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Car Forum / MINI / November 2003Automatic Gearbox Repairs
Hi I have a 1990 metro Automatic , the gearbox seems to lack power and when you pull away it just makes a lot of Squealing noise until it is moving. I believe it is the brake bands that need adjusting, but can`t find any reference to this in the Haynes manual or the net. Can anyone offer any advice or where to find the procedure to adjust the bands. > I have a 1990 metro Automatic , the gearbox seems to lack power and when you > pull away it just makes a lot of Squealing noise until it is moving. I > believe it is the brake bands that need adjusting, but can`t find any > reference to this in the Haynes manual or the net. Can anyone offer any > advice or where to find the procedure to adjust the bands. The squealing is probably slipping bands or clutches, probably the forward clutch. When the engine speed picks up, the oil pressure rises and the clutch grips better. The root cause may be wear of the forward clutch or it may be an oil pressure problem. There is a plug on the oil filter housing base for a pressure guage to check the gearbox oil pressure with a special guage. You should get someone to check the oil pressure first. If it's OK, expect the forward clutch to be knackered. Actually, you can also check-does it squeal in reverse too or only forward? If only forward, then it's almost certainly just a knackered forward clutch. It's worth getting a professional diagnosis even if you do the repair yourself so you know you're fixing the right thing. If you do a major rebuild such as bands or top and reverse clutch yourself involving removing the gear train from the housing, email me for some important clues..... The forward clutch is not adjustable, but it is the first thing that comes out when you take the end cover off the gearbox, so it's a (relatively) easy fix. You can do without the special tool (1067? 1097?) for holding the forward clutch and the tool for aligning the pipes at a pinch. Use a screwdriver through the hole in place of the alignment tool; you'll need an assistant or 5 hands. For the pipes you can make up your own alignment template from cardboard or do it carefully by eye. If you get it wrong, then when you start the motor you'll have no oil pressure and you'll have to pull it apart again.... I've also seen an auto with a stuck oil pressure relief valve in the pump body (not external like in manuals). It would stick when I turned the motor off hot and strand me with no oil pressure and no drive, and when I towed it home cold, the auxiliary pump would dislodge it, leaving me with nothing to fix. After several cycles of this game...... > > I have a 1990 metro Automatic , the gearbox seems to lack power and when you > > pull away it just makes a lot of Squealing noise until it is moving. I > > believe it is the brake bands that need adjusting, but can`t find any > > reference to this in the Haynes manual or the net. Can anyone offer any > > advice or where to find the procedure to adjust the bands. Hi, Auto boxes are not really for the faint hearted. They can be absolute devils to re-assemble. But as far as the brake bands are concerned, these can be adjusted in the car. First, jack the front up as high as you can. Remove the front cover from the gearbox (after draining the oil). You will see three brake bands inside the box; when the bands are fully released and are against the stops in the casing, adjust the large nuts to give between .040 and .080 inch clearance between the rounded base of the nut and the operating lever. Refit the cover and refil with oil. If it is the clutches that are worn, then I am afraid it means a major strip-down, and I would advise not to attempt it unless you have the correct manual. The re-fitting of the forward clutch is the worst part of the whole job, and it entails making sure that the notches on the clutch plates inside the outer drum and exactly in line and central in the housing before you offer up the housing to the shaft. be aware that the clutch is spring loaded as you push the housing in and if you allow the housing to move back just a tiny bit, thee plates will move out of alignment you will have to start all over again. Keith > > I have a 1990 metro Automatic , the gearbox seems to lack power and when you > > pull away it just makes a lot of Squealing noise until it is moving. I [quoted text clipped - 35 lines] > when I towed it home cold, the auxiliary pump would dislodge it, leaving > me with nothing to fix. After several cycles of this game...... This problem has got worse having changed the oil and filter, it sounds like it could be an oil related problem. I am using 10w40 as per the book, would you have any recommendations this ? Make sure the oil level is a bit higher than full on the dipstick. Some automatics are more picky about this than others. Cheers, Kelley >> > I have a 1990 metro Automatic , the gearbox seems to lack power and when >you [quoted text clipped - 40 lines] >it could be an oil related problem. I am using 10w40 as per the book, would >you have any recommendations this ? > This problem has got worse having changed the oil and filter, it sounds like > it could be an oil related problem. I am using 10w40 as per the book, would > you have any recommendations this ? OK, it's either a friction element on it's way out or the torque converter is slipping, typically due to foamed up oil. There are two friction clutches, a one way clutch and three bands in the auto gearbox. In first gear, only the forward clutch and the one way clutch are used. In second the 2nd gear bands engages. In third the 2nd gear band releases and the 3rd gear band engages. In fourth the bands all release and the "Top and reverse" clutch engages. In reverse, the forward clutch does not engage. Drive is via the reverse band and the top and reverse clutch. You're getting slip sometimes. Diagnostic procedure: A) Manually engage 1st. Does the problem occur? (presumably yes). So it could be the torque converter, the forward clutch or the one way clutch. Go to B. B) Manually engage 2nd and attempt to drive away. Does the problem still occur? If yes, then it's not the one way clutch. Since it happened in first, it's not the 2nd gear band. Go to C. If no, then it's the one way clutch. This is very unlikely. C) Manually engage reverse and attempt to drive away. Does the problem still occur? If yes, then it must be the torque converter. If no, then it must be the forward clutch. This testing should take you about 2 minutes and you won't even have to open the bonnet or get your hands dirty! 8-) Get back to us with results... If it's the forward clutch it's not too bad to fix. Certainly by the time you've got the motor and box out, it's easier to fix than to find another motor and box. If it's the torque converter the solution is so simple you'll be kicking yourself if you've pulled anything at all apart, but it's not in the manual! I've never seen the one way clutch fail. Hi Graham, thanks for all this help. Its slipping in 1st , 2nd and 3rd, but does not seem to be slipping in reverse, so it would seem to be the forward clutch. One point I would make is that my other half (who`s car it is ) has suddenly mentioned that it has sometimes been making a sort of graunching / squealing noise when you change into reverse. She says that it does not do it that often, and to be honest I have never noticed it , but it may be relevant to the problem. Thanks again for the help > > This problem has got worse having changed the oil and filter, it sounds like > > it could be an oil related problem. I am using 10w40 as per the book, would [quoted text clipped - 50 lines] > > I've never seen the one way clutch fail. > Its slipping in 1st , 2nd and 3rd, but does not seem to be slipping in > reverse, so it would seem to be the forward clutch. That would be my assessment too. > One point I would make is that my other half (who`s car it is ) has suddenly > mentioned that it has sometimes been making a sort of graunching / squealing noise > when you change into reverse. She says that it does not do it that often, and to > be honest I have never noticed it , but it may be relevant to the problem. It will do this if the revs are too high when you put it in reverse, but it may also do it if the oil pressure is too low. At this point, we know the forward clutch slips until the revs come up (which always improves things with a worn clutch because the oil pressure compressing the plates increases). The torque converter problem I was referring to presents quite differently to this, so that's not the issue. I think at this stage you need to get someone to put a pressure guage on it and see what the pressure is doing. It may be a low pressure problem or it may just be a worn out forward clutch and a less worn out top and reverse clutch. BTW, the reason it doesn't do it in 4th is just that the gearing is too high for it to happen. Thanks again Graham, I will try and find somewhere that can check the pressure for me and take it from there The forward clutch may slip and squeal before it dies completely. The auto is easy to work on, it just looks bad! especially if you read the manual! Michael. > Hi > I have a 1990 metro Automatic , the gearbox seems to lack power and when you > pull away it just makes a lot of Squealing noise until it is moving. I > believe it is the brake bands that need adjusting, but can`t find any > reference to this in the Haynes manual or the net. Can anyone offer any > advice or where to find the procedure to adjust the bands. > The forward clutch may slip and squeal before it dies completely. > > The auto is easy to work on, it just looks bad! especially if you read the > manual! I'll second that. And I'll repeat, if you do remove the gear train from the box (such as to replace the top and reverse clutch or the bands) email me for the minor but essential clues which are not in the book.... Hi everyone, Thanks for all the help and advice. I`m gonna start by checking if the bands need adjusting, but to be honest if its not the bands, I think I`ll probably just try and get another gearbox from a breaker or another car !!! Its only worth a few hundred pounds and I don`t realy think I`m up to stripping a auto box. > Hi everyone, > Thanks for all the help and advice. I`m gonna start by checking if the bands > need adjusting, but to be honest if its not the bands, I think I`ll probably > just try and get another gearbox from a breaker or another car !!! Its only > worth a few hundred pounds and I don`t realy think I`m up to stripping a > auto box. The bands are not used when moving from a standstill in first gear. Adjusting them WILL NOT HELP and is a royal pain in the arse to do. The workshop manual has copious diagrams of things like the power path through the gearbox in each gear and which friction elements are engaged in each gear for very good reasons - to make it easier to diagnose problems. Instead of treating the auto gearbox like some mysterious black box and adjusting the bands just because you know they can be adjusted, read the manual properly and diagnose the problem properly BEFORE dismantling anything. Have you tested if the problem happens in reverse yet? I am confident you will find there is no problem in reverse, and if that is the case then the forward clutch is sick and needs removing and the friction plates replacing. That's probably under 50 quid of parts and is pretty straightforward. Hi The gearbox is slipping and squeeling in 1st 2nd and drive. It does slip and squeel in 3rd but is not quite so bad. It doesn`t however slip in reverse, so it does sound like it could be the forward clutch. > The gearbox is slipping and squeeling in 1st 2nd and drive. It does slip and > squeel in 3rd but is not quite so bad. It doesn`t however slip in reverse, > so it does sound like it could be the forward clutch. Back when Morris 1300 autos were still relatively common in Australia you used to see advertisments for them all the time - "Morris 1300, excellent condition, but only goes backwards" - they were easy repairers either to fix and sell or for the motor and box assembly. Hi all, I own a 1992 rover mini mayfair automatic catalyst 998cc carb. 1) on "hard" accleration, the second gear is engaged a few seconds or not enaged at all (and skips from 1st to 3rd). 2) At high rpms transmission slips from 3rd to D, does not slip in other gear changes or during kikdowning. 3) when engine and trasmission are really hot (highway driving), forward ranges are not engaged at idle speed and i have to accelerate a few to engage (in this case it makes noise) Can you help me? I obviously want to keep my mini alive, it's so cool! I live in rome, italy, and rover no longer provides service for old minis. Other mechanics are really afraid of automatic gearboxes, as in italy most people prefere manuals. Excuse me for my funny english, and thanks in advance for replies! Ciao emilio (Rome, IT) |
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