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MG TD TF 1500 - gearbox oil leak

i have noticed over the last few months i was getting more oil than usual under the car. i was back behind the engine so i took a look at the gearbox today. after checking the dipstick i noticed it was at the low mark.

most of the oil leak seams to be coming around the speedo mount.

but i also noticed a bolt missing. it is on the bottom. Moss calls it the cluster lock bolt. part #78 on the gearbox page. the manual calls it part number 51 or the screw lay shaft.
if i look up in the hole i can see part of the bolt is still there. i am guessing it broke off since i did not notice the hole before.

so my questions:

1) can i drill that bolt out and replace? trick to getting to it to get out? or just leave it alone since it shifted fine?

2) before i pull out the gearing for the speedo, is there something i should know there? some sort of trick to seal?

oh last thing... i drained the oil and found a small spring in the plug. see pic. again no issues with shifting so may have been left in there when something was rebuilt. just curious what it might be and something i may need to look out for.

thanks

TLW Wright

The speedo mount issue is easy to fix with From the Frame Up’s GE185 modified pinion housing. See this recent thread on the subject: SPEEDOMETER CABLE. I was losing lots of oil and just installed the modified housing and now my garage floor is squeaky clean. The biggest problem is access to the housing. I was able to get at it while lying on my back under the car without removing the floor boards. Per FTFU’s recommendation I used black Permatex to seal the unit. I can’t help you with your other issues but I’m sure you’ll get lots of good advice very soon.
Joe
Joe Olson

Is there any part of the bolt showing above the trannnie case??
Steve

Steve Wincze

TLW,

Make sure you have all the selector shaft springs (Item 27)
http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=32771#top
Gene Gillam

the bolt is broken off about a qtr inch up in the hole. So nothing to get hold of. i am going to try a steel sheer pin in the hole and drill thru that? then use an extractor?

thanks
TLW Wright

Gene
whether i have all the springs, i can't say. but the gearbox works now so i would assume it was a spring someone dropped while fixing something before?

Joe
i have sent "from the frame up" and email about the pinion housing to see what i need to do.
i have removed the screws on the outside of the gearbox but the housing does not seem to want to pop right off. Maybe sealant holding it on?

TLW Wright

Drilling through a hollow split pin is a good idea. Then use a reverse direction easyout,, or once the drill is into the broken bolt, try reversing it.. It might come right out!!


Steve
Steve Wincze

You said: " look up in the hole and see part"

That would mean that perhaps there are some exposed EXTERNAL threads in the hole.

If you have a lathe, or have a friend with a lathe, take another bolt, of the same size and thread. Drill a 1/8 hole through the bolt.
Screw it into the hole and use it as a guide to drill a hole in the broken piece.
You will need to start with the drill guide tight against the broken bolt. Use a LEFT HANDED drill. As the drill starts to go in back the drill guide screw out a bit. The LH drill may unwind the broken screw by it self. When the drill is about 1/8 deep into the broken screw remove the guide. If the broken screw does not come out on its own, go a little bigger on the LH drill size.

If this does not get it out, I would NOT recommend using an EZ-out. If you break the EZ-out in there you are in deep do-do.

As you go bigger you may be able to jam an old small screw driver into the hole and unscrew the broken part.

I dont know which screw you are talking about. A moss number would help. Some have little nibs on them you dont want to drill into the nib.

Jim B.

P.S. LH drills are available at McMasters.
JA Benjamin

Kim,
In the original post TLW indicated part # 78 in the moss catalogue

Steve
Steve Wincze

On the speedo gearing,
I am not sure I can get it out past the floor board....

I did note a part number on the bolt above.
TLW Wright

Yes that bolt has a nib.
Be careful not to rotate the shaft it goes into.

Jim B.
JA Benjamin

Personally, I would remove the gearbox and disassemble it. Replace parts needed.

I had never seen the inside of a gearbox until I rebuilt mine, so anybody can do it.

Buy Barrie Jones video from the NEMGTR on rebuilding a gearbox and follow it as you disassemble and reassemble. I have other documents that I can send to you plus info on the correct clearances and tollerances.

Try to slide out the layshaft with a dummy shaft. If the tip is locking the layshaft in place, then you can't do anything until the broken tip is removed.

I don't believe that you can drill our the broken tip with a hand drill. The bit will wobble and destroy the threaded hole, and probably still not be able to bite into the tip.

The tip of the locator bolt on my TF gearbox was broken like yours. Didn't know until I started to take the gearbox apart to rebuild it. The head and threaded shaft were still in the case and prevented me from removing the layshaft. I sat the gearbox upside down on my drill press table. A club member held it firmly in place while I drilled into the hole with a bit small enough to clear the threads of the hole. The bit chewed out the broken tip that was lodged in the layshaft. Unfortunately, the Harbor Freight bit was not straight, so it shaved off just enough of the theads to keep them from gripping a new locator bolt. Still looking for a machine shop that can drill the cast iron case and properly insert a Helicoil.

I bought another gearbox and used the case for my rebuild. The tip of the locator bolt in that gearbox was worn about half way through.

The worn tip and the broken tip may have been a result of the layshaft moving in the case. The layshafts in both gearboxes were worn under the first gear needle rollers.

The spring probably came from the first gear sliding hub. If other springs or balls are still in the case, then it's probably just a matter of time until they lodge between a couple of gear teeth and destroy your gearbox or lock up and cause you to wreck.

Since I had two gearboxes, I switched around the speedo housings and pinions until I found a set that doesn't leak (much.) I wouldn't attempt to remove it with the floorboards in place. If you could replace it, I don't think that you could lockwire it with the floorboards in place.

Lonnie
TF7211
LM Cook

My speedo pinion housing was firmly attached to the gearbox with old sealant and didn't pop right off either. I used a small metal putty knife to work my way around it and eventually I got it off. It would have been much easier if the floorboards were removed. The floorboards made it very tight getting it back in, too.
Joe
Joe Olson

ok, i got the bolt out. i used two steel split pins, one inside the other, to start a small pilot hole. i used 1" long pins because the bits this size are short. after i got the pilot bit in as far as i could, i went to the aluminum sleeve with a #6 hole. this bit was large enough to use the extractor. once i got this bit in a little, the extractor grabbed and turned it right out.
Next i went to the hardware store and bought a M6 x 1.00 bolt to make sure my threads were still good. the bolt went in fine and took up nicely, at least hand tight. i also ran a tap up in there to make sure the threads were clean.
Now just waiting on a new bolt from Moss to put back in. looking up in the hole with the snake camera, it looks like the shaft hole is still lined up. no reason not to be really, i have not moved anything since starting this project.
guessing that bolt is a bit brittle so i plan to put in without much torque and just smear the threads with some blue locktite.

i also took a chisel and worked out about an 1/8" of the plywood floor just bigger than the speedo pinion housing. it slid out. then repainted the bare wood black so it does not show.

just getting ready to order a new housing with the o-ring.

see pic below of the pins/sleeves i used..

TLW Wright

Penny wise and pound foolish, IMHO. If I found a loose spring like you the gearbox would come out and be taken apart. The likelihood that someone "dropped" a spring in the box is very small; it came from somewhere. Every spring in a transmission does something and works in concert with other parts, so expect to break some expensive teeth when things come apart while you are driving.

My opinion.

Tom Lange
MGT Repair
t lange

I agree with the "pull it" advisors.

Gene
Gene Gillam

Changing with the floorboards in place. The screws for the speedo pinion housing, in my opinion, for what ever it's worth, don't need to be safety wired if lock tight is put on the threads. That unit fits so tight it'll never fall out. The screws in mine have not had safety wire on them for an undetermined amount of time (years) and they were very tight when I broke them loose. On this unit, with Lock Tight available, safety wiring is an over kill. For a concurs inspection, I seriously doubt if a judge is going to craw under there to inspect it. JMHO. PJ
Paul161

By the way, your idea/method of centering your drill bits to drill out that small bolt was brilliant! I've never seen or heard of anyone using that before and I'll have to remember it in case I run across something like that in the future!

Gene
Gene Gillam

Gene
i actually saw that on an older thread here. so i can't take credit but it worked quite well.i think it works even better sizing the opening to the bit size.

Paul
i agree on the wiring. mine were not wired and i know that gearbox has not been touched for a lot of years. at best early 90's. but since i have the car on a lift, i am going to try and get a wire thru them. not too worried about it though.

Tom
appreciate the suggestion. since there was no ball or plunger in the cap, i figure it was not one of those springs, else there would be another part with it. also the spring is not broken.
i am sure it has been a very long time (if ever) since this gearbox may have been opened up or the oil even changed. but maybe the ball or plunger was in the cap then and removed???? And now the spring has fallen out? can it work like that? or not likely?
keep in mind the car has been shifting fine. no strange sounds or issues with changing the gears. i only went under to change the oil because the leaking was getting worse.

rather wait until this winter for a major job, if possible.
TLW Wright

Never, never, never ever use one of the tapered, left hand threaded stud extractors. They have to be hardened to bite into the stud and are thus brittle. If they snap in the hole in the stud you cannot drill it out and the only way of removing it is by spark erosion. If the stud is sticking out a little you can try slipping a nut over it and securing this with MIG Weld. If the stud is below the level of the casting you can drill a central hole in a bolt using a lathe, screw this into the hole above the broken stud and use this as a pilot to drill out the stud. However most times the broken stud is level with the face of the casting. You can start by drilling a small hole off centre and open this out with progressively larger drills. Eventually you will just touch the side of the female thread in one position. You can the collapse the stud using a small chisel. It is possible with care to remove the stud and retain a good thread in the casting.

Jan T
J Targosz

Jan is right, taper stud extractors can be a PIA, as they go in they spread and tighten the stud in the hole and then snap.
Pickavant type parallel fluted extractors are the ones to use. Expensive, but they work.
Ray TF 2884
Ray Lee raybar2(at) tiscalidotcodotuk

Thanks but i have the bolt out now. just waiting for the replacement, which should be here today.
TLW Wright

This thread was discussed between 27/06/2016 and 30/06/2016

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