chassis strengthening 911 race car

jonny911 · Post by **jonny911** » Tue Oct 13, 2009 9:16 pm

Just about to start work on my 1969 911 for HSCC roadsports championship. Can anyone advise me as to where a 911 chassis- body can be improved in the way of stiffening either by adding bits or welding seams.
I know that the factory did work like this but I have no details.

911hillclimber · Post by **911hillclimber** » Tue Oct 13, 2009 10:28 pm

Search for pics of old race 911's.

Years ago Bob Watson made an RSR from a ratty 911E. The build details were shown in a series of a glossy classic car mag in good detail.
or
Simply go to a historic race meeting (ie SPA) and take a zillion pics.

Finally:

go to www.race0cars.com

Find Archives section: click
Find Porsche : click
There are lots of race cars for sale of every type with great pics.

Above all the basic shell has to be tip-top before the multipoint cage goes in.

Nick Moss · Post by **Nick Moss** » Wed Oct 14, 2009 8:10 am

What is allowed in the regs?

davidppp · Post by **davidppp** » Wed Oct 14, 2009 8:13 am

hello, Nick.

Nothing at all..in the regs.

What happend under the skin is of course a whole 'nother story.

Kind regards
David

Nick Moss · Post by **Nick Moss** » Wed Oct 14, 2009 8:33 am

What is disallowed then?

johndglynn · Post by **johndglynn** » Wed Oct 14, 2009 4:36 pm

nick-moss wrote:What is disallowed then?

LOL, liking this thinking :D

You can seam pretty much everything in a 911. Seam welding it makes a nice difference. Adds some weight though.

Nick Moss · Post by **Nick Moss** » Wed Oct 14, 2009 5:32 pm

We have seam welded several shells, but it's very obvious, so if not allowed you will be in trouble. There is a lot of strengthening in rally shells, but should be unnecessary in a race car. All you should need is a good cage, welded to the pillars if allowed.

Lightweight_911 · Post by **Lightweight_911** » Wed Oct 14, 2009 7:09 pm

I'd speak (or send a pm) to Robert Barrie (one-two here on DDK) - he's been racing 911's in thr HSCC for years.

Bill Brown · Post by **Bill Brown** » Thu Oct 15, 2009 9:37 am

A few years later as the wheels got wider for racing tyres, the factory found it necessary to weld additional brackets in the centre of the rear suspension cross tube which were then welded to the floor tunnel.

If you have it apart I would think this is worthwhile although you will not be using such wide tyres.

Alan @ CanfordClassics · Thu Oct 15, 2009 9:10 pm

Hi John,

In case a pic helps here is the mod Bill reffers to.

HTH

Alan

Nick Moss · Post by **Nick Moss** » Fri Oct 16, 2009 7:42 am

As Bill mentions above, those areas of strengthening were designed to help with 300+ bhp and 11" rims with very sticky tires, but will be unnecessary with your 2.2L and 150ish bhp on narrows tyres.

one-two · Post by **one-two** » Fri Oct 16, 2009 11:10 am

2.2L?

Nick Moss · Post by **Nick Moss** » Fri Oct 16, 2009 5:04 pm

2.0>

pete917 · Post by **pete917** » Tue Oct 27, 2009 11:59 am

You should maybe put some strengthening fins/webs on the rear shock towers and a solid mount strut brace in the front.

Cortina · Post by **Cortina** » Tue Oct 27, 2009 12:11 pm

...and if you can weld the back of said gussets (shock towers) properly , please come and do mine.
I tried with a mirror ............ oh dear.
Did a sub assy for the back horizontal fillet onto a plate - which I was then able to see and weld OK (and it spreads load) - but the vertical was not feasible (my opinion)
Wall thickness of tube is quite thin - bit at top is not !!

Having studied the amount of spot welds Porsche do - I have decided against seam welding for majority of shell .... time will tell !

DDK - Die Deutschen Klassiker

chassis strengthening 911 race car

chassis strengthening 911 race car

hscc