Lotus Elan

Weld On Coil Overs

PostPost by: gearbox » Mon Oct 08, 2012 6:49 am

Hello all, I have a 69SE that I am thinking about making some weld on coil overs for the rear struts. Basically a threaded tube welded on the original strut tube after the original spring seat had been cut away. I'm away from home (and the Elans) but I like to get a jump on getting parts and CADing up the design. I will be going with 2 1/4" ID springs. Can anyone help me with the following:

1) Diameter of the strut tube where the threaded tube will slide over and be welded
2) Spring free length of the Original Spring
3) New 2 1/4" ID Spring free length (suggestions?)
4) Compression rate of the new springs (100 lbs.?)

I see that several vendors offer a 12" free length spring in either 100 or 110 lbs. for this conversion. But would like to get the collective wisdom of those who have gone down this path before me. The car will be mostly stock and used for high spirited weekend drives. I will be staying with either the 155's or going to 165 tires (depending on what is available) on the stock steel wheels (KO) or may fit a set of 14" minilites I have (maybe) or even buy a new 13" set. So tire clearance should not be a problem. But the mod will be mainly for corner weighting the car. Also any suggestion on front coil over shocks will also be appreciated. Thanks Allan
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PostPost by: upnorthelan » Mon Oct 08, 2012 3:22 pm

Hey Allen,
D Bean makes a kit that acomplishes this pretty cheap with minimal work. Could be fun doing it yourself though. I've got 120 lb. springs on the rear which are alittle unforgiving on public roads, at least im Michigan!

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PostPost by: ceejay » Mon Oct 08, 2012 8:19 pm

spring rate of 120Lb for the front coils, and 80Lb for the rear coils is a good
balance. Do the conversion for both with adjustable platforms and you
have a good set up to change and alter things the way you want.
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PostPost by: CBUEB1771 » Tue Oct 09, 2012 1:57 am

Allan,
Ray, at RD Enterprises near Philadelphia, offers two options. One is a threaded sleeve with the correspondingly threaded spring perches and locking rings. This is essentially what you propose to fabricate. Ray also offers a complete replacement strut tube for threaded perches.
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PostPost by: garyeanderson » Tue Oct 09, 2012 5:10 am

Hi Allan

Bud posted his solution and it is worth a look for you to see what he has done. He posted it earlier this year and I remembered the post so I searched his posts for

adjustable and perch
bud-english-u6452-posts.html

and got a couple of hits

Take a look at this and see if it's something you want to do

post163735.html?hilit=%20adjustable%20perch#p163735

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PostPost by: gearbox » Tue Oct 09, 2012 2:29 pm

piss-ant wrote:Hi Allan

Bud posted his solution and it is worth a look for you to see what he has done. He posted it earlier this year and I remembered the post so I searched his posts for

adjustable and perch
bud-english-u6452-posts.html

and got a couple of hits

Take a look at this and see if it's something you want to do

post163735.html?hilit=%20adjustable%20perch#p163735

Gary




Thanks Gary, that is a perfect solution. I actually found those kits before, but disregarded them as I was thinking it had to be welded to the Elan strut and being made from aluminum that would not work. But Bud's solution of epoxy makes perfect sense, especially when the load is born by the partial ring left on the original strut. As long as the threaded tube is tight enough on the strut, it shouldn't move. I've used this 3M epoxy that bonds quarter panels on to late model cars and it is strong stuff, so it will be perfect for this application. I have a PM out to Bud asking a few questions, fit of the tube, spring I.D. diameter, and spring length, and adjustment range. But for 50 bucks, you can't go wrong, and you have enough for two cars lol. But thank you again for finding the thread, I searched under weld on coil overs and found nothing of value. Didn't know they were called perches lol. Cheers Allan
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PostPost by: gjz30075 » Tue Oct 09, 2012 3:17 pm

Allen, I like Bud's solution, too. I bought a set of threaded sleeves with perches from Summit Racing but the perch is held in place on the sleeve via a set screw. I prefer a second collar underneath for locking. The problem I had when looking at those on ebay, is that all of the vendors that I emailed asking about length and i.d., either didn't know or didn't return the answer. I got a feeling many of the vendors simply dropship the product to your door and only know the application.

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PostPost by: elj221c » Tue Oct 09, 2012 6:51 pm

It is a thought and only that but do you really need adjustable spring seats?

I didn't alter mine myself but it would appear that the original large spring seat has been cut away to leave about a 3/8" width ring on which my springs used to sit. According to the sketch in my note book, the seat is 4" up from the alloy bearing carrier so you could compare. My struts are shorter than standard. There is a further 5 1/2" above the ring. It may be that they were supplied as 26R Armstongs. I am not sure. They were AS 1512 so maybe someone would know? The spring is 120 lb/" but I have no dimensions for the free length, sorry. These matched the 200 lb/" fronts nicely on the road.

When I had shortened Koni inserts made, with the appropriate valveing for the heavier spring, I also bought some aluminium spacers, 1/2" I think, as the car was too low.

I have to admit that I do have adjustable spring platforms on the front Spax but it does seem a waste of money as once my suspension was set it was never altered.
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PostPost by: Bud English » Tue Oct 09, 2012 6:57 pm

Allan, I answered your PM before I scanned the new posts. I see that you are in New Jersey. I'll throw my two leftover perches into a medium flat rate box and you can have them for the cost of the postage ($10.20). I don't need them and you can play with them to see if that's truly what you want to do.
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PostPost by: gjz30075 » Tue Oct 09, 2012 8:01 pm

Roy, I guess it's the 'intended consequences' I'm after, such as easily obtainable springs of different rates. Springs of 2 1/2" of almost any rate can be obtained from Summit, Jegs, Speedway Motors, Pegasus Racing, etc., all 'hot rod and racing' parts vendors in the US. I also just had to change out my rear brake lines going to the calipers. It was a tough job with a the full width spring in place and I could see it would have been easier with the narrower spring.

That said, you're right. For a street car, once you're set, no need to really change anything further.

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PostPost by: gearbox » Wed Oct 10, 2012 5:40 pm

elj221c wrote:It is a thought and only that but do you really need adjustable spring seats?


I think many of us go through this route in order to gain more room to fit modern day wider tires as the selection of 155's these days are few and far between. Personally I was interested in this mod mainly for corner weighting. I intend to fit the car with no larger than the Dunlop D83 165 R13's which I believe should should fit with the stock struts but I will tell you why I am interested in this mod. After I had completely stripped my 69 SE, body off, I was amazed at how fragile the frame was for a road car. It actually made my Formula Ford Frames look robust, and if you ever raced FF, you know that the frame tweaks after each race. Maybe the Lotus frame is not as bad, but it wouldn't hurt to have the ability to adjust and tweaks out of our now 40 year old plus frames. Needless to say, I have to figure out what to use on the fronts to allow for the same adjustment. Once I get the suspension set up I most likely would not put it back on the scales for another year, but the adjustments gives me the ability to play with the suspension to get it balanced for the way I like driving the car. A worth while mod in my opinion, especially for a weekend car and not something I would do to my daily driver. But these are our toys right? LOL.
Last edited by gearbox on Wed Oct 10, 2012 6:29 pm, edited 1 time in total.
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PostPost by: gearbox » Wed Oct 10, 2012 6:26 pm

Bud English wrote:Allan, I answered your PM before I scanned the new posts. I see that you are in New Jersey. I'll throw my two leftover perches into a medium flat rate box and you can have them for the cost of the postage ($10.20). I don't need them and you can play with them to see if that's truly what you want to do.


Bud, Thank you for the perches, I will put them to good use. To expand on my conversations with you for the others reading this post, Bud tells me that his threaded tube has a I.D. of 2.044". Given that our struts are 2" I will look into shiming it with 26 ga aluminum (.0178) stock and see how that works. Bud pointed out that this is not a weight bearing issue as the tube is supported by the reminants of the cut off OEM perch. I intend to use a 3M epoxy used to bond modern day body panels to cars which is the strongest bond I have ever experienced. So a light coat should keep the moisture and dirt out while preventing it from ever moving. Be careful with these ebay coil over kits, they are not all the same. And yes, I experienced the same thing trying to get some information from the sellers. The differences are material, some are steel, stainless steel, and aluminum. I believe you want the aluminum. Also they come in different lengths, some are 0-3" adjustable and some are 0-4", although they all look the same. But there are ones that are obviously shorter and taller. Needless to say, try to get the longest ones you can. I am estimating that the most common length is about 4". You also want the version with the two perch locking nuts on each tube, the single nut with the set screw to lock the setting does not work from what I have read. The springs on the kits are worthless but we don't need them anyway. The kit you are looking for is for a Honda Civic/CRX 1988-00 Coil Over Kit. There are many listed for the Civic and CRX without a year, and the one reply I did get, told me the I.D. for the tube was 5".

The springs used on the kit is a 2.5" I.D. which is readily available in the US. As opposed to the 2.25" I.D. used in the UK. DB's kit is also an aluminum tube and 2.5" springs. I decided to go with 12" QA1 Springs 80#as I believe this will put the perches 2/3 the way up on the tube for a stock ride height. Maybe. Bought them from directly Summit Racing for $37 a piece on their website, which is strange as they sell the same coil on ebay for $47.90. So it pays to search a bit.
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PostPost by: elj221c » Thu Oct 11, 2012 3:35 pm

gearbox wrote:
elj221c wrote:It is a thought and only that but do you really need adjustable spring seats?


I think many of us go through this route in order to gain more room to fit modern day wider tires as the selection of 155's these days are few and far between.


Yes, of course. I probably didn't describe my set up too well. What you see is what I ran, with the addition of an alloy spacer at the bottom of the spring as after the body was fitted it ran too low. Plenty of clearance even with 7" rims! Adjustable platform Spax on the front.
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