5MT Grinding Into 2nd When Shifting with New Clutch

[flevum16]

First off, the car is a 2005 Legacy GT 5MT, 210,000 KMs with a few basic mods, nothing too crazy. The clutch failed a bit ago and I had to get it towed because it wouldn't properly engage/disengage. Turned out the friction plate came apart.

So I installed a replacement exedy clutch and flywheel, the install went pretty smooth.

I also changed the tranny oil, using redline 75W90NS.

When taking it for a test drive I noticed immediately a relatively nasty grinding when shifting both up and down into second. All the other gears are ok. The only other issue is a smaller grinding shifting into first while coasting at low speeds. I have tried double clutching, rev matching, different speeds and nothing seems to help with the grinding.

Im reluctant to tear everything apart and reinspect the clutch install as I'm not sure if that is the issue.

There was no grinding when shifting before I had to replace the clutch.

Things I have read and what I can think of are,

 

1.Clutch is not disengaging the transmission properly, maybe a problem with the fork or the throw out bearing on the shaft. I did notice a bit of play in the fork when inspecting it. The nose of the shaft the where the TOB sits also did seem slightly worn.. ie. the bearing had a bit of play on the shaft.

 

OR

 

2.The sycros are bad in second and possibly first, and the change in fluid just let the problem crop up.

 

I'm not sure if there is anything else that could be looked at before tearing the entire thing apart again, and I hoped that someone on here may be kind enough to offer some insight. I was also considering taking the car to a dealer and seeing what they thought of the issue.

 

Thanks!

Edited November 4, 2018 by flevum16

[bugblatterbeast]

Hi,

 

If you can, put the car up on 4 stands, facing a safe direction (not in garage) and confirm that the clutch is actually disengaging fully. I had a new clutch fail to fully disengage when brand new, but after some wear it started working right. It dragged just enough to cause some occasional problems in 2nd and 4th. If the clutch is disengaging properly, I would ditch the 75w90NS and dump some cheap conventional gear oil in to see if things improve. I ran 75w90NS years ago, and ditched it pretty quickly because 2nd would grind. Subaru Extra-S fixed that problem for nearly a decade. When I could no longer get Extra-S, Motul Gear 300 doped with ~ 0.5L of Shockproof worked. Even better than that blend was MotulGear 300 doped with the GM branded version of Castrol Syntrans (it only took 2-300 mL IIRC). I'll try to dig up the part number.

[bugblatterbeast]

AC Delco 10953477.

 

 

It doesn't take much to do the job. So far I haven't found anything else that made the 5MT shift as well. The last fill was Motul Gear 300, to which I added the Delco product 100mL at a time. By ~ 300mL, the gear box shifted better than new, and also better than the Motul 300/Shockproof combo. That being said, there was probably still some shockproof in the box from the last fill.

[E46erak]

i concur with bugblatterbeast's thoughts here. If you were shifting fine before (no grinds/difficulty getting into gear) it seems like your clutch may not be fully disengaging. It's also possible the pedal is moving the clutch too far.

 

Does it go into gear more easily with your foot on the floor, or with the clutch slightly off the floor (by 10mm, 20mm, etc.)?

 

Either way you can make a pedal adjustment to the clutch in the pedal box, to give it more or less engagement (depending on what you need).

 

Read through this thread for some more background: https://legacygt.com/forums/showthread.php/spec-clutch-and-flywheel-pedal-travel-question-71531p2.html

 

 

Also, make sure your fluid is topped off! I second the recommendation for the Motul Gear 300/Redline Lightweight Shockproof combo.

[Max Capacity]

I would try one of the cocktails using Motul Gear 300 before I pulled the tranny.

 

"uncle scottys cocktail" google it.

 

Here, https://www.google.com/search?q=uncle+scotty%27s+cocktail&oq=uncle+scott&aqs=chrome.2.69i57j0l5.7190j0j8&sourceid=chrome&ie=UTF-8

 

Some of the Vendors sell it as a package.

[flevum16]

I appreciate all the responses.

 

I have already changed the oil, not to a nice motul but rather a cheap oil just to see if it would make any difference. So far no change whatsoever.

 

I have also played with the pedal setting on the clutch itself.

 

This morning when driving into work I made sure to try shifting at different levels of clutch depression, it didn't seem to change anything.

 

As of yet the only thing that improves shifting so far is low rpm shifts.

 

Tonight I will try putting the car on stands and test full disengagement.

[natemj]

Would the clutch master cylinder have a play in this issue?

[flevum16]

So to follow up on this long post. I ended up sourcing a used transmission and replaced the tranny. I minimized the other changes made and used a slightly different oil in the replacement transmission. Clutch looked good when i inspected it and I couldn't find any other problems.

 

Started it up and its worked great ever since. My thoughts are it was 100% syncro issues. likely aggravated by a change of fluid and by the clutch failure.

 

Thanks for everyones help on this.

[GEE-OTTO]

Each oil affects the snychros ability to speed up and slow differently. Prob the oil you had in the gearbox when the clutch/pp failed was the optimal formulation to allow to the synchros to operate without issue. When you went to 75w90NS, while a GL-5 oil, its "slipperiness" may have exposed a worn synchro.

 

 

 

Like my engine oil I always run the same brand and weight and type (Motul Gear 300 75w90) with one exception, I used to run Extra-S. I wouldnt cheap out on gear oil however the scale of "works good and doesnt work optimally" has shifted over the years.

[Max Capacity]

I'll assume the OP will not be back, but for others, may be that old tranny had the cocktail in it before the clutch went.

 

Would have been interesting to see if another cocktail would have fixed the issue ??? we'll never know now...

[flevum16]

Nope I am still around! It's impossible for me to know what was in the old tranny before hand. The original owner was 2 before me and had it for over ten years and seemed to look after it well. He did alot of maintenance right at subaru and also took the time to remove the restrictive banjo bolt oil filter for the turbo feed line.

 

The biggest challenge I had was sourcing or deciding on oil. I had a hard time finding much in Canada that didnt cost a fortune and realistically, once the synchros are at that point they are only going to get worse.

 

The used JDM import transmission was only $ 600 CAD and went in with no easy and worked great. Of course if anyone wants the old tranny it's still sitting in the shop !!

 

Sent from my SM-G960W using Tapatalk

[Max Capacity]

Thanks for checking in.

 

Hope you plan to hang around here.

 

FWIW, I have a spare 5mt in my shed. Just in case.

 

Oh the one in the car has Moore Performance Blast Plates. It shifts great at high RPM's.