Lotus Europa Forums > Technical Articles and DIY tools and tips
RICHARD MANN'S UPPER LINK AND REAR SUSPENSION MODS TO 7004100119Q
Lotus 47:
I'll get some more photos of the drive flange, and show how it replaces the existing Europa bits. There are a few things to observe for the uninitiated!
This next photo shows the forward mounting for the trailing arms. I pulled the engine out last weekend and thought I should take a picture of the mount in situ. I have more photos buried on a hard drive somewhere. I'll dig them out.
I never liked the rubber bushes at the front of the trailing arms. They were designed for axial load in the rear suspension of a Rover P6. My original ones were stuffed, and I bought new replacements, but they looked dodgy to me. So after fitting ball joints and upper links at the rear of the trailing arms it made sense to locate the front of the trailing arms precisely with ball joints.
The bolt is 7/16", so I bought 2 generic 7/16" ball joints. I machined a tube about 25mm long, which would accept the ball joint inside with a light push fit. The wall thickness of the tube is about 2-3mm to fit. The rest is 3mm flat plate and some simple stiffeners. I used a stick (arc) welder to make these 20+ years ago and they are still working perfectly with no signs of wear to the bush, or cracking of the fabrication. I also made a steel spacer so I could re-use the existing 7/16" bolt.
Note that the ball joint is held in by simply crimping or distorting the tube. Crude but effective! No point in over engineering.
Cheap & cheerful, and very effective. I did experiment with different rubber bushes, and it was a complete waste of time. I found under hard acceleration the car squirmed. You could feel the rubber bushes deflecting each side which cause a touch of rear wheel steer.
Now you can hit the accelerator, drop the clutch, light up the rear wheels and it will launch straight.
This is one of my favourite mods because it is so simple, and one that is rarely mentioned.
BDA:
Nice mod, Richard! It looks very efficiently done (on many levels)!
What am I missing? That picture is taken from the inside of the backbone, right? (it seems like it would be easier to adjust the rear toe if the bolt were turned around - i.e. we would see the bold head in this pictures - another reason why I think I'm missing something) The crimps in the tube keep the ball joint from going into the backbone. What keeps it from falling out?
I have found with the rod ends on my rear suspension that they wear pretty rapidly. After a few thousand miles (don't know how many because my speedo didn't work then) the rod ends lost all their preload and they could easily be moved in the race. Obviously, they aren't worn out but I was concerned enough to get rubber boots for them. It sounds like you don't have any issues with the ball joint wearing out? Do you think that's because it is shrouded in the tube or do you have some sort of seal to protect it (given how simple you made it, I thinking not).
I remember the bolt fits either the trailing arm or the original rubber bush but I don't remember which. Is it the trailing arm?
Has your toe setting been very stable? Have you had to adjust it over time?
TCS4605R:
I have always thought that the rubber in the trailing arm mounts and in the gearbox mounts at the rear of the frame deflect enough to change the rear toe-in when you back off the throttle or brake hard. My thought is this rubber deflection is what can make the car 'tail happy'. Anyone have any thoughts on this?
Lotus 47:
--- Quote from: BDA on Tuesday,October 04, 2016, 02:18:41 PM ---Nice mod, Richard! It looks very efficiently done (on many levels)!
What am I missing? That picture is taken from the inside of the backbone, right? (it seems like it would be easier to adjust the rear toe if the bolt were turned around - i.e. we would see the bold head in this pictures - another reason why I think I'm missing something) The crimps in the tube keep the ball joint from going into the backbone. What keeps it from falling out?
I have found with the rod ends on my rear suspension that they wear pretty rapidly. After a few thousand miles (don't know how many because my speedo didn't work then) the rod ends lost all their preload and they could easily be moved in the race. Obviously, they aren't worn out but I was concerned enough to get rubber boots for them. It sounds like you don't have any issues with the ball joint wearing out? Do you think that's because it is shrouded in the tube or do you have some sort of seal to protect it (given how simple you made it, I thinking not).
I remember the bolt fits either the trailing arm or the original rubber bush but I don't remember which. Is it the trailing arm?
Has your toe setting been very stable? Have you had to adjust it over time?
--- End quote ---
1 - the photo of the trailing arm bush is taken from inside the chassis
2 - the bolt heads are on the outside, because the trailing arm is VERY close to the chassis, and there is not enough room for a nut and washer
3 - the steel bracket I fabricated has a clearance hole for the 7/16" bolt. Lets say the hole is 1/2". That stops the ball joint from falling outboard. A picture tells a thousand words and I don't have a picture on hand.
4 - My first upper link design was fitted to my 4 speed, and I used ball joints with nylon races. They pounded out in no time. So spend the money here and buy ball joints with stainless steel balls and stainless races, with a Teflon insert.
5 - the bolt in the front of the trailing arm is 7/16". There is a steel bush welded in to the trailing arm, with a 7/16" holes through it. I didn't want to unnecessarily modify the trailing arm, so I kept it standard and re-used the original bolt.
6 - I particularly dislike the 105E Ford engine mounts and rear gearbox mount (R16 part) They provide heaps of compliance, which means the engine can roll around like one of these silly emojis :FUNNY:
As soon as you drive the car hard, the engine and gearbox are jerking around all over the place. You go from 2nd gear and can't find 3rd cos it ain't where it used to be. The twin cam went some way to solving this by adding a decent mount to the rear of the box. You can clearly see my solution in the "bare chassis " photo
7 - my rear suspension settings are stable. I run 5.5" Cosmic mags and 205 rear tyres. I trimmed the rear guards to make this fit with the original suspension, and my twin link runs identical track as far as I can tell. The camber is no more than 0.5 degrees negative. I like to run the tyres fairly square to the road to maintain a big tyre contact patch. I run about 4mm toe-in. That is a difference of 2mm per side between the rear of the tyre and the front of tyre.
Lotus 47:
--- Quote from: TCS4605R on Tuesday,October 04, 2016, 02:31:41 PM ---I have always thought that the rubber in the trailing arm mounts and in the gearbox mounts at the rear of the frame deflect enough to change the rear toe-in when you back off the throttle or brake hard. My thought is this rubber deflection is what can make the car 'tail happy'. Anyone have any thoughts on this?
--- End quote ---
Hi Tom,
I see you have found my thread!
In the previous post you'll see my thoughts on the rubber in the standard set-up. I am not a fan!
On a road where you have 2 lanes , often I would find the car darting all over the place as I changed lanes.
Fitting ball joints helped.
Fitting the twin cam style rear gearbox mount helped.
Fitting different engine mounts helped. MORE ON THIS LATER
Understanding what the front suspension was doing helped. THAT'S A WHOLE NEW TOPIC CALLED BUMP STEER!
There are many many interlinked issues going on in the rear, and I will try and address all of them.
A standard 80hp S1 is a delightful and nimble car to drive. Put 100hp or 120 hp into and S1 or S2 with fat sticky tyres, and things start to move, loosen, break, etc.
Hopefully I can answer all your questions on line here, so they can be shared with everyone, but feel free to contact me on email richard.mann047(at)gmail.com
Cheers!
Richard
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