'72 MGB gear selection issue
Discussion
I've got an intermittent problem (aren't they the best kind?) with the selection of 1st and 3rd gears. When i try select either 1st gear from neutral or go up to 3rd from 2nd, its as if there is something preventing the actual gear lever moving forward, you can feel resistance rather than a total stop. Theres no grinding of cogs or any nasty sounds and i you release the clutch the gear isnt selected or, if it is pops out very quickly. (so i don't do that)
If you leave the clutch depressed, then (in the case of 1st gear) selecting 2nd then putting it into 1st works every time without fail, with the same method for 3rd (exept pulling it into 4th) Letting the clutch up and pressing it down again seem to make no difference.
I checked the clutch fluid, and that was low, so i tipped it up and for a while it seemed to do the job but its doing it again and the fuild level it the same.
My next step was to be to check the gearbox fluid but I thought I'd ask here before i got stuck in any further.
My thoughts were at first that it might be one of the clutch cylinders having issues ifnot actually leaking, but would that account for it being intermittant and only affecting 2 gears and then only when selected in a certain manner? I don't want to go changing stuff like that unless its actually a possibility.
the car was rebuilt 40k ago (not by me, i got it at 19k) and the engine was rebuilt etc at the same time, but i can't rememebr if there were any reciepts for the gearbox as that sort of paperwork is in a box in my parents loft. I dont think so, in which case its probably got 140k on it. (verifiable 140k in total for the car is what im basing that on if it the original box) I changed the fluid last year and last checked it about 9 months ago and all was fine. Car gets used everyday.
Any ideas? (oh its an O/D box but that works just fine.)
Cheers all. Neil
If you leave the clutch depressed, then (in the case of 1st gear) selecting 2nd then putting it into 1st works every time without fail, with the same method for 3rd (exept pulling it into 4th) Letting the clutch up and pressing it down again seem to make no difference.
I checked the clutch fluid, and that was low, so i tipped it up and for a while it seemed to do the job but its doing it again and the fuild level it the same.
My next step was to be to check the gearbox fluid but I thought I'd ask here before i got stuck in any further.
My thoughts were at first that it might be one of the clutch cylinders having issues ifnot actually leaking, but would that account for it being intermittant and only affecting 2 gears and then only when selected in a certain manner? I don't want to go changing stuff like that unless its actually a possibility.
the car was rebuilt 40k ago (not by me, i got it at 19k) and the engine was rebuilt etc at the same time, but i can't rememebr if there were any reciepts for the gearbox as that sort of paperwork is in a box in my parents loft. I dont think so, in which case its probably got 140k on it. (verifiable 140k in total for the car is what im basing that on if it the original box) I changed the fluid last year and last checked it about 9 months ago and all was fine. Car gets used everyday.
Any ideas? (oh its an O/D box but that works just fine.)
Cheers all. Neil
Neil I'm a bit lost with your post - is the clutch fluid level where it was when you topped it up?
Sorry I might be misreading your post
You also say you checked the fliud 9 months ago, surely you check the brake and clutch fluids more regularly
Clutch fluid may need bleeding(??? - fluid changed a year ago) - was the flexihose changed, that could be collapsed inside itself (???)
I suggest you also check the gearbox oil, when was that last checked or changed (check every 6 months or 6,000 miles, change every 3 years or 36,000 miles - whichever is sooner)
yeap, g/box oil and clutch flexihose are well worth checking if clutch fluid level is at same level and you can see no signs of leaks
Sorry I might be misreading your post
You also say you checked the fliud 9 months ago, surely you check the brake and clutch fluids more regularly
Clutch fluid may need bleeding(??? - fluid changed a year ago) - was the flexihose changed, that could be collapsed inside itself (???)
I suggest you also check the gearbox oil, when was that last checked or changed (check every 6 months or 6,000 miles, change every 3 years or 36,000 miles - whichever is sooner)
yeap, g/box oil and clutch flexihose are well worth checking if clutch fluid level is at same level and you can see no signs of leaks
Sorry! The clutch fluid level was the same. It was the gearbox oil i was talking about being checked 9mnth ago, actually it must have been less as i checked it about a week before classic le mans. (your right, i dont check my fluids once every 9mths though!)
No sign of leaks but ill give it all a check. Is there a good way to test the clutch master and slave cylinders to see if its the seals? The pressure on the clutch pedal doesn't vary at all and seems completely normal.
I know the B's box is supposed to be tough as old boots, however, could the fact that pulling it into 2nd gear, then back into first while the clutch pedal is still depressed, point to something oterh than hydraulics? There are no grinding / misc other noises at all in any circumstances. Doent help that its an intermittent issue either.
cheers.
No sign of leaks but ill give it all a check. Is there a good way to test the clutch master and slave cylinders to see if its the seals? The pressure on the clutch pedal doesn't vary at all and seems completely normal.
I know the B's box is supposed to be tough as old boots, however, could the fact that pulling it into 2nd gear, then back into first while the clutch pedal is still depressed, point to something oterh than hydraulics? There are no grinding / misc other noises at all in any circumstances. Doent help that its an intermittent issue either.
cheers.
Might well be the seals in the clutch release bearing or the slave.
I replaced the gearbox on my last B at over 300k miles, mainly because it was starting to pop out of 3rd when I took my foot off the throttle and first was getting awkward. 2nd hand gearbox cost me £20 iirc.
We're having similar but more regular snags with the family MG 1300 and it's all do do with the master cylinder not working properly.
I replaced the gearbox on my last B at over 300k miles, mainly because it was starting to pop out of 3rd when I took my foot off the throttle and first was getting awkward. 2nd hand gearbox cost me £20 iirc.
We're having similar but more regular snags with the family MG 1300 and it's all do do with the master cylinder not working properly.
same applies:
could be a few things including clutch and gearbox but I think it may not be serious
don't forget to check the clutch flexihose, it might look alright on the outside so you'll need to feel it
also might be air in clutch fluid
I'm told master and slave cylinders are better replaced than repaired now
could be a few things including clutch and gearbox but I think it may not be serious
don't forget to check the clutch flexihose, it might look alright on the outside so you'll need to feel it
also might be air in clutch fluid
I'm told master and slave cylinders are better replaced than repaired now
Edited by Nigel At on Thursday 27th January 12:31
Nigel At said:
could be a few things including clutch and gearbox but I think it may not be serious
don't forget to check the clutch flexihose, it might look alright on the outside so you'll need to feel it
also might be air in clutch fluid
I'm told master and slave cylinders are better replaced than repaired now
ahhh - just had another thought, gear lever bush perhaps and/or gear lever spring
alfa - my VP 1100 used to jump out of second gear, a common thing I think on those gearboxes
Cheers for the advice, but it's not that it jumps out of gear, it's more like the clutch works fine for about 10 or so miles and then fails. Not wishing to hijack this thread, but the master cylinder is not the original one and just isn't maintaining pressure properly.don't forget to check the clutch flexihose, it might look alright on the outside so you'll need to feel it
also might be air in clutch fluid
I'm told master and slave cylinders are better replaced than repaired now
ahhh - just had another thought, gear lever bush perhaps and/or gear lever spring
alfa - my VP 1100 used to jump out of second gear, a common thing I think on those gearboxes
thought I'd done this already !?! bl**dy computers
still check:
could be a few things including clutch and gearbox but I think it may not be serious
don't forget to check the clutch flexihose, it might look alright on the outside so you'll need to feel it
also might still be air in clutch fluid - (updated - still)
I'm told master and slave cylinders are better replaced than repaired now
still check:
could be a few things including clutch and gearbox but I think it may not be serious
don't forget to check the clutch flexihose, it might look alright on the outside so you'll need to feel it
also might still be air in clutch fluid - (updated - still)
I'm told master and slave cylinders are better replaced than repaired now
neilr said:
Meant to post back a few days ago....
I bled the clutch and its cured the issue 9 times out of ten so i'm thinking it must be a master or slave cylinder issue..
anyway thanks for the pointers...
now to sort out the snapped handbrake cable from today!
Just read your original post on this thread and the first thing that came to mind was hydraulic seal wear. I had this problem with my second MGB as long ago as 1968. Professional advice was that I had gearbox problems. They were wrong. I replaced the seals in the hydraulics. First 'complicated' job I'd ever done and I was delighted with both the cost effectiveness and end result. Gear selection became as it should with that 4-H Gate Bolt Action Box with electric overdrive... a delight to use.I bled the clutch and its cured the issue 9 times out of ten so i'm thinking it must be a master or slave cylinder issue..
anyway thanks for the pointers...
now to sort out the snapped handbrake cable from today!
That experience with pro-advice and many others since, convinced me to do as much as I can on my own cars.... even the new ones! That's just about everything since and my cars only visit a pro-workshop come MoT time. Turbo engine swaps a doddle now...
MGJohn said:
I had this problem with my second MGB as long ago as 1968. Professional advice was that I had gearbox problems. They were wrong. I replaced the seals in the hydraulics. First 'complicated' job I'd ever done and I was delighted with both the cost effectiveness and end result. Gear selection became as it should with that 4-H Gate Bolt Action Box with electric overdrive... a delight to use.
That experience with pro-advice and many others since, convinced me to do as much as I can on my own cars.... even the new ones! That's just about everything since and my cars only visit a pro-workshop come MoT time. Turbo engine swaps a doddle now...
yeap if your good enough - pro-advice change whole units, master and slave as replacing seals is not now reliable, they might be wrong but it's difficult to trust some small parts now so perhaps they are right to say replace whole unit with new unless you like to replace seals or want to risk it - the pros could be wrong or just after your money - personally I prefer reliability as I wouldn't trust myself or seals but I could be wrongThat experience with pro-advice and many others since, convinced me to do as much as I can on my own cars.... even the new ones! That's just about everything since and my cars only visit a pro-workshop come MoT time. Turbo engine swaps a doddle now...
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