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420A 5th gear grinding/loud scratch

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Stizzydrew

Proven Member
101
17
Nov 11, 2021
Los Angles, California
My 5th gear grinds when I shift normal into it, no other gear grinds or makes a loud scratch noise but only 5th. I recently had a new clutch kit installed and I believe so was the fluid as well. Everything was changed that came with the clutch kit. Ever other gear shifts normal (1,2,3,4) reverse has a problem of not wanting to enter or sometimes I put it, it goes it but then i release the clutch and put gas , it dosent move and just makes a weird noise. I have to kinda make sure and shove it in reverse. 5th gear ONLY shifts correct with no noise when I double clutch. It’s the only gear that I have to double clutch with. Maybe you guys know why it grinds/scratches noise because it worries me that most of the time I don’t use 5th gear. Only 1-2-3-4. When I am on highway yes I’ll use 5th and double clutch. one more thing is that when I am in Neutral and I use no clutch and softy push my shifter into 1-4 there is no scratch or loud grinding, but when I do that for 5th there is a loud scratch/grind but I remove it very quickly. I did it just for a small test so I don’t know if it’ll enter even with out clutch while being still, but when I’m driving I am able to shift into 5th gear with no clutch as well. I’ve only done it once and after that I never did it again bc I wasn’t so sure if that was a good thing. If you need anymore info just ask me and I’ll do my best to provide.
 
What year/model/fwd or awd is this? Can you shift into 5th (and all other 1-4 gears but not reverse) when engine is off without the noise? You should be able to.

One common possibility is the 36mm nuts on the end of the tranny input and intermediate shafts may be loose. You can pull the tranny end cover off while still in car (after draining it) to check the 36mm nuts and shafts end play.
Here's what's under the cover: see post 13 here: https://www.dsmtuners.com/threads/5th-gear-shift-inside-tranny.480233/post-153435492. In his case it wasn't a loose 36mm nut but you can see the excessive gear play which a loose 36mm nut would also do (as well as eventually destroy shaft bearings).
And how to remove/install the 36mm nuts: https://www.dsmtuners.com/threads/5th-gear-shift-inside-tranny.480233/#post-153435439.

Another possibility is a very worn select lever shoe (https://www.dsmtuners.com/threads/97-gs-t-fifth-gear-grinding-help.376341/#post-152266167) hindering the select lever outside the tranny from moving far enough).

Some other ideas: http://www.wcengineering.com/articles/popout.html
 
What year/model/fwd or awd is this? Can you shift into 5th (and all other 1-4 gears but not reverse) when engine is off without the noise? You should be able to.

One common possibility is the 36mm nuts on the end of the tranny input and intermediate shafts may be loose. You can pull the tranny end cover off while still in car (after draining it) to check the 36mm nuts and shafts end play.
Here's what's under the cover: see post 13 here: https://www.dsmtuners.com/threads/5th-gear-shift-inside-tranny.480233/post-153435492. In his case it wasn't a loose 36mm nut but you can see the excessive gear play which a loose 36mm nut would also do (as well as eventually destroy shaft bearings).
And how to remove/install the 36mm nuts: https://www.dsmtuners.com/threads/5th-gear-shift-inside-tranny.480233/#post-153435439.

Another possibility is a very worn select lever shoe (https://www.dsmtuners.com/threads/97-gs-t-fifth-gear-grinding-help.376341/#post-152266167) hindering the select lever outside the tranny from moving far enough).

Some other ideas: http://www.wcengineering.com/articles/popout.html
It’s a 1999 eclipse FWD non turbo. 420a. I will read up on all that when I can. I will also talk to my mechanic too. Yes I can shift into all gears when car is off and on, only when car is on 5th grinds. Thank you for the forums links !
 
Common problem with the F5MC1 / A578 / NVT350 manual transmission. It requires a teardown, and special tools to disassemble. You would have to inspect the gearset, and then replace the worn components.
5th synchro shown in red circle. Reverse cone is also a notorious problem with these transmissions.

A lot of it stems back to a worn out clutch fork pivot ball causing disengagement issues with the trans burning out the 5th/Rev synchros.

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Attachments

  • F5MC1 Transmission Rebuild Manual.pdf
    1.2 MB · Views: 20
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Common problem with the F5MC1 / A578 / NVT350 manual transmission. It requires a teardown, and special tools to disassemble. You would have to inspect the gearset, and then replace the worn components.

You must be logged in to view this image or video.
Since I do plan to keep this car for as long as possible, It would be worth to just rebuild the transmission and build it at the same time as it’s getting rebuilt because I do plan to turbo down the road. Win/win eh :sneaky:
 
Well, as a heads up, the input shaft inner bearing (bellhousing TOB sleeve bearing with integrated input shaft seal and shaft bearing) is discontinued, along with the end case shaft roller bearings. The BK414AWS / BK414WS kits are basic parts. I would strongly suggest finding a new set of OEM shift forks, and gear needle bearing set. The "hard parts" kits are all gone.
References:
bearing / synchro kit - https://www.transmissionpartsdistri...with-synchro-rings-nvt350-fits-94-00-bk414ws/
The shift fork pads were once available too, you can still find them in other random kits, otherwise new OEM forks are your only option for worn out pads. 5th/Rev fork is discontinued.
*New 1st/2nd Shift Fork4796650
*New 3rd/4th Shift Fork4796649AB

There are essentially zero gears, shafts, hub and sliders, shift rails, etc remaining for this transmission. Which is sad because it was used in about 5 million neons, cirrus, stratus, pt cruiser, eclipse/talon, etc equipped with a 420a LOL.
 
I can't speak for the 420a or FWD, but...

I had a similar issue in my 1g with only 5th gear grinding. Turned out to be a broken synchro spring that holds the keys in place. I ended up replacing the synchro ring, keys, and springs on that gear and was all good. This was part of full trans rebuild but would have been possible to replace with the trans still installed in the car.

As far as reverse, might be some adjustment needed in your shifter/cables/linkage to get it to fully mesh. Have a buddy help you by shifting into reverse from the cabin and then see if your shift levers on the trans will move beyond what your buddy could do from the shifter.
 
The transmission is completely different than
I can't speak for the 420a or FWD, but...

I had a similar issue in my 1g with only 5th gear grinding. Turned out to be a broken synchro spring that holds the keys in place. I ended up replacing the synchro ring, keys, and springs on that gear and was all good. This was part of full trans rebuild but would have been possible to replace with the trans still installed in the car.

As far as reverse, might be some adjustment needed in your shifter/cables/linkage to get it to fully mesh. Have a buddy help you by shifting into reverse from the cabin and then see if your shift levers on the trans will move beyond what your buddy could do from the shifter.
The transmission is completely different internally.
 
Well, as a heads up, the input shaft inner bearing (bellhousing TOB sleeve bearing with integrated input shaft seal and shaft bearing) is discontinued
Discontinued, but Transmission Parts Distributors still has some in stock. I will order an extra before they're gone.
 
Discontinued, but Transmission Parts Distributors still has some in stock. I will order an extra before they're gone.
Make sure they actually have any. Same goes for the 63mm shaft bearings. Most of the kits have been with the wrong size 66mm shaft bearings supplied. My last order from Allstategear.com last year was a shitshow and they were useless for help getting the proper parts. They charged me for a 63mm kit, and I didn't receive the 63mm bearings or the input shaft sleeve bearing. Numerous emails to them, zero help, had to finish the job with used parts for the customer because of the problems. Ridiculous.
 
Make sure they actually have any. Same goes for the 63mm shaft bearings. Most of the kits have been with the wrong size 66mm shaft bearings supplied. My last order from Allstategear.com last year was a shitshow and they were useless for help getting the proper parts. They charged me for a 63mm kit, and I didn't receive the 63mm bearings or the input shaft sleeve bearing. Numerous emails to them, zero help, had to finish the job with used parts for the customer because of the problems. Ridiculous.
I just ordered the last input shaft bearing they had in stock. Lori from customer service thinks they will get more in stock, but being discontinued I'm not sure.

Hopefully I don't run into the sizing error you did with the other bearings, since I just ordered a set of those too. I'm trying to keep stock of the needed parts for these transmissions because most used ones are garbage and one day I know I'll need the parts.

By the way. The BK414 kit is supposed to have the 63mm OD bearings and the BK414A kit is supposed to have the 66mm OD bearings according to TPD.
 
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