Lotus Elan

Concentric clutch slave cylinder

PostPost by: mct340 » Mon Nov 28, 2005 3:45 am

I saw a different type of clutch slave cyl. somewhere on the net and now that my conventional one has let go I can't seem to find the site where it was listed.
The website called the part a "concentric" slave device that was to be installed inside the bellhousing ala something Colin Chapman used on one of the F1 cars. Sounds good to me. Does anyone have one of these?
Thanks,
Mike
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PostPost by: GrUmPyBoDgEr » Mon Nov 28, 2005 8:10 am

Hi,
Concentric clutch slave cylinders fit inside the clutch bellhousing and fit around the g/box input shaft. They are suitable for tight installations where there is no space to provide a bellcrank arm and external slave cylinder. They are expensive and if they go wrong, it's an engine out job.
They become necessary when fitting e.g. a 5 speed MT75 g/box to an Elan. These were designed for use with a cable operated clutch and a hydraulic concentric clutch therefore makes the conversion easier.
Hope to have been of some help.
John
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PostPost by: john-c-elan+2 » Mon Nov 28, 2005 9:17 am

Hi, I don't know if you've seen the Alan Voights 5 speed conversion gearbox ? (using type 9 ford box). He uses a concentric clutch set up with that. Not sue if he has a website - if so 'spect there wud be a picture ? Also Burtons catalogue has small pic of one in (www.burtonpower.com)
and appear to offer kits for Rocket box/sierra type 9box/2000e box, cost in 2003 catalogue was about £120 + vat.
Regards jon
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PostPost by: M100 » Mon Nov 28, 2005 10:35 am

D.J.Pelly wrote:Concentric clutch slave cylinders fit inside the clutch bellhousing and fit around the g/box input shaft. They are suitable for tight installations where there is no space to provide a bellcrank arm and external slave cylinder. They are expensive and if they go wrong, it's an engine out job


They are now used in many modern vehicles, failure rate is supposed to be quite low and to my mind anything that gets the clutch slave cylinder away from the vicinity of the exhaust has got to be a good idea.

I've been looking at a few of the commercially available options but I'll probably be knocking one together from scratch instead over this coming winter
Martin
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PostPost by: simon.mitchell » Mon Nov 28, 2005 10:48 am

They become necessary when fitting e.g. a 5 speed MT75 g/box to an Elan. These were designed for use with a cable operated clutch and a hydraulic concentric clutch therefore makes the conversion easier.


John,

I modified the pedalbox in my plus 2 so that I could use a cable operated clutch with my MT75 gearbox. It's an easy mod and the cable is easy to change if things go wrong..
Attachments
Speedo.jpg and
Pedal_box.jpg and
Gearbox.jpg and
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PostPost by: GrUmPyBoDgEr » Mon Nov 28, 2005 11:14 am

Hi Simon,
it's good to hear that a pedal box conversion to cable operation is not too difficult. I agree with you entirely about the slave cylinder / exhaust proximity radiation problem.
I was looking at the feasability of an MT 75 for quite a while.
That problem and a mechanical drive for the speedo were the two things that put me off.
How did you fix the speedo drive?
Sorry no intention turning away from the main thread.
John
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PostPost by: simon.mitchell » Mon Nov 28, 2005 1:10 pm

Hi John,

Two options for a speedo drive when using an MT75 gearbox; firstly, Spyder make an adapter which fixes to the gearbox with a circlip, into which fits the standard angle drive. I went for option 2 (since the speedo drive housing of my scrapyard gearbox was damaged); an electronic speedo with a sensor which takes it's input from the driveshaft (in my case) or propshaft bolt heads. Smiths will custom make one which matches in pretty well with the existing instruments, at a total cost including sensor & postage of c£200; I'll post a picture in the gallery later and you can see what you think!

Simon
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PostPost by: GrUmPyBoDgEr » Mon Nov 28, 2005 3:19 pm

Simon,

very interesting information.
It's making the option to go to MT 75 more interesting. Can you post a picture of the speedo as well please.
Which version of the MT 75 did you use?
I have been told I need to look for one from a "Left Hooker" in order to keep the starter motor on the driver's side & thus provide sufficient room for Elan's my fancy exhaust manifold. "Wiggy" also told me once that a van version has a factory fitted concentric clutch cylinder.
I'm sure you know what I mean when I say,
"It's always the same with these "oddball" things trying to get definitive answers".
By the way, how do you get pictures into a thread or into the gallery?
You don't have to answer that, I'm sure it's a long one!
Thanks.
John


Miked,

Please hold fire on that 4 speed g/box for a while please.
But don't worry if you've already committed.
I am sometimes a man? of honour?
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PostPost by: simon.mitchell » Mon Nov 28, 2005 8:45 pm

Hi John,

See Pictures above of the speedo. pedal box mod and the MT75 gearbox in the Spyder chassis.

The modification to the pedal box is basically to remove the clutch slave cylinder and weld a plate over the hole, then weld a short piece of tube to the front of the box to take the clutch cable, which then attaches to the pedal with a clevis pin.

As for the gearbox, I used a standard right hand drive one - but since it's connected to a Zetec engine I didn't have any clearance problems with the starter!

Cheers,
Simon
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PostPost by: storrar54 » Tue Nov 29, 2005 2:04 am

Mike, In issue No.70 of "Chicane" there is a superb article by Victor Hollnagel assessing different gearbox replacements and detailing how to uprate the Lotus 5 speed box. One of these uprates is a change to a concentric slave cylinder using a Saab 900 unit. I have a copy of the article if you are interested.
Richard
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PostPost by: paros » Tue Nov 29, 2005 4:38 pm

I have used concenric release systems in various race Elans and the only real advantage I can see is that you stop the release arm bending when using strong clutch springs. The other advatage is that it seems more sanitary to push the polo mint release system than the lever arm and it stops the horrible circlip failing on the slave cylinder to bell housing lug. The Burton kit is not elegant and uses O rings for the seals. These I found needed replacing every seson - not expensive or difficult when you have everything apart for rebuilding. You also bneed to make provision for bleeding by having a seperate pipe coming up from the bell housing with a nipple attached. If you look around you will find people such as Super Clutch offer a much better engineered concentric release sytem, as does Tilton etc.
Hope this helps
Richard
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PostPost by: Petter Hval » Tue Nov 29, 2005 10:49 pm

Hi Mike
I modified aT5 gearbox to fit a Rver V8 IN MY Son`s Wstfield and used
a Saab unit. Saab have 3 diferent types of the unit so be sure to get the right one. Price for the Saab unit ca. £ 10 in Norway. It may also be
necessary to get a masterpump with a diferent bore.
Cheers
Petter
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