Shifting Into 5th gear grinds at high rpms

[tadaima]

Hmm so should i go with Redline MTL or MT90?

 

[Ma-fia]

I wouldn't make recommendations on fluids (let it to the pro's), but do buy a couple of jack stands. 20 bucks -- and you don't have to worry about dropping a car on yourself! The first time you change your tr. fluid, you'll get the 20 back.

 

[olddognewtrks]

Ma-Fia: Regarding hard/impossible shifting to first gear while moving...First gear on all of my cars has been a pain, it's the nature of the beast because of big ratio spreads when dropping down from second to first. Here's how to double-clutch like all the big truckers do. Figure out approximately how many MPH per thousand RPM you run in first gear. My Protege 5 runs about 5 MPH per thou, i.e 10 mph equals about 2000 RPM. For example, if I needed to shift down at about 10 mph, I shift to neutral for a second and release the clutch, then blip the engine to 2 thou. This spins the input side shaft parts up to closely match the speed of the output shaft parts. Quickly/gently stomp in the clutch and shift. Since the parts are closely matched on speed, the synchros need to do very little work and it should slide into first easily. Practice first at slow speeds till it cones naturally. FWIW, I double clutch ALL my downshifts now-it's fun and it helps my synchros last forever.

 

[Ma-fia]

quote:

---

Originally posted by Kestas:
I've never tried rev-matching. I heard it's a technique where, when properly executed, you can shift gears without using the clutch.

---

Here's a somewhat relevant funny story: I drove my old car to the dealership (with no intention to get rid of it), bought a new car. It was the rush hour by the time I was done "buying", so I figured, I'd drive the old one home (just in case), pick up the spouse and then we can get both cars safely back.
Didn't work this way: the old car got jealous and broke the clutch cable when I tried to engage the clutch to pull out of the parking lot. To make it short, we managed to hold the clutch cable with vice-grips so that the car could be started and 1st gear engaged, after that -- a nice drive of about 35-40 miles with no clutch and without a single grind -- magic of rev-matching.

olddognewtrks, thanks for a good explanation; I wouldn't say that my shifting is even hard (most people wouldn't notice a thing), but after I figured out how it feels when the stick slides into gear almost by itself, I started trying all little tricks that people suggest. Perhaps I wasn't revving it consistently enough, it doesn't seem to be working for the 1st in my case. Also, I ask myself a question, if it's good for the engine to jerk it like that? After all, a tranny is cheaper...
Someone mentioned it in this thread, and I found out that it seems to be working for me: 1) slow down to about 10 mph, 2)quickly disengage the 2 and immediately start applying light pressure towards the 1st. 3)It slides right in.

More thoughts on rev-matching:
I'm wondering if it's possible to calculate the rpms for rev-matching, based on gear ratios... Any ideas?

 

[Gary Allan]

quote:

---

so are you saying 5th gear is uselss when high revving?

---

No ...I'm saying that others THAT BEAT their V-techs evidence this WEAR in their trannies.

 

[tadaima]

That's some great advice, I guess the syncros are suppose to buffer the need for double clutching and rev matching, but you would think that trying to rev match would help allieve some stress on the syncros.

To get good a rev matching, I think you would really need to know your car and tranny to memorize what rpms are in which gear at what speed, lot of work though.

 

[Bob Woods]

To get good a rev matching, I think you would really need to know your car and tranny to memorize what rpms are in which gear at what speed, lot of work though.

Or just use the right lube oil.

 

[Ma-fia]

Tadaima, I hope you (and others) liked this little discussion. I was simply thrilled when I heard all this for the first time. I have below zero knowledge of how it really works, and tons of desire to make it work as long as possible.
For some folks this may be ABC, but until I've heard it on another board, I didn't have a clue.
Rev-matching is indeed kinda tricky, but giving the tranny some time to line up gears isn't all that hard, and the wear on syncros is minimal then.
I love my cars, I'm not the type to change them every 3-4 years, therefore I NEED to know how to treat them well.

 

[tadaima]

Well I have MT90 in it and drove 60miles on the freeway. General shifting seems smoother, though I still have to double clutch to go into reverse most of the time.

Havent try going past 5K on 4th gear into 5th yet, to see if the grinding still occurs.

 

[Bob Woods]

Sometimes too good of lube is bad, in order for a syncomesh to work there must be some friction. Improper lube had caused many a posi-trac to fail or not work right.

 

[tadaima]

Bob: So should I dump the redline out?

 

[Bob Woods]

No way, if its rated by the Redline for the application use it. The point I should have made was, with transmissions friction modifiers are not always helpful.

REDLINE MTL® Manual Transmission Lubricant
a 70W80 GL-4 gear oil (SAE 5W30/10W30 engine oil viscosity) designed for use in manual transmissions and transaxles. Provides excellent protection of gears and synchronizers and its balanced slipperiness provides a perfect coefficient of friction, allowing easier shifting.

[ February 03, 2004, 12:52 PM: Message edited by: Bob Woods ]

 

[tadaima]

Still grinds into 5th when shifting from 4th at over 5K..oh well, shouldnt be doing that anyways =)

 

[Kestas]

It appears you've reached the design limit of the transmission.

 

[MolaKule]

Tadaima,

Try a 50/50 mix of Redline MT90 with MTL before giving up. Viscosity plays a critical role in some of these manual trannys.