Super Seven S2 Clutch Issues

[SENC]

From memory, the radiator needs to come out.  The engine will just barely clear the crossbar behind it (cut and slit a piece of hose to cover and protect it and electrical wires running along it).  I don't remember if the others are necessary or if they were just as easy to remove first.

[SENC]

On 6/14/2024 at 9:07 PM, TEM said:

Sounds good. I'll be waiting for your reply with interest.

 

 

Studs and AN jet nuts made the job a good deal easier.  The only tough ones were the outer ones between the intake manifolds and the outer exhaust manifolds - can't get a socket in there.  I ground the lobes off an extra 3/8" wrench and that worked perfectly - though those locations are the easiest for the allen key to reach so the ideal solution might be to retain those bolts and just use studs/nuts elsewhere.

 

 

Got the carbs reinstalled today - hopefully will get it running later in the week to check for leaks. 

[SENC]

Came across this thread while searching for something on lotuselan.net.

 

https://lotuselan.net/forums/viewtopic.php?f=37&t=51905

[TEM]

I have the engine out and engine/trans separated.  There were no loose clips or obvious breakages.  There are some metal shavings at the bottom of the bell housing that appear to be coming from the starter motor gear teeth.  Let me know if you see anything out of sorts.  I will pull the clutch plate out next.

Is this the correct pressure plate?

 

[TEM]

With pressure plate removed:

- No blueing of the flywheel or pressure plate

-  Clutch disc was stuck to the pressure plate

- Disc appears in good condition

- Pressure plate fingers are all intact and work properly.

 

[MV8]

Assuming that is the right spacing release bearing, you could just put it back together if the clutch facings are not oily if you want. No grooves to check clutch wear against but it looks to be new. Apparently the preloaded test (pushrod adjusted too long) did not cause the clutch to unload/slip. That looks to be a correct, original type PP. The springs in the clutch hub should be tight/not rattle. Installed, each of the borg and beck PP levers should be the same height from the clutch hub. It also looks like the ring gear is very worn and may be flippable on the flywheel. Borg and beck PP is thicker than a modern diaphragm PP that is lower pedal effort for the same holding power.

I expect driving in 3rd, pressing the clutch pedal, then flooring the throttle would release a disc stuck to a flywheel. It sounds like everything has been working as it should.  

[SENC]

Looks identical to the one I pulled out of mine.  And same release bearing type as well.

 

I can't see the ring gear clearly enough to tell whether there is any wear or damage.

 

Have you opened the gearbox to see how it looks?

[TEM]

OK, I have a theory.  Let me know if it's totally crazy.

 

Condition: The flywheel and flywheel side of clutch disc are smooth and dry.  But the The pressure plate and pressure plate side of the clutch disc are sticky.  I was able to drive the car so the disc and pressure plate are not stuck together all the time.  But when I removed the pressure plate the disc was stuck to the pressure plate such that I had to knock the disc loose with a screwdriver handle.

 

Theory:  When squashed between the pressure plate and flywheel the disc sticks to the pressure plate.  Sticks but not stuck such that playing with the clutch pedal can unstick the two and shifting is as normal.  Perhaps adding heat to the two surfaces makes the sticky stuff more sticky so when the system warms up (driving) and clutch pedal is pressed, the disc sticks to the pressure plate enough to keep the transmission spinning making shifting difficult.  When I could not get into gear I could play with the clutch pedal e.g. slip the clutch to unstick it then a gear change was possible.

 

I may be able to clean up the surfaces and it should work fine.  But I don't want to take the engine out again next weekend if this isn't the solution or if some of the parts are not correct.

[TEM]

Ring gear and starter gear both look very worn.

 

I assume the ring gear is pressed on.  I don't have a fixture big enough to press that off and back on.  I may have another starter or just replace it with a reduction gear starter.

 

I have not opened the gear box yet.  I'll open the top cover tomorrow.  I'm not sure what to look for though other than the obvious damage or metal chips.

 

[TEM]

I measured there is 0.2" of clamping force on the clutch disc.  I measured this to be about 165# with my press and bathroom scale.  Which is about right.  The Elan standard clutch has about 210# with about 110HP.

 

The release arm is not quite 1:1.  I measured 0.71" of throw at the release bearing for 0.875" of throw at the slave end.

[SENC]

You cut the ring gear off, but it doesn't look that awful to me.  You can get a new one on by popping the flywheel in the freezer overnight and heating a new ring gear in an oven.  It took me a fair amount of effort with a mallet to get mine in place.  The pinion gearing does look pretty chewed up - you can still find these NOS, just match the number of teeth.  I have a tool to aid in removing the pinion - happy to loan it to you - I'll see if I have any pictures when I was rebuilding mine, might give you an idea of alternate solutions you have on hand.  As long as that starter is off, might as well look in on the brushes to make sure they have life left.  Check before you change starter types - that ring gear looks to want engagement from only one side, and gear reduction starters (I think) engage from the other side.

 

Your theory doesn't sound crazy to me, but I still wonder about something in the gearbox.  I can change gears in mine even without the clutch with a light touch and if I time it right.  If I'm understanding your problem correctly, you can't select a gear at all in certain circumstances - whereas I'd think a stuck plate would result in grinding gears.

 

I'll find pictures of an open gearbox.  One note as you open the top - there are 3 springs under the tailshaft end of the cap (putting pressure down on detent balls that keep the gear lever bars from popping out of gear) - be aware of them so you don't drop them down into the gearbox.

Edited June 27 by SENC

[MV8]

The facings should not be tacky/sticky or oily. I've seen a facing stick due to rust. Materials for facings are similar to brake pads except for strands of copper and other materials to cope with the centrifugal force. I suggest a new clutch with your existing flywheel and PP if the contaminant has been absorbed into the facings.   

The ring gear is installed hot and cools in place for a shrink fit. This can be done with an oxy-acetylene torch and rose bud tip, moving around the ring for even expansion or the method Senc suggested. Consider taking it to an automotive machine shop to have it heated and flipped. They may also lighten the flywheel and balance the flywheel and PP together. In situations where slippage is a concern (such as very high compression engines and gear reduction starters), blind holes are drilled where the ring meets the flywheel and roll pins are pressed in and trimmed flush.

Make the pushrod much shorter (slave piston still bottomed in the bore and fork within the limits of the bell fork window), then recheck the throw at the release bearing with a stroke of the pedal to see if you get more travel.

You could also install everything but the transmission to test. The flywheel may have a minimum thickness specification embossed in the front side. They make crank shims for that or you could fit a spacer to the release bearing to position the fork to have a better ratio through the range of motion.  

[SENC]

A few pictures from my project...

 

My ring gear, notched after cutting it for removal. 

 

 

It doesn't look all that different from yours until you look at the areas of most wear.  If you have portions that are this worn, you might go ahead and change it out.

 

Picture of an open gearbox.  Blue circles the location of the springs and detent balls.  Red arrows to the baulk rings.  Green arrows to the gear selectors.

 

The brass baulk rings ride on a tapered cone and have internal ridges that wear.

 

You obviously can't see those ridges without pulling everything apart, but manually shifting the gear levers you can observe them and how they move - if they but up right next to the gears with little/no gap, they are very well worn.  Also look at the teeth of both the baulk rings and gears for signs of damage/gear crashing. Here is a closeup of 2 sets put of the gb during my rebuild.

 

Also try to look down at the gear selector forks to see if you can identify excessive wear.  I don't have a side view of a fork showing high wear, but here is a picture of the areas you're looking to observe.

 

[SENC]

Found an image of selector wear on lotuselan.net.

 

[jbcollier]

Ring gear looks fine, almost new. The teeth are cut like that to assist with engagement.  The starter pinion looks well worn, not unusual though.

 

I just knock ring gears off.  Heat the new one to a dull red and it will drop on — not that you need one though!

[jbcollier]

Define “sticky”?

 

Rusty, corroded and catching/dragging?

 

Gooey, slimy, or tacky?

[TEM]

SENC: I have another starter with a good pinion I'll drop in.  I had already pulled the starter and inspected and cleaned the brushes.

 

Good catch on the reduction gear starters.  I'll confirm before I buy if I go that route.

 

With my gear selection issue I never tried to jam the shifter into gear causing grinding.  I'm sure that if I tried I would get an earful of grinding.  I stopped pushing when I felt more resistance than normal but, your point is well taken and I will look for wear tomorrow.

 

I am familiar with the three springs in the transmission cover.  I dropped two of them into the transmission on my other car.  Not fun getting them back out.  I just wish they had made the passages longer on the transmission side so the springs could be placed there rather than in the cover.  I'm sure it will be a lot easier with the transmission on the floor than it was with the trany in the car.

 

Thanks for the picture, very helpful.  I'll send back picture of what I find.

 

MV8: I have a lot of experience with clutches rusting to the flywheel and/or PP and the various methods of popping them loose.  But this is a first time I have seen this kind of stickiness.  It's not oily, just sticky.  I'll try to clean it but agree the best solution is to change the clutch disc.  I'll have Ken at DB put one in the mail tomorrow.

 

I'm not following your suggestion to shorten the slave pushrod.  The pushrod is set to however long it needs to be to obtain the proper gap between pushrod and release arm.  I'm already getting good slave stroke.  Based on what I'm seeing with this PP, you shouldn't need any more than 0.25" of slave stroke to fully disengage the clutch.  My stroke is already in the area of 0.8-0.9".

[TEM]

Hmm, sticky? 

Not rusty

Not corroded

Not gooey

Not Slimy

Not oily

Yes, slightly tacky.  Doesn't come off on a rag when dabbing.  They don't feel smooth when you run your fingers across the surfaces like the flywheel side surfaces do. Kind of like the adhesive left behind when trying to pull off a price tag but not that tacky.  If I just put the disc back on the PP and give it a little pressure, they don't stick together.  But if I add more clamping force for a couple of minutes, they stick together.  I'll hit the surfaces with brake cleaner tomorrow to see if that resolves it.

[MV8]

8 hours ago, TEM said:

MV8: I have a lot of experience with clutches rusting to the flywheel and/or PP and the various methods of popping them loose.  But this is a first time I have seen this kind of stickiness.  It's not oily, just sticky.  I'll try to clean it but agree the best solution is to change the clutch disc.  I'll have Ken at DB put one in the mail tomorrow.

 

I'm not following your suggestion to shorten the slave pushrod.  The pushrod is set to however long it needs to be to obtain the proper gap between pushrod and release arm.  I'm already getting good slave stroke.  Based on what I'm seeing with this PP, you shouldn't need any more than 0.25" of slave stroke to fully disengage the clutch.  My stroke is already in the area of 0.8-0.9".

It was a suggestion for a check if you were still concerned about the linkage. A bit more than 0.25" at the slave is needed but it sounds like you have plenty. .040" disc air gap x 6:1 (typical borg&beck) plus the release bearing to PP clearance that must be taken up x the effective fork ratio of 0.81:1. I expect the sticky coating was applied by the installer. With Senc's pics I can see the ring gear is not reversable and the starter design selected must be compatible with the ring gears that are available in two different versions.

[TEM]

Thanks for the Borg&Beck ratio, I had not check that yet.

I ordered a new clutch disc and will install along with my good spare starter.