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Discussion Starter #1
Hi all,
To recitre the Beatles, "It's been a hard days work all night, and I've been working like a dog".
I am working on my 1990 Turbo SE to change all bushes. So missing the radius arm bushings, I need a good advice or two to loosen the bolt that goes through the bushing end of the radius arm. I've managed to take it all off the car and left side is completely dismantled. But right side is now on the bench or floor, depending on what I tried.
So, I tried penetration fluid, heat, cold shock, a big hammer, but to no avail. No go. It's stuck. I would very much like to free the bolt (11,1mm as per rubber bush), and save the arm, so I can try to finds someone local to me, who can enlarge it to 12,2mm to adopt the later style 12mm bolt for the Lotac poly arm bush. Small machine shops are very hard to come by around my waters.
For now, I've left it after 9 hours of trying, and gone home ;) Sprayed it many times with penetration fluid, not wd40, but a "rust loosener". Will check back tomorrow and bring it home and spray it every couple of hours over a few days.

Any idea are most wellcome.

Cheers,
Redfox.
 

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Wingless Wonder
1988 Esprit Turbo
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My past experiences (not with a Lotus though) have included the need to slice the bolt away with a Dremel...then pressing the old bushing out.

But first, continue spraying with penetrant, and don't forget to caress it with a BFH each time so that the vibrations will help work the solution in.

Anecdote: A friend had similar stubborn hardware to loosen, and the final thing that worked was to drip Armour-All into it. No kidding! :giggle:
 

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Discussion Starter #3 (Edited)
Thanks!
Okay, so success!!
I bought a bottle of ATF oil and mixed it 50/50 with acetone in a small oil lube can. Dripped it every½ hout for 2 hours, and then the darn thing went loose.
Could rotate it, and then drive it out witut too much force.
So, what I can say is this: ARF and acetone is by far the most efficient rust dissolver/screw loosener I've ever tried. Worked miles better than the expensive sprays I have bought for the occasion.
Highly recommended.

1262365


Here, after only 2 hours with atf/acetone every ½ hour, it's loose to turn and I have moved it a bit deeper into the radius arm-tube. More fluid for 20 minutes.
1262366


And here are the parts minus a big thick square shimplate, that is outside the picture.
1262367


Perfect. Now I can continue to clean it up, glas bead blast it and have it rebored to 12mm, so it can fit the thicker 12mm bolt which is needed with the late Lotus Lotac polyurethane radius arm bushings.
Thanks to all,
Redfox
 

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Thanks for sharing the detail

Great road map for me as i will be changing this bushing.

Question - does that arm move in two axes, up and down and in and out little. Or, does it just move up and down.

I was looking at it last night and was not sure. As I think about it has two move in and out because the top suspension arm gets shorter as it moves up and down which would pull the radius arm in and out.

My point is, i may look at designing a way to capture a spherical bearing there.

Installing a stiffer bushing seems like it would add resistance that the suspension is fighting as the arm tries to move in and out against the poly. And this causes the wheel rate to vary.

I could see that causing me at least a 10th of a second in the HDPE grand prix ;-)
 

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Discussion Starter #5 (Edited)
Ha ha! Possibly.
But seriously: no, I don't think so.
Yes, as the suspension travels, the distance will vary. The softer standard rubber bushing will deflect more in all directions, amking the track more unstable. This is solved by Lotus by doing this relatively stiff but still soft polybush. It is a tad softer than you may find many other poly-ones to be (hard track ones).
If it just moved up and down with no radius change, a normal tube-like polybush like on the link arms could have been used, I suppose.

I think the positives overdo the negatives.

I have btw. ordered spherical bearings for that same purpose ;)
These have no weather protection, and have to be taken off and lubed regularely. I was thinking for example Campagnolo white grease, which is temp. and water resistant.
There may well be something smarter. Can be done every year (on a low milage basis) together with regreasing wheel bearings ;)
And what is your roadsurface like?

Here's my procedure:

1/ jacked the car up both sides rear over a pit.
2/ removed both rear wheels.
3/ placed old rusty steel wheels under the sides og the car.
4/ sprayed rustloosener (now home mix of ½ atf/½ acetone - works brilliantly) on all connections that I need to work on.
5/ loosened and semitightened both ends on brake tube on each arm.
6/ removed the heat shields on left side next to tubular manifold.
7/placed a small jar under each brake tube connection and let it drip and drain.
8/ loosened outer upper rear link arm each side.
9/ loosened the through bolt on the radius arm, each side.
10/ loosened and removed the two shim-holding bolts on radius arm mounting plate, each side.
11/ loosened the two bolts beetween the rear hum and radius arm each side.
12/ pushed the bolt out of the upper rear link arms, so they remain in the hub only.
13/ removed brake pipes and lay aside.
14/ removed the nut and pushed the central bolt in the radius arm bushing a little bit out, not all the way, each side, and lifted it carefull out and away from the car.
15/ this is to avoid mixing and eventually loose any shim setup there may be, as I've just measured the rear toe before doing this, and it is precise.
16/ the bolt through the radius arm on the right hand side, was stuck inside the tube in the radius arm, so lubed it with acetone/atf mix, and did this a couple of times, and voila, it came out and no harm was done.
17/ split washers from later v8 models fit and are easier to use, check and remove/install, when doing geo in the future.

I used a mix of ring spanners (on for example outside nut on the through bolt at the bushing on the radius arm), 1/4", 3/8" and 1/2", plus various extensions for each set.

Again, I cannot stress how helpdull the home mix of acetone and atf was. Nothing happened with expensive aerosols, no heat, no freezespray, no big hammer etc. but this did it in just two hours, and I could be her eon the forum meanwhile, drinking a nice cup of tea.

In the same line of thinking, I was thinking about adjustable lower front ball bearings, as they can be dialed in to have extremely easy move, but no play. All the time. They exist fot Elise, but are too small, and noone wants to make them for the Esprit. I'd certainly have two sets, and have less stiction in the complete front setup.

Cheers,
Redfox
 

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If it just moved up and down with no radius change, a normal tube-like polybush like on the link arms could have been used, I suppose.

In the same line of thinking, I was thinking about adjustable lower front ball bearings, as they can be dialed in to have extremely easy move, but no play. All the time. They exist fot Elise, but are too small, and noone wants to make them for the Esprit. I'd certainly have two sets, and have less stiction in the complete front setup.
Very good point and I think we should work on front bearings. There is a company that sort of specializes in this type of suspension bearings in the US. I have been wanting to send them front bushes and ask them to quote doing a run. I bet we could sell 10 sets and get the price to be palatable.
 

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Discussion Starter #7 (Edited)
take a look here: I am not affiliated in any way, shape or form, other than wanting these for my Esprit ;) Take a look at these. Ifind them pretty trick. I don't know at this point, if they have any downsides, though. I spoke to the company, and they are too small and exists onlyfor the elise. But as an inspiration I think they could be worth looking at.


To me at least, it seems a little bit counter productive to spend all the money on fine polished non-stiction suspension (I just did) and then loose some on stiction on balljoints (etc.).

Cheers,
Redfox
 

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Don't fool yourself. That bolt is "special". It is just the right hardness so it won't bend but not so hard that it will break. That bolt is VERY important. A single point failure of that bolt and you can lose the rear wheel. As for the bushing, as the wheel rises and falls, the rear of the trailing arm is restrained and made to rotate not just up and down but in and out. A spherical fitting could be used but it MUST have enough range to allow for the movement in several planes. Unless you know what you are doing redesigning the suspension, the best advice is to put it back together with the best parts you can. Another point, torque that bolt to exactly the spec and only when the car is at ride height so you don't pre-load the bushing. If the bolt is bent AT ALL it should be replaced. Split shims are handy but if the bolt loosens up the shims all fall out. Whenever under the car that joint should be inspected.
David Teitelbaum
 

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Discussion Starter #11
Will do.
I intend to use the Lotac radius arm bushing for now, and only use original bolts, nuts and washers I ordered from the usual suspects. If they are selling original bolts, I just don't know. Some seems not to be original, as I discovered when working on the front end, hence me ordering new bolts from another supplier.
Redfox
 

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Hi Redfox
I am replacing all my bushings with Lotac on my G car.
I will not drill to enlarge the hole in my radius arm to 12mm, but instead use a thin wall sleeve to center the 7/16” mounting bolt in the Lotac bush.

Lars
 

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Discussion Starter #13
I am not an engineer, but married to one ;) But that's not her field. So, what would be the best technical/mechanical way to do?
Cheers,
Redfox
 

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I would not "drill" to enlarge. As Red mentioned several times he will use a local machine shop to precisely enlarge the hole. If you drill the hole out by hand the tolerances will not be tight enough and there will be some "slop". If the radius arm can flop around the whole point of a nice bushing is lost. The suspension will not stay in the correct alignment as the loads are applied during driving.

I dont have much experience with a home garage drill press, the tolerance would be better using a drill press but I think a lot has to do with the drill bit.

In my opinion a sleeve on the bushing end could also be a solution if done correctly. It seems like a sleeve would have to be made and it would be cheaper to have the hole enlarged.
 

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The tolerances we are talking about are not that fussy. Once tightened up the bolt moves WITH the arm, not moving around the bolt. The rubber bushing is what allows movement. The only concern about drilling is making the bushing too thin. If you do, then you remove the bushing and weld in a thicker one. If you are worried about tolerances you drill undersize and finish with a reamer. A thicker bolt would be a nice upgrade, giving that joint more strength and allowing you to torque the fastener more tightly. Don't overdue it and collapse the metal bushing in the rubber bushing. Install the bolt with Never Seize on it's shank so it won't get stuck in the trailing arm again.
David Teitelbaum
 

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The idea with a sleeve is only to center the bolt in the bushing with the larger 12 mm hole. This sleeve could be of plastic, or whatever!
When tightened, there is no contact between the bushing and bolt at all.
Personaly I will not enlarge the bushing in the radius arm. If, I would not drill it, but use an adjustable reamer, not to crook the hole in the bushing.
BTW. The electroplating on my radius arm is in perfect condition. I will not mess with that.
Lars
 

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Not to get off topic...I did a quick drawing/draft (attached) of what I think would work for a spherical bearing in this application. Similar to other bearings I have installed on race cars and street/track hot rods. I should add NOT TO SCALE :)

The only "hard" part is the bearing retainer, which would have to be cut. The rest is off the shelf or easily made in the home garage. If I made up 10 sets would people be interested? I would have to do one for my car first to test, so it would take a while. I would use a high quality bearing that can accept very high loads. After the prototype I could determine if we need a "high misalignment" bearing, this would ensure no binding but I think unnecessary.

The bearings are ~ $15 each. The conical spacers are a couple bucks a piece, safety washer ~$0.50. The bearing retainer plates are an unknown, have to be quoted from a machine shop.

i am thinking $200 a set?
 

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The rubber is there to isolate some of the road vibrations from the frame. You also must design in some method of adjustment for rear thrust angle (rear toe). I would also design a rubber cover to keep dirt and water out of the bearing. Some types of this kind of bearing also have a way to inject grease but now you are getting expensive.
David Teitelbaum
 

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It would potentially increase NVH a bit. In my experience with fun/stiff/loud hot rods its not really an issue.

Yeah, I was going to look, some of the spherical bearing/rose joint kits now available have a rubber cover. I would think there would be such a cover available in various sizes that could be added.

I also noticed when I was looking at the bearings that are commonly available there is a Teflon coated bearing, its a few more bucks. They advertise as being more weather resistant.

Bearings like this are definitely a maintenance item. Easily changed every five years in the proposed "design".

I think this bearing combined with the available adjustable top arm with rose joints added would take care of all of the joints that move in two directions, eliminating some stiction and designed in wear in the rear suspension. In the older Porsche 911s that have a swing arm its a popular modification and really seems to reduce stiction in the rear suspension on those cars. I felt like it improved ride quality and allowed the dampers to do their job more efficiently.

I was looking at the top arm on my car as its on stands, with wheels off and at full droop the rubber bushings are heavily contorted.
 

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Discussion Starter #20 (Edited)
Erik, have you measured it with the rubber bushing (17/404)?
And have you done the same with the LOTAC polybushing?
What is the deflection under a realistic wheelmovement up/down/in/out?
It would be interesting to plot that into a curve and print it out. Well, to me at least ;)
Are you using rose joints at both ends of the adjustable top arm, or only on the outside (near wheel)?
Do you plan to run this setup s a road car, or a track car (or a mix)?
What about stress cracking the chassis because of too little compliance when used on public roads?

I think that the teflon coated bearing may be for lubrification purposes and to avoid the need for greasing it? And to make it more silent in operation? Several companies describe that.
It would seem that a good bonded teflon liner in the bearing would have a minimum compressive strength of 40.000psi. If the bonding resin for the teflon liner should fail, it gets nasty. But if it works, possibly a tighter tollerance could be used, making it even more precise than a greased bearing. That's what I understood anyway.
I ordered a set from a UK dealer, so we'll see how that turns out to be designed.
I don't know how what rubber protection would look like, but I was thinking that it may last for a few years, and then be changed with the whole bearing. And possibly look into a poly protection in stead, but it needs to be closed somehow.
Meanwhile, I'll install the LOTAC bushings and see how that fares.

I've now had the radius arms enlarged to 12,05mm precisely (both ends and inside the bore), as the bolt I want to use, measure 11,9mm, possibly 11,92mm (not 12). Some of them even down at 11,7-11,8mm. So I steer clear of those.
Therefore reaming to 12,2mm is too much (as I've read that's the size to do some places).
The new bolts are now slick and fit in the bores. No slop but they can move. And be greased. Feels right and very snug.
I am having the radius arms regalvanized in "blue" - shiny as they were when new. They looked okay on the outer surfaces, but inside the bores in the tubes, they were not. So nothing is lost there. I'll make sure to block the bores before being glass bead blasted before regalvanising.
Personally, I like the idea of going 12mm setup from 7/16" as cars over the years developed morepower, more torque and having bigger wider tires and harder suspension. I want to make a repeatable good setup for my car, which makes 315Hp and 415Nm and rund harder bushings, harder coilover suspension and bigger wider wheels (8,5" with 235/40-17" front and 10,75" with 315/30-18" rear). I also want to do all alignment myself. I don't want to waste more moneyand time on geo-stations.
Another thing is, that measuring the bores in the radius arms when I took them off, revealed that over time, they bores have been ovalised a little bit. Hence another reason to enlarge that to the larger M12 spec imho.

There are many small "invisible" things under way, but I don't want to make it a pure track monster only. I drive "semi-hard" to "hard" on narrow curvy hilly backroads, but want the possibility to go on a trackday once in a while with maximum output from the cars setup.
It became an Interesting thread ;)

Cheers,
Redfox
 
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