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RICHARD MANN'S UPPER LINK AND REAR SUSPENSION MODS TO 7004100119Q
Lotus 47:
I've started this topic to record lots of details on my upper link rear suspension fitted to my 1970 Type 54 S2 - 7004100119Q
There is some existing information at
http://lotus-europa.com/0119q/index.html
A number of modifications accompany this upper link, so there is a lot to absorb.
Why did I do this? I was sick and tired of changing universal joints, and frustrated by the LH drive flange constantly coming loose. A fellow Europa owner lost his LH rear wheel on the track, probably as a result of constantly applying high torques to his LH stub axle nut, to the point where the end of the stub axle and nut disappeared into the weeds, while his whee,l brake drum and drive flange shot off and hopefully didn't hit anything.
My initial aims
- replace the U/J's with CV joints
- add an upper link because the CV joint is designed to change length, and cannot replace the fixed length drive shaft
- find an alternative to the Hillman Imp stub axle
My assumption for the upper link was that it should have a length that is a close as possible to the fixed length drive shaft it was replacing, and that the installed angle of the link should match the installed angle of the fixed length drive shaft.
As a starting point, let's look at the inner upper link mount. The casing of the Renault box is massively strong where it mates to the bell housing, so I built some brackets to pick up existing bolt holes.
I used a piece of 3mm mild steel for the rear flat bracket, and a piece of 3mm thick steel angle for the front bracket. The front bracket dictated where I could mount easily onto the bell housing.
Look at the photos and it is all pretty much self explanatory.
Please note the photos show a Type 395 box which is a 5 speed. The Type 336 4 speed will be very similar.
This design assumed CV joints, and used a complete CV drive shaft from circa 1980 Alfa Romeo Alfetta. These cars used a rear mounted transaxle and de Dion. I happen to own an Alfetta when I did this modification.
The drive shafts are unmodified . I did not want cut/shut shafts in this design, or get new shafts made. I am always very cost conscious when I make a modification.
The drive shafts and links have now been installed for about 200,000km with engines varying from 120-160hp.
In this first batch of photos you will see my links. These are simple ERW tube 1" diameter, with mild steel bosses. The bosses are brazed using what Aussies call "silver solder" or COMCOAT silver 45. I used 1/2 ball joints so they would mount to the existing fasteners for the lower links. All ball joints are RH thread. Half a turn provides accurate setting of the suspension.
EuropaTC:
Excellent, I'm looking forward to the next installment. Your take on mounting the top link is an interesting one, I don't think I've seen anyone do that before.
Brian
BDA:
I'm interested in the next installment, too. A friend who is building an S2 with a Ztech is implementing your design and I've been following his progress.
My understanding is that you are preserving the original geometry and taking loads off the drive shafts. I understand that the rear wheel bearings were a weak point in the S2s. Does your mod help that situation?
Bainford:
Yes, I'm very interested as well. I'm interested in the modifications and the reasons for them. Cheers :beerchug:
Lotus 47:
I have found the rear wheel bearings to be Ok. My BMW stub axle conversion has a 30mm shaft, so the inner bearing is now a standard 6006-2RS. The 2RS means the bearing is fitted with 2 Rubber Seals. I might be onto my 3rd set of of rear wheel bearings after 29 years and 250,000km.
Here are a few photos of the CV, the mounting flange and its proximity to the inner upper link mounting brackets.
I've also added some photos from inside the bellhousing to show the tightly bunched bolts
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