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Clutch master cylinder

Engine/Gearbox questions and discussion
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Scott560
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Clutch master cylinder

Post by Scott560 » Wed Dec 16, 2020 6:51 pm

At the beginning of last week - I noticed it was becoming increasingly strange trying to get into reverse gear. It would go in, but felt strange and generally not solid as before.

A few more days of my commute passed and I noticed a few more times not being able to get into reverse, and once at a set of lights, being stuck in 5th with the clutch hard down. It was very strange, shifting through the gears was fine , it was obviously dragging very lightly, but enough to prevent smooth reverse selection.

With the help of an assistant (mrs scott560), I bled the clutch system to buy me some more time - worked a treat. The fluid was very black, despite having been changed not even 2 years ago id say. A few days later I'm back to the symptoms again. Stole the wifes car for a few days.

Since I used the car to commute - I went straight onto the ebay and interwebs to confirms the part numbers for slave and master, then find a seller with both in stock and get it ordered. I ordered both because rubber seals of this vintage, if 1 is going (master or slave), then the other generally isn't far behind. Makes sense to replace them both as a pair, then your only bleeding it through and testing it once, safe in the knowledge the other isn't going to give out soon. Work smarter not harder - especially when its dark/cold/rainy out!

In my case its the master cylinder, there is tell tale weeping coming out of the seal into the footwell.

Both items arrived today (from the same seller), lo and behold, the slave cylinder box is a bit grubby and opened , along with the plastic bag. It's the wrong slave cylinder in the correct box. FFS.

Luckily the master cylinder is correct, but I don't fancy doing the job twice, so have to wait and source another one now before I'll get started.

Not a terribly exciting story - but there are few posts these days so we need all we can get!

Cheers,

Scott
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Scott560
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Clutch master cylinder

Post by Scott560 » Sat Jan 16, 2021 3:51 pm

Since not many posts these days, thought i'd give you an update.

Since the wrong slave cylinder turned up, I went ahead and replaced the master cylinder before Christmas on its own. The old one was leaking into the cabin, and was definitely causing the deteriorating gear change. Bled it all up which was a bit of a pain by myself. However, after believing all was well (wishful thinking), reverse was still a bit reluctant to go in, engine off or on. Pumped clutch or single press, made no difference. The car could engage reverse if you held the lever into reverse and slowly lifted the clutch - it would eventually go in as the clutch engaged, but it wasn't a great feeling, and it never really felt 'home'

So I ordered a slave cylinder for completeness, and replaced it today. The old one had no signs of leaking so it was unlikely to be a fix. Shoved an inspection camera into the clutch release lever hole , but couldn't get much room to wiggle around, but I couldn't see any strands of clutch material or similar (a thought is that damaged clutch friction disc could be dragging causing the hardness to select reverse), so nothign wrong with the clutch side of things.

So, the hydraulic side is fine, new master and slave, new fluid properly bled, full actuation of the clutch, and all forward gears are perfect. Visual inspection of all the fluid lines and damper revealed no other leaks, and the linkage is operating perfectly - 2nd and 4th pull fully.

However, reverse is still reluctant to go in - I can only conclude that their must be damage inside the gearbox with the reverse gear.

The only history leading up to this issue is that as the clutch began to drag because of the fluid leak, i did have a particularly nasty gearchange on the journey that the issue first cropped up. Since the clutch was dragging, a shift from the top end of 2nd in to 5th resulted in more than a slight grind trying to go in to 5th. I can imagine that a nasty shift into 5th with some grinding might cause trouble to 5th gear selection, but not reverse?

All i can say is balls - the weather is cold , the evenings are dark, and i really cannot muster the energy to remove the gearbox, and inspect/replace.

Anyone ever experienced anything similar? I'm pretty convinced the issue is inside the gearbox. The fluid has been changed recently, so doubt changing it will bring any improvement. All other gears are fine.
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Clutch master cylinder

Post by CARRisma » Sat Jan 16, 2021 4:46 pm

I had a similar issue but wasn't with just the reverse gear. The gear stick moved left and right as normal, but refused to go forwards or backwards into any gear, as if something solid was in the way. It was like it was locked out. Then all of a sudden, it would start working again, but the first shift was quite stiff and a bit crunchy, then it would be fine, shifting smoothly as ever. On a few occasions, it had grinded slightly when changing up a gear, as if I had not pressed the clutch pedal down properly. I had sometimes been stuck out of gear for about 10 seconds coasting along while trying to entice it into gear. It happened with all gears even when the revs had dropped to idling speed. It wasn't temperature related as it still had the same problem after a journey of 60 miles (mostly motorway). Clutch fluid level was fine. The clutch fluid and MTF were replaced within ther previous 6 months.

Like you, I replaced the clutch master cylinder to no avail. After the clutch master cylinder replacement, I noticed a quiet rattle/rustle noise from the transmission side of the engine bay when parked which stopped when I pushed down the clutch pedal. Also, sometimes the motion of clutch pedal didn't feel normal. Changing gear without the engine running was faultless, with and without the pressing the clutch pedal but the fault was intermittent. To further help diagnose the fault, I drove the car along a quiet dual carriageway, changing gears without the use of the clutch. I was also able to change gear successfully without the clutch through all gears, apart from 5th gear. Maybe the revs were not right when I tried to change up into 5th gear or maybe that's a sign of a warn synchromesh?

I decided to replace just the clutch & flywheel during February 2009 instead. The flywheel was not suspected to be at fault, but I fancied an upgrade. An Exedy Standard Clutch Kit and lightweight Fidanza aluminium flywheel were purchased. Upon inspection of the original clutch, the friction surface of the clutch disc wasn't too badly worn, however the metal lips which retain the springs were damaged, causing the springs to be loose and one of them was able to freely come out.
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Clutch master cylinder

Post by Scott560 » Sat Jan 16, 2021 6:17 pm

As I read through your reply, I was thinking 'yes, yes....' up until you said it would be fine changing gear with the engine off.

Sadly my reverse feels suspect even with the engine off, and no other funny noises present. I'm ruling out worn selector forks, as you can tell the engagement is not right from the gearstick, it still has all it's normal travel, that's how you can tell it's not in (eg, it will only move an inch instead of 2.5).

The clutch is less than 2 years old and was genuine Honda Accord type r one. Either way the gearbox would have to come off to do a proper inspection :(

Good to know my thinking about the clutch dragging would cause similar symptoms though, which is what this started with (due to leaky master).

Can't blame the car though, 21 years old, 130k on the clock. Hard driving and track days all starting to take its toll :thumbup:
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Clutch master cylinder

Post by Vtecmec » Sat Jan 16, 2021 6:28 pm

The issue is more likely than not the syncromesh for 5th and reverse, which are shared. Worth swapping the oil for redline MTF as its known to help this kind of issue.

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Clutch master cylinder

Post by Scott560 » Sat Jan 16, 2021 6:34 pm

Vtecmec wrote:
Sat Jan 16, 2021 6:28 pm
The issue is more likely than not the syncromesh for 5th and reverse, which are shared. Worth swapping the oil for redline MTF as its known to help this kind of issue.
Trouble is, I think the damage is done? If it always grinded into 5th say, then yeah I'd try some new oil. But, warm or cold, engine off, it's just won't go in to reverse all the time smoothly. Driving forwards all gears feel good.

Ive pretty much resigned myself to the fact the gearbox is going to have to come off. Somehow the shift from 2nd to 5th which caused a grind has brought about the demise of reverse it seems.
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Clutch master cylinder

Post by Scott560 » Mon Jan 18, 2021 11:24 am

Pretty decent explanation here (except the picture links are dead):

https://honda-tech.com/forums/honda-pre ... ost5691330

So because of the slightly/slowly failing master cylinder, and then just a couple of crunches into 5th (due to clutch dragging), seems to have finished off the synchro.

One thread seemed to suggest that the slight deformation of the sycnro can be corrected by repeatedly slamming into reverse. This will eventually wear the syncro so that it doesn't bind... Don't have much to lose so may give that a go next time I get stuck unable to get in reverse.

Insult to injury, car tax reminder just arrived :cry:
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Clutch master cylinder

Post by Vtecmec » Mon Jan 18, 2021 12:12 pm

Scott560 wrote:
Mon Jan 18, 2021 11:24 am
One thread seemed to suggest that the slight deformation of the sycnro can be corrected by repeatedly slamming into reverse. This will eventually wear the syncro so that it doesn't bind... Don't have much to lose so may give that a go next time I get stuck unable to get in reverse.
Having messed with the insides of these gearboxes, I can't see how this would help.

Try a Redline oil swap, its slightly thinner and 'slipperier' than most gearbox fluids and completely sorted out my 2nd gear crunch on an e90 BMW, still good 40k later............

It's £20 of fluid and an hours fiddling or an expensive gearbox rebuild.

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Clutch master cylinder

Post by Scott560 » Sat Jan 23, 2021 11:00 am

Sorry for the long post - not much going on these days so feel I should add some useful content.

I'm not using the car much at the minute, so decided I had nothing to lose by abusing the gearbox in this situation. I think it has actually had a positive outcome. I did not replace the gearbox oil, it was replaced in October last year before my track day with fresh Honda MTF 3.

With the engine running and clutch right down, I simply moved it from neutral to reverse, then up into 5th and back into neutral, over and over again.

Where it jammed (not grinding) initially going into reverse (the stick would not move down fully into reverse), I simply retried over and over, increasing the force to do so. Once it went in, I just went up into 5th, back to neutral and repeated. Also, rather than force it into reverse by pulling the gearstick down with greater and greater force against the jam, I was conscious that this could damage the shifter mech/cables/forks, so instead of forcing it in, I would try to 'bang' it down from the neutral position, using the inertia of the moving parts rather than force the assemblies.

After doing this for a couple of minutes (so maybe 40 times or so), the force needed to get into reverse did reduce. Most of the time (9/10) I can now go into reverse fine, with the satisfying clonk sound, and the gearstick moves fully down, and it feels home/seated/fine like before.

Infrequently it will still feel overly notchy half way into reverse, but this is quite rare now and easily overcome with a single retry- where as before it was hard to get reverse at all.

So lessons learnt:

Do not do shifts from the limiter in 2nd to 5th, the gearbox internals don't have enough time to spin down. Any kind of grinding into 5th is going to, without much warning at all, take out your reverse gear selection at some point (and from what I've read, possibly 5th gear too). I was really surprised. I had no warning that reverse was getting harder to select or anything, until 1 'bad shift' into 5th , 5 minutes later I absolutely could not get into reverse.

If you have any clutch hydraulic issues or concerns (usually a small leak in master or slave or both), do not 'buy time' by doing a quick fix refilling/bleeding - you're on borrowed time. Buy the master/slave cylinder immediately and do not drive it (slave is only 25quid, master is about 60quid, blueprint parts from ebay). I suspect my master has been leaking for a while with no detectable symptoms. As the clutch disengages less and less as the fluid leaked out, the dragging of the clutch is probably accelerating wear on the shift components inside the gearbox.

Check your master and slave cylinders now! fluid leak is usually visible around the rubber dust seal. Give it a squeeze and a feel, if its wet it's on its way out. Both are not hard jobs to do, just a little fiddle due to space and took a little longer than planned.

If you do end up accidentally grinding 5th gear and your reverse then feels dodgy, some respite evidently can come from the controlled/moderated banging/slamming from neutral to reverse then into 5th over and over. This must wear away whatever burr/deformation has formed from the grinding. Obviously this just wears out the gearbox further, but id rather have a slightly more worn gearbox where I can get into reverse than one where I cannot or having to remove the gearbox.

Tips for replacing the clutch master and slave cylinders:

1) Be careful of brake fluid, it will damage paint. You can drain the fluid easily by opening the slave bleed valve and pumping a few times (gently). This will clear the top end.
2) before refitting the master, on the bench fill it up with some fresh fluid and orientate it everyway otherwise it will take ages to draw in new fluid once refitted. Also worth actuating it a few times to make sure the seals are lubricated and airtight. Do not squirt brake fluid into your eye!
3) Same goes with the slave, push the cylinder in (I used a woodworking clamp), syringed in some fluid, and then released/repeated until it was full. Shake it all around, then squeeze the fluid out. This helps prevent air bubbles when bleeding.
4) The slave cylinder, the mounting holes were slightly larger than the bolt shanks, leading to a reasonable amount of movement in its finally fitted position. Before snugging up the bolts upon refitting, I used a breaker bar against the front engine mount to gently push the assembly leftwards, then snugged up the bolts. I can now be assured the mechanism is in its maximum clutch disengagement position (rather than it being place rightwards, which would compress the clutch cover less).
5) when replacing the slave, be mindful that slight casting/fitting differences means the hydraulic pipe and union (which is very finely threaded) may not line up perfectly as before. I had to remove the little 10mm nut for the pipe bracket under the distributor which gave me a bit more wiggle room for the pipe. It is easy to bend the pipe when removing the old cylinder, so it required a slight re-adjustment to get the union to start off nicely in the thread and to ensure the pipe was straight on.
6) When bleeding the system, I like to use both methods. Initially, with the bleed valve open, have an assistant pump and return the clutch pedal over and over until fluid is present. Close the valve. Then have them push the clutch down so that the fluid is under pressure, then open the bleed valve so that the clutch diaphragm is pushing the slave cylinder back home and emptied. This only needs doing a few times, and will help remove any air in the slave.
7) beware when bleeding, the upward stroke of the clutch pedal can create quite a backwards flow in the small reservoir, which can trap air bubbles from the surface. Be sure to pop them with a clean implement, and don't let it run too low naturally.
8) the rubber dust seals that come with the parts are quite dry - I used a small amount of silicon grease (safe for rubber) around the fitting lips and orifices so that they sealed better and also to reduce damage when inserting the slave rod which was a very tight fit. Don't forget also some grease on the slave rod internally and externally as well. Be sure to clean up all the crud from the clutch release fork with a little brake clean and a rag also.
9) Don't forget to adjust the master cylinder rod tension after fitting. I didn't check the manual to see if a procedure is listed, but you want to ensure that it is not under pressure/compression when the clutch is fully up. Fit it with the lock nut / clevis pin bracket loose. You can then easily by hand rotate the rod with your fingers to adjust the pre-load. I started off with it completely loose/rattling, then gently twisted it JUST ENOUGH until it no longer was able to jiggle about. Do not twist it any further than this, you do not want the system to remain under constant pressure or for the master cylinder to not return fully.

Sorry for the long post - hopefully help some people in the future and give people something to read. The prelude lives a little bit longer, so I've stopped looking at auto trader lol...

Perhaps I need to take some pictures as well , then I can write less :lol:
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