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MG Midget and Sprite Technical - UH-OH Not what we thought!

Hello all,

Finally got a nice day to remove engine/box. I anxiously awaited the sight of a decimated release bearing. Imagine my surprise when discovering said bearing is just fine! Moving on to the clutch itself I noticed that the outside had a fine brownish residue on it. As I loosened the pressure plate, I got the same noise that I got when pushing the clutch pedal down. Removing the pressure plate and disk allowed a curved piece of metal to fall out from the pressure plate. Another one was still in the plate (part that faces the disk), a quick shake dropped it out. The clutch disk itself shows no wear except for marks on the plate side of the springs, apparently from the breaking up of the pressure plate. The spigot (pilot) bushing is still intact, although I can turn it round and round with my pinkie, it slides back and forth a little, but won't come out that way. I'm told this is OK as the bushing only serves to support the input shaft and can turn with it.
Now the question ...WHAT HAPPENED? and how to prevent? I was very careful in even tightening the plate...so I'm scratching my head on this one!! Thanks, in advance!

AH
ah harad

For those just tuning in...car is '75 1500. Thanks!

AH
ah harad

God dosnt like you AH, 8 ^ P

Do you have any pics? My guess its got to be a manufacture defect, esp. something this new. Ive never heard of this happening ...Ive heard of springs falling out from being so badly worn, but thats not the case here

the part that scares me is the pilot bushing is worn to the place of being able to move it around inside the flywheel, on the surface that dosent sound to bad but ya think about it for a while...and well, not good if you think it wasnt designed to do that

seriously I think we need some pics

If you want, we got lots of rain here ... come take as much as you want, its free for the taking.

Prop
Prop

Prop,

I think He likes me...just likes to goof with me at times:)

I'll take some pics...good idea. As to the pilot, it did that when it was installed two years ago. I also remember the original bushing behaving like that, and it lasted 30+ years, still...Think I'll replace it anyway, once I get the thing out! I hope it's a defect only, not sure of whether it was B&B or QH kit.

AH
ah harad

Pictures attached. All opinions are welcome..winner gets famous Philly Pretzels! Thanks!

AH


ah harad

This is the disc..pressure plate side showing the damage done by the pressure plate. Never saw this before either..hoping someone out there knows. Thanks!

AH


ah harad

There is another snap ring, just like the one you can see, but on the other side of the diaphragm spring. I can't see the ends of the visible ring, so they must be toward the camera, which means the ends of the other one should be visible at the top of the pic, since they are 180 out. The ends have 90 deg bends and locate in the holes in the spring. Whatever, it's broke, and would probably rate as a defective part. Don't think it's anything you did or can prevent.

I will note that sometimes people wash pressure plates and/or release bearings and remove all the lubrication that is supposed to be at the various pivot points = sure death. Or Phoo Ben Wump left the grease out.

The pilot bush is not an issue, as long as it's not sloppy loose.

Send mustard with them pretzels!

FRM
FR Millmore

FRM,

Thanks for the detail.I couldn't find the other spring...must be tucked inside. No matter though, this wouldn't be the first poor part I got from old supplier (haven't had much luck with Vicky Brit during the past 35 years...very "hit or miss", but that's just my experience). Heading down to BRG in Delaware for new parts, Hopefully, this will do it for a buncha years. I guess there's a first time for everything! Funny how there doesn't seem to be a torque spec for the Allen screws holding the works to the flywheel...always just tightened evenly...worked in the past. My OCD would rather have a definite number...oh well:)

THANKS AGAIN TO ALL WHO HELPED!
Prop..nice of you to offer free rain, but we're soaked through here as well.

FRM, please e mail address and I'll send out some of Philly's Finest (but you'll have to supply your own mustard...gets messy in the mail). I always keep my word.

AH
ah harad

<< Funny how there doesn't seem to be a torque spec for the Allen screws holding the works to the flywheel. >>

"Clutch attachment to flywheel: 22 ft-lbs", per The Complete official MG midget 1500 1975-1979

New Allan screws are nice too as the old ones always seem to strip a bit when taking them out, probably alters the torque setting going back in...

R
Richard 1600 5 speed

AH -
The other spring is those pieces that fell out, after a certain amount of gnawing, which is what made the noise! And the marks on the other bits.
VB is not a place I buy anything, except under extreme duress, but this one is beyond them I think. Has to be at MFR level - and/or it's a pirate part!
Second the new Allen screws; make it good quality ones. I have probably cut as many of these out as I've unscrewed. One install remove cycle and the next time they don't come out. I think the factory wrenches were set at 22 ton-feets.

FRM
FR Millmore

22ft-lbs and new 6 new Allen screws...got it gents. Actually mine had 5 Allen screws and one cap screw from the factory??? Guess they ran out:) Thanks!

AH
ah harad

Hi, AH. My diagnosis of your fault from your original description of the 'grinding noise' and your findings having dismantled the clutch is the reason that I'm not a betting man! I would have lost my shirt on that one.

I concur with the consenus of opinion - faulty manufacture (or metal fatigue) of the clutch cover from new.

Probably best to return to supplier and/or replace with new.

Sorry that's not very helpful advice but that's all I can think of at the moment.



Andy Hock

Hello all,

Well I finally got the definitive answer. I showed the
parts to my recent supplier who does this work every day. The broken parts came not from the pressure plate, but from the clutch disk itself! He showed me where it broke and, judging by the poor build quality of this no-name disc, he believes it was a mfr defect and just broke apart. He couldn't identify the brand, but the difference between it and a good quality B&B disc was obvious. The pressure plate is a good B&B one and is like new. Apparently, former supplier (VB) mixed brands in the kit ( an absolute no-no) , and stupid me didn't notice. You certainly get what you pay for. A new B&B disc to match the plate and release bearing was all I needed. Clutch is installed, and waiting for time to put it all together. Stay tuned.

AH
ah harad

Well,
New B&B clutch and bearing installed and car us back in one piece. Quiet and smooth for several miles.
This morning, when pulling put out of garage.
I get a vibration and low pitch noise when clutch pedal
is about half way down. Ok fully or a little depressed. Clutch takeup is nice and smooth, no judder, etc. Goes into first every time. Happens about half the time. Does not go up in
pitch with revs, Also notice revs drop about 100 rpm when clutch pedal down...may have always been that way... Never noticed.
NO WAY i'm pulling this out again . Just want to know what's happening. Willing to live with it cause it works fine. Thanks, in advance!

AL
ah harad

Al-
Did you check the crankshaft end float?
Those thrust washers may have suffered even more with the disintegrating clutch thing.

FRM
FR Millmore

FRM,

Yes I did, thanks. All seems well in that area. Issue is NOT consistent, comes and goes. With engine off, punping clutch produces smooth operation for maybe 5 out of 8 tries, the last couple result in "crunching" sound and jerky pedal return...then it's fine.

Also, when shifting at low rpm (2500-2800 or so), I get the quietest response. Higher revs will give me the "condition" more often. Either way, there is no slip, no judder, consistent normal take-up of the clutch.

In other words, depressing the pedal gives me a sequence as such: quiet---"cruching/vibration"(for maybe a 1/4 inch or so of travel in the middle)--quiet operation by the time the pedal hits the floor. Revving the engine with the pedal fully depressed results in normal, quiet, vibration free operation.

Again, I'm tempted to leave it alone...will probably go another 100k (wishful thinking), but I'd really like to avoid another "oops". Thanks!

Al
ah harad

another hail mary to the end zone...was the rear engine plate crack free, I know those things like to crack at the oil filter housing and go straight across to the crankshaft hole
Prop

Okay ...scratch that...sorry, I forgot you have a 1500 and not a 1275

Prop

agian...the oil pump cover,,,sorry not the oil filter housing
Prop

Thanks gents,

I'm not aware of any cracks anywhere. Engine has about 6300 miles on it before all this stuff happened. What puzzles me is the following:
1. clutch worked perfectly for awhile...still does but with this noise.
2. problem occurs more often than not, bit I do get some sequences where everything is just fine.

Sooo... What the #*## can break "sometimes" ???

PS Thanks for hanging in there with me on this!

AL
ah harad

Al-
Are you sure the hydraulics are correct? It is not good practice to pump up the clutch other than to bleed, since this can result in over travel of the pressure plate diaphragm, which will kill it. Not usually a problem unless the slave is not returning as quickly as the master cyl. Over travel could conceivably be what killed the last clutch.

FRM
FR Millmore

FRM,

interesting point. My issue with pumping the pedal came accidentally. I pushed it in to park in gear w/ handbrake(old habit), and it felt "funny" coming back. I pumped it slowly to see if I could hear anything odd. This wasn't the rapid pumping one would do I an emergency (sudden pressure loss). Sorry if i gave wrong impression. Hydraulics seem fine. Master and slave are recent and no air in system as far as I can see.
Anyhow, you got me thinking along those lines, so I took car for short ride. Now what happens us that it's either completely quiet , or it's noisy from about 1/2" from the floor to the rest of the way down. Very unsettling. Oddly, It seems to work better as things warm up. Since this new disc takes up higher than the old one, I'm wondering if I should block the pedal from that last 1/2" or so. I tried it on a TEMP basis with a thin piece of wood on the floor and got smooth shifts. Seems kinda screwy though... There is only one size pushrod on a1500, so the pressure plate can only move so far??? I'm just plain stumped.. and getting very frustrated with what is otherwise a great running car!

AL
ah harad

Al-
Travel is determined by the ratio of the cylinder sizes, assuming no air. Pushrod length has nothing to do with it, so long as the slave cylinder is not running into stops at either end. Only other place for hangup is the release arm and the sleeve the bearing is on, and the pedal shaft.
Is this noise rotational or solely to do with the pedal movement?

FRM
FR Millmore

FRM,
it's solely rotational and coming from the bell housing, still comes and goes. The best way to describe the sound and feel would be that it's from an uneven spinning surface, that is, a very fast " badabadabada" feel as opposed to just a smooth vibration. And the thing is, for about the first 175 miles, it was perfect! next day, the crap started. If new disc is now damaged, why then does it work so smoothly? And why doesn't it stay "broken"?
Agian, Thanks so much for your help!

Al
ah harad

A thought - on the 1500 the clutch lever pivot bolt can come loose or even drop out. Surprisingly the clutch will still work as the pressed steel lever arm pivots against the edge of the bell housing. But it makes for an erratic clutch that sometimes seems to work properly, and other times to only partially disengage.

Guy
Guy Weller

How can it be "purely rotational" if this is true: "With engine off, punping clutch produces smooth operation for maybe 5 out of 8 tries, the last couple result in "crunching" sound and jerky pedal return"??

"very fast "badabadabada" feel as opposed to just a smooth vibration." sounds like a bad release bearing OR a cockeyed pressure plate, which could be caused by over travel damaging the diaphragm, maybe the same thing that killed the first one. Despite that bad disc, did your man say anything about the apparently missing second circlip in the old pressure plate?

Guy- Somewhere up there Al said it has a bolt in it, hopefully still there!

I will be out of touch next few days, so you are on your own.

FRM
FR Millmore

FRM,

The broken part shown in my pics actually came from the clutch disk itself, not the pressure plate. That was deemed good as new and re-used. Now I'm wondering if there was some kind of damage to it from the friction disc breakage, and it's not always pushing evenly. I just can't figure anything else out! Yes, I do have a bolt and hyloc nut in the lever...still there...still tight.

Al
ah harad

Sorry Al - I missed the earlier mention of a pivot bolt.
I'll go back to sleep.....
Guy Weller

The burning question that keeps bouncing around my OCD-riddled mind is...why did it work like a charm when first driven (actually first few days...I was so happy), and why does it occasionally work fine now. Wouldn't it make sense that it endfloat excessive or pressure plate off center (used an alignment tool engine mating went pretty well) would go "boink" right away? I've replaced these in the past for friends and they're still happy years later.

ARRRRRGGGGG!

Al
ah harad

Guy,

No worries...I appreciate your input. Just really upset about this issue.

Al
ah harad

Al,
If the fingers of the pressure plate get unevenly bent you do get odd graunching sounds as the clutch is disengaged - particularly at "half pressure" I have had this as a result of overthrow of the clutch - i.e. depressing the clutch pressure plate too far in causes stress on the spring fingers.

I wonder if this is consistent with your experience. - when you first replaced with new parts it drove nicely and was quiet. But after a few days use the noise has re-appeared. Pure conjecture but perhaps this might explain. I forget, does the 1500 has an inspection hole that you can look through with a torch to see if there is any damage to the fingers?

The next question would be what might cause overthrow. Mis-matched parts can, wrong M/c and S/s combination although I think this unlikely on a 1500. Somewhere I recall something about a by-pass hole in the master cylinder wall. Designed to allow fluid to flow back when you release the pedal I understand that these can get blocked or the piston seal can be fitted wrongly and then it works like a valve. Then it doesn't properly release the pressure and successive presses of the clutch pump up the hydraulic pressure.

This is just theorising and I don't want to get you chasing after wild geese but it might be an explanation worth investigating.

Perhaps someone else knows about this possible M/c issue?

Guy
Guy Weller

Guy,

well thought. Thank you!
One of the "tests" when deciding to reuse the pressure plate was checking the fingers. They were straight and level. The other was to examine the release mechanism for any warping or breaks...again Ok. The surfaces of both the pressure plate and flywheel were still polished and free of scores, etc. The m/c and slave were both purchased new from reliable sources a few years ago. Btw this same grouch noise ( a good word) happened when old disc part broke off. I also got terrible car shaking judder. A piece of it lodged behind the pressure plate surface and wouldn't allow it to move...pedal would not depress. Even with all this, the pressure plate looked and measured fine, and clutch is very smooth. There is no inspection hole to check. I'm wondering if my guy did me any favors by advising reuse, even with only 6000 miles on it. I just don't want to spend more time on removal and money on parts if it won't solve the problem.
This the third clutch car has had. First came at 85,000 when I renewed the rear seal as it was already out. Second one was at 130k when it was time for a rebuild. Thought it would be a good Idea (hah!) That's the one that went bad. Now, 6400 miles later , I'm in this situation. Drove it into work today, because other than this, it runs great! My head hurts!

AL
ah harad

Hello all,

Just go off the phone with ClutchMart in California. They specialize in that area and work on some pretty interesting hardware. They are well user reviewed. The manager (Frank) actually has family In New Jersey (go figure), and, after comparing the weather there and here (boy am I jealous), he was interested in hearing my tale of woe. Not only did he listen, but he asked some very pertinent questions about what was happening.

He also agreed that the original disc failure was due to a defect.

He also said that it appears that there may still be a small fragment lodged in the release mechanism which is causing the mid-pedal noise. It probably got jarred loose temporarily during removal and installation...which is why it was quiet at first. He imitated the noise and the symptoms exactly. His advice: the pressure plate is doing it's job properly and there is no risk of damage to the clutch disc. As long as it takes up in a good spot and is smooth in pickup, and quiet as normal when engaged (pedal up)there is no reason to go through the hassle of changing it. It will eventually free itself, and through centrifugal force make it's way to the bottom of the bell housing and stay there.

In other words: drive and enjoy...that's what I'm gonna do!

Wishing everyone a joyous Thanksgiving, and if you don't celebrate where you live...just be joyous!

Al
ah harad

This thread was discussed between 15/11/2009 and 24/11/2009

MG Midget and Sprite Technical index

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