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Post by robhill on May 23, 2016 19:16:15 GMT
Hi everyone I'm after some advise if anyone can help
I have a 1275 mini auto I have recently changed the oil as normal but a few days later I have lost reverse not sure if it's a coincidence or not. When I jack the car up so there is no weight on the wheels the wheels spin backwards as normal
Also I seem to have quite a bad oil leak coming from the bottom of the torque converter area not sure if that's connected either
Any help will be much appreciated
Thanks rob
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Post by limby2000 on May 23, 2016 20:16:55 GMT
Hi Rob, did you have the leak prior to reverse loss, I know its a mini so oil leaks come as standard. Also is top gear (4th) still working ok, as top & reverse share the same clutch pack. Finally check your cable adjustment. Good luck Terry.
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Post by robhill on May 24, 2016 15:21:52 GMT
Thanks for the reply terry
I think the leak was there before to be honest it's only because I took it in the motorway it got worse or showed up more When I move the shifter into reverse I can feel it engage just no drive It's like something needs adjusting Or do you think it might be broken somehow
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Post by robhill on May 24, 2016 19:23:21 GMT
Oh yes sorry all the forward gears work as normal
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Post by mra-minis on May 24, 2016 23:16:08 GMT
I can be contacted on martin@kmprecisionengineering.com
What have you done since it last worked ok ? And how long ago did it last work ok ?
List everything you have done, even things you think are insignificant !
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Post by robhill on May 25, 2016 7:50:38 GMT
Hi The mini worked fine until about two weeks ago The fault started on a trip to Belgum I noticed after I had to rev more than normal to get reverse then the next time I tried nothing at all
In the last month I have
Changed the head gasket Renewed all the cooling system Changed the manifold and carb Changed oil and filter Refilled with millers 20-50
Thanks
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Post by mra-minis on May 25, 2016 11:16:43 GMT
I can be contacted on martin@kmprecisionengineering.com
What year is your Mini ?
Is it slipping ?
Also how did you check the oil level ?
********
If post 79 you will need to change the oil to 10W40.
If it's slipping, it's too late.
Checking the oil is very specific on a Mini fitted with an AP automatic unit.
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Post by robhill on May 25, 2016 12:37:39 GMT
Hi
I just check the oil as normal using the dipstick But because of the leak I have been topping up quite a lot It used 5 litres on a 700 mile trip
It's an 81 mini But the engine has been replaced for a more modern unit at some point
There is no slipping on the forward gears just no reverse So do you think my first thing should be to change the oil And is one make any better than another ?
Thanks for your help Rob
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Post by mra-minis on May 25, 2016 12:56:22 GMT
I can be contacted on martin@kmprecisionengineering.com
You should be using 10W40, there are some good threads on here about using MA2 spec oils a quick search should show them.
No reverse ? if everything else is fine it could be one of 2 things, your method for dipping the oil or the oil pressure is low, I would suspect the first, as "simply dipping an auto is very wrong.
Try this...
start and warm up your engine oil stop the engine and time 60 seconds now dip your oil.
Make sure you are on flat level ground
If low just top up and see if all is good before shelling out on new oil, if you get reverse then certainly 10W40 is the correct oil and should be changed as a matter of priority.
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Post by robhill on May 25, 2016 22:09:12 GMT
Thanks for your advice it's Mutch appreciated I have checked the oil as described but it's ok
I'm going to chance the oil and filter over the next few days and I will let you know how I get on
Do I need to check the valve clearences behind the front plate as I've read this somewhere but unsure if this could be a cause
Thanks again
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Post by mra-minis on May 26, 2016 1:31:13 GMT
I can be contacted on martin@kmprecisionengineering.com
The actuator valve lever adjustment is critical, however it is not something that can be adjusted in service, to clarify that point I mean it is not an adjustment to reset for band wear, it is for initial setting only.
Ok, it can be worth looking at to see if it needs to be reset or if it was adjusted incorrectly, if other parts have worn then you may get a little adjustment.
The bands need to be sitting on the 3 abutments and the lever arm requires between 1mm and 2mm of clearance. you must not lift the bands off their abutments.
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Post by robhill on May 26, 2016 9:00:43 GMT
Ok Thanks for your good advice I will tackle over the weekend
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Post by limby2000 on May 26, 2016 17:59:39 GMT
Hi Martin, I know there,s certain thing,s Rob has to check first but is it possible the reverse brake band actuator seal has gone. Have you had this symptom before.
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Post by mra-minis on May 26, 2016 18:21:50 GMT
Hi Martin, I know there,s certain thing,s Rob has to check first but is it possible the reverse brake band actuator seal has gone. Have you had this symptom before. Rob mentioned a leak, this may cause the oil pressure to drop off, reverse has a higher operating pressure than forward so is often symptomatic of pending doom, in the main, it i seals that fail and cause the failings that then display the symptom mentioned by Rob. To answer your question, yes it could easily be a split seal, again they really only split when they are hard, hardening of the seals is normally poor oil changes, however they will go hard eventually, unless you add something that will soften the seals. Brake fluid softens rubber but I would never use it in an engine, dextron fluids are pretty good at maintaining softer seals. Yes, I have seen loss of reverse loads of times, mostly down to loss of oil pressure. I am currently working on a device to read oil pressures in the AP unit.
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Post by robhill on May 29, 2016 0:27:14 GMT
Hi all I have changed the oil And checked Adjustments behind the front panel By no difference I'm afraid You can feel reverse engage just no movement The left hand lever in the box felt very loose compared to the other two I'm not really sure what route to take now.
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Post by limby2000 on May 29, 2016 10:14:53 GMT
Yeah the left hand actuator arm (ironically the reverse and top band) always seems to have a lot more travel than the other 2, I even stripped a 998 box recently that had over 20mm of travel (1-2mm being the factory spec), and yet that particular box had no reverse gear problems. As Martin mentioned the reverse gear uses a lot more working oil pressure to function, so if your pressure,s low it will surely show up while using reverse gear first. Checking your oil pressure via the outlet bolt on the oil filter head must be your first port of call. You will need a pressure gauge that will read at least 150 psi. Once connected there is a proceedure to check in all gears when at running temperature. What is the age and mileage of your car?.
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Post by mra-minis on May 29, 2016 10:40:51 GMT
I can be contacted on martin@kmprecisionengineering.com
You really need a gauge that reads to 200psi I have seen some AP2b units go over 165psi in reverse.
I would like to reiterate the band adjustment.
the band must sit on the 3 points when released, the slack is literally between the actuator and the rocker arm, if you push it down further you will feel a very light pressure, however this is moving the or closing the band and must not be "adjusted" out, the actuator has quite a lot of movement so easily copes with wear and manufacturing tolerances.
This adjustment is very important, if it too slack, it will cause damage and harsh engagement, if too tight it will cause drag (until it wears away) in most cases if left too tight it will wear the drums away, although this can also be just down to wear and tear.
The other thing to look at is the actuator spring/s these can break and as these units get older the springs are more prone to breakage.
So, the on position is at the point the band is tight against the drum/s the off position is when the band is relaxed and freely sitting on the 3 abutments, the rocker lever then has 1mm to 2mm of slack.
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Post by mra-minis on May 29, 2016 10:42:57 GMT
Yeah the left hand actuator arm (ironically the reverse and top band) always seems to have a lot more travel than the other 2, I even stripped a 998 box recently that had over 20mm of travel (1-2mm being the factory spec), and yet that particular box had no reverse gear problems. As Martin mentioned the reverse gear uses a lot more working oil pressure to function, so if your pressure,s low it will surely show up while using reverse gear first. Checking your oil pressure via the outlet bolt on the oil filter head must be your first port of call. You will need a pressure gauge that will read at least 150 psi. Once connected there is a proceedure to check in all gears when at running temperature. What is the age and mileage of your car?. Terry, the travel is not the adjustment, they are 2 different things
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