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To add to AJ's note...all that black greasy looking stuff on the wormgear housing (at the bottom of the photo) is the remnants of the disintegrated OEM bushings. They basically turn into greasy paste. These gaps are what allow the rocking to take place.
Fix is very easy just somewhat time consuming. (Worth every minute!) "How to" videos available on YouTube.
To add to AJ's note...all that black greasy looking stuff on the wormgear housing (at the bottom of the photo) is the remnants of the disintegrated OEM bushings. They basically turn into greasy paste. These gaps are what allow the rocking to take place.
Fix is very easy just somewhat time consuming. (Worth every minute!) "How to" videos available on YouTube.
Hey, Johnny. Is this actually rocking, or is it the seat sliding back and forth?
I can vouch that the seat definitely tilts back and forth - it's not just sliding in the tracks. No idea why as I haven't pulled mine out to fix yet, but it's going to get done as soon as DST ends and the car gets parked for the next several months.
Having driven mine daily (2 days a week) for the last 7 months I can say this coupled with the overall poor shifter linkage setup and clutch feel (compounded by disintegrated prop shaft couplers and shifter mount bushings) makes the M6 version of this car somewhat disappointing when they start to show their age. My ZF equipped C4 has 50k more miles on it and is nowhere near this sketchy.
Give me a week or so, I'll tear mine down and give a full dissertation of what I find as mine moves in every way imaginable except sideways. I just had a "spirited" commute back from work where not one but two dipsh][ts thought they would try to show me how their yuppie crossover AWDs/4WDs could (attempt) to keep up on a winding two-lane that I know better than they do. They were wrong.
At the end when I took a left to merge onto interstate with yuppie #2 still behind me I laid into the throttle hard. When I let off to grab 2nd I felt the seat move and something strange happened - the (edit: clutch) pedal stuck down at about 2 inches off the floor. Once I used my foot to flip it back to the return position everything was fine, but my butthole was puckering hard for a good minute afterwards b/c the buggy was rolling at about 60mph at the point of the initial "malfunction".
Last edited by spfautsch; Oct 28, 2022 at 07:56 PM.
Give me a week or so, I'll tear mine down and give a full dissertation of what I find as mine moves in every way imaginable except sideways. I just had a "spirited" commute back from work where not one but two dipsh][ts thought they would try to show me how their yuppie crossover AWDs/4WDs could (attempt) to keep up on a winding two-lane that I know better than they do. They were wrong.
At the end when I took a left to merge onto interstate with yuppie #2 still behind me I laid into the throttle hard. When I let off to grab 2nd I felt the seat move and something strange happened - the (edit: clutch) pedal stuck down at about 2 inches off the floor. Once I used my foot to flip it back to the return position everything was fine, but my butthole was puckering hard for a good minute afterwards b/c the buggy was rolling at about 60mph at the point of the initial "malfunction".
When was the last time you changed your clutch fluid? Odds are good it's shot. Pop the reservoir cap and see what it looks like. If it's black (from boiling) a fluid flush may be all you need. If it's clear and that's happening it's either the clutch master cylinder, throwout bearing, or the clutch itself is on its way out.
Not such a "strange" occurrence in the C5. Especially if regular maintenance like fluid swap is not regularly performed. Go with a high temp fluid the next flush and upgrade your clutch if a new one is imminent.
Lol, ok, no. As I (edit: thought I) mentioned the clutch was still disengaging or I would have been crashing gears upshifting. I thought it might initially be a hydraulic problem, but it clearly wasn't because when I manually returned the pedal to top the weight and feel of the pedal returned to completely normal. This car has 136k miles and the propshaft couplers are gone. I know because in neutral with the clutch engaged it sounds like a rod knock. Disengaged it goes away completely. This winter I'll be dropping everything (possibly even the engine) and giving everything a thorough once-over. This includes clutch hydraulics and mechanicals as well as a new pilot bushing.
For the record, I know a thing or two about hydraulics, and boiling fluid will cause the pedal to feel spongy. The only way changing the fluid will solve a major malfuntion like this is if there was a massive amount of air in the slave cylinder. Also, the black you see in the reservoir isn't from the fluid boiling, but residue from the master and slave piston seals wearing.
I was mainly blaming the rocking chair for causing me to sidestep or whatever I did that caused the pedal to do that. My guess is the pedal return spring popped out of place, though that's just a wild guess. Enough about that, lets talk about the reason the seat rocks instead of just sliding.
Last edited by spfautsch; Oct 29, 2022 at 06:53 PM.
While you're in there it's likely worth replacing the bushings anyway. If they are the OEM ones that deteriorate.
Thanks Johnny. Mine are shot. When I leave the starting line at the strip, I have 1,320 feet/1/4 mile to go. When the seat stops moving, it feels like I've got 1,322 feet to go!!!!
Thanks Johnny. Mine are shot. When I leave the starting line at the strip, I have 1,320 feet/1/4 mile to go. When the seat stops moving, it feels like I've got 1,322 feet to go!!!!
That sounds like the bushings to me. My car was doing the same. Especially on hard starts and stops. The shims are pretty thin but the seat travel was really pronounced with me in the seat and felt like it was rocking.
Good thing is once you have the seat out and cushion off you can inspect if you have a popped or loose rivet causing the rocking or if it's just the shims. Sometimes it's both a loose rivet and degraded shims. I only had a shim failure in mine. Which is the more common issue.
Assuming it likley starts out as just a shim failure then leads to the rivet issue if ignored.
Less cheeseburgers and more salads may help mitigate the rivots from coming loose.
That sounds like the bushings to me. My car was doing the same. Especially on hard starts and stops. The shims are pretty thin but the seat travel was really pronounced with me in the seat and felt like it was rocking.
Good thing is once you have the seat out and cushion off you can inspect if you have a popped or loose rivet causing the rocking or if it's just the shims. Sometimes it's both a loose rivet and degraded shims. I only had a shim failure in mine. Which is the more common issue.
Assuming it likley starts out as just a shim failure then leads to the rivet issue if ignored.
Less cheeseburgers and more salads may help mitigate the rivots from coming loose.
I installed the nylon spacers this weekend and found a ton of slop in the height adjuster pivots, as well as some endplay in the front worm drive gearbox. Links to a couple short videos. This is what's causing the rocking.
I improvised some bushings to tighten up the pivots and that eliminated 90% of the rocking. There's still a small amount but it's much more tolerable and feels less like I'm sitting in granny's rocker. If it comes back when my bushings start to wear I might look at a pair of the billet pivots like vette4fl posted above. Pretty pricey tho.
One thing that really surprised me was how heavy these seats are. I don't remember my C4 sport seats being this heavy, but it's been several years so maybe they are. Woof!
I think my issue is back and forth. When I first get in the car, before I start the engine, I select my memory position, and the seat moves and stops where it should. Then, if I use my legs to pull it forward until it stops, and then push it back, I'm getting what looks to be at least 3/8"-1/2" total movement!! But, as Johnny or someone else posted, labor is getting the seats out. Having a NICE CLEAN bench to lay the seat back on is important, too. When I get back home to my Michigan garage, I'll yank the seat(s), and fix whatever is needed. 23 year old seats need a LOT of work. Need new covers, etc. So this year, the seats get the few thousand the rest of the car has gotten!!
I think my issue is back and forth. When I first get in the car, before I start the engine, I select my memory position, and the seat moves and stops where it should. Then, if I use my legs to pull it forward until it stops, and then push it back, I'm getting what looks to be at least 3/8"-1/2" total movement!! But, as Johnny or someone else posted, labor is getting the seats out. Having a NICE CLEAN bench to lay the seat back on is important, too. When I get back home to my Michigan garage, I'll yank the seat(s), and fix whatever is needed. 23 year old seats need a LOT of work. Need new covers, etc. So this year, the seats get the few thousand the rest of the car has gotten!!
That sounds like the shim issue. Getting the seat out is easy it's the bolts hidden under the rear part of the seat cushion hoolding the base to the seat that are a PITA to get to.
It was a nice sunny morning when I did mine. So I used the tailgate of my truck with a moving blanket as my clean workbench.
On the bright side you get to do the skin the cushions and the shims all at once. It will be as good as new when you're done.
Rocking Seat Repair
