Lotus Elan

Suspension settling after re-assembly?

PostPost by: The Veg » Sun Jan 20, 2019 2:50 am

Update- just ordered the height-adjustable TTR units for all four corners. Can't wait to get those on and put this problem to bed!
1969/70 Elan Plus 2 (not S) 50/2036
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PostPost by: Gorpon73 » Mon Jul 01, 2019 10:41 pm

Hi,

Hoping to resurrect this string for some advice. I performed the full refresh on front and rear (S4 Elan). Arms, dampers, springs, bushes, trunions, ball joints, lotocones, etc. Kept the original hub assemblies front and rear.

My front settled immediately to the correct position. Looks great. My rear is still ridiculous. Like 8 inches too high upon dropping under load! All the parts measured up to my original parts dimensionally. I'm wondering if the springs are too stiff because was it exceedingly difficult to get the damper far enough through the lotocone and threaded with the bolt. I'm hesitant to even drive it like this as I don't want to damage the CV's.

Seeking any suggestions before moving ahead. My hands are too demolished from the assembly to rush into a disassembly without thorough contemplation.....Cheers.
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PostPost by: mbell » Mon Jul 01, 2019 11:30 pm

Possible wrong springs, might be worth checking with the supplier that they didn't accidently ship you the wrong ones.

You didn't tighten all the bolts with the car in the air and the suspension in full droop did you? (They should be tightened with car in ground at normal ride height and a set weight in the car)
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PostPost by: Gorpon73 » Tue Jul 02, 2019 3:02 pm

Yup. All links not tightened until the car was dropped.

I hate to heap it on the supplier, but its not the first part I received that was incorrect.

The springs are very close to 14.7 (just slightly longer), but compressed they are about 11. According to the manual, they should be 8. :cry:

On the plus side, I am now an expert at removing and installing the rear suspension.......
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PostPost by: Craven » Wed Jul 03, 2019 11:05 pm

Just a bit of supposition, the spring is supporting a corner weight of 452.2lbs then a spring with a free length of 14.7 that is compressed to a fitted length of 8 will be 14.7 – 8 equals 6.7 compression 452.2 div by 6.7 indicates a 67.5lb spring.
Now 14.7 compressing to just 11 will be 3.7 so 452.2 div 3.7 indicates a 122lb spring.
Anyway you should get the idea to do your own thing.
Spec for rear spring is 67.5lb
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PostPost by: Gorpon73 » Fri Jul 05, 2019 9:07 pm

Thanks for the insight. Interesting. I knew the correct spring rate, but did not know that was the relationship/equation to length and coils.

Hoping some driving will sort it out. Need to plumb the brake lines first, which I was reluctant to do if I needed to re-disassemble the spring. Settling is normal, but 4+ inches seems like alot...
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PostPost by: 512BB » Sat Jul 06, 2019 6:55 am

Donkeys years ago I bought new rear springs from Vic Moore at Spyder for my first car restoration, whilst also fitting a Spyder stressed skined chassis.

After fitting them, the rear of the car was so high in the air that I worried that the donuts would not fit and it looked ridiculous. Spoke to VM who assured me that after driving for a while, the springs would settle but I was not happy and changed them.

FWIW

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PostPost by: Gorpon73 » Mon Jul 08, 2019 10:23 pm

Good to know. Thanks for the insight, Leslie. Hopefully will get everything stitched back together for the weekend.

I'd like nothing more than for a nice 10 mile drive to flatten them out a bit, but we'll see.
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PostPost by: 512BB » Thu Jul 11, 2019 8:48 am

I think you will find it will take a lot more than 10 miles to settle a new set of springs. More like 500 - 1000 miles, but you have got to start somewhere.

As I have previously written, I changed the new set of springs that I bought as there was no way they were going to drop 3 inches. They were just wrongly supplied.

Best of luck

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PostPost by: Gorpon73 » Fri Jul 12, 2019 10:57 pm

Any recommendations for sourcing the appropriate fit? These came from a reputable vendor.
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PostPost by: nmauduit » Sun Jul 14, 2019 10:57 am

512BB wrote:I think you will find it will take a lot more than 10 miles to settle a new set of springs. More like 500 - 1000 miles, but you have got to start somewhere.

As I have previously written, I changed the new set of springs that I bought as there was no way they were going to drop 3 inches. They were just wrongly supplied.

Best of luck

Leslie


yes, good quality springs may settle as little as 1-2%, standard 3-5% cheap ones 5-10% so to get 20% (3" out of 14.6") sounds like a lot.

As mentionned above, the free length is stock, so if the rate is higher than stock the result won't be stock and the car will stay high. Unless something has gone wrong in the assembly causing the spring resting too high than it should or something equivalent, besides talking to the vendor checking for spring rate would be the next thing I would try (since the car is assembled, by loading the trunk a know amount (between 50 and 100kg) then measuring the body going down and inferring the rate (taking in account the lower arm geometry).

ps: I have 120 pounds rear springs on my stret 2 seater (they are about as firm as I would go for a street car), I took 10" free length and raised the plateform via an adjustable setup by about 1" - 1.5" iirc (they did settle 4-5% , were not top brand springs, rather the standard grade by a reputable supplier)
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PostPost by: Gorpon73 » Tue Jul 16, 2019 2:38 pm

Hi,

Problem solved. Original coil diameter removed part ~3/8, new coil diameter ~ 7/16.

Thanks for the suggestions.

Cheers.
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