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MG TD TF 1500 - Stuck in 4th gear

Out for a Sunday drive, heading home after visiting the purveyor of beer, attempt to downshift from 4th to 3rd, get a grinding noise and gearstick won't move.

Got home OK, pulled remote and I can see that the 3rd/4th selector shaft is forward, without much effort it slides back and is aligned with the reverse gate, and gearbox is in neutral.

Attach remote and find I can select 4th, or go to neutral, cannot select 3rd. With remote off third/fourth selector shaft slips into 4th gear easily.

It would appear that the first/second selector shaft is a little aft and causing an issue.

Is there a way to get it into the correct location easily?

Anybody experienced this in the past?

Thanks.

Peter


P G Gilvarry

Not sure Peter, but there looks like an excessive amount of space between these two. the gap in mine is much closer. PJ

PJ Jennings

I agree Paul, took another look at it and noticed that the detent on the center selector shaft is further forward than the other two.

The gearbox will not go into third which requires that selector to go aft in the box.

Maybe instead of the RH shaft needing to go forward maybe the center one needs to come back. The move into 4th is easy, takes a little leverage to have it go to neutral.

Peter

P G Gilvarry

It could be possible that one of the (wired) location screws has sheared.

Bob Schapel
R L Schapel

I reckon you're onto it Bob
That centre selector looks too far forward
Could be a broken detent spring on that centre one or as you say a sheared locating bolt, but if it's that it would have to be the one on 1/2 selector fork further forward in the box
Just have a little check to make sure the centre selector 1/2 moves into gear and then clicks back into position in neutral
Maybe temporarily sit the housing back on and select 1st gear and give the lever a good push forward feeling for some/any movement then take the housing off and see if the centre selector block has realigned--if it has it's that front locating bolt

With the top off like it is you could try levering that centre one back till it's all lined up and holding that one there then using one of you other seven free hands try the 3/4 selector to see if it moves freely while held like that
William Revit

I am a little confused. The center shaft is the 3/4 selector in my mind the center shaft.

Why is it not flush like the others?

But I get 4th gear just fine.

Peter
P G Gilvarry

I think it could be either locating bolt. Reminds me of an issue with my brother's race TC. In his case a sheared locating bolt allowed the shaft to move .. sometimes going too far into 4th and not enough into 3rd .. and sometimes the other way round.
Bob
R L Schapel

William, the center selector is 3rd/4th gears I believe.

The only gear I can select is 4th, it slips in and out of 4th easily with the remote in place, have not tried reverse.

By locating bolt, are we talking about one under the top cover?

Thanks.

Peter
P G Gilvarry

Sorry Peter, you're quite right the centre one is 3/4 --I've got myself mixed up
Let me think---
Yes, it must be the one under the main cover that locates the 3/4 fork on the selector shaft
If it were the one you can see in your pics the shaft would still come back to have the detent in line with the other two but the slotted head where the gearlever locates would be out of line with the others while the detents were still lined up
Does the gearlever move into the third gear position and not select 3rd or won't it move at all
If it will slide into 4th ok and come out but won't slide into 3rd it's a bit strange
Maybe because it's easy to get at,cut the wire off the centre one there that you can see and screw the stud out and check it- If it's ok then it has to be the other one under the main cover or something drastic has happened to the synchro hub itself
If you do take the main cover off be carefull not to loose the 3 detent springs that are just under the rear of that main cover
I had a gearbox problem like this once (not MG) where the gears had been grated that much that it had burred the ends of the teeth inside the synchro slider which stopped the slider sliding over the hub to the other gear on that slider but I doubt that's what's happening here as grating into 4th gear doesn't really happen, it's more when going back through the gears
See how you go with the studs first and we'll go from there
willy
William Revit

Actually, if you have the main cover off it would pay to check the stud in the 1/2 selector as well, as Paul noted that 1/2 selector looks twisted over so the problem could be a sheared stud on that shaft allowing that to be twisted over and out of place---If it is twisted over that would cause the lockout pin to be jamming against the 3/4 selector shaft
William Revit

Looks like the tunnel has to come out, but will check the bolt on the 3/4 shat first.

It will not go into third gesr, cannot get any rearward movement on the 3/4 shaft.

Thanks.

Peter
P G Gilvarry

What size safety wire do I need to get to redo the safety wire.

Thanks.

Peter
P G Gilvarry

.032” Aviation stainless steel safety wire will work.


Regards, Tom
tm peterson

Thanks, ordering some tomorrow.

Peter
P G Gilvarry

Thecar was able to go into top gear and the 3/4 selector shaft would not move back enough into neutral. The rear detent on the 3/4 selector shaft was partially obscured while the reverse and 1/2 shaft detents were fully visible.

Today, after lots of procrastination I removed the transmission tunnel which a boat load of fun to do alone, the head of the bolt is in the passenger compartment and the nut is in the engine compartment, but I managed it.

Now the gearbox top cover was visible so I removed all the nuts from the studs but there was no sign of a gasket so no way to get a putty knife between the case and cover. The last overhauler had used RTV compound to affix the cover. Worked the joint with a utility knife and got a tiny screwdriver blade into the gap and the cover was free. Carefully lifted it, the 3 springs stayed in the cover.

MY first gasp was of horror, all 5 bolts under the cover that needed to be lockwired, were not, only the 3 visible at the selector forks were lockwired. Keep in mind PO had the transmission rebuilt in Melbourne, Australia, I have the receipt, somewhere.

Then I looked in the box and saw nothing i knew anything about, but I did know that the 3/4 selector shaft needed to go rearward, so I applied a little leverage and it popped right back to the correct place and I shouted with joy! All selector shafts were now able to be wiggled where as before they were rock solid from the action of the 5 balls and 3 springs lockout.

Put the cover back on, 3 springs stayed in place, added the remote and I can now select all gears including reverse. Cannot road test yet as I have to reconnect a ground that was removed when I removed the tunnel.

Tomorrow I rig that ground cable, and take it out for a road test. Then I will order the gasket, get some lockwire and lockwire the 5 bolts under the cover.

I need to find shorter bolts for the tunnel fixing to the firewall, currently there is 3/4" thread showing beyond the nut. could probably use 3/4" and 1" for the one with the ground strap, or even relocate the ground strap.

Thanks to all who made input, I will post results of my road test ASAP, I think tomorrows weather is going to be OK. I will source a replacement selector for 3/4 as it looks a little worn.

Right now I am having a beer of happiness!

Peter
P G Gilvarry

Hmmm
All good but I wonder what made it jam up---
The end of the gearlever isn't worn down real thin is it--? and going up between the selector blocks and jammed that 1/2 block over on the angle it was --is that straighter/closer to 3/4 block now that you have released things
When you pull it apart to fit the gasket, it might pay to get the 3 top balls out and check that they are still nice and round, might have a flat on one -----------maybe

willy
William Revit

As I don’t have a photograph of what the selectors should look like it is hard to tell.

When I am fitting the gasket I will see if the 1/2 shaft has rotated at all.

I don’t believe the business end of the remote is worn.

I am missing the “sleeve” thst is bolted to end of remote to receive the 3/4 selector shaft when in 3rd gear.

Hoping to get the ground cable sorted today so I can drive it.

All selector shafts are nice and free when in neutral.

Peter
P G Gilvarry

See my post on the other board. The "sleeve" was only on later cars for a longer shaft that was introduced. George
George Butz III

Looking at the 3/4 shaft on mine I don't know that it would enter the sleeve, mine is a later car TF9503, but no guarantee that the gearbox is original.

The remote (which could be original) does have the holes for the sleeve.

Peter
P G Gilvarry

Peter,

It looks as if your box is from a Y type saloon. I mention this because it has a reversing light switch.
You can ID it from the serial number stamped on the top of the main housing, top left corner. If the number begins with a "T" then it is from a T type, if it begins with an "S" then it is from a Y type. If it is from a T type then someone has added the switch.


John

J Scragg

What are the differences in the 2 boxes?

I can get a TF box that needs a rear seal and is usable even if synchros are shot for not a lot of money.

Thanks.

Peter
P G Gilvarry

There are no gear ratio differences, but the bell housing will be for an 8" clutch. The TF box will have the extra detent ball in the 3/4 sliding hub, an extended 3/4 selector shaft and of course, no reverse light switch.

John
J Scragg

Thanks, got photos of one from a TF1500 and can see the extender sleeve on remote.

Looking for the numbers you speak of, not seeing them.

Peter
P G Gilvarry

Here is a snapshot showing the serial number position. On your box it may have been painted over.

J Scragg

Thank you, will look at mine this morning.

I see it now on the photo of box I have been offered.

Thanks.

Peter
P G Gilvarry

John Scraag, took a photo, it is a T box, TR1421 is the number.

I removed the bolt from the 3/4 selector shaft under the cover and the shaft moved freely as far back as needed for 3rd gear so it is the striking dog that is being prevented from moving.

Re-installed the bolt and cannot get the shaft to move aft as far as neutral as witnessed by the after detent being partially obscured rather than fully visible as on the other selector shafts.

There is something that is preventing aft movement of the 3/4 striking dog.

Thanks.

Peter

P G Gilvarry

See my post on the other board. George
George Butz III

See my reply, with bolt removed shaft slides freely.

Peter
P G Gilvarry

This thread was discussed between 08/09/2019 and 30/09/2019

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