Lotus Elan

Adjustable rear control Arm

PostPost by: alexblack13 » Fri Nov 06, 2009 4:51 pm

Hi all,
Turned out the l/h die works fine even on the en8 steel. Made the 1st turnbuckle and moded it slightly. You might be able to see the dimensions from the wee sketch Mk1 is laid on. Still have to grind the flats for a spanner.

I have cut metal for 4 sets of these turnbuckles. Remember you guys will need to supply your own nuts and the tube adaptors to be welded into your 'A' frames. The set I bought from mcGill are fine but I need to run a tap through them just to finish the threads. They still need turning to fit the inside of your A frame tube. The inside dia of which can vary I am informed. So dont turn these untill you have prep'ed your A frames. You can custom fit these using the cutting of tube you remove.

I can also let anyone with their own machining facilities have the steel blanks. (25mm Dia EN8) Good quality nice strong stuff. As you can see below cutting it is not a problem.

Makes a good winter project this. I am fitting a recon'd 3.54 diff at the same time as doing this mod'.


Getting there. I will keep you posted.

Alex....
Attachments
A frame mods etc 005.JPG and
near finished turnbuckle.Tube adaptors and nuts shown also..
A frame mods etc 010.JPG and
thats me sitting on my bike sitting on top of my machine
A frame mods etc 008.JPG and
mounted and centered
A frame mods etc 009.JPG and
Onto the lathe with it...
A frame mods etc 007.JPG and
Half way thro after about 20 seconds
A frame mods etc 006.JPG and
Band saw makes quick work of cutting off the 90mm long blanks
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PostPost by: john.p.clegg » Fri Nov 06, 2009 7:33 pm

Alex

Just looked at your turnbuckles and it seems that there may be a problem,I had to make the screwed portion longer to allow the tube adaptors to fit inside the tubes??

John :wink:
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PostPost by: Jas » Fri Nov 06, 2009 9:17 pm

Hi Alex

What a nice machine park you have there can't help being a little envious.
Only have a MIG welder and a pillar drill myself, but luckily have access to the rest at work.
Your turnbuckles will fit nicely with the rest of the winter project.
Attachments
IMG_2017.JPG and
Winter home work
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PostPost by: alexblack13 » Sat Nov 07, 2009 12:23 pm

Hmmm... Lookin good Jas... Very neat n tidy. My place looks like a bomb site! There is a fully stripped Lambretta sitting there most of it on my bench !! :? :?

Cool...

Alex 8)
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PostPost by: alexblack13 » Sat Nov 07, 2009 7:25 pm

Hi All,
Yep! Poss right John, I am testing with two pc's of tube clamped to the bench right now and I am going to narrow down the center flatted section and make the threads 40mm long. One needs to make the center section as narrow as poss'. I am getting 20 mm thread engagement right now. Looks fine. The adaptors protrude about 1cm from tube ends. perfect welding space. I will see what happend when I slim down the center section. Trying to get a dimension of the complete component, inc lock nuts of no more than 50 mm. Easy to do when making the wishbones at the same time. Cutting a lump out of the 'A' frame and fitting the device into the 'A' frame iss a diff matter.

I should have the final design / part ready tomorrow morning.

As Normal I will keep you popsted. No one with an old A frame I can use for testing??

Alex B.... 8) Welding goggles at the ready! 8)
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PostPost by: alexblack13 » Thu Nov 12, 2009 2:46 pm

Hi Guys

Just a pic or two of the turnbuckles I made. Machined from EN8. Tough stuff but V strong. They are 92 long with 40 mm thread length. Now
plucking up courage to take off my a frames and fit them. Any day now.

Off to the N.E.C. (Via London!) this weekend for the classic show. I don't have a big shopping list this year though.

Have fun...

Alex..
Attachments
turnbuckles 003.JPG and
turnbuckles 001.JPG and
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PostPost by: h20hamelan » Thu Jan 02, 2020 7:21 pm

11 years and counting
Wondering please, has anyone used anything more modern. Or with modern parts cross reference?

Can?t seem to find on

http://www.springfixlinkages.com/en

I absolutely hate Amazon facial recognition

https://www.amazon.co.uk/Tyagi-Racing-S ... -1-catcorr

Ebay changes it to .ca or Canada, and I am sure the country you are in will correct

3/4"-16 UNF Thread Adjusters Jack Screw Turnbuckle AutoBlack Insert Half Jam Nut

https://www.ebay.ca/itm/332079963838?ul ... noapp=true
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PostPost by: snowyelan » Thu Jan 02, 2020 7:53 pm

The last 2 links look like what I used. I'd have to check which size it was. There's a thread on here about how to do it.
Lessons learned. A step and a chamfer are required to get them into the arm on one of the sleeves. The other just requires a step. Drill a small vent hole in each side of the arm tubes. It allows the heated air to escape somewhere besides thru the last bit of weld.
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PostPost by: Foxie » Thu Jan 02, 2020 7:57 pm

andyelan wrote:Hi Eveyone

This design looks a bit scary to me. I would have thought the idea behind the frame being fully triangulated was specifically to prevent it flexing. With this arrangement I can't see how adjustments can be made using the turnbuckle without putting a lot of stress into the welds. Still I suppose the designer has done all the appropriate stress calculations and is satisfied it's all ok

Regards
Andy


I had my Plus 2 for many years before I eventually checked out the rear suspension alignment. The design rear toe-in turned out to be considerably (and unequally) toed-out.

The cambers were also (and unequally ) wrong.

I fitted a pair of Spyder adjustable rear arms, also a rose jointed upper arm on my Spyder IRS, and set them exactly to spec.

The straight-line stability of the car was completely transformed for the better.

I had a problem with an upper rose joint pulling out of its mounting ring. (Rose joints are not meant to take acceleration and braking axial loads, as they do with the Spyder IRS )

I contacted Spyder and they very soon supplied a set of uprated rose joints, which have been trouble free.

BTW, the rear arms are still fully triangulated, and the tubes are only axially loaded (apart from minimal inner bush torsional stress )

Working with similar section tube, there would be more than enough flex to accommodate the adjustment, and there would be very little stress on the welds.

:)
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PostPost by: snowyelan » Thu Jan 02, 2020 8:00 pm

Scott
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PostPost by: h20hamelan » Thu Jan 02, 2020 10:35 pm

snowyelan wrote:The last 2 links look like what I used. I'd have to check which size it was. There's a thread on here about how to do it.
Lessons learned. A step and a chamfer are required to get them into the arm on one of the sleeves. The other just requires a step. Drill a small vent hole in each side of the arm tubes. It allows the heated air to escape somewhere besides thru the last bit of weld.



Not sure if CeeJay (or even if it was Col) dimpled the rod end, and recessed the insert to accommodate heat. Maybe drill there, and fill or...
It looked like a depression, where the rod end was peened into the recess. Presumable to keep from rotating, or any other inward or outward movement.
Ive been looking for the thread or pic for a while. Ah well.

Good stuff, thanks folk
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PostPost by: ceejay » Thu Jan 02, 2020 10:51 pm

The threaded Inserts/weldins are/were bronze welded in, Tubes were drilled and cleaned, the dimple you refer to is the shrinkage of the bronze as it is pulled into the joint on cooling. Method is also called plug weld...common when TIG welding inserts into tubes. Carroll Smith covers all this kind of work in his fantastic books.
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PostPost by: h20hamelan » Fri Jan 03, 2020 2:11 am

Wow, cool. Thanks
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PostPost by: h20hamelan » Fri Jan 03, 2020 7:47 am

It was in your video I noticed the dimpled wishbone tubes Dr CeeJay
Thanks for all your efforts
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PostPost by: ceejay » Fri Jan 03, 2020 10:11 am

Hey Wow...thanks for the Dr reference, never had that before, but used to get called the Colonel on other forums because I used to sign off as Col. Hope your project all works out OK.
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