loose 6 mm stud in 915 gearbox

[luckydynes]

Hello,

Was running an autocross last weekend and I started hearing a "squeak" (wearing a helmet and driving hard it was probably more than a squeak) when engaging second gear. It went away during a session and then came back later. When I drove around the parking lot the squeak was really more like a grind (when shifting it on the track I was just pulling it right through this grind point ... um ouch) when I would try and engage either 2nd or 4th so I declared "game over" before timed runs.

So the obvious grinding seemed to occur only when pulling the shifter down for 2nd and 4th gear engagements, although I do think 3rd seemed a bit more finicky. I started reading about 915 function, etc. and thought maybe it would be related to shifter alignment .... but ...

I drained the oil this morning and out dropped a 6 mm stud. No large metal chips on the magnet though. I've been looking at several diagrams but I can't seem to find where there are 6 mm studs? I looked at a page of torque specs too and didn't see anything that looked like the right torque for a 6 mm studs except for pump related fittings(no pump on gearbox). The threads looked pretty rounded like it was maybe cross threaded, but there is also a piece of aluminum (or magnesium) that is on the first thread (which would be deepest in the hole). It was very strange that the threads looked nakered and rolled over like it had been cross threaded or was the wrong pitch because I've not seen steel thread damage like that when screwed into aluminum/magnesium.

Looks like I'm going in there but I'm curious where this stud goes, and if there is ANY possibility of doing a repair without a complete tear down. I just did the clutch two weeks ago!

Thanks for any feedback or thoughts,

Sean

[Trackrash]

There is a plate on the bottom of the trans that mounts a shift guide in the trans. It is common for the studs to come loose. You will have to remove the plate from the bottom of the trans to fix it. Not necessary to remove or disassemble the trans.

[luckydynes]

Thank you brother!

[KTL]

The hole is probably stripped out. So you'll need to source a replacement fork plate, or modify your plate to take a different means of securing the fork. I found in my racecar's trans that the fork mounts were drilled thru and thru-bolted to reduce the likelihood of them coming loose again.

Here's good thread that discusses this problem.

third gear squeal

Also, you can consider buying an aftermarket billet aluminum fork plate from CMS or WEVO. Just a thought. Not saying that the aftermarket plate is a must-do.

[luckydynes]

Awesome thank you for the additional info!

I'm trying not to get distracted by it with work to do but you guys have compelled me to at least remove the cover and av a look.

[john walker's workshop]

Use a timesert to fix the threads if they are stripped.

[kwikt 911]

Mine did the same. Lock tight the stud and been holding for 10 years now.

[luckydynes]

Thanks gents she's back on the road!

[RDM]

Originally Posted by luckydynes

Thanks gents she's back on the road!

So tell us the story.