My new project.........

Mike · Post by **Mike** » Tue Feb 17, 2009 10:53 pm

great offer thank Andy, but now found the right stuff and changed it, will update the picture

Mike · Post by **Mike** » Sun Mar 15, 2009 1:29 am

Finally found the most beautiful standard/standard crank which is just back from polishing and balancing with the Patrick Motorsport RSR flywheel, ring gear and a Sachs power clutch.
Coated here with a tectyl protective wax, which has given it the golden colour.

Mike · Post by **Mike** » Sun Mar 15, 2009 6:07 pm

Well here's a great way to start the engine build, spend a couple of thousand pounds on some brand new Mahle cylinders and take an angle grinder to them

I went and made the coffee while Neil did the first one, couldn't bare to watch
but they turned out beautifully. That's the windage, polishing and gas flowing done, now to start putting it together..........

Highfield · Post by **Highfield** » Sun Mar 15, 2009 6:14 pm

Mike

Allow me to be the one to ask .....

Why ?

Ian

Mike · Post by **Mike** » Sun Mar 15, 2009 11:15 pm

Ian, the shape of the cut-out is exactly to the shape of the spark eroded arched web where the cylinder sits in the case, so this helps with the free flow of gases within the engine. As I understand it, the main concern is the massive flow of gas on the down stroke, now with the cut-outs that volume of gas can escape quickly from under the piston and out along the whole length of the case internals allowing for a freer revving engine and the associated increase in power, hopefully as much as 15hp.

The pics below shows where the cut-outs line up, and then that area seen from below with the cylinders in place.

abash914 · Post by **abash914** » Mon Mar 16, 2009 10:02 am

Just a discrete observation, but good old Black & decker, eh?? Those files are a wondrous tool with so many uses.
I winced, Mike when I saw the Grinderette being taken to the skirt, but fab finish on the job, as ever.
This thread is just bloody wonderful!!
AA

Nick Moss · Post by **Nick Moss** » Mon Mar 16, 2009 10:09 am

Hi Mike, what material are you using in the background for the barrel shots?

Mike · Post by **Mike** » Mon Mar 16, 2009 10:31 am

Hi Nick, it's a piece of carbon fibre sheet I found lying around at Neil's and using the matt underside inside of the shiny top side. I think it's a bit modern looking for old parts though, might try a piece of aluminium sheet instead next time.

Ferry Man · Post by **Ferry Man** » Mon Mar 16, 2009 12:15 pm

Mike wrote:it's a piece of carbon fibre sheet

You'll never get FIA approval now...

Roadrunner · Post by **Roadrunner** » Tue Mar 17, 2009 6:08 pm

Quite a well shot model of the Martini RSR here -

http://www.flickr.com/photos/24758892@N05/3212168417/

There are some good early 911 photo groups on Flickr too, well worth checking out.

Mike · Post by **Mike** » Sun Mar 22, 2009 8:08 pm

Had all the gearbox internals 'Superfinished' which is a shot peening and polishing treatment that Formula 1 teams use on their gears to reduce friction, heat and wear, the parts come out beautifully smooth and shiny, fantastic to hold and put together.

Started on the box by doing the diff set, it's a ZF lsd which we have rebuilt to the standard RSR setting of 80%. The unit components are pictured below, then the disc's and plates selected to give the required torque bias which is then tested with the torque wrench to see if it's right. Took us 3 goes of building it, testing, stripping it down changing plates re-building and re-testing to get it right.

Just waiting now for the rods to arrive and the oil pump modifications to be done, then the engine can start to go together!

Cam Arnott · Post by **Cam Arnott** » Tue Mar 24, 2009 10:26 am

Nice test rig Mike!

Mike · Post by **Mike** » Tue Mar 24, 2009 10:57 am

Thanks Cam, the hand on the wrench is Neil Bainbridge's who's doing all the work at BS Motorsport.

Mike

oliveR · Post by **oliveR** » Tue Mar 24, 2009 4:32 pm

Nice mike!
I like the home made LSD test tool ...

Mike · Post by **Mike** » Wed Apr 29, 2009 2:46 pm

It's been a bit quiet in the restoration section for a while so thought I'd bore you rigid with some more detail from the RSR gearbox build.

One of the weak links in the 915 box when used for racing and high hp is the splines on the input shaft, the end bits which hold the gear sets on the shaft tend to break off, so this is the modification to prevent that.

You grind off the around the raised part of the splines, cut this specially made collar in half and weld it on. The shaft is then heat treated and shot peened to optimise it's hardness and finish. Easy really, the problem is each of the 3 steps, welding, heat treatment and finishing takes place in 3 different places around the UK, which is why this one part has taken a month to make!