swb reinforced banana arm

[andrea70]

Hallo. I'm not able to find a photo about an swb banana arm reinforced with welded pieces. I found lot's of st and rsr photos (long arm) but nothing with my short arm. I know that bonomelli used it during first years in targa florio.
Thanks for any help, i appreciate so much.
Best
Andrea

[andrea70]

.... Nothing?....
And photos about reinforced engine mounting bracket?

[chris_seven]

The best thing to do is to shorten a longer steel arm as this will also give a much better bearing arrangement, a cheaper ventilated disc and a 3" caliper mount.

It will slightly widen the rear track but if you fit 911T/R type flares it will all work out.

Engine Mounts

[andrea70]

thank you Chris.
About the first question, i'm afraid to cut an re-weld a so important piece.... i'd prefer to add a reinforcement plate to the original...

e.g. what about this item?

http://cgi.ebay.it/ws/eBayISAPI.dll?...#ht_1032wt_907

About the second question, i'm reffering not about the engine mounts (i made the same reinfocement), but about this item:

[1QuickS]

The LWB trailing arms were reinforced for racing (RSR) because they are weak in bending where they attach to the bearing housing, the swb attachment is MUCH stronger as the banana tube is merged with a tubular extension which is integral with the cast steel bearing hub...this is probably reason for the redesign, to reduce cost of an expensive steel casting.

[Alan.uk]

Hi Angrea,

I am not sure if you have seen these pics. We did this work to a standard steel 72/73 arm, but could do the same to a shortened arm. We have also done this mod to the steel 69-71 steel LWB version.

Original RS compared to standard


close up of an original


These things are not easy to find so instead we made the additional metal support and welded it in as per original RS.



Porsche's welding was never that tidy so I guess our re-creation is not exact :lol:

[chris_seven]

Lets face it neither design is particularly stiff in the bearing housing area and the RSR reinforcement makes sense.

The stiffening web on the standard LWB arm is generally cracked on older arms and it is a good idea to replace this part with 3mm thick steel.

There is also generally a bit more leverage on the LWB arm so I imagine it will flex with 11" wheels.

The SWB arms tend to bend at the bush end on rough roads but I think that they also flex significantly around the bearing housing and cause some toe changes.

When you shorten LWB arms and add the RSR style stiffening and fit them to a SWB car the improvements are significant.

DUEL Motorsport in the Netherlands advertise modified SWB arms with modified bearings but I have never found out the detail of the changes but their cars are stunning around Spa.

[Flieger]

Wow, the stock pieces do look rather weak in bending at the bearing housing. Seeing those photos, I really wish I had the RSR reinforcements on my LWB, but I did not think of that when I had the rear suspension off. Oh, well. That is something for next time.

Alan or Chris, do you offer reinforced arms in exchange for cores?

[chris_seven]

Max,

If you fit aluminium arms they will be very good and easier than shipping across the pond.

or I could send you all of the strengthening plates so you could have them welded up locally.

Cheers

Chris

[Flieger]

If I use the Aluminum arms, I run into geometry issues with my '71S. It is even more so since my rear damper towers have been sectioned and raised by about 2 inches. The dampers would hit the inside of the holes through the crossmember. I would rather use RSR reinforced steel arms, like Neunelfer (Eric Shea) is doing, and maintain the correct geometry.

Otherwise, I would go with the Aluminum, for its greater stiffness to strength ratio over steel (due to less density and having material further from neutral axes).