metroplex

I heard the gears grinding while downshifting from 3rd to 2nd gear before coming to a stop. I had the clutch pedal fully depressed and I generally find downshifting requires a lot of effort with the shifter. But in this instance I actually heard some grinding. I realize that without synchronizers, we'd have to double clutch to do a proper rev match but I'd think that this isn't necessary with the TR-3650. Should I just wait a bit longer next time to let the synchros do their thing?

RPM

Sounds like a clutch disengagement issue. Check your hyd throwout for air in the system.

metroplex

Do I just have to bleed the clutch hydraulic system?

RPM

First, how is the trans on upshifts and how easily can you put it in first right after depressing the clutch? Poor release would create hard shifting all the time. Have you changed the trans fluid?

Kenichi Mifune

Give your syncros some help. They can't do it all for a down shift. Double clutch.

metroplex

Starting from a standstill, it is normally easy to shift into 1st. Upshifts are fairly smooth and I don't have a problem going from 1st sequentially all the way up to 5th on a normal street.

metroplex

Update: Revmatching seems kind of odd at first but it worked OK. Double-clutching seemed more "natural" to do and worked even better. With rev-matching or relying only on the synchros, I'd hear a "turbine" spool sound coming from the shifter area (synchros trying to match speeds?) and I figured that wasn't a good sound. With double-clutching for downshifts, I never hear anything weird or grindy... it shifts like butter!

theedge67

Yeah, that 'turbine' sound is the synchros.

RadBOSS

Double clutching is a pain. You have to be pretty quick to do it like Steve McQueen, and with our characteristic throttle hang it slows the shift sequence down even more. Double clutching is really only necessary to compensate for really bad syncros. I think a light blip of the throttle while down shiffting is as effective (provides for a smoother transition as well) and more efficient than double clutching ... blip the throttle is going to spool up the input shaft anywaybecause there will be a little bit of drag between the disk and the pressure plate / flywheel.

Assuming nothing else is really wrong, it may have been the clutch was not quite fulling disengaged (premature engagement) as you pulled it into the lower gear and the syncros jumped and tumbled thereafter. Sounds and feel terrible, but usually no harm done.

metroplex

I do think it might be delayed clutch disengagement and/or the throttle lag. I had the clutch pedal all the way to the floor and I felt a bit of resistance through the shifter.

Double-clutching for downshifts was as smooth as normal upshifting. The shifter floated right into position! I think I'll just practice this method from now on. I tried rev-matching a few times and I didn't like the sound of the synchros.

RadBOSS

Well what I was referring to is foot and hand motion not quite synchronized. I have done it myself a couple time with this car. If you had your foot to the floor, the clutch is about as disengaged as its going to get, unless you have air entrapment, which I imagine is not very likely unless you have been messing with the clutch hydraulics. What you heard was the synchro's grinding, not the gears, as the all gears are in full mesh all the time in a transmission that is synchronized.

I assume you understand what double clutching means, Its not double pumping the clutch (which might work if there is air entrapment). It's disengaging the clutch, pulling the shifter into neutral, engaging the clutch. goosing the throttle, disengaging the clutch and then pulling the shifter into gear and then engaging the clutch. Steve McQueen was demonstrating this art in the movie Bullitt (I never had to do that with my top loader). When he did the movie Lemans and was driving the Porsche GT coupe, you may have noticed he was not double clutching. This is a technique used with some synchro-less race transmission or a trans w/o synchro's in poor condition. I have driven some race cars with synchro-less transmissions (just dogs) and they shift as smooth as silk.

Anyway if its working for you, that's great ... but that should not be a necessary technique and you may need to look deeper if dropping into 2nd from 3rd and tumbling the synchro’s is a chronic problem.

metroplex

Yes I understand the concept of double-clutching and I was indeed double-clutching for the downshifts: Clutch disengaged from flywheel, shift into neutral, engage clutch to flywheel, blip throttle to speed up intermediate shaft, disengage clutch from flywheel, downshift, release the clutch pedal (slowly for smoother transition). The shifter floats into the next position like butter. I never had to fight it once nor did I hear any synchro turbine whirring or the splines on the synchros grinding. For upshifting, I do it the standard way on a synchromesh gearbox but I double-clutched a few upshifts and didn't notice anything different.

I tried regular rev-matching for downshifting (disengage clutch from flywheel, blip throttle, downshift, re-engage clutch) and heard the turbine whirr a few times (no resistance felt in the shifter) not to be confused with a mechanical grinding sound.

I even did 3-2 downshifts to utilize engine braking while coming to a stop or a slow curve (cool engine sound) using the double-clutch method and never ran into any problems. Recall that I couldn't do this easily if I tried to rely solely on the synchros. I agree that it does take a lot of "feel" to get everything synchronized

theedge67

Hearing the syncros whirring while downshifting normally (no double clutching) isn't necessarily a bad thing IMO. As long as you don't try and downshift into 2nd at like 80mph, you probably won't hurt anything or wear the syncros out prematurely. If it takes a little bit of effort to push the shifter into gear, then push harder.

In my experience a blip of the throttle is more than adaquate in getting it into gear smoothly and there is no "CLUNK" of the driveshaft when I hit the gas because the engine is already spooled up. If you enjoy double clutching though, go right ahead...it won't hurt anything either.

karman

"Blipping" is all I ever do. It smooths things out just fine.

RKNMACH

Blipping is good....

metroplex

I tried downshifting directly and as long as you ignore the *whirr*, it seems to go rather smoothly. I'm not sure, but I think rev-matching affects the clutch / flywheel engagement more than the intermediate shaft and rotating components since the clutch is in (disengaged from flywheel) during the throttle blipping.

RPM

That's why you keep the clutch engaged. Rev-matching only works with trans in neutral and clutch engaged, hence "double clutch". BTW, up-down shifting 2-3-4 and 4-3-2 I use all the time since the ratios are close. It is only the split from 1 to 2 that being so large I give the trans some time for the synchros to work and avoid 2-1 unless going quite slow.

metroplex

Well I found out that the FSM considers anything greater than 1" of clutch pedal reserve to be normal. CP reserve is defined as the distance from when the clutch is disengaged, to when the vehicle begins to move forward. I have not measured my reserve, but it's definitely longer than 1".

RadBOSS

I think the whirring you are hearing is the whole input side (input shaft, cluster gear, and the free gears on the output shaft being spun by the cluster gear), as the synchro hub and blocker rings are all turning constant at driveshaft speed, not input shaft speed.

Unless you have revmatched with the clutch engaged in netural, what happens during a shift is the blocker ring for the gear you are shifting into presses onto the free gear on the output shaft, slowing down (upshift) or speeding up (down shift) the whole input side. The blocker ring does this by acting like a clutch against the free gear. When the speed of the input / output sides match the slider easily engages the free gear and you are on your way.

Stang281

Mine would frequently grind when downshifting too, after installing the Steeda shifter it doesn't do it anymore. Which leads me to believe that it is the stock shifter that's causing it.

My stock shifter was so bad that I thought the clutch needed to be replaced because it felt like it was slipping, with the Steeda shifter on there, it doesn't feel like it's slipping anymore.