Blown Clutch Pressure Plate? Advise needed

[R'elise Me]

Problem: Can't get into ANY gear while depressing clutch (clutch does not release).

Background:
1. Was driving car on a HOT day (100F), lots of turns and shifting - having a real good time, not being 'abusive' or overreving the car. Engine temp was 210F.

2. Go for 3-2 downshift - no luck, try again, got it. A few turns later, no shifts possible up or down. Clutchlessly upshift to 4th at 30mph and hobble to a safe stopping place. Try to restart car while in gear and clutch depressed - car lurtches - prognosis of the century: clutch not releasing.

3. Let car cool down for an hour thinking fluid is boiling (OEM - 6000 mi). No changes. Checked clutch slave visually (lots of fun on hot pavement) - no problems, clutch actuation clearly operable thus ruling out air in the slave, loose slave, bad linkage (at least outside the bell housing).

4. Figured I'd have to hobble back home w/o a clutch, but miraculously the problem resolved itself and I was able to use the clutch (no grinds at all). Note, I was driving gently. Next day - no problems.

5. NO unusual noises, brake fluid reservoir level was unchanged,

6. One person I spoke with about this suggested blown pressure plate mechanicals. He said he experienced similar symptoms, lotus replaced the tranny, experienced the same problem again afterwhich the pressure plate was found to be faulty.


Anyone have an idea of what's wrong here and weather this is a warranty issue? I figure I'd get some advise before I take the car in just in case I get neg feedback from Lotus USA.

Thanks

[mikelr]

I just did a clutch job on a new S where the clutch lining came free from the plate on the pressure plate side. Symptoms where similar to yours, where as the clutch pedal felt fine but was not able to select gears. Clutch material was jambed up into the edges of the pressure plate draging on the clutch disk when the pedal was depressed. With the input shaft spinning no gears could be selected.
Is you clutch slipping now that you can select gears again? You may have suffered the same failure.
LCU did not want to cover the clutch which had only 1500 miles.

[mlk_f1]

Glen, good to hear you made it back !! Her eis what I was talking about. There were a number of ppl with this failure. The strap on the your Pressure plate might be broken.

http://www.elisetalk.com/forums/show...19&postcount=3

http://www.elisetalk.com/forums/show...pressure+plate

[Donelise]

Originally Posted by mlk_f1

Glen, good to hear you made it back !! Her eis what I was talking about. There were a number of ppl with this failure. The strap on the your Pressure plate might be broken.

http://www.elisetalk.com/forums/show...19&postcount=3

http://www.elisetalk.com/forums/show...pressure+plate

Bump..... presure plate strap or disk failure, sometimes one of the three small
v-springs fail without notice and the trans starts crunching-grinding on second gear down shifts, Your issue is more advanced at this point
Cheers, Don.

[mlk_f1]

Hi Don,
My second gear downshifts will grind at high revs everytime. But I think it is the 2nd gear synchro. No grinding occurs when I do double clutch and rev match downshifts. BTW this is my second tranny already. The dealer did not catch the source of the problem before replacing the tranny. After about 2k miles with teh new tranny, the problem came back. Guess what, the culprit was a sticking crossgate cable. The orginal cable's heat shield was way too low. The heat from the exhuast manifold busted the cables rubber housing causing it to go bad. I'm sure Lotus already caught this on the later cars. I have a June 05 built car btw. Because the replacement crossgate cable have the heat shield at the location where my original one melted. And I also see the newer cars have the revised cable too.

[MikeW]

Originally Posted by mikelr

I just did a clutch job on a new S where the clutch lining came free from the plate on the pressure plate side. Symptoms where similar to yours, where as the clutch pedal felt fine but was not able to select gears. Clutch material was jambed up into the edges of the pressure plate draging on the clutch disk when the pedal was depressed. With the input shaft spinning no gears could be selected.
Is you clutch slipping now that you can select gears again? You may have suffered the same failure.
LCU did not want to cover the clutch which had only 1500 miles.

Pretty much the same as my disc. They won't handle high rpms when disengaged and spinning free without bursting. The material on a full face lining needs to be bonded to a backing plate. Just having molded linings riveted to a flexy marcel spring (the flat thin area that's under the lining) doesn't cut it. The lining doesn't flex well and cracks where the rivets attach it. And regrettably the disc on mine wasn't warranteed. My mileage was about the same. Wear item. I say the part wasn't designed sufficiently for its intended application.

[R'elise Me]

Thanks everyone for the generous feedback. I'll post results following teardown.

[R'elise Me]

Verdict per Alan at Beverly Hills Lotus - broken strap spring on the pressure plate. Lotus was very cool about it - replaced pressure plate, disc and to bearing on warranty. Manley gets the grand prize for correct prognosis - shotgun with me at the next track day (I'm definitely getting the better end of this deal!).

Interesting tidbit - my flywheel and disc were almost as new contrary to my expectation. This basically says the disc is not slipping with the stock clutch and that rev matching is serving me well.

So why is the stock pressure plate such a POS? Because it basically warps when overrevved causing all hell (and hardware) to break loose. Doesn't help if your not disengaging the clutch on a spinout (I always do, but I never thought about how hard that can be going from fast forward to backwards with the tranny engaged.) I always thought of 'both feet in' as just a means of controling the spin path, but there's more to it I see now.

Great service at BHL - those guys are real old school - just the way I like it. They really racked their brains over this one and exhausted every possibility 1st before tearing her down.

[codymac]

Strap spring? You mean torque strap?

Nothing is warping. The straps break because they're weak on the OEM unit (or some production run of the OEM unit or something along these lines) and due to the way they function. In an upshift, the load on the torque straps is an extension load - in a mismatched downshift, for example, the load is a compression load. This compression can cause some deformation of the strap which can eventually lead to a failure.

Unfortunately, the torque straps are turning out to be a weak link in the OEM clutch - at least in out application.

Hopefully the Lotus Sport (AP?) part is stronger.

As a side note, you should consider a lightweight flywheel while the car is apart. If you were paying someone else to do it, book time on a flywheel/clutch would be pretty obscene.

[MattG]

Originally Posted by codymac

In an upshift, the load on the torque straps is an extension load - in a mismatched downshift, for example, the load is a compression load. This compression can cause some deformation of the strap which can eventually lead to a failure.

Unfortunately, the torque straps are turning out to be a weak link in the OEM clutch - at least in out application.

By 'mismatched downshift', are you referring to the rpm mismatch? Would blipping the throttle (not double clutching) on downshifts reduce the compression load?

[codymac]

Originally Posted by MattG

By 'mismatched downshift', are you referring to the rpm mismatch? Would blipping the throttle (not double clutching) on downshifts reduce the compression load?

Precisely. If the revs are not matched on downshifts or the clutch is used to slow the vehicle, the straps can be loaded "incorrectly."

[®ob]

Can the dealer order the motorsport clutch?
I'd like to know your impressions of that clutch.

[darkSol]

Same issue happened to me last Friday. I was able to plunk her into 4th, get on the highway, avoid all lights/straight stops, do only rolling rights and get her home. All my newfound power must have been too much for her.

It's either the lining or one of the clutch disc springs has popped out.

Getting a new ACT XTSS clutch / Fidanze flywheel installed next week. I think I'll flatbed it over there just to be safe.

[MikeW]

I think it would be worthwhile getting some detailed pics of the Motorsports clutch. AP makes it supposedly (maybe they just rebox it?). I ate a stock disc and considered the Motorsports one but no one had ever seen one. By the way, the stock disc belongs in your father's Oldsmobile, they can't handle the rpms and burst. Someone posted a pi of the Lotus Sport Elise clutch, supposedly Lotuses minor upgrade. It had the exact same disc (Aisin) that bow up. Don't understand the upgrade. Where's the beef?

As far as torque straps (aka drive straps), many clutch manufacturers actually stack several together before riveting to the cover and pressure ring. That increases the capacity over a single strap. I think you can go overboard on this however.

I have to say that I'm not happy with Lotus allowing the the Celica crate engine clutch to be installed in our cars. Too many failures for a light car with no great power.

[codymac]

Originally Posted by MikeW

I think it would be worthwhile getting some detailed pics of the Motorsports clutch. AP makes it supposedly (maybe they just rebox it?).

I'd love to see some good photos of it as well.

[mikelr]

Originally Posted by codymac

Hopefully the Lotus Sport (AP?) part is stronger.

The "Lotus Sport" clutch is a TRD/Exede piece.

[codymac]

Originally Posted by mikelr

The "Lotus Sport" clutch is a TRD/Exede piece.

Exedy? Thanks!


How does it look compared to the stock unit (I'd guess also an Exedy/Daikin?).

[MikeW]

I think the Motorsport clutch is AP. I would not be surprised to find it's a relabeled Exedy.

The clutch in the Sport Elise is not. The car was advertised as having an upgraded clutch. Somone posted a picture and it had the same disc that I have out of my stock clutch.

[mikelr]

I installed a "Motorsport" clutch in an S to replace the one pictured above, it was straight from Lotus and was marked with TRD and Exedy on the disk and pressure plate. They looked the same as the factory pieces but the clutch pedal had a more pronouced "over center" feel with the new clutch.

[R'elise Me]

Here are photo of the stock disc and pressure plate that came out of my car. Note the top spring on the pressure plate is toast. The disc looks like new. The bellhousing shows small nicks from the spring rattling around in there. Sorry, I don't have a photo of the new Motorsport clutch pieces I installed, but I'll inquire about their mfr.

See next post for photos