Rev matching

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Model T Ford Forum: Forum 2014: Rev matching
Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Sunday, June 08, 2014 - 12:49 am:

I have seen conflicting ways to shift from low to high, some reduce the throttle slightly, and some leave it at the same throttle speed as low when shifting, the ones I've watched when the throttle was reduced seems to lug the motor until it gains speed. Is it better to lug the motor for a bit, or try to keep it a constant speed?..I would think trying to match the revs and not lug it would be better for the engine.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Sunday, June 08, 2014 - 01:02 am:

Hi John, I'm far from an expert on the subject but it seems the more I drive my T's the more comfortable I've become taking off in low then decelerating until I'm in high, then bringing the RPMs up. I have a long hill by my house with a stop sign on the bottom. Even when leaving the stop sign and heading uphill I still drop the RPMs between low and high. One thing I'm always careful of is to not "slip" the transmission in low or when going into high. I'll be interested in hearing the answers to your question.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Sunday, June 08, 2014 - 01:36 am:

Mike, I've heard that it puts more stress on other parts of the drive-train, but like you i would be interested in what others here have to think about this.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Coiro on Sunday, June 08, 2014 - 01:45 am:

I've found that the "take your time" method works most smoothly for me. Two ways of doing it are:

a.) With the floor lever all the way forward, accelerate in low, then close the throttle completely as you lift your left foot into neutral (your throttle movement matching your left pedal movement), pause a beat and feather the clutch into high. Open the throttle.

b.) Start with the floor lever in neutral. Accelerate in low, quickly take your left foot off the pedal and snap the throttle shut in one rapid motion. Move the floor lever from neutral to the full forward position. Open the throttle and accelerate in high.

Either method feels really smooooth and will work on level ground where you can afford to coast for a few seconds in neutral, but you'll want to shift quicker (and consequently less smoothly) when accelerating uphill.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Sunday, June 08, 2014 - 01:56 am:

Thanks Bob,..I know everyone's car is different and has its own quirkiness..I will try your method for sure.


Top of pagePrevious messageNext messageBottom of page Link to this message  By George_Cherry Hill NJ on Sunday, June 08, 2014 - 02:09 am:

John,

There is no reason to lug an engine on reducing throttle...just move the spark accordingly. That's why we were given 'pinkies'! :-)

I can drive my T or yours or just about anyone else's, speedsters or sedans or even trucks and you'll swear it has a CVT in it! Probably took me 35 of my 45 years of driving T's to make that 2nd nature!

What is the correct shift point? Ahhh....the car tells me. I can feel it and hear it trying harder but having nothing more to really give.

On an upshift with my foot, the right pinky takes the stick to maybe the 2 o'clock position. At the same time the left pinky does the exact same thing to the spark advance. Then before the car really realizes it or has a chance to notice and balk or lug, both sticks have crept up on the proper power point with the 'pinkeys' for whatever RPM it actually is at that point in time. I 'feel' and 'hear' all of this. I then left stick down to full advance, and 'pinky' the throttle to where I want it.

I'm not a magician, it's just the way that I drive them. For that first 30/35 odd years, I think I was 'the slingshot special'...torque and rev the living breath out of it and 'pop' high. Then I stumbled on this 'works like a CVT way' and have done so since.

I get a bit smug when I return a car I've worked on, and tell the owner to sit in the passenger seat for a test run. I then do that seamless shift and their usual first comment is 'Holy Crap...' and their second comment is 'I was told to leave the spark all the way down!'.

FWIW

Go to a parking lot and give it a try...it can be as smooth as silk...get comfy with that, go charge hills and mountains :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Sunday, June 08, 2014 - 02:33 am:

Thank you George, this is exactly the reason i come here..Wisdom and experience. I will try all these techniques out till i find what feels right.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Sunday, June 08, 2014 - 11:15 am:

It depends on whether you are going on level, uphill or downhill. Going downhill, you can almost start out in high. So you don't need to rev very much in low before shifting to high when going downhill. Going uphill, you will need to rev more in low. Some hills are just too steep to be able to shift from low to high. That is where a Ruckstell comes in handy. On level, rev a little and then shift. The important thing is to estimate how fast the engine itself will be going when you shift into high. Usually it will be idle speed, so push the throttle all the way up as you move the pedal through neutral and then as soon as you feel the clutch take hold start advancing the gas until you get to the desired speed. Especially when going uphill it also helps to slightly retard the spark when you shift up into high and then advance it again after you pick up speed. If you are running on magneto, you can experiment with the spark lever and you will find that the spark advances in stages. You can move the lever a few notches without a change, and then the next notch it will advance and then a few notches it won't advance. I call these positions "nodes" When you shift into high, retard the spark one "node".
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kenneth W DeLong on Sunday, June 08, 2014 - 11:28 am:

After starting i fully advance my spark and that's where it stays untill just before switch off.Keep it simple.Bud.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Georgetown TX on Sunday, June 08, 2014 - 11:46 am:

Like many things, the right answer is "It depends".

If you are starting from a stop sign at the base of a steep hill you need all the acceleration you can get. In cases like that I will wind out low gear as high as it will go, reduce the throttle slightly as I sidestep the pedal, then open the throttle wide again.

Most of the time I don't shift like that because any time you apply maximum power while shifting you are shortening the life of every component from the Babbitt in the main bearings to the rear axle.

So it really depends on what top speed you are trying to achieve. Don't slam anything, don't use wide open throttle except when you need to.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mike Garrison_Rice Minnesota on Sunday, June 08, 2014 - 12:22 pm:

I seldom run with the spark lever full advanced. I find the "sweet" spot and run there. I make minor adjustments once the engine is up to running temp and once there, I leave it there. My engine runs cooler that way. It sounds for the most part like everyone lets up on the throttle a little between low and high gear. I agree, it's important to listen to the engine. I remember when I was driving truck I always heard people say "shift by what the tachometer is telling you". I'm sorry, I'm afraid my ears and feel are a lot more tuned into what that vehicle needs than some idiot gauge. As somebody said, when starting at the bottom of a hill, wind it up a little higher to get your speed up to where it doesn't lug the engine. I learned to drive the old logging trucks back in the sixties and it doesn't take long to "tune" your ear to what your engine needs. As far as feathering the spark and moving it back and forth and up and down; naw, that engine tells you what it needs. I guess my 45 years of driving experience :-) told me how to do that. If your worried about putting stress on the engine, that's fine, I worry more about stress on the clutch and the bands. The idea is to not let them slip and keep them cool. This is an interesting conversation. People's driving habits seem to reflect their personalities. There are people who drive more instinctively than with any set method. Let the engine tell you what it needs. Different cars do take different methods depending on their condition. A car that has a tendency to overheat isn't going to take running full advanced on the spark. The only time you need full advance is when, for what ever reason, you're in a hurry. Of course that's all tempered by how well you've done at setting the timing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Sunday, June 08, 2014 - 07:10 pm:

I live in Florida where
the biggest hill is a landfill so I don't worry much about starting at the bottom of a hill but I find that accelerating to 10 or 15 mph in low, closing the throttle all the way and letting the clutch out once the engine has slowed to an idle provides a smooth shift. The hardest part is opening the throttle up again at the right time to pick up speed without lugging. With a little practice it becomes second nature. I am not trying to break any acceleration records so I pick up speed in high evenly without straining anything.


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Monday, June 09, 2014 - 10:24 pm:

Been trying out all the great tips i got here the other night and i think I'm getting the hang of it :-) I think my first mistake was being afraid to go too fast in low gear and shifting into high too early even though everything sounded fine and the motor was not nearly as stressed as i was. Like lots of you said, you have to listen to what the car is telling you, and adjust appropriately. One thing i forgot to ask before was when shifting into high, do you just basically let up the clutch as fast as you can like you do when you engage it, or is less abruptly better?

On a side note, while driving the T today, in high i almost panicked when i was driving and realized my feet weren't doing anything and i was basically on cruise control...my T was driving me, a very strange feeling i hope to overcome soon :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Coiro on Monday, June 09, 2014 - 11:25 pm:

Don't just snap the left pedal from low to high. Pause in neutral long enough for the engine to wind down to idle speed (Val is right). After that, gently engage the high gear clutch and apply just enough throttle to accelerate without lugging the engine.

If you give it too much throttle after the up-shift, you'll get a heavy, low-frequency vibration that'll rattle the heck out of the whole car, and if you don't give it enough, you'll accelerate too slowly. The car will tell you how much to use.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Elliott on Monday, June 09, 2014 - 11:35 pm:

I think , sometimes I speak and don't think, lol, It's a matter of Luck, Shifting, with trial and Error and hang out with Motherlode T guy, Eric, we have lots of parts to put it back together , It's a driver !


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Elliott on Monday, June 09, 2014 - 11:37 pm:

Anyone, attempt Tioga Pass Yosemite ? In a TT or T, That's where I'm Heading


Top of pagePrevious messageNext messageBottom of page Link to this message  By John P Noonan on Monday, June 09, 2014 - 11:38 pm:

Thanks Bob, i guess this is just a trial and error procedure i am going through. Seems that it as just as bad going too slow as it is going too fast..i just have to find that happy medium where car and driver are one. thanks for your input like always.


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