Manual transmission, car moves in neutral.. huh?! [Archive] - Chevelle Tech

: Manual transmission, car moves in neutral.. huh?!


ChaosMalibu
Oct 11th, 10, 8:02 AM
Ok... After a 5 years restoration.. finally yesterday for the first time.. i drove my car.. http://72.22.90.30/phpBB2/images/smiles/icon_smile.gif <-- this smile is too small.. i need a bigger one that goes all over the screen here..


I made some modifications in the car, and the car has a T-56 transmission now..
I only drove it a little.. 1st and 2nd. The t56 was freshly rebuilt before i installed it. but it was sitting in the car for 3 years...

it goes, and with the 4.68 rear i have.. even 1st and 2nd give you a big ass smile..

BUT.. i had a weird thing happen to me..
While the car is in neutral.. engine running.. me outside the car tuning the carb.. out of nowhere, the car went into gear..

it didn't start driving or anything like that.. but it felt like an Auto transmission that you shift it into drive.. You know.. that first feeling of moving forward..

What may cause that thing?? Do i need to brake in the tranny? any ideas?
anybody heard of such a symptom?

Bow_Tied
Oct 11th, 10, 11:53 AM
Hi Shai! :waving:
That is weird. Check that there is free play in the clutch pedal - don't want the T/O bearing pressed against the clutch. I am just guessing. Wait, is this a hydraulic clutch?

Thinking about this more after rereading your post,
If the car didn't move forward, it wasn't in gear. So te symptom was the idle dropped similar to a trans going from N to Drive with a foot on the brake - I have to wonder if your tuning on the carb pushed on the throttle linkage which may have been a little stuck and the idle simply dropped. Check the throttle linkage for smooth operation.

Good luck.

ChaosMalibu
Oct 11th, 10, 3:18 PM
Hey Ron,
How are you buddy?

No the car did move forward.. Just a little.. As if you put it into drive..
The tob comment makes sence.. Maybe I need a big ass spring that will hold the fork back.. Because the slave cylinder is pressing on it..

ChaosMalibu
Oct 11th, 10, 9:21 PM
Thinking ok it again.. I don't think it really matters..
Yes, it is an hydraulic clutch.. But the tob is not hydraulic.. It's a master and slave cylinder setup..

But when the gear Is in neutral.. The rear end should not try to spin.. Even if the tob is pressed in or not..

Am I wrong?

AXEMAN39
Oct 11th, 10, 9:31 PM
Just a thought, but did you possibly forget to fill the transmission with oil? if it was run dry things may be binding in the trans and that would cause the car to want to move forward even in neutral. Just a thought.

Bow_Tied
Oct 11th, 10, 10:32 PM
Shai, I am not very knowledgeable on t56s. I wonder if they have some sort of shifter adjustment? If you don't get a good answer here on that, I think LS1tech is a forum that knows these trans.

Maybe you have a ghost in the machine? :D

Like Scott says, if the trans is actually in neutral, then something must be binding or dragging.

Can you make the problem happen anytime? If in neutral does a gentle pressure on the shifter toward a gear make the problem happen again?

cuisinartvette
Oct 12th, 10, 10:51 AM
If its the Fbody slave yes they push some against the fork but that wont make it depress it. They use Dextron III I believe if that helps.
That is weird wonder if the Keisler folks can pipe in.

joe58
Oct 13th, 10, 10:38 AM
is it cold there? Do you have the correct trans fluid in it?

One of my cars with 5 speed trans does this on very cold days, I can feel a slight forward motion in neutral. It does not move the car with any force, but I can feel it slightly.

I think it is a fliud drive effect between the gears and the cold fluid in the trans.
Similar to how a torque converter in an auto trans works but the torque converted is designed for this type of fluid drive.

ToocoolZ28
Oct 13th, 10, 4:51 PM
is it cold there? Do you have the correct trans fluid in it?

One of my cars with 5 speed trans does this on very cold days, I can feel a slight forward motion in neutral. It does not move the car with any force, but I can feel it slightly.

I think it is a fliud drive effect between the gears and the cold fluid in the trans.
Similar to how a torque converter in an auto trans works but the torque converted is designed for this type of fluid drive.Joe got it, I'll bet when the fluid is hot it wont do it.
Ron

swcash
Oct 13th, 10, 5:12 PM
A lot of strange things happen on that side of the globe. Probably once you get some miles on the trans the problem will go away.
Squido :confused:

69-CHVL
Oct 13th, 10, 5:21 PM
I dont think its a clutch/linkage issue - neutral is neutral. Do you have some heavy gear oil or something in the trans?

blumont
Oct 13th, 10, 5:37 PM
Could the pilot bearing/bushing be binding on the shaft?

MEJ1990TM
Oct 14th, 10, 10:46 PM
I would think that if the gear oil was thick from being cold the engine would just stall.

350_Malibu
Oct 14th, 10, 10:59 PM
I would think that if the gear oil was thick from being cold the engine would just stall.

:noway: Nope in neutral shouldn't kill it, but it might cause it to lurch a bit. I had this happen in my 4 banger Nissan pickup with a 5 speed w/140w. Once it was warmed it didn't do it. Went back to 90w and the problem disappeared. Maybe to thick of gear oil... Should be 90 weight, should it not??

MEJ1990TM
Oct 14th, 10, 11:16 PM
Hmmm. When the '70 was in cold weather ,like up in Flagstaff, out the engine would stall when you let the clutch out in neutral. It had to be warmed up a little bit before the gear oil stopped putting too much drag on it. Of course that didn't have a choke on it. Maybe that was it.

Tony65
Oct 14th, 10, 11:44 PM
On very cold days (~30 degrees) even with the choke on, I'd have to rev it slightly while letting out the clutch because the thick oil would definitely create too much initial drag in the M21 ( in nuetral). after a few seconds it was fine, but initially it could stall a cold engine.

My first thought on the OPs problem was a mis aligned transmission where the input shaft is slightly off center, therefore transferring some load through the bearing onto the mainshaft. That is of course if the two shafts are coupled through a bearing.

ChaosMalibu
Oct 17th, 10, 6:34 AM
I think the problem is gone.. It didn't happen again, i guess maybe i had to brake in the transmission... :)