Lotus Elan

Over Rev

PostPost by: miked » Sun Aug 12, 2012 9:29 am

I had an incident were the throttle return spring migrated across and caught on the side of the rear carb bracket. I have Weber 151's with that small bracket cast in the body. It was cut off but part of the stub remained. When in third under acceleration I decided to give the car more fuel (was at Lemans on the parade laps). Usually I am very light with the right foot. Unknown to me the above occurred so as I backed off the throttle and put the clutch in, to change gear, I heard the motor rev and Tacho whiz round. I think the action shocked the sticking bit loose as I went straight for the keys and turned the engine off. I am no fast draw gun slinger in getting to the keys, that quick, so feel sure if it had stayed stuck the motor would have been damaged. I coasted and wondering had I done any damaged. Needed to get off the circuit so decided to try the engine and it started without a problem, engaged gear and carried on. Upon slowing down and coming off the track (and a further 500 miles later) the only thing that has changed is an annoying metallic click when pulling off.

I have been around everything I can think off.
Engine and gearbox mounts. Touching exhaust etc.

It sounds like it is coming from the clutch bell housing area. I have checked the prop? shaft joints (new anyway). Has new TTR sliding spline drive shafts and just redone the diff hangers.

Ross, if you?re reading this, the diff hangers cured the light passenger side rear clicking when in right hand bends at low speed.

Any way, I fitted a new boot on the clutch arm as I thought that was rattling, also heat wrapped the exhaust "Y" piece and changed the clutch slave cylinder rubbers as the boot on that had hardened and come off. I even thought that had caused the slave adjuster rod to rattle.

Yesterday I removed the chassis cross brace as the roll bar drop links touch it. Noise still there!

When pulling off after you have taken up drive there is a click from the bell housing. Not like an engine mount as you are doing it but after. Sometime in second it happens. I got my son to drive it and he agrees and says he can feel the click come through the clutch pedal.

So, I think I did not get away with it! Anybody have any thoughts (Rohan). What could break up in the clutch? I am limited here, no experience of this. Could the spring petals on the pressure plate be breaking up? I am thinking I need to haul the motor out to find out and get a new pressure plate etc. Could I have sheared a fylwheel bolt?

My gut feeling is that inadvertently breaking load with the clutch has shocked something.

PS. Weber 151 casting filed off in France and an Electrical connector put on the waste part of the return spring. Can not go anywere now. Yes, I am going to get a rev limiter for this and the project car. Scary thought of the possible damage to the beloved twin cam. I note that the Accuspark guys have a new product soft limiter adjsutable 2 ? 12K RPM unit for ?29.00 on the eBay web site.

Advice Welcome.


Mike :D :?
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PostPost by: ardee_selby » Sun Aug 12, 2012 10:41 am

Hello Mike,

I guess you have Steve G's account in mind...? :(

elan-f15/catastrophe-elan-ownership-day-one-t20039.html

I would have thought that in order for one flywheel bolt to shear...the others would have to follow suit...and it wouldn't be a click but a thud...plus you have done 500 miles since the incident without anything else untoward...correct?

Wondering about what lives in the bellhousing to check out...that might fail and be felt through the pedal...

Bits that live in the bellhousing.jpg and


Can anything be sensed through the pedal when operating the clutch, engine running or not?

I'm wondering if the release bearing is now shot and/or is, perhaps, jamming on the nose piece, since Steve G also reported this:

elan-f14/what-this-under-clutch-release-bearing-carrier-t24111.html

Good luck with what you find. But doesn't seem (to me) to be too disastrous given the 500 miles travelled since. Might be prudent, however, to replace the bolts whilst you're about it.

Cheers - Richard
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PostPost by: gjz30075 » Sun Aug 12, 2012 11:26 am

miked wrote: I got my son to drive it and he agrees and says he can feel the click come through the clutch pedal.

Mike :D :?


Ardee, son says 'yes'.

Mike, I think I'd pull the clutch arm boot again and with your son working the clutch, you peer inside to see if anything is askew. He might be able to tell when exactly where in the travel he feels the click. Might have to run the engine for complete diags.

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PostPost by: ardee_selby » Sun Aug 12, 2012 11:40 am

gjz30075 wrote: Ardee, son says 'yes' Greg Z


Yes, read that. Was asking if anything could be felt (or sensed?) in the clutch actuation when stationary (engine running or not) or only when taking up the drive...

Cheers - Richard
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PostPost by: miked » Sun Aug 12, 2012 12:12 pm

Thanks guys I will investigate further and go back thorough those other posts. I did look in the clutch arm hole and could see the 3 clips in place. I must admit that I did not have anybody work the clutch though so will get her up up off the floor and try that. Thrust bearing is quiet with the clutch pushed in. I fitted a new one less than 1200 miles ago (means nothing). I agree that the miles since seem to prove it to not be too critical. But it was not there before!

Re: Fly wheel bolt. My brother found one broke on his Porsche flywheel recently when he parted it for some work. I was just thinking that if one was carrying slightly more load than another, it may have gone? I agree, it would be odd with torqued down bolts sharing the loading.

Nothing odd felt through clutch when stationary. We have even tried driving against the handbrake while watching and feeling the engine flex on the mounts. Won't click unless you start moving and get on the move. I guess he means that while he is still covering the clutch when you move off and are getting ready to go to second gear.

NB. Have noticed that reverse seems to be less slick to get as if not clearing, so prhaps the thrust is on its way. Son also reckons getting into first is not as clean. He had not driven it for a while.

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PostPost by: ardee_selby » Sun Aug 12, 2012 12:48 pm

miked wrote: Re: Fly wheel bolt. My brother found one broke on his Porsche flywheel recently when he parted it for some work. I was just thinking that if one was carrying slightly more load than another, it may have gone? I agree, it would be odd with torqued down bolts sharing the loading Mike


Porsche Schmorsche! :twisted: :wink:

Steve G was good enough to share his experience with his failed flywheel bolts & broken carrier/retainer...his pics are still available for reference here:

https://plus.google.com/photos/11580992 ... 4033066193

Cheers - Richard
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PostPost by: richardcox_lotus » Sun Aug 12, 2012 3:36 pm

A couple of things you might want to try (if not already), given that you have run the car against the handbrake.

1) Push the car whilst out of gear
2) Push the car whilst in gear (e.g 4th) with engine off

If the "Click" is present in scenarios 1) then check the other parts of the drive components, before assuming its something in the bellhousing.

I agree that chasing noises can be maddening & its sometimes very difficult to ascertain exactly where its coming from. Also paranoia usually reigns supreme with me !

A colleague at work had his engine replaced in his Citroen DS3 5 months from new after a flywheel bolt failed - but the noise was VERY loud - worse than a blown exhaust.

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PostPost by: miked » Mon Aug 13, 2012 8:53 am

Thanks both Richard's. Never got to it yesterday. Will try the tests and report back. Was helping my friend with his valve shimming and timing. Got in trouble with both wifes for an extended Lotus day. In Lotus land time has no meaning, days can pass in the blink of an eye. :lol:

Re: Porsche. I have no time for them either but my youngest brother loves them.

Mike :D
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PostPost by: mark030358 » Tue Aug 21, 2012 8:25 pm

Hi Mike,
Sorry to hear that, hope all turns out well. I bought an Omex Clubman rev limiter a while ago, push button set up. Still in the box in the garage, guess I should get my finger out and fit it.

cheers

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PostPost by: miked » Wed Aug 22, 2012 8:12 am

Thanks Mark. Yes I would fit it!
Progress update: I tried the rolling of the car in and out of gear and could not make any noises (apart from me groaning). I bit the bullet and the engine is out. At first look nothing glaringly obvious.
Upon closer inspection I see that the gearbox side of the actual clutch plate has some distortion. Part with the sandwich plate holding the springs in place. I meant to take a photo, will do tonight. In the centre there are 4 little (look like) bend over tabs in 4 inserts that appears to lock part of the centre in place. Well these are not centred. Things are migrated over to one side and one tab is bent back on itself. The opposite is nearly out of it slot and the other two are to one side. Also the new thrust bearing that I put in (less than 2k Miles ago) seems very sloppy in it case.
I am not that experienced on clutches but think that due to me unknowingly putting the clutch in under very heavy loading that the clutch plate has took a bit of a kicking. Would I be right in thinking that a clutch is no load breaking device (i.e. backing the revs off etc). I have separated this under heavy loading and wonder does this occur at a slight angle as a pressure plate can?t be guaranteed to lift uniformly. ???? I don?t know. Hence breaking load in one area more that evenly all around and causing stress making this part of the plate to distort.
I will try and grab the clutch plate centre in the lathe tonight and see if I can clock the opposite side just to see if something is running off centre.
The noise I believe I was hearing was the plate perhaps recentre/aligning itself when I started to move off. Hence the damage also to the thrust bearing.
One thing is certain, I won?t be putting the clutch plate back in or the thrust bearing. I am wondering about the pressure plate. I can?t see anything wrong with this whatsoever. What is the collective wisdom? I suppose it may not flex evenly when pushed?
NB I may not have this right but cannot see any other issues under close examination.
Mike
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PostPost by: john.p.clegg » Wed Aug 22, 2012 8:30 am

Spigot bearing in the crankshaft?

John :wink:
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PostPost by: ardee_selby » Wed Aug 22, 2012 8:59 am

john.p.clegg wrote:Spigot bearing in the crankshaft? John :wink:


+1 (and new flywheel bolts as already mentioned)

" NB. Have noticed that reverse seems to be less slick to get as if not clearing, so prhaps the thrust is on its way. Son also reckons getting into first is not as clean. He had not driven it for a while"

When you wrote that it reminded me. Spigot may have been contributing to difficulty selecting gears, but clutch drag is more likely since plate is distorted.

However, a failing spigot bearing on mine caused difficulty getting into 1st & reverse. Then it became impossible...had to get into 1st before starting engine! When I dismantled I found that the bearing had done a runner! :shock:

Cheers - Richard
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PostPost by: Chancer » Wed Aug 22, 2012 9:31 am

Are you sure that you indeed have a spigot bearing in the rear of your crankshaft and not just the plain bore waiting to recieve it?

Sounds to me like your clutch centre plate and first input shaft are able to go eccentric.

A photo of the centre plate would be good as would another try at explaining the following which I cannot understand

Would I be right in thinking that a clutch is no load breaking device (i.e. backing the revs off etc). I have separated this under heavy loading and wonder does this occur at a slight angle as a pressure plate can?t be guaranteed to lift uniformly. ???? I don?t know. Hence breaking load in one area more that evenly all around and causing stress making this part of the plate to distort.
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PostPost by: miked » Wed Aug 22, 2012 9:39 am

Thanks Guys,

Needle type spigot bearing is there and fully intact with cage and needles but I will replace it and the flywheel bolts. I will photo plate tonight, forgot to bring it work with me. Re: load breaking, all I am trying to say is that you would not normal break heavy driven engine load with a clutch. Is it a bit like someone pushing at a closed door with a lot of weight and then someone opens it and they go flying across the room. Release of stored energy!



Mike :)
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PostPost by: ardee_selby » Wed Aug 22, 2012 10:29 am

miked wrote: Release of stored energy! Mike :)


Your KERS wasn't working! :twisted: :wink:

Cheers - Richard
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