MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Shifting into 1st from stop

When sitting at a lite or stop sign It is sometimes a bit hard shifting back into 1st gear. I remember that the gear box does not have a system that makes this easy and it seems that the gears are hitting top to top, thereby not going together smoothly. I'm wondering if maybe something else is going on in there. Or is this just normal and I pay too much attention to it? Thanks Bob
Bob Ekstrand

Hi Bob
What you have is an early 3 synchromesh gearbox with no synchro on 1st.gear.The secret(that all 3synchro box owners know)is just lean the gearlever against 2nd.gear for about 1 second without actually engaging 2nd. gear, then engage 1st.gear.What this does is to slow down the moving parts making for a quiet engagement of 1st.gear.

Tony F.
a.d fisher

Bob,

I don't know what year transmission you have, but I find that what Tony says is applicable for the 3-syncro or 4-syncro boxes. It should work just the same if you select third, it is just more convenient to use second. In severe cases, you may need to fully engage second.

Charley
C R Huff

Hi Folks:

If the gearbox is 3 synchro, then the laygear must be near idle to shift into first. If you are having problems shifting into first with 1st/3rd motion shaft and laygear near complete stop, then you could have issues with a worn gear lever bushing (nylon); worn selectors or worn/loose shift forks. They are made of brass/bronze and will wear. This condition can also be found on a 4 synchro gearbox.

Good luck: Rich Boris 67B roadster
Rich Boris

Hi Bob!

It is possible that there is a slight clutch drag,which is not noticeable when shifting on the move.If you try double clutching when shifting into 1st gear when stop,this might stop the gears from crashing.

Hart
H Mayers

All BL boxes always did it, and most other manufacturers aren't totally immune in my experience. I've got so used to just bumping it towards 2nd (not fully in or holding it there) and back again into 1st with the clutch still held down that I don't even think about it anymore. On my car at least it isn't a case of the gears still turning as I can hear they have stopped, but 'tooth to tooth' baulking, once it has done it once it doesn't matter how long I wait or how many times I try it won't go in until I bump it towards 2nd (or go to neutral, clutch up then straight down again then straight into 1st).

It also happens in reverse, sometimes bumping it into 2nd helps sometimes not, but then 1st to 2nd to reverse always goes in.
Paul Hunt

My experience is the same as others have stated - I always "bump towards 2nd" (I'd describe it as "half" engaging 2nd gear) before going for 1st. Occasionally 1st will still not go in - it's a special design feature that this will only ever happen at busy junctions with impatient traffic behind. In this case going into neutral, lifting the clutch and then declutching and going for 1st again will always work. If not on a hill but in a hurry due to said impatient traffic I'll sometimes take off in 2nd instead, the B has enough torque to cope.

Cheers,
Tim
T Jenner

Thanks everyone, I appreciate the feedback. I wasn't sure if the issue was a gearbox problem or just in my head! By the way it is a 74B with a replaced O/D tranny in it. Not sure what year the box is but I believe it was the model used during that time period. I was a bit concern that the synchro in first was going out. Thanks again!
Bob Ekstrand

Okay I need to expand inquiry on this subject.

I test drove a 77B last night, and the drive went quite well. I tried to see if car would pop out of gear at different speeds and all was fine. Clutch didn't slip, and clutch appeared to be adequate.

However, when I returned from highway test, and was downshifting to enter owner's driveway, I went from 3rd to 2nd (no problem) and then proceed to go to 1st, but gears clashed. I tried again, and gears clashed.

In contrast to problem above, I can shift from 2nd to 1st without a problem when fully stopped - it just won't go into 1st on a roll. I did not try double-clutching.

I asked co-test driver if new B's went back to a non-syncro 1st, and he didn't think so. Then we wondered if it was not the more modern full syncro trans. Owner assumes it is all original equipment. This lead us to think 1st gear syncro is worn out.

Does this situation sound like the syncro is bad for 1st gear?

I've asked for an estimate to replace syncro, and its in the $1500 range to pull engine, trans, and open up gear box. (I've never liked working on transmissions myself.)

If it is a syncro, and I can live with full stops for 1st gear. Is a bad syncro going to contribute metal debris to transmission and cause more accelerated wear?

Your thoughts.

Thanks.

BobA
R.W Anderson

Bob E and Bob A, I'm having the same problem as you describe with gears clashing going into 1st. The trans is a rebuilt black label OD from a well-known supplier in New England. How can 1st gear synchro go bad so quickly in a rebuilt transmission? (less than 1500 miles). Did some supplier provide a batch of bad synchro parts in 2007-2008?

In my case, there is lots of gear clashing going into 1st if the car is moving any bit at all; when going into 1st from standstill, there is one or two teeth clashing.
willieL

Does sound like there is no or very worn synchro on first. BL didn't go back to 3-synch at any time.

If you have OD the 4-synch type at least have magnets in the sump which will trap ferrous debris at least, and the oil circulates in both gearbox and OD. Whether any large particles from the gearbox would get as far as the OD is another matter, one would hope they are large enough to stay at the bottom.

Rubber bumper cars (i.e. your 77) had a filler level plug on the right-hand side of the gearbox casing, whereas chrome bumper (3-synch and 4-synch) had a dipstick on top accessed via a rubber plug in the top of the transmission tunnel under the dash, also on the right-hand side. Later cars kept the bung, but there should be nothing underneath it. But even if you find the dip-stick and don't have a level plug it could still be a 4-synch.

The 3-synch and 4-synch *ODs* are quite different, so should be easy to tell apart, and I don't think you can put a 4-synch OD on a 3-synch box, never heard of it anyway. 3-synch have an external cylindrical solenoid, whereason 4-synch it is internal. 4-synch have a large rectangular sump plate with six screws, 3-synch don't.

3-synch gearboxes have a *non*-rectangular plate on the left-hand side, 4-synch have a *rectangular* plate.
Paul Hunt

This thread was discussed between 27/06/2009 and 02/07/2009

MG MGB Technical index

This thread is from the archives. Join the live MG MGB Technical BBS now