Lotus Elan

40 DCOE throttle linkages

PostPost by: bloodknock » Wed Jun 05, 2013 12:54 pm

:idea: Does anyone have any suggestions as to how the throttle linkage could be improved to my twin 40's on the Elan Sprint?
Also when my car was on the road in '73 the carb bodies used to thump the top of the drivers footwell. I recall ensuring that the correct engine mounts were fitted and the carb couplings were set up correctly but to no avail, what else could be the problem? Could this be related to body shimming????
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PostPost by: GrUmPyBoDgEr » Wed Jun 05, 2013 1:26 pm

For a throttle linkage solution you can't really beat the TTR solution; a well made, solid & compact solution but a bit expensive.
The racers use it so that's good enough for me :wink:

Something that I've never considered but if as you say everything else is "correct" then yes another possibility is that the body could be sitting too high on the chassis.
Goodness knows how you might confirm what the relationship of the body to chassis should be though.
I don't recall this being discussed on here----------------Food for some thought? :roll:

For what it's worth the spacers I used on my S4 between the body & backbone flange obviously varied but were a maximum of 5mm thick.

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PostPost by: Elanman99 » Wed Jun 05, 2013 5:12 pm

What aspect are you looking to improve?

The standard 'Between-Carb' link, and the Bowden cable has done the job for 50 years on the Elan and works for me.

Ian P
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PostPost by: bloodknock » Thu Jun 06, 2013 7:50 am

Thanks Guys.
I guess i'll have to just get the body located correctly on the chassis and hope for the best on the carbs.
Regards
Bob
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PostPost by: Elanman99 » Thu Jun 06, 2013 8:20 am

bloodknock wrote:Thanks Guys.
I guess i'll have to just get the body located correctly on the chassis and hope for the best on the carbs.
Regards
Bob


Bob

Changing the height of the body to chassis dimension is not for the feint hearted, in fact its only really feasible when a new chassis is being fitted. Two of the front bolts are threaded (horizontally) into holes in the front upright chassis legs. The bobbin hole would have to be elongated to allow any movement (packing would not help here) but more importantly would only allow you to 'raise' the body which is the opposite of what you are looking for. I'm assuming the body was not deliberately fitted in a an incorrect position.

Does you engine look canted over when you view it from the front with the bonnet off? It should do.

If the correct engine mounts are fitted (worth double checking) then the easiest corrective method might be to elongate the holes in the engine mount as at least its a replaceable part so you are not doing any damage.

What about the carb linkage?

Ian
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PostPost by: sprint4dm » Thu Jun 06, 2013 11:25 am

Hi Bob

I had a similar problem with my carbs hitting the top of the footwell as you describe but cured mine by replacing the gearbox mounting and using the correct spacers, this raised the rear of the engine enough to give clearance to the carbs actually my car didn't have the spacers fitted at all

Dave
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PostPost by: fatboyoz » Thu Jun 06, 2013 12:51 pm

Bob,
The original throttle cable setup works just fine. There is a secondary spring (quite large and very springy?) that fits between the cable inner, end mount (part of the carbie air box backplate) and the cable outer end mount. Without this spring fitted, the throttle feels a lot less positive. If you look closely, you can see the holes where the spring should be fitted.
Regards,
Colin.


bloodknock wrote::idea: Does anyone have any suggestions as to how the throttle linkage could be improved to my twin 40's on the Elan Sprint?
Also when my car was on the road in '73 the carb bodies used to thump the top of the drivers footwell. I recall ensuring that the correct engine mounts were fitted and the carb couplings were set up correctly but to no avail, what else could be the problem? Could this be related to body shimming????
Bob Skerritt
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PostPost by: [email protected] » Thu Jun 06, 2013 6:31 pm

I would recheck those engines mounts are correct for a Weber twin Cam and installed correctly. We use the Rally Design throttle linkage kit RD4200 if the original isn't suitable for some reason. That throttle linkage kit is easy to get full throttle travel and still have a correct pedal height because it is very adjustable.
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PostPost by: [email protected] » Thu Jun 06, 2013 6:33 pm

I would recheck those engines mounts are correct for a Weber twin Cam and installed correctly. We use the Rally Design throttle linkage kit RD4200 if the original isn't suitable for some reason. That throttle linkage kit is easy to get full throttle travel and still have a correct pedal height because it is very adjustable. Not sure if that is the same as the Tony Thompson unit .
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PostPost by: adigra » Fri Jun 07, 2013 1:44 pm

I have a Mangoletsi linkage and it's the nicest I've seen with a huge range of adjustment and smooth bushes everywhere. It's really smooth and positive, plus it looks great as it's flush fitting and matches the carbs. I removed a sytec one as it had a lot of sideways play in the arm and the spring kept popping off (and it looked too modern).

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PostPost by: 1owner69Elan » Wed Dec 30, 2015 5:56 pm

Adigra:

Did the Mangoletsi linkage require any modification to the intake manifold for Webers? Another poster indicated he had to cut the manifold for Dellortos.

I have a newly built high output twincam and have switched to Webers from Strombergs. As such I have no linkage yet. With the high output and a lightened flywheel I am looking for something like the Mangoletsi with its various adjustments to allow maximum drivability.

I will not cut the head however if that is needed by the Mangoletsi.

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PostPost by: simonknee » Thu Jan 07, 2016 10:16 pm

Best improvement is made not by changing the throttle linkage but with a decent throttle cable. I could not get one that felt smooth. They always felt sticky no matter what you lube them with. That was until I made one myself with Shimano teflon brake cable. It feels wonderful.
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PostPost by: nmauduit » Fri Jan 08, 2016 10:43 am

1owner69Elan wrote:Adigra:

Did the Mangoletsi linkage require any modification to the intake manifold for Webers? Another poster indicated he had to cut the manifold for Dellortos.


I have fitted a Mangoletsi linkage after an engine swap, and had to file just a bit (maybe 1 mm) the edge of the central rib that links the intakes to clear the balancing hex screw. I could probably have avoided that by changing the screw for something else (e.g. Allen screw or shorter one), but was eager to get the new engine going... and had a file at hand. You know the saying "when your only tool is a hammer everything looks like a nail"

mangoletsi-side.jpg and
Mangoletsi side


mangoletsi-top.jpg and
Mangoletsi top
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PostPost by: 7skypilot » Fri Jan 08, 2016 11:39 am

I have used a very simple modification on my S4, using a Caterham 7 throttle cable bracket. This mounts underneath the carbssecured with one bolt from each of the Weber lower covers. The inner cable then pulls the butterfly levers from below with the outer cable secured on the 7 bracket. Very simple and works well - the spacing between the carbs is exactly the same on BD, Kent and Twincam manifolds. The original bracket on the airbox had been removed by a PO so I had to develop another method.

I've also used both Weber and Jenvey linkages on BD carbs. Both are good, with the Jenvey setup having, in my opinion, the edge but they do require a fair bit of room between bonnet (hood) and carbs, which might not be availabel. Mangoletsi set-up looks excellent, as does TT's and both fit low and neatly.

I would recommend having the cable(s) made up by a specialist (I use Hywel Absalom at Spot-on Cables in the UK) for super smooth operation. The cost is reasonable and they really do improve throttle operation.
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PostPost by: prezoom » Fri Jan 08, 2016 3:46 pm

I also pull from the bottom and use Teflon bicycle brake sheath and cable. Buy the sheath in bulk, along with the ferrels from a local shop, and, because of LHD, use a rear brake cable from a tandem bicycle. Smooth as a babies butt. As far as throttle return issues, I have two light springs attached at the outer ends of the throttle shafts that are connected to the air box back plate. Old habits from years of racing and not wanting a stuck throttle at the most inopportune time.
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