oil through frame?!?!

[John]

this video says that the 917 had engine oil flowing though its frame to help cool it... but it also says that the frame was built of steel which we know is wrong... Anyone know anything about this? Drive It! - Porsche 917 do filme Le Mans

[Lynn]

John,

I can't verify this, but it wouldn't surprise me at all. Tube frame members can make great reservoirs/accumulators/pathways for air, hydraulic oil, freon (generic sense) and other non-corrosive gasses and fluids.

Indeed, it just made me think about the fact that I am having fits with where to place my accusump. One or both legs of the roll hoop could have made an excellent accusump if the tube had been machined out and a piston & plugs made for it (both of which would be easy to do for most any descent machine shop.) A couple of bungs, one high for the schrader valve and one low for the on/off valve, and Bob's your uncle.

Lynn

[Doc Watson]

The frame was rather badly welded and had pressurised gas inside it. A pressure gauge was then put on the frame and if the pressure went down then the drivers got out as a crack would have developed in the tube frame... had some pictures of a frame from an original 917... see if I can find them.

Andy

[Pat Buckley]

I had a friend who used his frame (it was a Caldwell D-13 Formula Vee with 4" round tube frame members) as his gas tank.

It didn't work.

LOL.

(Frames are known to crack)

[Russ Noble]

It was common practice for rear engined single seaters, in the sixties at least, to use the frame rails to transfer coolant to and from a front mounted radiator. There were two drawbacks with that, firstly they added heat to the cockpit area and secondly if a tube got torn in a bad shunt you could get boiling water dumped on you.

It wouldn't surprise me in the least to know Porsche were doing that with oil.

Cheers

[Chris Melia]

Hi guys

running oil through the chassis on racing Porsches is not unusual here are pictures of a 906 chassis showing the oil tubes going into and out of the chassis rails.
regards

Chris.

[Doc Watson]

Here is the famous Porsche welding... original 917 frame.

Superb information here.....

Carl Thompson's Photo Galleries at pbase.com

Andy

[91740Gt]

All of the original 917s used the main top and bottom chassis rail to carry the oil from short flexible hoses at cooler and engine ends. This was a complete no-go as far as Gulf/Wyer etc teams were concerned as the frame would crack at various points on a regular basis thus making a hot oil spray a distinct possibility, especially in the event of a shunt. The chassis were subsequently gussetted at the weak points and long flexible oil lines run through the cabin on the passenger side, into the sill area and into the engine bay.
This i have done with my own car and all subsequent builds will be that way. The scrutineers will not accept any fluids running in chassis tubes on reproduction cars for racing. I,ve tried !!

The main chassis rails were pressurised and used a small Schraeder valve mounted on the upper cross member and a gauge mounted in the cockpit, usually on the passenger side sill, but sometimes on the dash. Loss of pressure was frequent !!!!

[Mal]

I read some years ago that fuselage frames for highly sressed rag and tube aircraft were ported into every tube segment before welding up. Once welded, the frame was totally filled with boiling linseed oil, allowed to cool, and then drained as a corrosion preventative.

Subsequently, they were filled with nitrogen to well above atmospheric presure, to purge oxygen and further avoid corrosion. Pressure was monitored via a guage somewhere on the frame, and served as a warning of frame fatigue. Dont recall whether the guage was visible in cockpit, or only ground accessible.

Suspect that this info came from an early kitplanes mag, from a welding series by someone who had been in the game for many years.

Not quite oil/coolant transfer through the frame but a neat means of detecting fatigue or cracking at an early stage.

[Jac Mac]

Frank Gardner ( Australia) published a small handbook on Race Car Prep in conjunction with Castrol many years ago and an excerpt that always comes to mind was when Frank was driving for the Porsche Factory Team( cannot remember which porsche in particular sorry). The following is the basic outline of the story.

After having a look at his new toy for the first time Frank noted one gauge on the panel that appeared to be faulty as the needle had a constant reading, on pointing this out to one of the team engineers he was told ' Herr Gardner, when that needle reach's zero you will drive the wagen back to the pits with great care. Frank asked why and on being told about the chassis pressurization turned to the engineer & replied ' Stuff the pits- if that needle even flickers I will park the thing on the side of the track & you can come & get it ! '

Reading between the lines you could get the impression that Frank felt the Porsche team perhaps pushed the lightweight boundaries a little too far.

Jac Mac

[Rick Muck- Mark IV]

Originally Posted by Doc Watson

Here is the famous Porsche welding... original 917 frame.

Superb information here.....

Carl Thompson's Photo Galleries at pbase.com

Andy

DEAR LORD!

I weld better than that AND I CAN'T WELD!!!!

So much for the "fussy schwabians"

Rick

[Scott Calabro]

91740GT,

So only the "Main top and bottom chassis rails were pressurized then?

Or were all the tube joints opened to allow monitoring of the complete chassis via the gas under pressure?

Did they put dye in the gas medium to locate suspect cracks?


Malb,

You are correct about the light aircraft trussed fuselages, except it is Boiled linseed oil !

Some Sikorsky Helo's have pressurized rotor blades to monitor integrity.


Cheers,
Scott

[Jim c]

Yes interesting welding I think someones parrot escaped and got into the welding booth.

Jim

[K-Style]

Originally Posted by Mark IV

DEAR LORD!

I weld better than that AND I CAN'T WELD!!!!

So much for the "fussy schwabians"

Rick

Compare that to the later Penske prepared 917/30. There is a big difference.

[John]

Wow, this welding job looks pretty rough. I'm guessing this is gas welded which is pretty damn hard to do.

Originally Posted by Doc Watson

Here is the famous Porsche welding... original 917 frame.

Superb information here.....

Carl Thompson's Photo Galleries at pbase.com

Andy

[Ron Earp]

Lots of bikes used to carry gas or oil in their frames, then the practice died away. It is back now it appears, my Buell motorcycle carries the gas in the frame and the oil for the dry sump in the swing arm.

[vs]

Another bad consequence of running fluids through the frame tubes is the different expansion rates of the tubes with hot fluid in them, causing frame distortion and weight jacking across the wheels, resulting in uneven braking and cornering loads.
Suspension set-ups need to be done with all the fluids up to temp, and then hope for the best on the track!
Kind of defeats the purpose of designing a stiff chassis as a constant suspension platform. Basically this is why the fluid in chassis tubes was retired to 'Oh yeah!' file.

[David Morton]

Does anybody know who's owns chassis in the 917 photos above?
Two additional "chassis" were made in High Wycombe when the Piper car was
dismantled and overhauled. One was sold and apparently went to Switzerland and then the U.S.A., and the other is still in the UK as a spare - unbuilt I believe.
It may be unfair to lay the blame on seemingly bad welding on Porsche as the tube used was a one off and apparently a pig to work on, and if the photo is one of the two "replicas" [for that is what they were - identical in every way right down to the tubing] then they were never built by Porsche in the first place. Fran might know better than me.

[Hellem]

Dave, the chassis is own by Carl Thompson and is build up by himself (see the link above) and had the body work done by Gunner Racing (see their past projects). The frame is aluminium tubed and if I remember right it was exbition piece at the reception of the frame manufacturer. Carl Thompson bought it in Switzerland in 2003.