Model TT worm drive rear end

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Model T Ford Forum: Forum 2012: Model TT worm drive rear end
Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Bohannon on Monday, August 20, 2012 - 10:25 pm:

Does anyone know where I can get info or a service manual on the TT rear end. I think I have a bad vibration in mine. Is there a way to diagnose it. Any help would be appreciated.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Fred Miller, Sequim WA on Monday, August 20, 2012 - 10:53 pm:

Joe, you should first drain your oil and look at it. That should tell you something according to the metals you find. You can cut the gunk with gasoline to get the old oil to release smaller fragments so you can see them easier. If all looks good it could be a driveshaft bushing. They do cause a vibration as will the U-joint when they have issues.. I have never heard of the outer axle bearings having a vibration when they go bad but if they do they will have lots of slop up and down. Ford kept changing the engineering of the rear thrust bearing because of gouging issues in that part and its facings up until 1931.

The worm drive is pretty simple to work on but I would start with an oil change first. I'll have to look through my library for the Specifications on these drives. Joe I'll PM you when I come up with it I'm not sure where it is right now.

Fred

Fred.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Henry Petrino in Modesto, CA on Monday, August 20, 2012 - 11:00 pm:

I'm just guessing, but a vibration in a TT worm drive rear end would suggest to me that a bearing has gone bad. There are a total of 6 bearings. There are 2 outer axle bearings (1 on each side), 2 inner axle bearings (one on each side), and 2 (one on the front and one on the rear) on the worm gear.

Of these, 4 can be checked without disassembling the whole rear end. The 2 outer axle bearings can be checked by removing the wheels. The worm drive rear bearing can be checked by removing the rear cap. If I remember correctly, you must remove the drive shaft to check the front worm gear bearing. The 2 inner axle bearings can only be checked by disassembling the whole thing.

First thing I'd do is check the bearings you can get to. If you find a bad one, then you've probably found the problem. Remember that unlike other rear ends the TT worm dive rear end does not have any adjustments, so it's not possible for something to just need adjusting. If the vibration your experiencing is in fact from the rear end, then it pretty much must be a badly worn or damaged part. Of course, there are other possibilities besides a bad bearing, but it's my guess.

Good Luck!!


Top of pagePrevious messageNext messageBottom of page Link to this message  By John Danuser on Monday, August 20, 2012 - 11:40 pm:

I sell a small booklet on the TT chassis and body parts it shows the parts, danuser88@ktis.net also have 60 years worth of TT parts


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthony Bennett on Tuesday, August 21, 2012 - 02:56 am:

I think the TT can suffer vibration in the form of tailshaft whip. Even if the shaft is perfectly straight it doesn't take much to generate a harmonic vibration that will mean it wobbles about furiously.

I believe some blokes have drilled and tapped the torque tube about half way along it's length so they can install 3 brass bolts as guides, much like a fixed steady in a lathe.

cheers

AB


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark on Tuesday, August 21, 2012 - 11:07 am:

Here's a couple diagrams of the inside of a TT rear axle.

cross section 1

cross section 2


Top of pagePrevious messageNext messageBottom of page Link to this message  By Anthony Bennett on Wednesday, August 22, 2012 - 11:10 am:

I havn't done the modification to prevent tailshaft whip but I would guess that the bigger the brass guides are (within reason) the better they'll last.

If I were to guess I think I'd start with some 3/4 brass hex stock, turned down to take a 9/16UNF thread. Drill the torque tube and tap it to suit. screw your new brass bolts in until they just touch the shaft inside and then lock them with a half nut.

My only doubt would be wether the existing surface finish on the tailshaft might be a bit rough or not exactly round.

Perhaps others might chime in here?

Cheers


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Bohannon on Wednesday, August 22, 2012 - 01:51 pm:

Thanks Anthony Bennett, I appreciate your input. I have read some more threads some say it will not work at all. One said he drilled one of the 3 brass bolts for a grease fitting and it has done well for 8 years. Some actually welded a nut to the tailshaft to hold it instead of tapping. Since I am not a welder I think I will try tap first. Anyone know how thick the torque tube is I am going to tap. Thanks, Joe B.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hal Davis-SE Georgia on Wednesday, August 22, 2012 - 08:05 pm:

Mine has that vibration at about 15 mph. I just accelerate through it as quickly as possible. It is indeed a harmonic thing as it goes away at higher speeds (Frequency). I drive between 20 and 25 and seldom give the vibration any thought as it only lasts a few seconds as I'm accelerating.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Bohannon on Wednesday, August 22, 2012 - 08:27 pm:

Mine simply gets worse with increase in speed until you think it is going to shake the truck apart.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Wednesday, August 22, 2012 - 09:46 pm:

Your drive shaft may be bent causing the vibration. Find a good one and solve the problem. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Lovejoy, So Cal on Thursday, August 23, 2012 - 12:03 am:

Would any of you guys have the dimensions of the universal joint bushing? My old one is pretty mangled, I am going to try and make a new one. I am no machinist, so I would feel better, more confident with the correct numbers. My surfaces vary and due to age and or damage, no longer very true. I will git it done, just would appreciate the info if you got it, thanks Tom.P.S. thanks for those drawings of the rear end.


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Stroud on Thursday, August 23, 2012 - 04:12 am:

Tom, the u-joint bushing is (at least it used to be, not sure now) available from Chaffin's Garage. It is made from bronze, if I recall correctly. I bought one many years ago, but I didn't need to use it as my original bushing was in great shape.
Joe, get your driveshaft checked for straightness before you get too carried away with making a bunch of unneeded modifications. My TT that is on my profile picture ran a tad over 42 MPH (it has a high speed rearend and a Chicago transmission with overdrive) with NO vibration from the driveshaft. Dave


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willie K Cordes on Thursday, August 23, 2012 - 11:40 pm:

Joe, a vibration in the TT driveshaft is common at about half throttle. A friend of mine actually put a shaft in a lath and check for run out, but found none. His solution was to put a bearing on the drive shaft near the half way point. I do not have the numbers of the bearing, but it solved his problem and I have a TT that was fixed with the same bearing in the torque tube. Torque causes the shaft to vibrate, not a bend drive shaft.
PS There are some posting somewhere on this same subject.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Thursday, August 23, 2012 - 11:56 pm:

My TT has been over 40 mph several times and the drive shaft never vibrates. It is not common if you have good parts. Putting a whip support in the tube is just a patch. Fix the problem. The shaft is the problem, change it. It is out of balance, bent or has been overworked some time in it long life. You will enjoy your TT when you FIX the problem. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Lovejoy, So Cal on Friday, August 24, 2012 - 12:30 am:

Right on, Thanks David! calling tomorrow :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Joe Bohannon on Friday, August 24, 2012 - 01:52 pm:

Robert, I am considering going through the differential drive shaft and u joint but I understand it is very complicated job. Has anyone out there done this. Where do you start. Do I have to remove truck bed or what.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Friday, August 24, 2012 - 03:02 pm:

Remove the front of the shaft from the tranny. Remove the 6 bolts holding the tube to the shaft. Slide the tube off. Knock the pin out of the coupler and remove the shaft. A machine shop with a long lathe can put the shaft between centers and spin the shaft and check for run out. The rear end stays together. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willie K Cordes on Friday, August 24, 2012 - 04:00 pm:

Scott, I am glad that you are so sure of your diagnosis. There must be a lot of TT's out there, according to you, that need repair because there are a lot of them with that vibration problem.
Have Fun


Top of pagePrevious messageNext messageBottom of page Link to this message  By Willie K Cordes on Friday, August 24, 2012 - 04:03 pm:

Scott, I forgot to add, the vibration goes away with a slight bit more throttle. If it was in that bad a shape, it probably would not go away, but get worse as the speed was increased.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Robert Scott Owens on Friday, August 24, 2012 - 05:24 pm:

Willie, I deal with shafts that turn in the 18,000 rpm range all the time. If a shaft is straight and in balance it will not Vibrate. So you can fix the problem and make a run to the ice cream parlor of let your TT shake the nuts and bolts on to the ground. Scott


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Lovejoy, So Cal on Saturday, August 25, 2012 - 12:03 am:

Joe, I am doing mine right now. It's not that big a deal, their about as simple as they git - I believe. Just got to think and or remember, your working on a model T.They did things different in those days. Got my rear end and wheels all apart too, same thing pretty simple. Lot's of work and some of those parts are heavy. Just use the manual and ask questions, that's what I am doing. Put my drive shaft in the lathe today - looked pretty good, think I might have it balanced. Just sounds like a good idea, though I don't ever plan on trying to go fast in my TT. Don't know if I need to really, but sounds like good advice. You can do it ;-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don C. Elbers on Wednesday, September 12, 2012 - 10:41 pm:

We are rebuilding a fire truck built on a TT for the Mandeville fire department. According to the historical information on the truck the TT dates to 1917. Among other things, we retrofitted an electric starter (new transmission housing and flywheel etc.). We are now working on the rear end. The felt wheel bearing seals were installed between the cup shaped bearing cover and the wheel hub. I was told that there is supposed to be a big flat washer on the outside of the bearing and the felt seal goes next and then the cover. There is not room for the seal next to the bearing. The drawing on the forum is nice, but the location of the felt is hard to see. Any suggestions will be appreciated. Don.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Don C. Elbers on Wednesday, September 12, 2012 - 11:34 pm:

TT fire turck


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