Radical rebuild of my 1967 Elan - Page 3 - LotusTalk - The Lotus Cars Community
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post #41 of 79 (permalink) Old 01-05-2015, 10:39 AM
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Linear movement but progressive springing via the tender springs.

Yeah, I don't know how it will work either. I think most of the magic is in the bespoke dampers.

The Elan doesn't have a rear ARB as standard so we are not removing anything from this end.

The proof will be in the pudding. This amount of modification to a road legal Elan has not been done before, as far as I am aware, so we are in uncharted waters and may hit a few submerged rocks :-)
lol! yes, but its not really rocket science to put together a suspension - just lots of math and geometry, most beyond me as well

the tender spring with just give you soft before harder, and then valving the damper to do work in those positions.... but the actually wheel to damper rate is consistent. (i suspect you have about .8 motion rate now... but thats a wild guess imagining geometry from the pics)

all just a 6 of one, 1/2 dozen of another ways to skin a kitten. changing the motion ratio would/could radically change your damper valving - particularly if its valved to match the progressive spring positions. i "think" i prefer bump stop over droop limiters... still playing around with that...

well it looks super cool and best of luck and can't wait to see it rolling!! keep it up!

and i would keep an eye on the pushrods and upper arm, that nothing is rubbing under high loads.

"I really started paying attention to cars was when they came out with the Nissan Z, the first body. Then I seen the Cherokees, the old square ones, and I was like, “Wow, that’s cool.” Then I seen the Isuzu jeeps and I seen the Wranglers."
-Lotus Cars VP of Global Design
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post #42 of 79 (permalink) Old 01-05-2015, 11:52 AM Thread Starter
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lol! yes, but its not really rocket science to put together a suspension - just lots of math and geometry, most beyond me as well

all just a 6 of one, 1/2 dozen of another ways to skin a kitten. changing the motion ratio would/could radically change your damper valving - particularly if its valved to match the progressive spring positions. i "think" i prefer bump stop over droop limiters... still playing around with that...

well it looks super cool and best of luck and can't wait to see it rolling!! keep it up!

and i would keep an eye on the pushrods and upper arm, that nothing is rubbing under high loads.
Motion ratio and damper valving are matched.

Bump stops won't help with droop :-) I am still looking at whether I need bump stops. Suspension is hard with a design movement of 2" and I don't plan to do any yumping :-)

An eye will kept on a lot of things, but thanks.

Should be in a rolling chassis situation in the next week.
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post #43 of 79 (permalink) Old 01-05-2015, 12:07 PM
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actually they do, because your creating anti roll in the chassis and then transmitting forces to keep the other wheel back down - in which case, it can't droop. as opposed to bottoming out the chassis and not generating any anti roll. anyways since your not using the damper droop limiters, it is easy to adjust and or remove as you see fit. the only really reason people do droop limiters (other than off road / keeping the springs seated / not using/or able to use enough keepers / too much stock damper travel for application) is to not have an positive force (if even fairly light) keeping a corner extended and helping it get down faster (go kart), which... another approach is to transfer load to keep that corner down and not lift so much. again - a dozen approaches... don't think one or the other is right or wrong.

so the first issue is chassis roll parameters and chassis stiffness, and then based on that... you have option on how to keep the roll you want.

"I really started paying attention to cars was when they came out with the Nissan Z, the first body. Then I seen the Cherokees, the old square ones, and I was like, “Wow, that’s cool.” Then I seen the Isuzu jeeps and I seen the Wranglers."
-Lotus Cars VP of Global Design
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post #44 of 79 (permalink) Old 01-05-2015, 01:21 PM
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Maybe simple minded but a lot of people put droop limiters on Elans when they do the CV conversion as on full droop, the joints can bind due to the short length versus suspension travel. They are not required on the Plus 2.

Would love to hear a little more detail on the chassis strengthening as it's taking far more than today's 26R's or the BDA swaps (250bhp)

Great build!!

Cheers

Rob

1969 Elan Plus 2
1990 Esprit Turbo SE
1986 Porsche 911
1982 Esprit Turbo SOLD
1970 Europa SOLD
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post #45 of 79 (permalink) Old 01-05-2015, 02:34 PM Thread Starter
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actually they do, because your creating anti roll in the chassis and then transmitting forces to keep the other wheel back down - in which case, it can't droop. as opposed to bottoming out the chassis and not generating any anti roll.
Good point. I was thinking of static or straight line suspension movement.
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post #46 of 79 (permalink) Old 01-05-2015, 07:21 PM
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The wire straps are droop limiters, but they are also being used as part of the suspension geometry in lieu of ARBs. Don't ask me how this is going to work as I haven't a clue. I am leaving this to my suspension/handling guru who I have complete trust in.

Thanks for the thumbs up. Have you started a thread for your Dad's restoration? If not, why not? :-)
No thread because he started restoring it before there was digital cameras and the interweb! Haha

He's On the home stretch though
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post #47 of 79 (permalink) Old 01-06-2015, 12:39 AM Thread Starter
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I know that feeling :-)

There must be photos now, though, that you could share with us?
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post #48 of 79 (permalink) Old 01-06-2015, 10:05 AM
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I know that feeling :-)

There must be photos now, though, that you could share with us?
Yeah, you bet. I'll snap a few next time I'm over at his place.
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post #49 of 79 (permalink) Old 01-08-2015, 10:39 AM Thread Starter
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At last, a rolling chassis :-)



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post #50 of 79 (permalink) Old 01-12-2015, 10:05 AM Thread Starter
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Anyone on here had any experience with these guys? This only weighs 95o grams (2lbs)

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post #51 of 79 (permalink) Old 01-12-2015, 10:44 AM
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ha! i have the same tanner scale

"I really started paying attention to cars was when they came out with the Nissan Z, the first body. Then I seen the Cherokees, the old square ones, and I was like, “Wow, that’s cool.” Then I seen the Isuzu jeeps and I seen the Wranglers."
-Lotus Cars VP of Global Design
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post #52 of 79 (permalink) Old 01-12-2015, 03:14 PM Thread Starter
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ha! i have the same tanner scale
:-) When I bought them on eBay I didn't realise that they were for go-karts and the max weight was 1000lbs! However, we weighed my friend's Ford Pop on them before we knew this and it recorded the weight at just over a ton which was correct.
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post #53 of 79 (permalink) Old 01-12-2015, 04:23 PM
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well, my car weighs under 1,000 lbs...

but i think thats 1,000 per corner? - i should check my pad calibrations anyways....

"I really started paying attention to cars was when they came out with the Nissan Z, the first body. Then I seen the Cherokees, the old square ones, and I was like, “Wow, that’s cool.” Then I seen the Isuzu jeeps and I seen the Wranglers."
-Lotus Cars VP of Global Design

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post #54 of 79 (permalink) Old 01-13-2015, 09:00 AM Thread Starter
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Mine are the 10" junior scales, 250lbs per pad. I wouldn't have bought them if I had known at the time, but I think they will still work.
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post #55 of 79 (permalink) Old 01-13-2015, 09:47 AM
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ahh.. i have the big ~12" sq. pads. the brain/display looks the the same though.

i just did my dynamic roll bar weights with one pad, and was getting accurate (repeatable/consistent) readings over 600 lbs.

"I really started paying attention to cars was when they came out with the Nissan Z, the first body. Then I seen the Cherokees, the old square ones, and I was like, “Wow, that’s cool.” Then I seen the Isuzu jeeps and I seen the Wranglers."
-Lotus Cars VP of Global Design
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post #56 of 79 (permalink) Old 01-26-2015, 11:50 AM Thread Starter
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Slight hiatus on engine installation so I have been playing with the wheelie bar construction. Dry assembly went well. Since these photos were taken I have dismantled and glued rod end supports into CF tubes:







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post #57 of 79 (permalink) Old 02-01-2015, 02:36 AM
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Garage
Awesome build.
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post #58 of 79 (permalink) Old 02-21-2015, 06:08 AM Thread Starter
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Thanks, but Captain Cockup has just flown in. Just realised that wheelie bar won't work. With rod ends at each corner it can be lifted up and down. Triangle stiff, quadrilateral not. Modifications are in hand.

Chassis still has a lot of twist, even with the 26R mods, so we looked at how to stiffen it. We decided that we could improve things by mounting the body more securely to the chassis and stiffening the central section of the body with carbon fibre. Long discussions ensued with my carbon guru and a method was worked out. A lot of cutting and laying up required.

However.....

After a lot more thinking and discussions, I have decided to ditch the carbon fibre stiffening idea and revert to the tried and tested roll cage method, even with the considerable weight increase. However there isn't an off the shelf cage designed for chassis stiffening so, as usual, we will have to work it out ourselves. Below is the sort of thing we are envisioning, although we have to wait until the body is back on to see if our ideas will work, especially the front section. Image grabbed from web, red/black tubes are our additions.

38mm T45 will be the tube of choice. 3 times as expensive as CDS, but stronger even with thinner tube walls and there will be a weight saving of around 10-15kg.


Last edited by stevebroad; 02-21-2015 at 06:13 AM.
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post #59 of 79 (permalink) Old 03-05-2015, 11:37 AM Thread Starter
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Engine and gearbox finally back in. Hoop in photo is being replaced with a full roll cage. The plan is to modify body so that is fits then off to the cage fabricators, hopefully Monday week.

Wheels are temporary, I will order the proper wheels once body is on and I can confirm offsets etc.









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post #60 of 79 (permalink) Old 06-21-2016, 03:10 PM Thread Starter
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I seem to have been a little tardy with posting updates on here, for that I apologise.

Since last post we discovered that, despite a lot of triangulating of the chassis, it twists in the middle like a stick of liquorice when one corner is picked up, not conducive to good handling when we plan to put over 500BHP through it.

So, after much heart searching, I conceded that we would have to install a full roll cage, from the front suspension uprights to the rear ones. Once that was decided a design had to be formulated, not easy when there isn't a floor to weld tubes to. The 'off the shelf' offerings were useless for our requirements so it had to be bespoke.

The car was at the fabricators for 4 weeks as we designed the cage as we went. The first couple of days were spent trying to get chassis and body level. Had to give up and just level the chassis as the body is badly out of shape. We built the cage square to the chassis and I will sort the body out as best I can once I get back home. For example, the right hand A pillar was 20mm shorter than the left hand one! I had to cut it so the roof could be squared up and the front hoop fitted properly. The green tape is holding it in place.

I was there every day to discuss and agree each tube. Fortunately, I had expert help on hand, Graham Hatherway of GH Racing.

I have used T45, as this reduced the weight of the cage by 13.5Kg whilst still being stiffer than CDS.

The side tubes will be connected to the chassis with 38mm T45 which will double as seat fixings, once I harden up on the seat positions.

I recently noticed that we, somehow, managed to leave out the tube between the rear uprights. This will be rectified in the next couple of days.

This is Martin the fabricator, not me :-)












Last edited by stevebroad; 06-21-2016 at 03:28 PM.
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