I think it's because of the way that I have my home made dust seal over the pro 5.0 and the carpet under the console.  I'll fix that when I pull the engine. If that doesn't fix it I don't know why it would come out of gear.

Me thinks there is a tach wire on the cruise control that will shut it off if the engine revs. Check your install manual. 

You did install the clutch switch which cuts off the cruise?


 

Last edited by RV6 (9/22/2019 4:14 PM)

RV6 wrote:

TKOPerformance wrote:

If its not related to the shifter, worn synchronizer engagement teeth on the 5th speed gear can cause the trans to jump out of gear. 

To push my T5 out of gear while cruising would take quite a bit of force.


 

That's the thing, its not being pushed out of gear.  When the teeth get worn down the slider gets flung backwards off the gear and the trans winds up in neutral.  Its typically most pronounced when you let off the throttle and then get back on it, as it suddenly applies rotating force to the geartrain in the trans.  The teeth are supposed to have nice crisp points.  Bad or sloppy shifts over time wear those points round.  Its not the loss of a lot of material really, just that a hard corner holds the slider and a radius allows it to rotate just a tiny fraction of an inch and that's all it takes.  This is why whenever I rebuild a trans I pay very close attention to the engagement teeth on the gears, and replace any gear that has damaged teeth.  Damaged teeth are most common on 2nd and 3rd gear from people missing fast full throttle shifts, but its also quite common on 5th, I think because by 5th people are half @$$ing the shift.  They aren't banging gears anymore and are just throwing it into OD to cruise, and their attention to making sure the gear is fully engaged before letting off the clutch isn't what it should be.  That's how the teeth get rounded over.  The teeth are supposed to hit a slider that isn't moving with engine power behind it (clutch disengaged).  When the clutch becomes engaged before the gear locks into the slider wear occurs. 

If the teeth are worn it won't make any noise, bang, etc.; it will just pop out of gear.  A synchronizer is a multi part affair.  The synchro rings are just part of it.  The ring rides on a cone on the speed gear, which has matching teeth.  They work by slowing down the speed gear as the fork moves the slider into engagement.  The slider wants to remain centered without shift input because of the springs and dogs on its hub.  When its moved off center it hits the ring, oil is exhausted from under the ring, and friction slows the speed gear, allowing the slider to couple to it.  In my experience, though I always replace them during an overhaul, the rings rarely see any wear.  What gets damaged are the engagement teeth on the speed gear.  There's no way to replace them other than to just replace the gear.  They are the thing I probably spend the most time examining after tear down.  Any wear and I replace the gear.  On average I've replaced at least one gear in every T5 I've rebuilt, and two to three in a lot of them depending on how they were driven and driver skill.  When those teeth get worn it doesn't take much to fling the hub back off the gear, and it returns to center, because that's where it want's to be due to the preload of the dogs and springs, and the notches inside the slider that interface with those dogs. 

Now hopefully this is all academic, and all that's going on is the stop bolt on the shifter is too far out.