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Kaos · Joined: 13 Oct 2003 Posts: 76 Location: Detroit

Hi All,

Went to an SCCA autocross on Sunday with my E-stock 1988 924S SE. High grip concrete at the Toledo Express Airport with 225-45-15 Hoosier A3S05's.

The course was fairly fast, and required 3rd gear in two locations (225-45-15 tires makes for 55mph on the rev limiter in second gear). The first location was no problem, as it was at the entry to a flat out widely spaced slalom. Relatively low G's, and an easy shift to third. The second shift point was at the end of a high speed (at least for autocross) 50mph sweeper leading to an offset. When I went to shift to third, it just wouldn't go! I was frantically trying to jam it into third, but no dice. Kinda felt like I was mixing something in the Kitchen! Eventually it went, I started letting out the clutch and Woooohhhh- the engine starts screaming. Obviously 1st. Ouch. By this point, the car was no longer at high G's, and snicks into third easily. My time obviously sucked.

Second run, I wait a little longer to shift, and try to get the car a little straighter before shifting. This time the shift took maybe 1 second (as opposed to the usual 0.3-0.4secs on my G-Analyst). OK - getting somewhere now. Third run - waited even longer and was a normal easy shift.

Fourth run, kicked some butt. Came in 5th in the PAX (handicap scoring based on class), and was the 3rd fastest stock class car at the event (200 vehicles).

924S SE rocks.

Anyone else ever had this shifting problem? Seems like the transmission is just moving alot at high G's (1.15) and the shift linkage is no longer aligned properly.

On another note, this was the first event where I had some inside rear wheelspin on corner exit. Looks like it might be time to replace the clutches in the ZF LSD.

Jon A

Kaos · Joined: 13 Oct 2003 Posts: 76 Location: Detroit

Link to event results:

http://www.nworscca.com/modules/event_results/results/2005_e6_web.htm

924RACR · Posted: Fri Sep 09, 2005 1:22 am Post subject:

Worn mounts - either engine and/or trans. You can see the shifter leaning in some of my videos too. I still haven't gotten new trans mounts in, I don't think... though I have done engine mounts. The shift lever was probably hitting the opening on the tunnel.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Kaos · Joined: 13 Oct 2003 Posts: 76 Location: Detroit

The engine mounts on my car were replaced a few years ago with the updated turbo mounts. The trans mounts are original, but they sure looked fine to me when I had the trans out last winter. I guess it wouldn't hurt to replace the trans mounts.

When you say weak mounts, what failure mode are you talking about in particular? In my experience, rubber gets harder with age, and eventually rips or tears. An inspection of my trans mounts reveals malleable rubber in reasonable shape with no tears or cracks.

It seems strange that I would be the only one to experience this phenomenon. I would think this would be quite prevalent on a track car.

Jon

924RACR · Posted: Fri Sep 23, 2005 10:20 pm Post subject:

You may need adjustment to the shift lever position - if you've assembled it incorrectly, with the wrong fore-aft angle... then it could hit the tunnel. It should be leaned back maybe 15 degrees as I recall.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype