Lotus Elan

When to replace a clutch plate

PostPost by: ericbushby » Tue Feb 23, 2021 4:25 pm

Good day gents,
I have searched the forum history and not found the answer.
I have the engine out just now for other work, but I do not know whether to replace the clutch plate as well.
It is in good clean condition. The thickness is 7.5mm with the working surface 1.5mm above the rivets.
It may not have been in very long and may not have had much use. The previous owner did a lot of work on the car but never finished it. I have done about 10,000 miles since I put it on the road in 2011.
So, can anyone tell me the thickness of a new plate or what is a reasonable measurement above the rivets.
I appreciate the thinking where you change it because you are there, but would like to know how much it is worn before I decide that.
Thanks
Eric in Burnley
1967 S3SE DHC
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PostPost by: fattogatto » Tue Feb 23, 2021 5:10 pm

Replace it as a matter of course if you have the lump out and access to the unit. Cost is minor compared to engine removal at a later date.
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PostPost by: 1owner69Elan » Tue Feb 23, 2021 5:47 pm

Consider replacing the pilot(spigot) bushing/bearing as well. At least inspect it carefully. Don’t assume it’s ok.
Avoid an additional engine out situation.
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PostPost by: ericbushby » Tue Feb 23, 2021 6:12 pm

Yes Charlie, I could agree with you, but as this is the first clutch plate I have had in my hand, it could be as good as new for all I know. I am asking, is it worn and how much?

1 owner.
I am replacing the bearing and many other things as well.

This started with a small water leak into the oil, believed to be from the water pump but may have been the head gasket, so this is quite a big job already.
Eric
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PostPost by: 1owner69Elan » Tue Feb 23, 2021 6:48 pm

ericbushby wrote:Good day gents,
I have searched the forum history and not found the answer.
I have the engine out just now for other work, but I do not know whether to replace the clutch plate as well.
It is in good clean condition. The thickness is 7.5mm with the working surface 1.5mm above the rivets.
It may not have been in very long and may not have had much use. The previous owner did a lot of work on the car but never finished it. I have done about 10,000 miles since I put it on the road in 2011.
So, can anyone tell me the thickness of a new plate or what is a reasonable measurement above the rivets.
I appreciate the thinking where you change it because you are there, but would like to know how much it is worn before I decide that.
Thanks
Eric in Burnley
1967 S3SE DHC


Some friction plate measurements that may inform your decision:

Slightly used (~500 miles) friction plate, high torque (170 lb-ft) pressure plate:
Thickness: 8.25 mm
Distance to rivets: 1.6mm

New, for T9 gearbox, standard torque:
Thickness: 7.87mm
To rivets: 1.7mm
(Came with my Voigt's 5 speed conversion, chose not to use this and supplied pressure plate because of lower torque rating.)
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PostPost by: mbell » Tue Feb 23, 2021 7:06 pm

My memory is that I measured mine at ~8mm.I believe that to be very lightly used clutch 5 speed, with very few miles. But unknown for certain.

I think I had a similair thread and to find out the thickness when new and answer came out likely 8-8.5mm.

I reused my clutch as it was known to work, seemed to have little wear and the perceived cost/hassle to get a 5 speed plate in the US didn't seem worth it.

It seems like your clutch plate is quite new and has a lot of life left, but whether you should replace it or not probably come down to a few factors you are best placed to judge:
- How many miles you'll be putting on the car a year
- How likely it is you'll be removing the engine in the next few years
- How much of annoyance it would be to have to change the clutch a little sooner
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: RichardHawkins » Tue Feb 23, 2021 7:42 pm

Eric,

My old clutch plate is 8.6mm thick and 1.7mm to the rivets.

My new clutch plate is10.3mm thick and 1.8mm to the rivets. My new plate will be used with a 5 speed MT75, so the overall thickness may not be relevant.

Hope this helps,

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PostPost by: ericbushby » Tue Feb 23, 2021 7:44 pm

Hi 1owner,
Thankyou, that is what I wanted to know.
I will have to dismiss the high torque clutch figures because there could be other differences in that plate that I am not aware of.
The new standard one from Alan Voigts is good information and exactly what I was asking for. Thanks.
According to that I have only lost 0.2mm per side (8 thou`) in 10,000 miles. On that basis I still have 1.3 mm. to go which is 6 times the wear so far. This puts the life of a clutch plate as at least 70,000 miles.
I have read that the clutch is lightly loaded in an Elan and has a long life.
The plate is clean, dry and un- marked and on that basis I am thinking of putting it back in.
I am interested in comments from anyone else or better still some dimensions. or if you can see any snags in this reasoning please say so.
mbell.
All those thoughts are exactly what I am also thinking. Unfortunately without asking on this forum I was doing so without information. Thanks
Eric in Burnley
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PostPost by: ericbushby » Tue Feb 23, 2021 7:53 pm

Hi Richard
I overlapped your post and didn`t want to type it again.
1.7mm and even 1.8mm on the thicker plate still suggests not much wear on mine at 1.5mm left.
I had no idea whether it was badly worn or nearly new.
Isn`t it good when you can just ask and get solid information like these replies just like that.
I am further encouraged now.
Thanks
Eric
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PostPost by: alan.barker » Wed Feb 24, 2021 9:52 am

Hi Eric,
about the Clutch i would ask when you drove your car how did the Clutch feel.
e.g. When the car was hot and you reversed was it nice and smooth or was there sometimes any vibration or snatching. If the it operated perfectly put it back.

If you have some vibration when hot then get the Flywheel lightly refaced. On my Sprint when hot there was vibration when reversing or pulling away slowly. I checked the Flywheel and it was nicely polished but not flat, it was slightly convex. I got it refaced and now it is 100%.
Have fun
Alan
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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PostPost by: ericbushby » Wed Feb 24, 2021 10:19 am

Hi Alan,
I have no problems with the clutch. It is fine and smooth when driving.
So far, with the comments and details received up to now, I am putting it back in when rebuilding.
It seems the wear on it is minimal and it is in very good clean condition.
Thanks for the thoughts.
Eric
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PostPost by: Slowtus » Wed Feb 24, 2021 6:09 pm

ericbushby wrote:Hi Alan,
I have no problems with the clutch. It is fine and smooth when driving.
So far, with the comments and details received up to now, I am putting it back in when rebuilding.
It seems the wear on it is minimal and it is in very good clean condition.
Thanks for the thoughts.
Eric


I have never burned out/worn down a clutch but I have broken a couple with LCA (Lotus Cortina Abuse).

One of the clutches I broke looked new and had minimal wear, for the cost - I would replace it.
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PostPost by: AussieJohn » Thu Feb 25, 2021 7:32 pm

Another option is to have it relined, usually cheap to have done.
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PostPost by: alan.barker » Thu Feb 25, 2021 8:12 pm

The problems are the Springs ratling lik a Tamborine and worn Splines
Alan.b Brittany 1972 elan sprint fhc Lagoon Blue 0460E
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PostPost by: AussieJohn » Thu Feb 25, 2021 8:54 pm

Of course if the springs aren't rattling and the splines are ok then relining is an option; we used to do this often on plates that had been contaminated with oil especially old minis.
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