speedometer drive

[cory]

I found that while driving the speedometer would only go to 20-30mph. After inspecting the drive unit and cable I decided to have the speedometer checked out. While out being rebuilt I cleaned the cable casing, greased the cable and drive unit. The speedometer returned and was installed. While driving the speedometer is doing the exact same thing. When a drill is attached to the cable and run in reverse it will rise to 80mph. I was told that 1000rpm on a standard 2500rpm drill is equivalent to 60mph. I removed the angle drive unit off of the overdrive and connected the drill directly to it in unison with the cable. Speedometer seems to work fine. I then removed the piece that slides into the rear of the overdrive to inspect it. All the teeth on the gear seem fine. With the rear tires in the air all moves freely while in gear. However when all are put back together the speedometer will not rise above 20-30mph. I don't believe I used too much grease on the cable. There are no broken pieces in the drive unit. It seems to be a pretty simple set up that I can't figure out. I did just have the overdrive and transmission rebuilt. What am I missing????
Cory

[Besters]

Sorry, but is there a kind of "clutch" in the angledrive ?
Normaly the gears are fixed that there is no sliping possible.

[Stevie]

I've seen a few cases where the square hole that receives the speedocable is worn out, and will become "round" allowing the speedocable to slip.

[cory]

Correct. The angle drive is a direct drive gear to gear contact. I don't understand where the lagging could be. With the angle drive moving freely and the cable moving freely how could there be a hang up. I don't know how the gear inside the overdrive, that is making contact with the angle drive gear, could possibly have an issue as it is driven off the main shaft. If it had missing teeth I would assume that it would have eaten up the angle drive by now. I have even wiped off all the grease I had initially put on the inner cable thinking that was it. Baffling??

[250GT]

Correct. The angle drive is a direct drive gear to gear contact. I don't understand where the lagging could be. With the angle drive moving freely and the cable moving freely how could there be a hang up. I don't know how the gear inside the overdrive, that is making contact with the angle drive gear, could possibly have an issue as it is driven off the main shaft. If it had missing teeth I would assume that it would have eaten up the angle drive by now. I have even wiped off all the grease I had initially put on the inner cable thinking that was it. Baffling??

Cory,

there is also a right angle gear on you're prim. axle at the end.
this gearwheel if fixated on the end axle.
if this get loose you can create the problems you describe above "slipping" especially on higher speeds.
see pic below.
these black gear parts are for SWB or Lusso but are the same for GTE/330 in steel
the plastic grey cup in front comes under the lever which is almost always worn.
best
c.

[cory]

I have just pulled the cable and casing, again, cleaned it in the parts washer and reassembled with white lith grease. I have double checked the routing of the cable to make sure there is no funky angles hanging up the inner cable. I have also spit the angle drive, inspected, and reassembled with regular grease. Those gears are all in tact and appear fine. I did notice that the initial grease I had used in the angle drive unit was a little thick and so I have switched to a little thinner grease and the angle drive seems to spin more freely now. If this doesn't do it then the problem has to be with the gears you posted. Likely the interior is not complete and pulling the overdrive unit will be easier. Having never done this is the there anything out of the ordinary with removing these gears.
Thanks C.
Cory

[250GT]

I have just pulled the cable and casing, again, cleaned it in the parts washer and reassembled with white lith grease. I have double checked the routing of the cable to make sure there is no funky angles hanging up the inner cable. I have also spit the angle drive, inspected, and reassembled with regular grease. Those gears are all in tact and appear fine. I did notice that the initial grease I had used in the angle drive unit was a little thick and so I have switched to a little thinner grease and the angle drive seems to spin more freely now. If this doesn't do it then the problem has to be with the gears you posted. Likely the interior is not complete and pulling the overdrive unit will be easier. Having never done this is the there anything out of the ordinary with removing these gears.
Thanks C.
Cory

Cory,
opposite of the fix.screw you can see and feel the gearwheel who activate the whole gear adopter.
before opening the overdrive unit check FIRST if this is the right diagnose.
put in a small screwdriver, and turn outside the main axle to check if this is blocked or not.
when your finger are not too thick, you can simple touch and count this theeth.
not to perfect this pic but 2-3 of the black theeth are visible
PDF of the whole unit can be find at Tom(GTE) Wilson side.
C.

[cory]

C.
All removed as in picture. Internal gear spinning appropriately with no marred or missing teeth. As I put it back together I was able to insert a small flat screwdriver into the piece protruding from the overdrive unit that the angle drive screws into. I then spun the driveshaft with my left hand while giving some resistance with the screwdriver inserted just to see if there was play or slippage coming from those gears. None found. I am hoping that by double checking the cable path, re cleaning and re greasing the inner cable with lighter grease in concert with splitting the angle drive again that I get.
Thanks for your help
Cory

[250GT]

If this all OK. Cory,

I would say you have to check the miles/KM instrument on the dash.

put a drill on the tacho cable and check.

best

C.

[cory]

C.
All removed as in picture. Internal gear spinning appropriately with no marred or missing teeth. As I put it back together I was able to insert a small flat screwdriver into the piece protruding from the overdrive unit that the angle drive screws into. I then spun the driveshaft with my left hand while giving some resistance with the screwdriver inserted just to see if there was play or slippage coming from those gears. None found. I am hoping that by double checking the cable path, re cleaning and re greasing the inner cable with lighter grease in concert with splitting the angle drive again that I get.
Thanks for your help
Cory

After doing all of the above and having the speedometer checked and any repairs done by D&M Restoration the speedometer will only go to 40mph on the highway when all is together. Mile counter clicks off to the appropriate speed.
My question: Is there a difference in angle drives from the tach angle drive unit to the tranny angle drive that runs the speedo. My only conclusion is that either there is a difference between the two and mine got switched out to the wrong. I had my overdrive rebuilt. Could there be a replacement gear not meshing correctly with the angle drive? After inspection all gears seem ok with no missing teeth or pieces. Could the angle drive gear be a wrong ratio? Perplexing to say the least. Any suggestions are welcome.
Cory

[cory]

Correct. The angle drive is a direct drive gear to gear contact. I don't understand where the lagging could be. With the angle drive moving freely and the cable moving freely how could there be a hang up. I don't know how the gear inside the overdrive, that is making contact with the angle drive gear, could possibly have an issue as it is driven off the main shaft. If it had missing teeth I would assume that it would have eaten up the angle drive by now. I have even wiped off all the grease I had initially put on the inner cable thinking that was it. Baffling??

Cory,

there is also a right angle gear on you're prim. axle at the end.
this gearwheel if fixated on the end axle.
if this get loose you can create the problems you describe above "slipping" especially on higher speeds.
see pic below.
these black gear parts are for SWB or Lusso but are the same for GTE/330 in steel
the plastic grey cup in front comes under the lever which is almost always worn.
best
c.

250GT (C) had already touched on this "slippage" issue. After speaking with my overdrive rebuilder, John at Quantum mechanics, he suggested I check the torque on the driveshaft flange. He feels that there is some "slippage" that could be happening since everything has been rebuilt from the speedometer back. I checked it and it was set at 80-90 ftlbs. The next suggestion was to install a spacer after the driveshaft flange as that inner pinion gear is free floating on the shaft sandwiched between two bearings. I removed the driveshaft and pulled the flange. A spacer is to be installed. Any other suggestions are gladly welcomed.
Cory

[250GT]

Correct. The angle drive is a direct drive gear to gear contact. I don't understand where the lagging could be. With the angle drive moving freely and the cable moving freely how could there be a hang up. I don't know how the gear inside the overdrive, that is making contact with the angle drive gear, could possibly have an issue as it is driven off the main shaft. If it had missing teeth I would assume that it would have eaten up the angle drive by now. I have even wiped off all the grease I had initially put on the inner cable thinking that was it. Baffling??

Cory,

there is also a right angle gear on you're prim. axle at the end.
this gearwheel if fixated on the end axle.
if this get loose you can create the problems you describe above "slipping" especially on higher speeds.
see pic below.
these black gear parts are for SWB or Lusso but are the same for GTE/330 in steel
the plastic grey cup in front comes under the lever which is almost always worn.



best
c.

250GT (C) had already touched on this "slippage" issue. After speaking with my overdrive rebuilder, John at Quantum mechanics, he suggested I check the torque on the driveshaft flange. He feels that there is some "slippage" that could be happening since everything has been rebuilt from the speedometer back. I checked it and it was set at 80-90 ftlbs. The next suggestion was to install a spacer after the driveshaft flange as that inner pinion gear is free floating on the shaft sandwiched between two bearings. I removed the driveshaft and pulled the flange. A spacer is to be installed. Any other suggestions are gladly welcomed.
Cory

Cory, i have just started to kill a 330GT GB to repair two 250GT GB with OD of mine.
SORRY 330GT LOVERS thats life.
I just started sunday will continue in two days.
I mentioned a wedge for anti rotation( keil)
I hope this was not forgotten.
its diff. for me to diagnose without seeing .
Normally I send the overdrives to a MG or TR specialist in NL.
but like to learn it my self this time( never too old to learn)
the explosion drawings don´t show this wedge.
will post on thursday -freeday- more to help I hope.

C.

[cory]

C.
Thank you. Great pictures. I was told by the specialist that rebuilt my unit that the gear in your pictures is "free floating". There was no mention of a wedge for anti rotation. I too hope it was not forgotten. Can I assume that the only way to get to that gear is by taking the back part of the overdrive case off or can the case stay on and it be pulled out?
Thank You
Cory

[Jumprun]

C.
All removed as in picture. Internal gear spinning appropriately with no marred or missing teeth. As I put it back together I was able to insert a small flat screwdriver into the piece protruding from the overdrive unit that the angle drive screws into. I then spun the driveshaft with my left hand while giving some resistance with the screwdriver inserted just to see if there was play or slippage coming from those gears. None found. I am hoping that by double checking the cable path, re cleaning and re greasing the inner cable with lighter grease in concert with splitting the angle drive again that I get.
Thanks for your help
Cory

After doing all of the above and having the speedometer checked and any repairs done by D&M Restoration the speedometer will only go to 40mph on the highway when all is together. Mile counter clicks off to the appropriate speed.
My question: Is there a difference in angle drives from the tach angle drive unit to the tranny angle drive that runs the speedo. My only conclusion is that either there is a difference between the two and mine got switched out to the wrong. I had my overdrive rebuilt. Could there be a replacement gear not meshing correctly with the angle drive? After inspection all gears seem ok with no missing teeth or pieces. Could the angle drive gear be a wrong ratio? Perplexing to say the least. Any suggestions are welcome.
Cory

If the odometer is accurate as you mention above, then I would suspect the gauge again regardless of the assumed restoration.

[Lowell]

Cory

If the odometer is accurate as you mention above, then I would suspect the gauge again regardless of the assumed restoration.

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