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MG TD TF 1500 - Pinion Gear Speedometer Drive

Well, Drat! I've had my instruments refurbished by Nisonger and I've reinstalled them. I was so looking forward to having a working speedometer. Alas, not to be.

It turns out that the pinion gear (Moss part 119, NA) does not turn when I have the rear wheels off the ground, the tranny in 4th (or any) gear and the motor running. I hope the speedometer gear (Moss part 117, NA) is OK and that I just need to pull the speedometer drive housing and replace the pinion gear.

I've searched the archives and believe that I understand how to pull the pinion housing (by the hardest with plenty of patience) but what I need is a good pinion gear. Turns out that Abingdon Spares has them in stock and I've ordered one.

I'll let you know how removal of the housing goes and I will appreciate any suggestions on installing the new pinion gear.

Thanks to all of you for being there.

Jud
J K Chapin

Jud, any chance that you have a later gearbox of the type that uses the key (Moss #118) to secure the speedometer gear (#117). If not, you will need to 'glue' the speedometer gear to the shaft. BTDT. Bud
Bud Krueger

The tailshaft nut may be loose, which normally clamps the helical gear to the mainshaft. George
George Butz III

Bud and George, both of those are possible but I think both will require opening up the tranny which I'm hoping to avoid until next winter.

Bud, my TD is a '53 (TD25009 built 11 Feb 53) and I have no reason to think the tranny is not original so I assume it used the key.

George, was the tailshaft nut still used after MG converted to the tranny that uses a keyed shaft to hold the helical gear to the mainshaft?

Thanks.

Jud
J K Chapin

Jud, the keyed shaft started at Car 16978, '52 ish car. The tailshaft nut can be tightened without having to open up the gearbox. You just have to disconnect the driveshaft.
I had a problem of that nature when I had the 4.3 gears installed. I did the measurements needed to have the speedometer recalibrated and had the work done. When I got it back I took the car out for a calibration check. Things weren't quite right and weren't consistent. The gearbox was an early one that I bought to replace the Volvo one that came in Lazarus. I didn't know about the non-keyed speedometer gear when I rebuilt the gearbox. It has since been attacked with loctite. Bud
Bud Krueger

It is the big nut outside the rear driveshaft flange (#116 on Moss tranny picture). Just remove the 4 driveshaft bolts and you will see it, likely with a cotter pin. Very common to come loose. Who knows if your car has the original tranny, or has been worked on before. Quick and easy to check. George
George Butz III

George,

Here is a trick to remove the speedo pinion with the tranny in the car.
First remove the speedo cable from the end of the housing. Then remove the two cheese head screws and safety wire. Next, using a soft drift and a hammer, rotate the housing 90 degrees by tapping the ends of the housing flange with the drift and hammer. Finesse not force is key here as the housing is brass. As the housing is starting to rotate, spray behind it with WD40 or similar. After you have rotated the flange, you will now be able get behind it to lever and pry it out. Lots of lubrication will help.

Good luck!

Terry Peddicord
T A Peddicord

OK, I've finally found #116 on the Moss view. Do I understand correctly that I remove just the drive shaft and not part #114 (rear flange) to get to nut #116? Is there a torque value for nut #116? Thanks.

Jud

ps: I'm still recuperating from my cracked elbow and kneecap so a neighbor is doing all of the crawling and wrenching for me. Progress is slow but I can't drive for a couple of weeks anyway so it's OK.

Jud
J K Chapin

Just disconnecting the front flange will allow to pull it away from the rear flange enough to get a socket on the nut. I don't seem able to find the torque spec, but I'll start hunting. Bud
Bud Krueger

Jud, I've looked in all the places I would expect to find it, but no luck. I even viewed Barrie Jones' video looking. He just tightens it up and acknowledges the cotter pin hole. I came across one document that just said there should be a few threads showing. Hopefully, one of our gurus will step in. Len Fanelli refurbs gearboxes. Maybe he'll step in. Bud
Bud Krueger

I used 2 bolts to attach a piece of angle iron to the flange and a ratchet on the nut and pulled it up pretty tight, checked with torque wrench to be about 50ft/lbs, then a little more to insert the cotter pin. It ain’t going nowhere

Peter
P G Gilvarry

Well, double drat!! The new pinion gear arrived today so we attacked the housing. Getting the housing out was semi-hard but less effort than expected. The housing is pristine and, more to the point, so is the old pinion gear. The bad news is that the helical gear (Moss # 117) appears to be AWOL.

Could it be that the DPO rebuilt the tranny and forgot to put the helical gear back in? Only the Shadow knows.

We inspected the rear nut (Moss#116) and it is firmly in place with split pin in situ so we left it alone and put it all back together.

Looks like I'll be pulling the motor/tranny pretty soon. That needs to be done anyway because the tranny will not stay in 2nd without a load on it.

The question of the moment is: Start in April when my knee is healed and miss the best TD driving weather or start in December? Here in South Carolina we drive all year round and I'm fortunate to have two other LBCs that I can drive while the TD is down for repairs so we'll probably pull the motor/tranny around the end of April.

Fortunately, I don't think the motor requires any R&R so it will just be the tranny but my understanding is that the best way to pull the tranny is as a unit attached to the motor. Is that the best way?

Thanks.

Jud
J K Chapin

You can pull the tranny out thru the cock pit. Support the oil pan and slide tranny to the rear. It was easier than I expected.
Peter Dahlquist

I pulled the gearbox out from inside, I did it alone.

Take out seats, gearbox cover, floorboards, transmission tunnel and the rails they attach to.

Disconnect speedo cable, clutch rod, tail shaft.

Support car on axle stands, support sump, padded with wood.

Remove 2 bolts at 10 and 2 o’clock, add 2 4 inch 8mmX1 studs in those positions.

Unbolt rear mont from chassis, 2 bolts.

Unbolt rest of bell housing, support gearbox on trolley jack aligned with car..

Roll gearbox back, lift gearbox out, easier with steering wheel removed.

Was not easy, but also not too tough.

Peter
P G Gilvarry

Torque spec for the flange nut is 65 ft lbs. 88.128+ NM, (Newton meters). PJ
PJ Jennings

Look at the gear (#117) in the Moss drawing. It may have been installed backwards. I recall it is about an inch long, and there would have to have been some kind of similar spacer in there if the gear was really left out. George
George Butz III

Jud, I'm puzzled (not unusual). I seem to recall that there is a 'distance piece' Moss #54, that butts up against the speedometer gear (117), as George was talking about. Or, maybe it's directly against the rear bearing #55. The rear flange nut puts pressure against the other end of the distance piece. Been a while since I was last inside of a gearbox, but I think that the distance piece would would be sliding around, noisily, if the speedometer gear were missing. It'll be interesting to see what you find. Bud
Bud Krueger

George, fascinating that we were just discussing that possibility over our beer-thirty cold one. We'll probably pull the tranny out (thanks PG) toward the end of next week and see what we see.

Bud, I agree that if the damned thing were missing altogether other stuff would slide around.

Once again, at this point, only the Shadow knows ...

Jud
J K Chapin

Found this in my images of the re-re-build of the gearbox. It shows the speedometer gear #117, at the end of the distance piece #54, with the rear bearing #55, being sandwiched by the rear flange #114. The tube contains the loctite that I installed to keep #117 from spinning on the mainshaft. Bud


Bud Krueger

Got it. Thanks. Jud
J K Chapin

I might have got out of order in my steps, you unbolt the rear mount 2 bolts before supporting the engine.

Only need to lift rear by about 1/2 inch, leave remote on, aids in the lifting bit, front the hole under the cover is a good lifting point.

Peter
P G Gilvarry

Just un-(insert bad word here)ing-believable! OK, we pulled the transmission out through the tub. The hardest part was getting the floorboards out but once that was done the rest went pretty smoothly.

With the tranny on the bench we removed the remote shifter and peered in. NO SPEEDOMETER GEAR! Just the spacer sleeve going all the way to the front. The attached picture is lousy but if you look closely you can see the absence of the speedo gear.

Next we undid the rear flange nut (barely more that finger tight) and removed the rear transmission housing. Lo and behold, there on the tail end of the main shaft behind the spacer sleeve is a pristine speedo gear. See second image attached. There are probably one or two examples of dumber POs but, for my money, this one takes the cake. The reason the speedo didn’t work is because with the speedo gear is 8 – 10 inches behind the speedo pinion gear.

Well, heck, now that we have the tranny out we might as well see if we can solve the jumping-out-of-2nd-gear problem. The springs and balls look good but there is considerable excess play in the 1st/2nd gear selector shaft. This could be a worn selector fork (used to be $330+ from Moss but now NA) or play from not having the rear flange nut sufficiently torqued. Suggestions and advice here will be very welcome.

Oh, and further while we’re at it, we removed the clutch disk for inspection. They are not too expensive so I might replace it just on general principles but does anyone know how thick a new clutch disk is so I can determine the amount of wear on mine?

The throw-out bearing will be replaced just because we have it out and they’re cheap.

Of course, taking out the floorboards meant ripping up the worn and faded but still serviceable carpeting so I’ll be getting all new carpeting and under-padding. The floorboards are OK but not great so new homemade ½” marine plywood floorboards are also in the offing.

Just for chuckles we also found that the super-duper racing seatbelts are securely fastened to only the 3/8” plywood floorboards. Probably wouldn’t be much help to EMS in finding the bodies.

More reports will follow as this saga of just getting a working speedometer continues.

Jud






J K Chapin

That has to be up there in the DPO standings! Glad u found the problem.
George Butz III

Well, we've got the tranny mostly taken apart and find considerable play in the sliding hub (Moss 101, double gear indicated by red arrow above) along the shaft. We've found some parts missing that we'll replace but we think the two mm movement of that hub along the shaft is what's making it jump out of 2nd gear.

Thoughts and suggestions are still welcome.

Thanks.

Jud


J K Chapin

I think the end play is in the archive- has been discussed in the past. You have an original type hub with the wide groove cut through the splines and around the balls. There is a lot of wear on the outer edge. The replacements for many years have continuous splines the entire length. Likely a combination of problems. What was missing?
George Butz III

Jud To add to the removal and replace info. Do you have the plastic bummy driven shaft tool?
To align the clutch plate when you bolt the clutch plate back on (if you are going to change it) Makes the reincert of the gearbox a lot easier and no coulorful language is needed.
Rod


Rod Jones

This is the new design hub. https://mossmotors.com/sliding-hub-1st-2nd-1?assoc=26176
George Butz III

Is there a trick or special tool for getting the springs and balls under the sliding hub on the main shaft? Thanks. Jud
J K Chapin

You can use one of these jublee clips of the right size The type you can open till it disengages and hold the balls in place till you can slid it into place. Then remove the clip.
Some balls were originally incerted and then pined to hold them there, but that made me cringe.


Rod Jones

Jud,

To assemble the sliding hub, there is another trick which was suggested by Dave DuBois, I used his method, it works really well.

copy pasted from archives.

"For holding the balls and springs in place, I got a tip from an old transmission mechanic for doing that. Use a center punch and punch a dimple on either side of the holes for the detent balls, very close to the edge of the holes. This will swage the edge of the holes enough that you will have to force the balls into the hole (be sure to put the springs in place first - a favorite omission of mine). Once past the swaged edge, the ball will stay in place without tie wraps or hose clamps. Better, if you ever have to take things apart again, the balls won't go shooting all over heack and gone."


John
J Scragg

I like the idea of peening but hammering in a piece of finely machined steel is scary. I'll give the hose clamp method one try and then get out the center punch.
J K Chapin

In the "While we're at it" category, I'm replacing the throw out bearing and clutch disk. The brownish disk on the left is the one I'm taking out and the blackish one on the right is the new disk from Abingdon Spares. The old one is by AMPCO and has no spirally radial grooves. The only thing I can find on the i-net about Ampco clutch disks is a bunch for various Nissan products.

Just curious, does anyone know anything about Ampco disks for TDs from probably the mis 70s?

Thanks.

Jud




J K Chapin

The saga continues. As some of you may recall, I started this project to achieve a working speedometer. My how things have evolved! The initial thought was that the teeth on the speedo pinion gear had been worn off so a new pinion gear was acquired and the pinion housing was removed. Inspection quickly confirmed (1) the pinion gear was virginal and (2) there was no helical speedo gear to drive the pinion gear. Thus followed removal of the transmission.

OK, most of you know that removal of the tranny means removal of the seats, removal of all carpeting, removal of the tunnels and removal of the floorboards. Not horrible but not exactly fun. The carpeting is trash and the floorboards are questionable so a tangential project is making and installing new floorboards and installing new carpeting. I’m pretty good with wood so as soon as the knee and elbow are fully healed (Oh! By the way, did I mention breaking my kneecap and elbow about a week into this adventure?) that project will start.

With the floorboards out, removal of the tranny was not too bad. Thank God for Peter who has no broken bones, is fairly strong and is a very competent mechanic. Of course, while we’re at it we might as well replace the clutch disk and throwout bearing. The first image attached is of the old and the new clutch disks. I’ll let you guess but the yellowish disk is the old one. It may have been installed by Cecil himself.

Now, when we opened the rear case of the tranny we discovered the primary reason for the non-functioning speedo: the DPO had installed the helical speedo gear at the wrong end of the shaft. A relatively simple problem to fix BUT WAIT, THERE’AS MORE:

While we’re at it, let’s see if we can figure out why the tranny jumps out of 2nd gear when not under load. To investigate this, of course, we go into the tranny case proper where we find lots and lots of complicated parts. Our first thought is that there is too much play along the main shaft but subsequent events and the March 2012 post by Keith McKenzie of Ontario, Canada, have convinced us that the roughly ¼ inch 1st/2nd sliding gear play is necessary. Unfortunately, in the meantime, we removed the sliding hub from the 1st/2nd gear allowing the balls and springs to escape. Like that genie or putting toothpaste back into the tube, this presented another problem.

We tried the hose clamp method and the three people/six finger method but all to no avail. Finally came the post by J. Scragg with the invaluable image of MG Tool T. 109. Of course, we don’t have a Tool T. 109 but Peter is a better than average welder and thus came into existence the DeJong Ball and Spring Compressor (see second image). With this marvelous device we were able to quickly and bloodlessly reinstall the balls and springs and get the sliding hub back where is belongs. This tool is available to any crazy person on the forum who decides against all wise advice to remove the sliding hub from the 1st/2nd gear. If you are thinking about doing this, leave the garage, sit down, have a drink and rethink your plan but the tool is available for the cost of postage to and from Landrum, SC, USA. I'll add an image of the DeJong Ball and Spring Compressor in action in the next post.

OK, so now all the gears are back in place (thanks to Bud for the DVD showing how to disassemble and, more importantly, how to reassemble the gears and to Abingdon Spares for having a pretty good used layshaft so that we could make a suitable dummy layshaft without which reassembly is simply not going to happen. Anyway, with the gears back on place we now turn to the selector shafts. This should be simple except that the locator hole for the stop (part 75) on the 1st/2nd gear selector shaft is positioned such that the shaft cannot go forward (i.e., engage 2nd gear) far enough for the locking ball to drop onto the slot on the shaft. We believe that this failure of the locking ball to drop into the slot is the reason that the tranny jumps out of 2nd gear when the load is removed.

I’ve ordered and am awaiting delivery of a replacement selector shaft and we’ll see if the positioning hole is forward by about 1/8 of an inch. If not, we’ll fill the existing hole on the old shaft and drill a new positioning hole.

In the mean time, DOES ANYBODY KNOW THE CORRECT DISTANCES BETWEEN THE LOCATING HOLES AND THE SLOTS ON THE 1ST/2ND SELECTOR SHAFT.

Thanks.

Jud










J K Chapin

Here are two images of the DeJong Ball and Spring Compressor in action. Slide the DB&SC on the gear, insert the balls and springs, slide on the sliding hub, press down very frimly and, to borrow a phrase, "Bob's your uncle!"

Jud

ps: I'll post these images in the other thread in case someone is looking for help in the archives.





J K Chapin

Well done, Jud. Bud
Bud Krueger

OK, stymied again. Looking at Jim B.'s picture in the other thread and Keith McKenzie's response ("NO!"), I have decided, against Peter's mechanical intuition, that the approximately 1/4" free play of the 1st/2nd gear along the main shaft is OK, I ordered a new 1st/2nd gear selector gear to see if the locating hole and detent slots were misplaced. Nope. They are in exactly the same place so the problem of the detent balls not being able to engage the slots must be in all the gears along the main shaft. We can't find the problem so we've decided to simply address the symptom by relocating the 1st/2nd gear selector fork locating hole. By moving the hole forward by about 1/8" the shaft should be able to come back enough when shifting into 2nd to allow the ball to seat into the slot thus holding the damned thing in 2nd when the load is taken off the main shaft.

I'm now the proud owner of a spare selector shaft so if we screw this up we can return to square one. We've drilled out the positioning hole and tapped it for a 10-24 screw. We'll polish the ends of the screw down so that the selector fork can slide easily over the butchered section and tomorrow we will drill a new positioning hole 1/8 inch forward to allow the ball to drop into place when in 2nd gear. After that we'll put it all back together and see how it goes. I wish I could find and fix the problem but if I can successfully address the symptom I'll be happy. Jud
J K Chapin

Jud,

Before you go to the trouble of moving the holes in the selector shaft could you check the following:

1/ The rear face of the centre bearing has the large circlip correctly installed in the bearing slot.

2/ This circlip is hard against the rear face of the main housing it should be held in place by the large cupped spring washer.

3/ The front face of the centre bearing is flush (within a few thou) with the front face of the main housing.

If you don't have these three conditions, then that could be the cause your problem.


John

J Scragg

John, I'm sure that the real problem is one of the items that you recommend checking. Unfortunately, by the time I read your post we'd already assembled the gear box and attacked the selector shaft. Hopefully, by treating the symptom we've bypassed the real problem. The first image is the filled hole in the selector shaft and the dimple that we made by locating the shaft so that the ball drops and the fork is fully engaging 2nd gear. The second image is the selector shafts installed with all the locating bolts tight and safety wired. We've reinstalled the transmission and, although we haven't bolted the prop shaft to the transmission yet, we've started the motor and (1) the transmission shifts through all the gears smoothly and (2) the speedometer works!! All in all, things are looking good. Next is the installation of Declan's improved clutch linkage, fabrication of the new floorboards and installing them and installing the new carpeting. With spring having arrived, thank goodness I have the MGA to tootle around in while all this gets done.

Jud






J K Chapin

Just a good news update. Like everyone else, we've been hunkered down avoiding the C-virus so progress has been made on the TD.

While reinstalling installing the transmission we discovered that the front U-joint was just a tad wobblely and, more importantly, the U-join grease nipple had come out of its hole. Efforts to install a new nipple without disassembling the fork/U-joint were all failures so a used replacement fully assembled front fork/U-joint was obtained from Abingdon Spares. It's mustard yellow (see pic 1) and has no U-joint nipple so I hope it will outlast me.

I used the old floor boards as patterns for new ones that I cut from a sheet of ACX plywood. Amazingly, after applying two coats of Rustoleum oil based paint, the new floors fit quite good. New carpeting was acquired from AS so installation of the underlayment began. The PO had used some kind of tan fiberous underlayment that was well glued to everything so stripping all of that off proved to be a bigger task than expected but it got done. The AS underlayment appears to be a good product and we perimeter-glued it with spray adhesive. Trimming the carpet pieces to fit and installing them made pulling and installing the tranny seem like a piece of cake but we finally got it done. It's all black so photos don't do it justice but I'm quite pleased.

Biggest update: (1) My knee is sufficiently healed to allow me to drive the TD; (2) I took the TD out for a short drive yesterday; and (3) THE SPEEDOMETER WORKS AND IT STAYS IN 2ND WHEN THE LOAD IS REMOVED!!

SUCCESS HAPPENED!!

Stay healthy and Safety Fast!!

Jud






J K Chapin

Congrats, Jud!! Bud
Bud Krueger

I forgot to mention that we also installed Declan's improved clutch linkage. Just beautiful. Jud
J K Chapin

This thread was discussed between 03/03/2020 and 01/04/2020

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.