Whenever I shift from low to high as I accelerate in high especially as the rpm increases I get a fairly violent vibration especially if going up a grade. Once past a low to medium rpm the engine runs smooth. I boost gently but this doesn't seem to make much difference. Any thoughts on this, should I pull the engine, what might correct this?
Sounds like the band in your transmission is slipping. Band might be too loose.
High gear clutch pack adjustment or problems.
Either of the above is a strong possibility and the finger adjustment if required might be in either direction.
Looking at the band is simple enough, and before going into fingers, try this...
Shift a little sooner than you have been, and as you shift throw BOTH levers up, and then bring them BOTH down is sync as you accelerate. Find the proper throttle, bring the spark all the way down, and then adjust the throttle.
If the shakes and shivers go away, it is just the way yours wants to shift. If the shakes and shivers stay or become more pronounced and perhaps stall, then it is time to start looking at the clutch pack finger setting and thats like a trip to the optomitrist!
Make an adjustment that is small, all three must be done the same, cotter pin it back and try again, and then it's another drive under identical conditions with a BETTER THAN/WORSE THAN judgement. You don't want to try a whole bunch of turns as you will loose sight of where you started.
Not knowing anything more about your case, the more severe hill comment makes me think that unless something else more obvious is in play, those fingers are maybe just one turn or so too tight!
Will,Being a member of the two pice crankshaft club i would at least pull the inspection pan,and the cover on the hogshead for a look?? If your trying to retard the spark on shifts i think your barking up the wrong tree?? Bud.
One thing that happens on some T's with is that when you go into low gear the parking brake lever will creep back. Then when you shift from low to high, the cam touches the clutch lever so that it won't completly engage the clutch. You can find out if this is happening to your T by pushing forward the parking brake lever as you release the clutch into high and see if that helps you engage high gear. This can be helped by loosening the parking brake rods a turn or two. They should be loose enough that when the lever is all the way forward, the clevis pin should go in without having to push the rods backward by hand.
Check the universal joint.
Are you sure it's not just plain old engine lug? My Runabout shakes when shifting into high. Retarding the spark a little helps some but it won't cure it completely. A loose band is not the problem since you are in high. Slipping high discs will cause the engine rpm to increase out of proportion to your speed. Norm, his problem is when he shifts from low to high. Bad u joints will usually vibrate all the time. Without being there, I'd say it's the nature of the beast. I don't like it but my T does the same thing. Try increasing you speed in low before shifting??? IMHO
Would agree with Dennis, the relese fingers on the clutch not hiting evenly will make for a violent connection into high. You should be able to correct it through the cover if thats the problem.
Yesterday I tried to accelerate quickly from a signal and I was going slightly uphill. The cars behind me were impatient, because this particular road is at the main freeway interchange of our town. As the engine sped up it started misfiring. Then after I passed that critical point, I realized that the ignition switch was turned to Batt. I switched to Mag, and it took off and ran fine. Many things can affect your performance.
In addition to this and my above post, I would also call your attention to the fact that the smoothest shift from low to high is when you slow the engine to the speed it would be going after you get into high. So as you move the pedal up, you also need to push the throttle and spark up. Then after you get into high, advance first the gas, then the spark and it will be much smoother.
Norm - I was going to make a similar comment. My '23 touring has wood bands and they tend to chatter a bit. I don't worry about it tho' because it's really not a problem. After accelerating in low, I close the throttle as I let the pedal part way up (neutral) and hesitate in neutral just for an instant until the engine (with closed throttle) slows down to idle speed. I then let the pedal all the way back (high) and open the throttle again. Smooth as silk! I really think that this is pretty close to the proper way to "shift" from low to high. I have read in this forum that people actually shift from low to high without touching the throttle; I can't imagine doing that and expecting a smooth shift. And talk about abusing the bands! Just doesn't make sense to me; for what it's worth,...harold
Harold I know what you mean about the high speed shifting. I've watched people on YouTube dump the (Model T) clutch into high without decelerating at all. When I was a kid, we used to call that power shifting. kids would do it while drag racing. It certainly wasn't good for a modern clutch, let alone an 85 year old one.
Thanks to all for this thread, lots to consider. I shift into high when the engine hits idle and I don't have any indication of clutch slip. I,m starting to wonder if it is caused by an engine/transmission inbalance. Once above the vibrating RPM, it runs relatively smooth. I will certainly recheck the clutch fingers for adjustment, never thought of that. I do find retarding the spark helps a bit and then advancing it with the throttle. In neutral if I rev the engine, I don,t get this vibration.
Do you have the wood blocks in the frame channels, behind the motor mounts? In addition to the two vertical bolts at the motor mounts, do you also have the two horizontal ones, (that go through the wood blocks, if there)?
By no means a challenge, just a further question relating to your barking up the wrong tree comment.
I am curious as that is the way my 15 has ALWAYS required shifting without getting a quick shutter/slingshot effect no matter what I do with the pedal or gas only control. I have never found an RPM that works as smooth as an automatic on this one with the spark lever full down, yet let up on the gas and spark, do what I said above and it is smooth as silk! If I've been doing something wrong with it all these years, then I'd like to learn why before I myself may find the 2 piece crank shaft...
I run the '15 roadster hard and many times at 45 on state highways since between county highways and state highways, that's the only thing that's available in the first 5-10 miles of driving about and I do it in a totally stock cam, crank, rear.
Wilf, just for giggles and grins, change or sandblast the spark plugs and see if the engine runs any different at all. I worked on a guys T a couple months ago that was having running problems and clutch problems. I adjusted the high speed clutch, all bands and cleaned up the crappy new day timer. We started the T and it ran great. Took the guy for a test drive, the engine pulled really strong in low gear and shifted nice into high with no slippage. Once in high I couldn't believe how badly the car vibrated. Getting it up to speed took awhile by trying to feather the throttle so it didn't shake. The guy was happy with the car and said he didn't run it as hard as what I was. I was going to pull the plugs and look at other things but when we got back, his wife was standing in the garage with clothes he needed to change into for a wedding they were supppose to attend in a 1/2 hour. I'll be back in his area next week so I'm going to look at it again. Let me know what happens with the plugs.
I think someone said to try to match the engine speed to road speed and that's the way i try to do it.Myself once i advance my spark on start up i never retard it untill shutdown but that's me.I think shifting a T is the same as a model A or truck,wait untill the engine speed matches road speed.The only time my T ever shook/viberated was just before i joined the two pice club?? Shure diddn't take long to tell what little i know about my T. Bud.
Your discription of your friends T fits the sysmptons Of ours EXACTLY. In addition of playing the throttle, I find it helps if I retard the spark as it starts to vibrate.
The Vibration only occurs as one accelerates through about 10km. speed increase after the shift into high and the vibration is bad.
My T does that same thing as yours, Willfrid. After shifting up, when I come back with the power, there's a fairly heavy, low-frequency, mirror-shaking vibration that clears up about 4 mph later. This effect is reduced quite a bit on a decline, but increased if I'm on an incline or carrying a heavier-than-usual load in the car. Retarding the spark only helps a little.
However, if, right after shifting, I add a big handful of power instead of being moderate (and by that, I mean 3/4 throttle instead of 1/3), the vibration is lessened by the way the engine handles the higher power demand and the fact that the car accelerates through the 'roughness region' much more quickly. Vibration is destructive, but so is putting a lot of torque throught the crankshaft at low speed, so six of one and a half-dozen of the other.
I don't think this problem would exist if the Model T had an intermediate gear between low and high.
Or, I could be completely off base.
Bob C., I think you have nailed it, at least as far as I am concerned. I have never had any vibration problems with my TT in our very hilly town, it has a Chicago three speed trans. so I can select the gear ratio that works best. The coupe is stock and I have a VERY hard time getting around. Low is too slow and high is too fast, I am either lugging or revving very high. It tends to vibrate when shifting into high on an incline. I just purchesed a Chicago trans. that I am going to install in the coupe. I think that will cure the problem, I hope. Dave
Experience with shudder/vibration was solved with a new commutator. Only one part of the ignition system, be sure coils are set properly, magneto output is optimum, clean connections & clean spark plugs with .025 gap.
In my experience, the buffeting/vibration/shudder is normal as you approach the speed of sound.
Im shure in this/some cases that solved the problem. On the other hand if the throttle/shift timming is off a little you can get the same shudder. Bud.PS Pass the Zinc.Bud.
Wilf, Just currious if you found anything on this issue yet? I worked on the T with the problem in southern Indiana last weekend. I replaced the coils with 4 rebuilt ones and installed new spark plugs. The engine ran better and pulled better but the vibration was still there after the shift. It was not as bad and the engine would increase the speed of the car faster to where it would pull through the RPM range where the vibration takes place. I'm thinking maybe the front drive shaft bushing is loose and may be causing the vibration.
One other note. This car has a weak mag and won't run well on it. I'm going to do the in car magnet recharge next time I'm in the area and see if that changes anything.
The shudder is exactly the same as you have discribed it. If I give a moderate dose of throttle just after the shift to high, yes it lessens the shudder. If on a decline ,yes, less or nor shudder. If I reduce the spark as I accelerate, the shidder is reduced.
I think I'm going to pull the engine in the spring and go through it again.
Thanks to all for your thoughts on this and I'll post my findings when I strip here down.
The cam shaft in this engine was reground I believe and I have wondered about the valve timing vers gap. I wonder if the valves were to be set to piston position vers just gap if this might reduce this shudder? I've considered a new stripe cam. the engine was rebuilt 30 thou over line bored, valves and Z head .The block was decked.
I have noticed that the engine will accelorate in low to a point, then hangs up. Coils where set on a hand crank tester and an Anderson timer installed. Plugs are new.
How many gaskets are in the ball cap to pan area? There should only be one - the one between the rear of the pan/hogshead and the ball cap. Many people erroneously put one between the ball cap and rear axle flange, thereby creating extra space for the torque tube ball and loosening the fit. It will cause issues exactly like this. Also, if things are really worn in this area, shims are available, but I've never really tried them. Something to check, anyway.
Robb, in my experience the controls start to reverse. A KC-135 is hard to push much beyond "almost the speed of sound".
I'm an old C-130, DH5,C-47,B767, B727,B737 driver..ex RCAF
C-130, the best darn pickup truck in the air.
315th Air Div. USAF (C-130's)
Viet Nam 66-67