Lotus Elan

How hard should Sprint standard suspension be?

PostPost by: Tahoe » Sun Jan 03, 2016 5:14 pm

elanfan1 wrote:I find Sean pretty straightforward, just send him a photo and your thoughts and give home a ring. I don't think you need ammunition as such he'll be keen to sort it out I'd have thought.


My experience is very different. Long delays when responding, several monthes waiting for order to be filled, and when a problem was encountered regarding ride height because of what I believe to be an incorrect rear spring(s). In the last experience I've emailed Sean and he responded the next day, however when I sent him pictures per his request he ignored me. I take it from his lack of response that he feels there is nothing wrong, and the high ride height is normal. Spyder will never get another order from me, and I'm solving the issue with new springs that I know will work.

Just my experience, I'm sure others feel very different, but I believe you'll find other threads questioning Spyder's ride height with regard to springs. If I had to do it again, I would choose a different supplier,

I wasn't going to respond to this because there are many faithful Spyder fans, and to those people, I'm glad you're happy with there products and service. I think many of there products are first class, but I question some of there suspension products.
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PostPost by: Craven » Sun Jan 03, 2016 5:18 pm

Just as an indication, this is an original shock/spring from an Elan. Free length of spring before fitting was correct, the gap between coils is now about 5mm. Clearly no weight from the car but it does show the original setup ran the coils fairly close together.
Spyder setup shown before measure just very slightly less between coils. Unfortunately the car to which they are now fitted is incomplete but has engine and gearbox there is no sign it will be low in ride height.
Ron.
PS, You either have rubbish springs or a very heavy car!

p1020941.jpg and
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PostPost by: TroonSprint » Sun Jan 03, 2016 5:46 pm

Hi everyone. I've been out in the garage and taken some photos and measurements as suggested by Rohan. The photos show both front and rear spring in full droop, and also with the car's weight on. I let the jack down with a suitably sized block under the hub carrier to approximate to the usual ride height, but it won't be quite as low as after the car has been running around. Still, it will be close.

The front spring in full droop, with no weight on it, measures 208 mm or 8.2 inch. With the car's weight on it it measures 165 mm or 6.5 inch.

The rear spring in full droop, with no weight on it, measures 355 mm or 14.0 inch. With the car's weight on it it measures 253 mm or 10.0 inch.

My inexpert take on this is that the rear springs are probably OK, but the fronts are not coping with the car's weight. Spyder quoted a fully closed length of 6 inch, and that means there is only half an inch or less of bounce possible before it is completely closed up.

In answer to Russ, I haven't had great success communicating with Sean in the past either. He rarely answers emails and doesn't always call back if you leave a phone message.

Springs are pretty cheap, so can someone give me an optimum size and brand that should work on the front of my car, just in case I don't get anywhere with Spyder?

Thanks for all help,
Mike
Attachments
front-droop.jpg and
Front Spring unloaded
front-weight.jpg and
Front Spring loaded
rear-droop.jpg and
Rear Spring unloaded
rear-weight.jpg and
Rear Spring loaded
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PostPost by: rgh0 » Sun Jan 03, 2016 7:41 pm

Looks like at normal ride height that the front shock is also very close to being closed with the top of the shock body contacting the bump rubber.

I believe if you pull off the spring you will find its free length is less than 14 inches now or its spring rate is less than 70 or both.

Assuming the shock body will take the standard spring ID which it looks like, then you should be able to fit new standard springs from any of the usual suppliers.

regards
Rohan
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PostPost by: Craven » Mon Jan 04, 2016 4:16 pm

Mike
As you are trying to set a standard ride height of 6 inches with a short spring then you get exactly the situation you have. Manual gives fitted length a preloaded 16 inch 75lb front spring ( 514 lbs ) of 9.22 inches.
You can?t get 514 lb preload on a 14 inch 70lb spring, to get standard ride height, without compromising compliant suspension.
Ron.
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PostPost by: denicholls2 » Mon Jan 04, 2016 6:33 pm

I'm not exactly known for mechanical knowledge but that spring looks very wrong even to me, there seems to be very little space for much dampening effect. Could it be you have Plus 2 springs - are they a bit longer? I suspect you've done very well getting them on!


Perhaps you have one of the very rare "Add lightness - bah!" bodyshells? These were the supplier's reaction to Chunky's maniacal obsession with weight and his tiresome insistence on removing every extra gram from the bodyshell castings. A limited number of shells were supplied that substituted lead for polyester. :)

Seriously, I think your ammunition for Sean is Craven's photo of Spyder-supplied components. Particularly if the spring rates are normal or below, there isn't sufficient travel left in the fronts for safety, let alone comfort. A rough road is going to launch the car they're installed on, and your experience with your setup is consistent with that. It is one way, however, to minimize bump steer -- just replace it with bump launch. :wink:
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PostPost by: TroonSprint » Mon Jan 04, 2016 8:25 pm

Mike
As you are trying to set a standard ride height of 6 inches with a short spring then you get exactly the situation you have. Manual gives fitted length a preloaded 16 inch 75lb front spring ( 514 lbs ) of 9.22 inches.
You can?t get 514 lb preload on a 14 inch 70lb spring, to get standard ride height, without compromising compliant suspension.
Ron.

Ron (and others) all this spring theory is new to me and very interesting. I see what you have done - if the standard factory spring is 16.75" free and 9.86" fitted, a difference of 6.89". Multiply that by the spring rate of 75 lb.in. and you get a preload of 516 lbs.
Now my current spring is 14" free and 8.2" fitted, a difference of 5.8". The spring rate is quoted at 70 lb.in, so the preload is 5.8 x 70 = 406 lbs. No wonder it is completely compressed with the car's weight on it.
When my car was delivered to me in a pile of boxes, included were a new pair of front springs and I have just been to look them out. They are 13.5" free and 10" fitted, a difference of 3.5". The rating painted on them is 115 lb.in. So fitted the preload would be 3.5 x 115 = 402 lbs, so still not enough. Is that right? I didn't use them because I thought they would be too hard riding.
Looking on various web sites like Merlin Motorsport and Demon Tweeks I can't find 1.9" ID springs any longer than 14". I must ring suppliers like Tony Thomson and ask the size of the springs they supply.
Meantime I have emailed a photo to Sean at Spyder and will have to see what he says if and when he replies.

Mike
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PostPost by: Craven » Mon Jan 04, 2016 9:05 pm

Mike,
Yes that basic idea, the supple ride of the original suspension is due in part to the long low poundage springs. Short higher rate springs can provide the required preload but ride characteristic will be quite different.
I have now checked the fitted length of the spring/shocks supplied by Spyder as per pic. It is 9 . something inches so it would seem on the face of it, they have a suitable spring available.
Ron.
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PostPost by: rgh0 » Tue Jan 05, 2016 9:36 am

Yes sorry I posted wrong standard free length..... it is 16 or 16.75 inches not 14 .5 inches I said --- must get my eyes checked as i read the manual wrong :oops: - The later US cars and some other markets had the higher riding front springs.

The normal load on the front springs is around 510 lbs each. It is greater than the car weight at the front due to the suspension geometry, which maybe Spyder did not allow for when they selected the spring. A 14 inch long 70 lb spring will end up under 7 inches long at this load and very close to the coil binding length of 6 inches quoted.

You definitely need new springs
cheers
Rohan
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PostPost by: TroonSprint » Tue Jan 05, 2016 5:28 pm

The normal load on the front springs is around 510 lbs each.
Thanks Rohan. This is all interesting stuff to me. Do you happen to know what the equivalent figure would be for the rear spring on the Elan Sprint FHC?

Mike
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PostPost by: rgh0 » Tue Jan 05, 2016 7:38 pm

Rear Spring load without driver or passenger is around 380 lbs each for the standard Lotus strut suspension design. The geometry of the Spyder rear suspension conversion is a little different so the spring load will probably be a little different also.

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Rohan
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PostPost by: TroonSprint » Wed Jan 06, 2016 6:52 pm

While we are talking about front springs I have asked Tony Thompson Racing for the spec on their fast road front springs. They replied with free length 10", fitted length 9.5". and rating 125 lb.in. How can that work? To achieve a preload of 510 lb it needs to be compressed by 4". That would mean winding up the perch by around 3.5" - that can't be right. Surely the 125 lb spring has to be longer than 10"? I'm confused.

Mike
Sean from Spyder still hasn't replied to my query about my front springs. :x
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PostPost by: pereirac » Mon Feb 08, 2016 12:53 pm

I bought some Gaz units from a mail order company in the Uk called Dampertech. They also supplied some springs ,although they did not fit them to the shocks. I had them fitted by Spyder as I don't have a compressor small enough and the suggestions on Youtube using various cable ties scared the life out of me!!
The ride difference compared with my old, 25 year + Armstrong units was very noticeable, softer and the car is a lot easier to drive on most road surfaces..

Carl
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87 Excel SE
97 Alpina B10

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