Replacing Elan Front struts

PostPost by: nigelrbfurness » Fri Oct 15, 1999 1:51 pm

On Fri, 15 Oct 1999 [email protected] wrote:


now normal practice to replace the coil-over dampers as one assembly.
These are available manufactured by armstrong or monroe from any Lotus
dealer + Chrs Neils and Paul Matty.

Nigel Furness







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PostPost by: Roadrash at xxx.xxx » Fri Oct 15, 1999 1:52 pm

Dear all,

I have purchased my fathers original 72 Elan Sprint #190. The car needs some
updating. I'm in the process of contemplating the replacement of the rubber
in the front end. I would also like to replace the front struts and springs.
I do not understand how I will compress the springs to remove the struts.
Can anyone provide some detail for me.

Thanks,

John





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PostPost by: Rob_LaMoreaux » Fri Oct 15, 1999 4:07 pm


I just went through this with my '69 Elan.

You basically can't remove the springs from the shock on the original
Armstrong coilovers. Removing the coilover shock from the car isn't too
hard; just take the lower control arms off and the shock can be removed
by removing the nuts at the top. I bought Spax shocks with adjustable
spring perches for my Elan, but you can get Armstrong and Spax shocks
without arjustable spring perch. I bought new 16.75" 75lb/inch springs
(original size and strength), and ended up exchanging them for 14"
75lb/inch springs since I was told the 16.75" with adjustable perch
would make the car ride about an inch high, and I calculated that I
wouldn't be able to use the adjustable perch with the 16.75" springs. I
did a bunch of calculating to make sure I'd get original ride with the
new shocks. Eventually I'll go to different springs, but for now I want
to get a feel for the original

Getting the springs on the new shocks was a pain. I took them to a
motorcycle shop (most autoshops I tried just scratched their heads since
they didn't know what to do with a 2.5 inch diameter spring) where they
ended up compressing the spring 4 inch (the stroke length on their
compressor) then locking the compressor, moving the activating arm of
the compressor up and compressing 4 inches more so the ring that holds
the spring on could be installed. With soft springs you need a long
spring to obtain the correct preload for the car to ride at the right
height, hence the multiple strokes on the compressor.

To replace the bushings I used a ball joint press and various sockets
and tubes. If you have a hydraulic shop press so much the easier.

The rear struts are easier since you can use a Chapman strut spring
compressor (sold as a McPherson Strut spring compressor) or the weight
of the car if the body and engine are still on the chassis. For the
strut itself you unscrew the cap and remove the guts from the strut then
drop in the new insert (I bought a Koni since I wanted adjustable
struts) add some cooling fluid around the insert (I used ATF) and screw
the new cap onto the old body. You probably will have to clean up the
threads on the body of the strut where they used a centerpunch to ping
the old cap in place.

I hope this wasn't too long, and helps. I'm working on the fiberglass
now, and still hope to be done with the restoration next spring.


Robert D. LaMoreaux
4096 Central Blvd.
Ann Arbor, MI 48108
Phone: (734)-971-5583
Work phone:(248)-449-8284
Work Fax:(248)-449-2577
Email:[email protected]
Work Email:[email protected]
Too many Hobbies, Too little Time, and way too much work.
1969 Lotus Elan...It's not a restoration, it's a never-ending adventure.










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PostPost by: gobw2 » Sat Oct 16, 1999 1:19 am

on 67 elan -Remove locknuts, washers, rubber bushings from end of strut
to disengage anti roll bar . remove wishbone bolt, and bolt to vertical
link. back off on wishbone chassis bolts, let wishbones drop. undo
nuts, remove washers, bushings at top of spring damper unit. drop down. I
had spring damper units rebuilt as an assembly. rebuilding a 28 year old
damper yourself is doubtfull. wear and corrosion.





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PostPost by: sprinterdave » Sun Oct 17, 1999 7:01 pm

In message <[email protected]>, [email protected] writes

firms, Pat Thomas, spider etc will do the job for you at around ?10
side. I compress my own springs with normal spring compressors but I
have two specially made end "boxes" with lugs for the compressors to
attatch to. These are made from 1/4 steel and have a hole cut in the
tops so that the shockers will just pop through. If you live in t he SE
of England I would be willing to lend them.
email [email protected]
Dave Shiers

--
David Shiers





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PostPost by: Foxie » Mon Oct 18, 1999 6:54 pm

Here is my 2 cents on front struts.

First remove the roll bar completely, disconnecting the chassis links first
(refit in reverse order)

It's not necessary to remove the lower wishbones, just loosen the chassis
pivot nuts and the trunnion nuts so the lower bush is no longer clamped
between the wishbones

Remove the lower shock securing bolt, top securing nut(s) and drop shock
unit down between lower wishbones.

You can make up a spring compressor using a piece of steel plate with a 1
3/4" hole (through which the lower end of the shock fits), and two more
holes drilled to take two 20" lengths of 1/2" threaded bar. Weld on pieces
of 1/8" x 1" flat bar bent to hook the spring coils to the ends of the
threaded bar. I found a suitably sized pipe flange with all the right sized
holes already in it.

Hope this helps.

I recently bought a set of SPAX adjustables and springs from SPYDER for my
Plus 2. The front end of the car was 3" higher with the spring perches in
mid position. I then replaced the 15 1/2" springs which came with the units
with my 14 1/2 " original springs. Even now with the spring perches wound
fully down, the front of the car is still almost 2" too high. I could use
a shorter spring, but I may be running out of bottom travel. I wonder if
these type of units are intended for another application, they seem far too
high for the Plus 2. Does anyone know if SPAX units are available in
different lengths ?

Sean Murray
1970 Plus 2S
Wexford
Ireland






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PostPost by: Rob_LaMoreaux » Mon Oct 18, 1999 8:24 pm



The shorter wishbones of the Elan (as opposed to the +2) make it
difficult to impossible to get the spring and damper out by going
between the wishbone arms. Since he was going to replace the bushings
also, taking off the arms made sense.

****Snip****

I'll have to look into you spring compressor design when I decide to go
to stiffer springs.

****Snip****

I don't know why they'd send you springs longer than stock. I found that
in order to take advantage of the adjustable perch I needed springs that
were about 2 inches shorter if they were the same rate.

You need to take the uncompressed length of the stock spring minus the
compressed length at the correct ride height times the spring rate to
get the static force on the spring. The static force will be greater
than the corner weight since the wheel travels almost twice what the
spring is compressed.

Now take the static force and divide it by the rate of the new spring.
This is the amount the spring will be compressed when the car is
stationary.

Now measure the length the spring will be when the car is at the correct
ride height (the shock/damper halfway compressed) and the perch is set
to mid travel. This is the new compressed length.

Add these last two numbers and you have the uncompressed length of the
spring.

On my Elan the stock spring is 16.75" x 75 lb/in, and I calculated that
a 14" x 75 lb/in will give me the correct ride height with the spax
adjustable perch. Of course I don't have the car back together yet, so I
can't say positively that I calculated correctly, but I am confident I
can adjust the perch to make up for any miscalculation. I would err a
bit on the shorter length since you probably will prefer a lowered ride
height over a raised height.

I hope this wasn't too confusing. I had to sit down with the physics
book, the vehicle dynamics book and a calculator to figure out what was
going on so I could understand what I needed. And people wonder why I
keep so many books. <grin>


Robert D. LaMoreaux
BT Electronics LLC
459 E. cady
Northville, MI 48167
Phone:(248)-449-8284
Fax:(248)-449-2577
Email:[email protected]
Alternate Email:[email protected]







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PostPost by: Foxie » Tue Oct 19, 1999 12:53 am

-----Original Message-----
From: Rob LaMoreaux <[email protected]>
To: '[email protected]' <[email protected]>; '[email protected]'
<[email protected]>
Date: 18 October 1999 21:29
Subject: RE: [lotuselan] Replacing Front struts

clamped between the wishbones


Yes Robert, you're right, I hadn't realised this. The longer wishbones
in the +2 must also mean that the springs are at a considerably greater
angle from the vertical, introducing another factor other than pure weight
when comparing the "Just 2" with the +2 springs. I've seen references to
the greater track of the +2 making a difference in road manners, but an
upper wishbone length of 9.07" compared to 5.75" must also have the effect
of reducing camber /track changes at extremes of suspension travel.

I discovered my front spring rates (110 lbs/in) using a bathroom scales, a
tape measure, an upper pivot with a wide base, and some concrete blocks.
(The springs were off the shocks, off course).

Sean Murray
1970 +2S
Wexford







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