Squeak/Slip on takeoff once warm

[6886auto]

Hi,

My 1986 998 squeaks at take off once it is warm (30 mins of driving). I have cleaned out the valve block in an attempt to fix it but it has not changed it. I have ordered the pressure gauge to test the transmission which I never did due to not having it.

I am now wondering if it is also related to the fact that when idling in drive there is a lot of vibration like the transmission is allowing too much power through? When the engine was last removed there was a broken engine mount so I assumed that it was causing the vibration, I haven't checked them again yet.

[jockduck]

Hi, a quick test, does the thing squeak/slip if you select 2 and take off? my Mini had a faulty 1st gear sprag clutch and would slip and squawk if given a bootful, it would take off better in 2nd, vibration at idle, are all the cylinders working equally?
Jock

[6886auto]

May 25, 2022 11:00:10 GMT jockduck said:

Hi, a quick test, does the thing squeak/slip if you select 2 and take off? my Mini had a faulty 1st gear sprag clutch and would slip and squawk if given a bootful, it would take off better in 2nd, vibration at idle, are all the cylinders working equally?
Jock

Yesterday I tried once to take off in second and it did still squeak, I will try again some time when I don't have lots of traffic behind me. The foulis overhaul book has also arrived so I will read that.

[notamini]

I find Foulis a fairly heavy read. Let us know what you think please.

Mark

[jockduck]

Still squeaking in 2nd may indicate a slipping forward clutch, could be worn clutch plates or lack of oil pressure.
Jock

[6886auto]

May 25, 2022 11:00:10 GMT jockduck said:

Hi, a quick test, does the thing squeak/slip if you select 2 and take off? my Mini had a faulty 1st gear sprag clutch and would slip and squawk if given a bootful, it would take off better in 2nd, vibration at idle, are all the cylinders working equally?
Jock

The vibration does appear to be power output related. If I increase the idle speed to around 800rpm in drive it goes away but the neutral rpm is too high so it runs on.

[6886auto]

May 29, 2022 11:12:50 GMT jockduck said:

Still squeaking in 2nd may indicate a slipping forward clutch, could be worn clutch plates or lack of oil pressure.
Jock

I think it is likely a worn clutch but want to check the pressure to confirm. I am of course not wanting to pull the engine out again.

[6886auto]

It has now started to squeak when stopping sometimes as well as between gears. I was working on it and decided I would quickly do a torque converter stall test, at 1500rpm there is a big squeak/squeal.

[jockduck]

Hi, without checking the manual I think 1500 is a little high for a 998, a 1275 maybe, which might suggest a T/C problem, still could be internal slippage with clutches or bands, did you check the stall test in other gears?
Jock

[jockduck]

Well I was wrong, I checked the manual and for a 998, 1400-1500 is deemed satisfactory and no rectification required !!! Over 1500 suggests transmission slip, under 1300 is engine down on power and under 1000 is T/C fault.
Jock

[6886auto]

Jun 5, 2022 11:38:13 GMT jockduck said:

Well I was wrong, I checked the manual and for a 998, 1400-1500 is deemed satisfactory and no rectification required !!! Over 1500 suggests transmission slip, under 1300 is engine down on power and under 1000 is T/C fault.
Jock

After I did it I read the book which says it shouldn't be done in drive which is of course what I did. I will redo it to confirm but really the next step (and what should be first) is to test the pressure. I am not sure when the gauge will arrive.

[6886auto]

I just redid the testing. All gears seem to result in 1500rpm. 2nd squeaks, reverse and third do not (can't test 4th on this version of the transmission)
It could be slightly over but I think saying 1500 is close enough.

[6886auto]

I have just done the pressure testing and the results all seem to be about 10psi lower than they should be.

[jockduck]

Hi, I don't think 10 psi is significant, presumably 1st does not squeak, Possibly a 2nd gear band fault, what to do next, carry on and ignore it until something worse happens or pull the front cover for a look?
Jock

[6886auto]

Jul 11, 2022 10:56:47 GMT jockduck said:

Hi, I don't think 10 psi is significant, presumably 1st does not squeak, Possibly a 2nd gear band fault, what to do next, carry on and ignore it until something worse happens or pull the front cover for a look?
Jock

1st does squeak, when I go to take off it squeaks before moving.

[jockduck]

OK, squeaking in 1st and 2nd, could suggest the forward clutch is slipping due to the higher torque, do you know how many miles the 'box has done since last overhauled?
Jock

[6886auto]

Jul 12, 2022 10:54:41 GMT jockduck said:

OK, squeaking in 1st and 2nd, could suggest the forward clutch is slipping due to the higher torque, do you know how many miles the 'box has done since last overhauled?
Jock

I believe it has only ever done 45,000km. It has at some stage had the sump smashed and welded but probably unlikely that it had work done then.

[jockduck]

Hi, I don't know what would be considered a significant mileage on an AP box, I think the later ones would run longer than the early box, my early box has done 30 K miles since overhaul and still performs as it did after O/H, I guess a lot depends on how the car is treated. I guess if the squeaking was not bothering you too much and everything else worked OK then carry on until the condition worsens, If the noise drives you nuts and destroys the confidence in the car then you will have to consider pulling the lump out and overhauling it.
Jock

[6886auto]

Jul 15, 2022 11:08:04 GMT jockduck said:

Hi, I don't know what would be considered a significant mileage on an AP box, I think the later ones would run longer than the early box, my early box has done 30 K miles since overhaul and still performs as it did after O/H, I guess a lot depends on how the car is treated. I guess if the squeaking was not bothering you too much and everything else worked OK then carry on until the condition worsens, If the noise drives you nuts and destroys the confidence in the car then you will have to consider pulling the lump out and overhauling it.
Jock

I want to not have to pull the engine out however it really doesn't seem good to leave it like this. It is what I drive to work so a transmission failure would be inconvenient.

I tried to record the sound today but of course it only made the noise when stopping not when taking off, here it is (ignore the brake squeal) transmissionissue.mp3 (344.34 KB)

[notamini]

Sounds like metal on metal. Could it be a dislodged or warn out band?

[6886auto]

Jul 15, 2022 12:04:54 GMT notamini said:

Sounds like metal on metal. Could it be a dislodged or warn out band?

Is that the brake squeal or the little transmission squeak at the end? When I stop like in the recording the squeak is pretty small, it is a lot worse when I go to take off.

[6886auto]

It is out! Due to the aircon I had to remove it from below unless I got the aircon degassed.

[6886auto]

Do these later transmissions require a slightly different oil pipe alignment?

I am using an Austaloy 18G1094 and the single oil pipe lines up easily in the tool but when I go to put the governor assembly on it is slightly to the side.

[jockduck]

Austaloy 18G1094 ?? sorry I don't know what you mean, I think you are talking about the pipe holding tool, I have never used one, I made up the little one that holds the clutch in place while you try to maneuver the governor cover on while trapping you fingers trying to keep the oil pipes going into their holes and the governor link in place, I assume you have had the clutch out it can be a little tricky getting the clutch plates splines lined up so that the clutch slides fully onto the shaft hub, its very much easier with the engine off!!! but it can be done, it needs some intelligent persuading, do not force, should close up to the gasket OK, if you can rotate the shaft it helps.
Jock

[6886auto]

Jul 29, 2022 11:23:46 GMT jockduck said:

Austaloy 18G1094 ?? sorry I don't know what you mean, I think you are talking about the pipe holding tool, I have never used one, I made up the little one that holds the clutch in place while you try to maneuver the governor cover on while trapping you fingers trying to keep the oil pipes going into their holes and the governor link in place, I assume you have had the clutch out it can be a little tricky getting the clutch plates splines lined up so that the clutch slides fully onto the shaft hub, its very much easier with the engine off!!! but it can be done, it needs some intelligent persuading, do not force, should close up to the gasket OK, if you can rotate the shaft it helps.
Jock

 
Yes I have had the clutch out and believe I have it back on the splines fully (took a few attempts). I am using the correct tool to hold the clutch in place. I am still stuck with the governor cover needing to go another about 1cm. I can just look inside and it appears the oil pipe is slightly off (too far towards the centre shaft). I can't see how I can fix the alignment so maybe it is correct and it is just a spline alignment issue (most likely governor end where the step is).

This is the 18G1094, I do know there is a different version of it but I don't know what the difference is. This one would be the "early" version.



What I found when I pulled the clutch out was that there was of course wear but not spectacular. What I did find unexpected was one of the oil rings on the clutch shaft was broken with a missing section I haven't found anywhere. What I have done is replace the plates, seals and the four oil rings. Is there anything else I should be changing/checking while I am at it (without pulling the entire transmission apart)

[jockduck]

Aggh! very sorry to hear about the broken seal ring, this is very common with the earlier boxes which had a slightly thinner shaft, I have a box of early clutches with grooves with rounded edges which don't give the rings a chance, I modified my spare box with a later clutch but have not had a chance to try it out. Yes the drive splines on the governor gear can be a problem, How is the little bush in the governor housing, is it a "top hat" bush or is there a separate thrust washer? feel kinda helpless at this end, sorry
Ian

[6886auto]

Jul 30, 2022 11:18:46 GMT jockduck said:

Aggh! very sorry to hear about the broken seal ring, this is very common with the earlier boxes which had a slightly thinner shaft, I have a box of early clutches with grooves with rounded edges which don't give the rings a chance, I modified my spare box with a later clutch but have not had a chance to try it out. Yes the drive splines on the governor gear can be a problem, How is the little bush in the governor housing, is it a "top hat" bush or is there a separate thrust washer? feel kinda helpless at this end, sorry
Ian

I am not sure what bush it has, I will have a look. The spline for the governor was not inline but I fixed it and it moved further. I took out the oil pipe and I got it to go on further (must have been all the way, I can't remember now) so it must be the oil pipe it is hitting as it looked.

I didn't want to pull it apart yet but I have a late 1275 I need to tear down entirely so I might open it up to compare if the pipe is bent.

[6886auto]

Turns out the pipe was bent, I compared it to my faulty 1275s one and borrowed its one. Basically went straight on then.

Now pulled off the front cover as the manual said there should be two o rings on the front cover. When I previously had the cover off I only put one as that is what came off but it seemed wrong (it wasn't wide enough). Now that I have it off again it doesn't look like there is enough room for a second O ring. What is correct?

About to check the manual but I assume all three brake bands should have equal play? The left one has significantly more than the others and has the nuts adjusted further down.

[jockduck]

Hi again, had a look at the JPAT diagram there is one O ring on the front cover where it plugs into the valve body, not sure if there is one on the other oil feed that goes through the top of the cover gasket, there is an O ring on the pipe fitting that screws into the top of the G/box casing.
The left most band is the reverse band, checked the manual and all band clearances are the same 1.0 - 1.5 mm which is apparently nine flats on the nut (1.5 turns?) turn the nut into the spherical seating until it has no clearance then wind back 9 flats.
Jock

[6886auto]

I decided to pull the gear train and top/reverse clutch at least for inspection but most likely replacement of the clutch plates and brake bands. I found the bands have worn grooves into the gear train and top/reverse clutch which sounds like what this user had: 

Mar 13, 2016 0:47:32 GMT mra-minis said:

Jan 31, 2016 19:40:07 GMT limby2000 said:

After striping down the 2x 998,s the wide brake band was showing serious degrading, the other 2 bands seemed to have left lines on the drums, or is this normal. I can seen the main issue when rebuilding is going to be locating the copper oil feed pipes and the " c " shaped kickdown rod. Very fiddly. I can see why most people get mra to do the rebuilds.

Hi Terry,



It is normal wear and abuse..... it is why my cores are fairly expensive, I did toy with the idea of plasma spray welding to build them up and then cylindrical regrind them to size.



The wear is thought to be caused by low pressure, low pressure caused by leaky actuator seals or other leaks, that cause the working pressure to be lower than required and hence slippage occurs resulting in this wear.



The bands are normally heavily worn at the ends, look at the friction material thickness, it will thin out at the ends.



3 to 4 flare is caused by the up-change not occurring quick enough, one reason is incorrect oil grade, another is worn seals allowing pressure to bleed off and the third is damaged friction surfaces.



I have a tool for aligning the pipes, however I just strip the AP2 off the engine and that way it is easy to fit the later pipes and control mechanism.





www.ebay.co.uk/itm/322007730061?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649



 

                                                             View Attachment



Here is my first batch, ready for sale at £24 plus shipping..

Otherwise the bands don't look bad to me but I have no idea how thick they should be. When removing the top/reverse clutch a small section of one did chip off so I think they have degraded the same way the clutch plates had in the forward clutch. After replacing the forward clutch plates I found that I could easily chip sections off by rubbing my finger on the edge of them which is why I decided to change the top/reverse ones.