Clutch Line Upgrade?

[JCSIX13]

The GT350 gearbox shift feel has two components - the detent is the one you should feel and the completion of rotation speed matching is the one you shouldn't feel.

If you move the shifter fast enough, you'll feel both. The rotation match is that second "click" that comes as the shift lever ends its travel. If you move more slowly and deliberately, the synchro's will have matched the rotation speeds of the gears and you'll only feel the detent as the shift completes.

What I've been looking for in the various fluids I've tried is a friction level that gives detent-only shifting at reasonable shift speeds. I tend to shift gently and deliberately - 40+ years of driving MT's makes you that way.

The reason I'm looking for a new fluid is that the Mercon LV fluid doesn't produce smooth shifts often enough for me. I don't know if others have noticed, but it occasionally fights going into gear on the first push, but if you ease off pressure a bit and then push again, it goes right in on the second try. 1 > 2 is the worst for this, but 2 > 3 and 4 > 5 do it too. Generally, downshifting works pretty well.

And, I've found fluids that are much better than Mercon LV, and some of them took me by surprise. RP Synchromax has been crap when I've tried it before, but it's a treat in the TR3160. And while it's a big improvement over Mercon LV, it's not the best.

So what is the best?

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[JAJ]

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So what is the best?

I don't know which is best yet. I'm still trying different fluids.

 

[JCSIX13]

I don't know which is best yet. I'm still trying different fluids.

Ok, Please keep us posted on your results.

Thanks
Jack

 

[EF300]

I got to be honest man, you just got a new Tranny I would give it a few thousand miles before you do anything to that car. You need to make 100 % sure any issues are ironed out.

Your crazy lol

 

[cking]

What to the clutch line discussion?

 

[altjx]

Thanks for all of the input guys. Seriously. It sounds like a better clutch line won't necessarily help out with anything, is that true? I guess my overall goal is to make shifting as easy as possible, even if it's a small change. First to second is the biggest issue for me, but it sounds like that's pretty normal.

When I asked a few months ago about the reasons shifting requires so much more effort in between gears, people thought I was crazy, but it does sound like 1st to 2nd is actually supposed to require more effort when compared to the other gears.

I'll assume you are not shifting with a WOT, but are depressing the clutch and letting off the throttle during shifts; that when you refer to WOT shifting, you really mean shifting at high RPM, which would be the natural result of shifting while employing a WOT.

If this is the case, the 1 to 2 shift will have a tendency to be the most difficult. This is because the 1-2 gear ratios have the greatest spread (or % difference) within the gearbox, meaning the RPM drop on the input shaft (at a given RPM) is the greatest when making this shift. This requires the syncro, which is there to facilitate this RPM drop, to work harder and harder, the higher the RPM is at the shift point (because the RPM drop increases). If you want to get a sense how hard the syncro works, drive in 2nd at 25mph and shift into first (don't worry, you won't blow up anything, but you'll clearly feel the increased shift effort).

Being cut from the more road racing cloth (as apposed to drag racing) I've always been extra respectful for gearboxes, realizing that they are generally to most fragile part of the drivetrain. I would suggest focusing on being smooth and deliberate with your shifts first, and worry about speed later, if ever.

Also, I might help to understand how a modern syncro-mesh gearbox works to begin with. There are several youtube videos out there which give good insight.

Exactly, I'm shifting at or near redline (as close to it as possible in some scenarios).

I got to be honest man, you just got a new Tranny I would give it a few thousand miles before you do anything to that car. You need to make 100 % sure any issues are ironed out.

Your crazy lol

Lol I've already got 700 miles on the new transmission. I put 28k on my the last one, but this concern doesn't seem to be something that'll go away in a few thousand miles. I just want to make the drive as easy and comfortable as possible. I've already got the car tuned and full exhaust (headers all the way back) and the dealership gave me no problems. I doubt they'll give me much problem with a clutch line upgrade if they don't believe it would have caused an issue of course, lol.

 

[JAJ]

...I just want to make the drive as easy and comfortable as possible. ...

Me too.

You can change the fluid and it'll shift easier.

If you want the fluid to look the same as factory, then try Pentosin ATF 1 LV with 4 ounces of Lubegard Black friction modifier added. It'll look the same but it'll shift easier. Even if you skip the Lubegard, it's way better.

If you don't care how it looks (not red fluid) then swap to AC Delco 10-4014 Friction Modified MTF. shifting is clean but a little bit stiff when it's 30 to 40 degrees, but once it's over about 60 degrees, it's easy and it's very clean.

These two alternatives to Mercon LV are the best I've found so far. I'm shutting down the testing program until spring, though, because I can't get the gearbox up to temperature because it's too cold, even with the cooler duct taped off.

 

[altjx]

Me too.

You can change the fluid and it'll shift easier.

If you want the fluid to look the same as factory, then try Pentosin ATF 1 LV with 4 ounces of Lubegard Black friction modifier added. It'll look the same but it'll shift easier. Even if you skip the Lubegard, it's way better.

If you don't care how it looks (not red fluid) then swap to AC Delco 10-4014 Friction Modified MTF. shifting is clean but a little bit stiff when it's 30 to 40 degrees, but once it's over about 60 degrees, it's easy and it's very clean.

These two alternatives to Mercon LV are the best I've found so far. I'm shutting down the testing program until spring, though, because I can't get the gearbox up to temperature because it's too cold, even with the cooler duct taped off.

Gotcha. Very interesting. Quick question -- although I'm by no means even close to being a mechanic, is this something anyone could pretty much do in these cars?

 

[JAJ]

Gotcha. Very interesting. Quick question -- although I'm by no means even close to being a mechanic, is this something anyone could pretty much do in these cars?

Changing the fluid isn't particularly difficult on the TR3160.

- The drain is on the bottom and the fill is on the driver's side just above the rear cross-member.
- The plugs only require a 3/8" square drive (a ratchet handle with no socket on it) to undo them, so it's pretty simple.
- A hand pump that screws on the top of the bottle works fine to fill and you stop pumping when fluid starts dripping out the fill hole.
- A change on a car with a cooler takes about 2.7 quarts, so buy 3 quarts or liters if it's Pentosin.
- Procedure is to loosen but not remove the fill plug, remove the drain plug, drain and replace the drain plug, remove the fill plug, fill and replace the fill plug. You loosen the fill plug first just in case it's stuck and won't come out.
- The manual says to fill, run the engine with the clutch engaged in neutral for two minutes to fill the cooler circuit. I've done it enough times that way to know that if it's full before you run it, it's still full after, and the step isn't necessary.

The challenge in changing the fluid is getting under the car. Unlike changing the engine oil, the car has to be level to change the trans fluid, so you have to raise all four corners. You'll either need a lift or a jack and a set of four stands.

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