Loading the TT up for a show tomorrow. I decide to take it for a spin before I load it on the trailer.
I know these trucks are slow and I'm not after speed with this one. But... when in high I can accelerate and it gets going but as I increase the throttle the engine Rpm goes up but the vehicle speed stays the same speed. The truck vibrates like its going to shake apart when this happens.
This is in high gear mid throttle.
Band problem? (Please just be a band problem)
Bands don't do anything when in high, clutch slipping maybe.
Sounds like a high speed clutch slip. Ay need to adjust the clutch fingers.
Also, make sure the emergency brake lever is all the way forward and she fully engage high gear.
Thanks guys. I will dig into it. That makes sense.
And before Steve says it, Yes I do have the books. :}
Steve, your reputation precedes you!
Looks like if I make sure that the spring height of the clutch fingers are exactly 2" the fingers would be properly adjusted.
In the Ford Service book, chapter 315, it give the initial setup for the clutch fingers;
315 Adjust the three clutch finger screws until there is a clearance of 13/16" between lower side of clutch shift and the drive plate shaft flange (see Fig 206). The adjusting screws are then locked in position by inserting cotter keys through fingers and screws.
I do not think there is anything in that book about 2 inches unless it is given the amount of pressure the spring should have when compressed to that height. (90LBS +)
From there you would adjust as needed. Be aware that because of the limitations of only having one slot in the screw there will be some small differences between the finger spaces when done.
I made my own tool out of sheet metal. Make an "L" shaped piece. The upright being about 3-4 by about 1/2 inch the lower about 1 1/2 long by 5/8 inches wide. Along the lower bottom toe end cut and bend up a small tab about 1/4 by 13/16. The adjustments are made with the clutch engaged.
The two inch is a reference IF you have a new clutch spring which will usually give about 100-110lbs when compressed to two inches. All the old ones I have checked are around 70 to 80. KGB
Thank you Mike,
The 2" I was referring to was from the MTFCA Transmission Guide page 26 last paragraph.
Thank you I will refer to the service book.
Correction Mark, Thank You
Paul, if it's any help, my TT firetruck does pretty much the exact same thing, at about the exact same time/throttle. So who knows, maybe it's just "built into the beast". I'm pretty sure my clutch fingers are at the 13/16th." distance, but now I can't remember for sure, with trying to keep track of 4 different T's. Starting to keep a maint. log book on each one finally! I also bought that neat little tool from Snyders to reach in there and take an accurate check.
If you find out anything concrete on it, please let me know! Taking mine to its first parade today too, hope it holds up!!
Paul, make sure the engine is running on all 4 cylinders. I've looked a number of peoples cars that had vibration problems and it ended up being a miss from bad coils, plugs and other misc.
I find that used springs can check out on my spring checker at 60 lbs up to almost 116 lbs. I have thrown many, many springs in the scrap pile. I would never put any ones transmission together that was under 106 especially if they were going to use a Watts Clutch.
Anyway I don't think that a weak spring or a misadjusted spring has anything to do with vibration (chatter). Slippage yes but not chatter. ANY STOCK T that I have driven will chatter if you don't have enough speed up when you shift from low to high. I don't know about TTs because it has been too long since I have driven one.
Paul, it sounds like you described a TT vibration problem at about 2/3 throttle. I have a 1924 TT bought new by my Dad that had the vibration as long as I can remember. The only difference is what you said about not going faster after the vibration starts. I just give mine a little more throttle and the vibration goes away. (Just at that exact speed it does a serious vibration)
A machinist friend did some serious testing including spinning the drive shaft out of the truck and could not find anything bend or out of balance. His final solution was a bearing installed inside the drive shaft tube. (Centered)
Since than we have installed the bearing in two more TTs with that problem, bearing solved vibration problem.
TTs suffer from 'driveshaft whirl'. The shaft is long and slender, and if driven fast enough, the slightest out of balance will cause it to bend and rotate like a skipping rope. If you're brave and the balance is not too bad, you can sometimes drive through it. Others have found that the best fix is a central steady bearing on the shaft.
Even three bolts into the casing with nylon ends, like a lathe steady.
Wow thanks guys lots to read up on.
There bronze bolts 120 degrees apart has also been used.
so then, adding an auxilary trans, thus making the shaft 12" shorter, should help to clam down the flopping shaft?
Clayton, I think the worm drive is somehow causing the flopping shaft.
Going thru the auxiliary transmission and being a little shorter may fix the problem. We have several TT trucks as you described that do not have that vibration.
Well I think you might be on to something.
If I try to power through the vibration it "slightly" goes away. I also think I pick up a little speed.
Why does it vibrate in the trucks and not in the cars? It's the same shaft correct? Weight issue?
I will look at the clutch fingers, this winter I may rebuild the drive line.
Thank you all for your help.
paul, you missed the point, re read chris barkers post, the shaft is longer. i've never delt with tt stuff, but i will say the last rear i had apart for just babbit washer replacement,(a car) we put the drive shaft on grumpys static balance rig, and it was straight, but terribly out of balance. i must have ground a 1/32 off untill it would spin without a heavy side. i had not owned the car long enough to say i noticed it, but the longer shaft of a tt would accelerate the condition. you want an over drive any way, so try it, just so happens i have several in stock, your lucky day, ps...dont forget your check book(just kidding)
Paul, you missed the cause. A model T car has a ring and pinion rear end. The TT truck has a worm drive rear end. These are a lot different.
Look at a car, the drive shaft enters the rear end in the center, in a truck, it enters in the top of the rear end. (Worm drive)Read up on them.
The whirl speed will not be affected by the type of final drive, although the shaft end bearing type will have some effect. Whirl speed is a function of the squares of both the length and diameter. So taking 12" out for an aux gearbox will help enormously.
I'm guessing that a TT shaft is about 80" long. So cutting it to 68" will increase the whirl speed by 38% - probably then above running range.
Last night I was looking at the truck and my touring. For some reason I thought they both have the same length driveshaft.
I now why it happens in the trucks more often.
Well Skip I told you I need one of your auxiliary trans. You might as well set me up, as long as it has overdrive... and now I need brakes also.
Paul, evidently the drive shaft design of the TT places it's critical frequency within the normal engine speed range, causing it to act like a nice tuning fork! My '22 TT had this problem when I changed over to a Ruxtel with a high speed gear set. My remedy was to add back the auxiliary two speed drive shaft mounted gear box I had on my old rear end which shortened the driveshaft about 16 inches or so. The vibration went away and I gained an additional two speed forward!
Well I bit the bullet.
I've always wanted a aux. trans. for the truck and this issue has pushed me over the edge.
I will be getting a cast Warford from Clayton. I also ordered a set of rocky mountain brakes.
Again not looking for speed but just a truck that I can take on the road and not be passed by a kid on a petal bike.