a lot more frequency than most.

DWNSHFT wrote: Suspension bushings age out. After six years they are toast just from age. So while you may have replaced them in the 1990s, they may be ready for replacement again. But yes, metal fatigues when stressed. The more it fatigues the more it flexes, and the more it fatigues. I say replace the bushings and other warm suspension and enjoy it as a DD for another 330K. David

Changed them all with in the last 18 months

iceracer wrote: When was the last time the shocks were replaced ?

I have koni Yellow sports. Replaced all of them in the last 2 years.

There may be a solution. I seem to recall someone with SCC used some form of expandable foam in all the recesses of a car to stiffen it up, and it worked. I don't think it was the consumer-grade stuff, but it might have been. This may have been Dave Coleman's 240SX.

That pretty much would make it impossible to do any welding on afterwards, but if you are looking for a quick solution that will get you through a few more seasons on this chassis, it might not be a bad idea.

jj wrote: Sorry for an off topic question, but I'm curious how many engines your car has seen through all that use?

Original motor was toasted due to oil starvation. #2 rod knock

2nd motor suffered the same fate (even though the builder said it would not.)

3rd motor (replaced by the builder) had an accusump system installed with it. It died due to hitting a battery at 100MPH at the glen when two formula cars and another car tangled in front of us and the battery squirted out of one of them and well. It hit the lower pulley allowing the oil pump to freewheel. It hit so hard that the transaxle dented the spar tire well in the back of the car. I was really sad to see this motor go. It was one of the stronges NA motors I had ever driven. It was an 89 motor that had been prepped to IT spec.

4 and current is a hybred. An 83 short block with each piece balanced individually and then I had the entire rotating assembly balanced. Used 89 cam and heads that were ported and polished and decked. It also has the accusump. It has been in the car since 2004. This motor is just a tick under the performance of motor #3 but I built this one and think it is the best compromise between performance and durability. It has seen street driven and hit has seen its fair share of track days. This current motor has probably gone 200+ thousand miles and other than it now starting to tell me it needs new connecting rod bearings (I am going to do them this summer) It is perfect. I did a compression test one it and it is as good as it was when I built it.

So the answer is 4 BUT motors 1-3 were all killed they did not die due to natural causes. I would like to think that I finally got the correct recipe in motor #4. The 83 short block has forged internals. The 89 head and cam have better flow. Decking of the head makes up a little for the lower compression of the 83 short block. The balancing of the motor is something that I truly believe in. Especially since it is a large 4 and has a large amount of rotating mass. Making sure it is in balance puts that much less stress on things. After allot of studding and trying to sort out fact from internet fiction I think I finally got the recipe correct for this motor. I put this motor together with what I think was the best of the stock parts available to build it. It is just a tick below the performance of motor #3 but I think it is probably a more durable motor. I could probably have brought it up to the performance of #3 by decking the head more to bring the compression up further but I wanted it to run on regular gas and I have always had a plan in the back of my head to add some sort of forced induction.

Project 924s-sc had been in the works for a long time. It is only recently that I have been able to get the proper supercharger unit cobbled together that I think is the ideal unit to use for this project. Then there is the semi plug and play MS system (that has taken 4 years to engineer) in conjunction with a cam triggered EDIS ignition system that I am currently running. This car has been a perpetual project. This is one reason why I would seriously consider searching out another 924s and swap over many of the parts OR find a S2 that is less a motor and combine the best from my 924s with it.

Years ago the FC RX-7 I had started to make a kind of cracking sound from the windshield when under hard cornering. I put in a heavier duty strut tower brace and the result was noticeably less flex and the noise from the windshield stopped.