Clutch Noise Root Cause Confirmed

The new owner decided to install a five speed Miata transmission in his car.  This also gave him the chance to address the occasional squeal issue with the clutch.  This squeal had continued over the last several years but at just every once in a while and only when the clutch was partially engaged.

Today we removed the engine and transmission and were able to fully inspect the clutch.  We are now convinced the root cause of the squeal was a mouse nest.  The clutch plate had lots of fuzzy material stuffed into the base of the fingers of the clutch.  Here's a picture:

That brown dusty looking stuff between the fingers is not supposed to be there.  Interestingly, the clutch disc had very little wear on it.  And probably the clutch plate could be cleaned up and reused.  But we are not taking any chances because we don't want to pull this transmission again.  So it's getting a new clutch plate to go with it's Miata clutch disc.

Technology Can Be So Cool

I bought a wifi boroscope camera that connects to my phone with a 1/4 inch lighted camera on the end of six foot long flexible line, only $32!  Seemed like a natural way to inspect inside the bell housing to learn more about our clutch and mouse next issues.

Here's some pictures of the throwout bearing, first are two on the side towards the transmission:

Then here's one of the engine side of the throwout bearing which includes a partial view of the clutch diaphragm:

We don't see any issues with the throwout bearing or clutch from these views.  Looking around further though we did see more evidence of mouse nest residue:

Plus we removed about a partial handful of stuff using our usual method of pulling the rubber boot back and trying to snag stuff with a piece of baling wire.

Bottom line is we still think the clutch is fine and the residue is somehow causing the squealing under particular conditions.  So monthly inspections will be continuing!

Is a Project Ever Completely Done?

We had a couple of smaller items to take care of.  The front brakes were dragging on the passenger side, determined the caliper piston was not retracting completely so installed two new calipers.  Fuse box barely held onto the two fuses, new box was fairly inexpensive so we installed a new one.  Float bowls on carbs were flopping around, removed them and installed new mounting pieces (rubber and special washer) to retain them correctly. 

Then for the third time we pulled that rubber boot back on the clutch fork and removed the following:

The parts in the front appear to be a mouse spine and a head, jaws open.  So we have now removed about four handfuls of mouse carcass and nest.  The clutch still squeals sometimes.  We could pull the engine and replace parts, but another fear is that we do all that work and we don't find the reason for the squeal.  Or we determine the mouse stuff was the cause and we could have just continued our removal process.

We have agreed with the new owner Greg to complete the transaction and transfer ownership.  He will bring the car in about once per month and we'll continue to remove mouse stuff as it shifts around inside the bell housing.  Meantime, either the clutch gets better as the mouse stuff gets removed, or something breaks and then we know exactly what to replace. 

So perhaps the project is done, maybe not, time will tell!

Finally Running Right. You Say A Mouse went Where?

Spent a half day with Clay adjusting timing and carbs.  Got the car running better but it still hesitated at partial throttle.  Greg decided since he intended to convert to Pertronix electronic ignition anyway, let's proceed with this plus a new ignition coil since the root cause seemed to be ignition related.

Parts came in, but now car won't start even before we install the new parts.  Determined no fuel, further discovered the fuel gauge sending unit was installed upside down so even though it said full it was really empty.  Matter of fact, it ran completely out of fuel about one minute after arriving back at the shop.  Hence much confusion - why doesn't it run?  No fuel.  But the gauge says full.  Put gas in tank, fired right up.  Go figure.

Then got new ignition parts installed, finally this car runs awesome!  Hesitation all gone.  Meantime installed new steering rack boot on one side plus door interior pulls.

The one final major concern is the squealing noise from the clutch.  Clutch works fine and most times does not squeal, just squeals occasionally when hot and engaging first gear or reverse.  Put the car on the lift, double checked slave cylinder bolts to make sure they weren't too long (touching clutch diaphragm), decided to pull back rubber boot on throwout bearing lever and - found a mouse nest in the bell housing!  Removed about a handful of fluffy material.  It appears the mice got in there through the opening for the starter motor.  Since removing this much material it appears the squealing is getting less severe.  Still confused over how this material can cause an occasional squeal.  All clutch parts or made of metal and should shred mouse nests and mouse carcasses to powder.  Greg is taking the car home and will just drive it and then in another week or so we'll put the car on the lift, pull the lever boot back, and see if we can get more mouse nest material out. 

Meantime, Saturday 9/22 was the annual British Car Show.  This car was there, here's some pictures from when Ray cleaned up the car the day before:

Good tip, Clay!

My friend Clay suggested that I confirm that the vacuum and mechanical advance functions were working on the distributor.  Turned out to be a good tip.  Here's a section of the vacuum line that had fallen behind the motor and gotten burned up:

It was sealed, so at least it was not a vacuum leak.  But the distributor was definitely not advancing it's timing with vacuum increases!  Guess there's a reason the factory made these lines out of metal.

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I patched it back together and checked it's operation with a vacuum pump and found that it still did not work because the small spring that connects the vacuum diaphragm to the distributor plate inside the distributor was disconnected.  Got that repaired, went out and drove car, and it's much better.  Still want to confirm dwell and timing adjustments and then fine tune the carb settings, but we're getting much closer now.

Check air, then spark, then fuel

Air, spark fuel - that's the sequence that I learned from my MG technical sessions I have attended.  So I started with air - checked all valve clearances (no major problems but had to adjust 6 of the 8 to get consistent 0.015" gap).  Then checked compression - 150, 160, 155, 150 from front to back.  This is excellent.

My dwell meter pooped out on me, so could not really confirm points gap.  And could not then confirm timing.  All indications are spark is OK though, so I violated the tech seminar and went on to fuel.  : )

Pistons move easily, but jet position was way too low on the back carb.  Corrected that, then confirmed the fuel level in the jets is about right for both carbs, ie float levels set right.  Front carb did seem kind of dry, but it's float was set for deeper fuel level than rear.  I ran car in garage, idles fine and revs up fine, saw good atomized fuel flow into throat of carb when revving engine.  But took it out and it still bogs down and hesitates under load.  Decided to take up my friend Clay's offer to bring car to him and connect it to his diagnostic equipment,made appointment for a week away unfortunately due to our schedules.

Had a little more time to I tackled the logo on the trunk lid.  There are 15 little holes that need to be in the trunk to install the four pieces of the logo.  These were all filled in with body filler, so they were completely invisible on the outside.   But you could see them from the back side.  So with some trepidation I drilled out all 15 holes very carefully.  I also bought some plastic screw anchors which do a decent job of retaining the pieces in place, should be using a speed clip.  Here's a sample of the plastic piece:

Here's the backside after installation:

Those little pieces worked pretty well.  Here's now the pretty side:

Those white stripes are the lights of my garage.  Turned out real well!

Top Installed, First Car Wash

Decided a really hot day like today would be a good time to install the top, it seemed like it would be a tight fit and it was.  But I got it on, and will leave it one for a while to let it stretch into the position for this car.  This was a very good used top we bought earlier.

Then I decided I couldn't stand the myriad greasy fingerprints on the car, so I washed it off.  Had to clean a little white stuff off the top too, not sure what it was.  Turned out real good, I think:

Now I need to get this thing to run right......