Intermittent 1st gear grind

[stuart720]

Hey guys, looking for a little assistance. 

 

So recently did a motor swap. From the z24 to the z20. (Long story, I didn't WANT to). Along with that, a new clutch kit and topped off the tranny with royal purple. 

 

So the engine swap went good, and still good. But I've got a random grind in 1st gear. Never had an issue with the tranny before and actually functioned fine for a month or so after the swap. 9/10 times no problem.

 

But when it does happen, about half way through 1st I get a grind like I'm meshing gears, foot off the clutch, not hotroding, and it seems to throw the shifter towards the right. Never kicks out of gear and seems to correct itself after a couple seconds...and a decent bang. 

 

I checked all oil levels, tranny full and clutch reservoir on max line.

 

Any ideas?

[datzenmike]

So you are not shifting gears nor using the clutch??? Well that ain't good.

 

I guess start with checking...

 

1/ transmission to engine bolts are tight.

2/ engine mounts tight

3/ transmission mount tight

 

[stuart720]

Never said that, of course Im shifting. I have to get through 1st to get to 2nd and I don't ride the clutch but I do use it. 

 

All of those connections are tight, I did notice some rot around the carrier bearing I know that's not great, but could that be part of it?

[Stoffregen Motorsports]

A loose or flapping engine plate could cause a noise similar to grinding gears. And you did just have the motor out. Are you sure you got all the bellhousing bolts tight? How about the lower plate bolts? Starter tight? How about the flywheel and clutch? Both of those torqued, with loctite?

 

I've also heard noises like that come from inside the bellhousing when there is a bolt or a rock inside the bellhousing.

 

Assuming it is inside the trans, did you have the trans apart? A roll pin that's not in all the way can grind against a gear. Also, the front cover bolts can hit gears if they are too long.

[datzenmike]

2 hours ago, stuart720 said:

Never said that, of course Im shifting. I have to get through 1st to get to 2nd and I don't ride the clutch but I do use it. 

 

 

 

But you did say...

 

17 hours ago, stuart720 said:

 

But when it does happen, about half way through 1st I get a grind like I'm meshing gears, foot off the clutch, not hotroding, and it seems to throw the shifter towards the right. Never kicks out of gear and seems to correct itself after a couple seconds...and a decent bang. 

 

 

 

 

Foot off clutch you're in gear and driving. (or in neutral) How can you be shifting? I use the clutch when shifting gears.

 

.

[stuart720]

How do you not understand? I put my foot on the clutch, depress, shift, let the clutch out and raise my foot off the pedal UNTIL ready to shift again then rinse and repeat. The truck is in gear driving down the road and at about 2000-3000 rpms, first gear only, I get a couple grinds. If my speed is adequate I then proceed to PUSH THE CLUTCH IN and SHIFT to second. No noise or problems 2-5 or reverse. I've been driving this truck for about 12 years and have a pretty good idea on how I'm supposed to operate it

Edited July 26, 2023 by stuart720

[stuart720]

Never had the trans open just separated from the old and married to the new. All bolts were torqued and triple checked

 There is definitely a mesh issue. It drives like normal till the noise the it almost acts like I'm pumping the clutch, kinda lunges as it loses contact and regrabs

[stuart720]

So Mike, you're just gonna pretend I'm retarded and laugh instead of offering assistance? That's extremely generous of you.

[datzenmike]

The two statements conflict. So you are not shifting then.

 

Simply put this happens only in first gear while driving, yes? If clutch is involved this could be something very different so it's important to me to know.

[banzai510(hainz)]

I would run regular old oil myself. but only guessing here.

 

If you think its a carrier bearing jack up and put on stands then runs thru the gears again. Maybe something obvious.  Loos bolts on drive shaft?

 

Z20 22 bolcks are pretty much the same and asssume same clutch stuff was used

Edited July 26, 2023 by banzai510(hainz)

[datzenmike]

But why only in first gear? Driveshaft won't know what gear you're in and it doesn't grind. It kind of flops around like a goombah in the trunk trying to get out. 

 

 

[datzenmike]

1 hour ago, stuart720 said:

So Mike, you're just gonna pretend I'm retarded and laugh instead of offering assistance? That's extremely generous of you.

 

My apologies, I thought the comment about knowing how to drive it was funny. 

[stuart720]

I see. So 100% driving it like a normal person would. Push the clutch in, shift to first, let clutch out, apply throttle, rpms hit 2000-3000, "rink"-"grind", let off throttle/ apply clutch/or power through, noise disappears. Not a problem in any other gear. And it's intermittent, It does not happen every time I'm in first. Roughly 1/10 times the noise is there

[datzenmike]

Good. Well like the carrier bearing the clutch cannot know what gear you are in so it can't know you are in first. Pretty much this is in the transmission I would think.

 

What happens if you hold onto the shifter and push firmly and hold it in the first gear position and drive it?

[stuart720]

No change, I thought that too, maybe kicking out of gear.

 

 

[datzenmike]

When the noise happens did you say the truck slows or reacts?

[stuart720]

Slows, no. Reacts, sometimes. Half the time just noise, the other half there's a bit of a *pop,bang* and you can feel it almost like I pumped the clutch 

[Stoffregen Motorsports]

2 hours ago, stuart720 said:

Slows, no. Reacts, sometimes. Half the time just noise, the other half there's a bit of a *pop,bang* and you can feel it almost like I pumped the clutch 

Are you 100% sure the clutch was installed properly on the flywheel?

[datzenmike]

On 7/25/2023 at 4:34 PM, stuart720 said:

 

But when it does happen, about half way through 1st I get a grind like I'm meshing gears, foot off the clutch, not hotroding, and it seems to throw the shifter towards the right. Never kicks out of gear and seems to correct itself after a couple seconds...and a decent bang.

 

 

Sounds like when trying to shift into reverse without the clutch? Like gears grinding? Or something other than that? Care to try an experiment?

 

Warm it up. Remove starter and look at the star gear on the starter and inspect the ring gear on the flywheel. Any unexplained shiny wear? Carefully wrap up the positive cable so it can't touch anything grounded. Push start it and try to get it to repeat the grinding sound. OR if you have a spare starter swap it NOT saying to go out and buy one.

 

 

 

 

[720_Jeff]

On 7/26/2023 at 11:26 AM, stuart720 said:

So Mike, you're just gonna pretend I'm retarded and laugh instead of offering assistance? That's extremely generous of you.

 

I think the thing we all have to realize, datzenmike fields a ton of questions.  Actually, no idea how he finds the time with some 100k comments.

 

Having said that, he responds to folks that know absolutely nothing, to some of the more knowledgeable.  

 

While I don't know a lot about cars, I do know a lot about my field.  Sometimes, it really does help, to break the problem down to the most simple of steps and clarify.  It does tend to piss my friend off, but I do find surprising knowledge gaps by doing so.  In the end, saves time.

 

[thisismatt]

Sometimes we're all retarded™

[720_Jeff]

5 hours ago, thisismatt said:

Sometimes we're all retarded™

And, sometimes I'm not😀

[stuart720]

So took the starter out, nothing unusual or extra shiny. Tried your test and results are still the same. 

 

Afterwards I realized the starter might fall under this a well..

On 7/26/2023 at 1:30 PM, datzenmike said:

But why only in first gear? Driveshaft won't know what gear you're in and it doesn't grind. It kind of flops around like a goombah in the trunk trying to get out. 

 

 

 

 

After some more driving symptoms have slightly changed.

 

Happens even less often now (weird).

 

While in first if I hold the shifter up and left I can combat it..

 

The grinding is occasionally accompanied by HARD pull to the right. (This does not happen every time it grinds tho... Riddle me that one batman)

 

 

[datzenmike]

Well if in gear and not shifting there is no change in gear mesh so no 'grinding'. Although it may sound like a gear grinding this can't be the case. 

 

There may be some damage to say the shift fork or synchro hub and it's rubbing against the first gear on the mainshaft. First gear on the mainshaft is also tight against the adapter plate. At the adapter plate there is a ball bearing that supports the mainshaft. If the bearing cage is coming apart it could stick out and rub the gear.

[Stoffregen Motorsports]

Too many variable to diagnose here. We could run through all the possible scenarios, but to be truly helpful, you'll need to try each and every suggestion and get back to us with answers. It's the scientific method. Verify before you move on.

 

To clarify, it grinds going into first gear, only some of the time, and when it does, the shifter pulls to one side violently and clunks? Does that sound about right?

 

You replaced the motor, but still not clear on if the clutch and/or flywheel were removed and reinstalled.

 

The trans has not been apart, in any way, correct? And it did not make the noise before the motor swap. It really sounds like an internal shifting problem, like Mike suggested, but if it didn't do this before, you must have changed something related to the shifting. Aside from the clutch assembly, the clutch hydraulic system could be the culprit, but doesn't seem like the right answer.

 

Was the trans out of the truck? That could be a thread worth following.