Missing a downshift,what did i damage?

[moresquirt]

I was running the car hard and came into a corner hot and went to shift from 5th to 4th and missed the shift into 2nd,redlined the motor,i guess thats not good for the clutch and motor,could i have damaged anything.Also do most when shifting go thru each gear or will you skip gears if you feel your at the correct speed .thx

[BYprodriver]

Originally Posted by moresquirt

I was running the car hard and came into a corner hot and went to shift from 5th to 4th and missed the shift into 2nd,redlined the motor,i guess thats not good for the clutch and motor,could i have damaged anything.Also do most when shifting go thru each gear or will you skip gears if you feel your at the correct speed .thx

did you see how high the tach needle went?

You should remove your oil filter & inspect it for metal!

[milliemax]

John99boxter and I were just talking about this 2 days ago and we think this is where most IMS failures come from. This is a good subject that is not talked about. "Secret Abuse" "Missed Gears" ???? Lets take a good look at our selves, not just the bearing.

[ekam]

Originally Posted by milliemax

John99boxter and I were just talking about this 2 days ago and we think this is where most IMS failures come from. This is a good subject that is not talked about. "Secret Abuse" "Missed Gears" ???? Lets take a good look at our selves, not just the bearing.

Really? Mine went when I was cruising on the highway on 5th at 3000rpm.

Over-revving by downshifting to the wrong gear = bent valves.

[moresquirt]

I did see how high,just touched into the red so approx 7200 rpms and quickly pushed in the clutch when i herd the roar off the engine,seems to be driving ok since,iam sure many that race have this happen.My extended warrany runs out in 2 weeks so if anything goes hope its covered!

[JFP in PA]

And just remember, your DME had recorded this event for future posterity..................

[san rensho]

If your motor is running fine now, then you probably didn't do any damage, but I would hook the car up to the Durametric reader to see what range of over-revs you are at. Sounds like you caught it before you did any damage.

As far as skipping gears on downshifts, I go from 4 to 2 on the track all the time. I just wait until I am almost done with braking before I downshift. Haven't had a problem at all. Many recommend never skipping gears because in the heat of battle, its easy to forget where you are and downshift too early, but I find its important to concentrate first on braking, and then when you have that under control, do the downshift.

[Topless]

Originally Posted by milliemax

John99boxter and I were just talking about this 2 days ago and we think this is where most IMS failures come from. This is a good subject that is not talked about. "Secret Abuse" "Missed Gears" ???? Lets take a good look at our selves, not just the bearing.

I think this is unlikely. Bearings like the IMS can often withstand very high rpm, some as high a 100k rpm. When an engine fails from temporary over-rev, it is usually either valve float causing piston/valve contact or rotating mass imbalance resulting in rod bolt failure or loads exceeding oil float. I'm sure Jake or JFP have a lot more direct experience in seeing the failure modes and causes, but most over-rev killed motors I have seen are characterized by valve knock or connecting rods sticking out of the case. The IMS bearing was still sound.

From the examples so far, I think IMS bearing failure is more likely moisture contamination causing pitting of the rolling surfaces and high load/low rpm such as lugging the motor off the line or in stop and go traffic. Cars that sit idle for many months do seem to have a higher failure rate than car with a lot of track miles.

No hard data so this is all a thought experiment based on anecdotal evidence.

[JFP in PA]

Based upon the limited amount of data we have seen from the DME's on engines with known IMS bearing issues, there is no apparent statistically sound relationship between over rev incidents and the IMS bearing going south. A shop like Jake’s, which sees a lot more IMS issue engines than we do may feel otherwise, but we cannot make that connection.

[The Radium King]

on the other hand, could high rpm situations lead to rms fatigue/failure? (sustained) higher rpms may get the crank rattling about, augmented perhaps by an old/failing flywheel, and a resultant weep into the bellhousing?

i spent a day at the track the other day with a great deal of quality time at or near redline, and now have a seep at the transmission/engine interface as a result.

back on topic, as stated, your durametric will tell you good info; if you have an earlier car it will tell you if you over-revved, if you have a later car it will tell you how much over redline the over-rev was.

[BYprodriver]

Originally Posted by ekam

Really? Mine went when I was cruising on the highway on 5th at 3000rpm.

Over-revving by downshifting to the wrong gear = bent valves.

Not necessarily, far more likely to stretch the rod bolts & then sooner or later opportunity comes knocking!

[BYprodriver]

Originally Posted by moresquirt

I did see how high,just touched into the red so approx 7200 rpms and quickly pushed in the clutch when i herd the roar off the engine,seems to be driving ok since,iam sure many that race have this happen.My extended warrany runs out in 2 weeks so if anything goes hope its covered!

Don't know what year your car is or engine size but if 7200rpm was max you should be fine. I would check your oil filter anyway to double check. If "moresquirt" happens to refer to NOS on your car you are on borrowed time anyway! :ah:

[moresquirt]

Thx for the feedback,great forum.I never stated what i have ,its a 2006 boxster s.
Its porsche white with white rollbars,blue roof and blue interior.I am the third owner.Purchased it last year from an owner that only clocked 1500 k in 2 years,previous owner leased it.I got it with 70000 kilometers and an extended warranty something that came in handy when i inserted the wrong key in the ignition and broke something inside when i turned it,had to get towed 2 hrs to nearest dealer ,Fun day! Just changed the plugs myself,wasent that hard,actually this car is pretty easy to work on as the motor is pretty accessable with the covers removed.I don,t care about mileage as i wont be selling it (i dont put plastic on my lamp shades) live life and enjoy every day!