Building a 904

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Bill Sargent
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Re: Building a 904

#16 Post by Bill Sargent »

Hi Adam,

Dennis Frick ( Europa Machina) built a 904 replica based on a 914 about 15 years ago for use in PCA club racing. It used a 914 tub from the front firewall back and a tube frame forward. Not sure what he did about the rear shock tower heights. The car is now in France and Barrie at M&W did some repair work on it a few years ago after a racing accident. He said when repairing it that the entire body work had been widened by a couple of inches.

If you need any body parts, Dennis seems to have the molds for just about any variant. I needed the fiberglass mount bracket for the Webasto gas heater and he was able to make me one in only a couple of weeks.

As for "...nice to see a 904 build not bound by budget concerns"; I do have a budget, just larger than yours :wink: . I am also hopeful, maybe delusional, that the sum of the parts may be worth more than the parts alone. If money were not a concern, I would have purchased Stan Gold's 904-006 8)!
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Adam Wright
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Re: Building a 904

#17 Post by Adam Wright »

Bill Sargent wrote: If money were not a concern, I would have purchased Stan Gold's 904-006 8)!
But where would be the fun in that? I've learned the journey is usually far more interesting than the destination, and building a 904 is a journey, any way you slice it. Keep us posted.
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Bill Sargent
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Re: Building a 904

#18 Post by Bill Sargent »

Adam - you hit the nail on the head. I am doing the 904 project because I love to build things that I can enjoy later. This gives me far more satisfaction than simply purchasing something. Now I just need to retire so I can do more of what I love .... and less negotiation with the Chinese government.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Adam Wright
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Re: Building a 904

#19 Post by Adam Wright »

My attitude aligns well with Ferry.

"I looked around and could not find quite the car I dreamed of, so I decided to build it myself. "

Mine is a little different, I couldn't afford to buy a 904 or a 550, so I put my hands to doing.

Same when I built Da Spoodster.
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Bill Sargent
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Re: Building a 904

#20 Post by Bill Sargent »

The first post in this thread showed a couple of photos Barrie sent of the 904 body parts in process. He took his molds off 904-063 owned by Bill Stephens in the U.K., and has added other body styles/parts since. He made his first car in about 1999 and has made about 25 cars since.

The 904 body consists of about 50 separate fiberglass parts (according to Barth’s book). At least 40 of them can be seen in the photo below.
Photo from Barth 904 book showing most, but not all, body parts.
Photo from Barth 904 book showing most, but not all, body parts.
There are many variants of the 904 body:
- Long door or short door. Long doors wrap under the body where short doors open at the top of the chassis. Short doors were only on the very late cars. Photo above shows long doors.
- Kam tail or spoiler
- Fender flares or no flares
- Small scoops on sides for rear brake cooling or larger ones on late 6 cylinder cars

My car will be long doors, spoiler tail, no fender flares and small side scoops.

The first post showed the inner part of the lower nose and the front fenders/windshield frame/roof being laid up. Barrie then mates these parts together in a large dolly as shown below.
Over the years Barrie has made dollies and supports for all the molds since they are used a couple of times per year.
Over the years Barrie has made dollies and supports for all the molds since they are used a couple of times per year.
Large unwieldy part!
Large unwieldy part!
Henkel made the original 904 bodies using chopped glass fiber sprayed into the molds. Depending on how Fritz felt that day, a body might be thin and light or thick and heavy. Barrie lays his bodies up using several layers of cloth, so weight is generally lower than a factory car and the thickness is more uniform. After all the body parts are laid up and removed from the molds, they are bonded to the chassis in stages. The roll care is installed in the car after the body is bonded to the chassis to ensure the cage is tight to the bodywork inside the car.

More photos will follow as Barrie makes progress. Thanks for following along.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Bill Sargent
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Re: Building a 904

#21 Post by Bill Sargent »

When Gregory Campbell was doing the final assembly of his M&W 904 one thing we discussed was the location of the fuel pumps. The factory owner’s guide said to remove a cover to access them, but it was not clear if the fuel pumps were located in the front trunk or elsewhere. Gregory eventually found a photo showing that the fuel pumps were located on the bulkhead behind the steering rack under the car. But Gregory’s car did not have a cover over this area.

Fast forward a few months and I was looking at auction photos for 904-107 and found a good photo of what this area looks like on an original car.
The portion toward the top of the photo is the cover for the oil cooler.  The two vents behind this are where hot air from the oil cooler exits under the car.  The panel behind that is the elusive cover over the steering rack, fuel pump and brake master cylinder area.
The portion toward the top of the photo is the cover for the oil cooler. The two vents behind this are where hot air from the oil cooler exits under the car. The panel behind that is the elusive cover over the steering rack, fuel pump and brake master cylinder area.
Knowing this, you can clearly see the panel in the photo with all the body parts:
Green circled part is the oil cooler and steering rack cover.
Green circled part is the oil cooler and steering rack cover.
Better picture of the part are shown below.
Oil cooler and steering rack cover
Oil cooler and steering rack cover
Side view of oil cooler and steering rack cover.
Side view of oil cooler and steering rack cover.
Looking at the part, it is easy to imagine that when it is removed (in the heat of a race for example) that the thin parts connecting the oil cooler cover to the steering rack cover might get broken and the steering rack cover discarded. Probably about half the 904s I have seen photos of are missing the steering rack cover half of this body part. Barrie said 904-063 that he took molds off of did not have this part, so he had not made the mold for it.

Barrie will now make a mold for this part, but we will modify the original design such that the oil cooler cover and the steering rack cover mount separately so your can take them off independently. I think there may be more times I want to access the fuel pumps and brake master cylinder than I want to access the oil cooler.

Always something to learn. Thanks for following along.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Bill Sargent
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Re: Building a 904

#22 Post by Bill Sargent »

Well it has been a while since my last post. Moving back to the US after 6.5 years in China and trying to get everything settled into the new home has left little time for Porsches. But Barrie Martin at M&W has been hard at work on the body and chassis for my car. The entire body shell is now complete.
Rear clamshell for my car in gel coat.
Rear clamshell for my car in gel coat.
Sargent Rear body.jpg (206.75 KiB) Viewed 5719 times
Barrie is now working on the chassis. All M&W cars to date have used square tube for the rear bulkhead around the transmission bell housing, and this is the only part of the chassis that is not almost identical to the original. See the photo below of an earlier M&W chassis compared to a factory chassis.
M&W Chassis, view from front of chassis.  Note square tube used for rear bulkhead.
M&W Chassis, view from front of chassis. Note square tube used for rear bulkhead.
2009 M&W Chassis 3.jpg (531.31 KiB) Viewed 5719 times
Factory 904 chassis.  Note rear bulkhead with large oval hole.  Bulkhead is two pressed sheet steel panels spot welded together.
Factory 904 chassis. Note rear bulkhead with large oval hole. Bulkhead is two pressed sheet steel panels spot welded together.
904 Frame - Marinello.PNG (811.07 KiB) Viewed 5719 times
Barrie has a chassis jig so all the pick up points are known. The problem in making the sheet metal rear bulkhead is knowing the shape of the oval hole around the transmission. We considered laser scanning the chassis of an original car, but then found a more low tech solution. I had a good end on photo of the rear bulkhead and was able to scale it in photo shop to match dimensions provided by Barrie. I then printed it out at 1/1 scale. Had to print it a couple of times to get the dimensions exactly right. The end product is below and was easy to mail to Barrie.
904 rear bulkhead 1/1 scale photo.
904 rear bulkhead 1/1 scale photo.
904 Rear Bulkhead Scale Photo - Final 17Oct18.jpg (115.68 KiB) Viewed 5719 times
Once Barrie had the scale photo he set about making a prototype of the rear bulkhead. He said it was easier than he thought, but he will need to remake his chassis jig in this area to accommodate the more correct bulkhead construction before he can install all the suspension pick up points. The photos below show Barrie's prototype compared to photos of 904-045, a car originally sold by AFN in London to Dickie Stoopes.
rear part of the prototype bulkhead
rear part of the prototype bulkhead
Sargent Rear bulkhead 1.jpg (351.46 KiB) Viewed 5719 times
Rear part of the prototype bulkhead showing connection to shock/spring tower.
Rear part of the prototype bulkhead showing connection to shock/spring tower.
Rear bulkhead 3.jpg (341.36 KiB) Viewed 5719 times
prototype top of shock tower.
prototype top of shock tower.
Rear bulkhead 6.jpg (264.03 KiB) Viewed 5719 times
904-045 top of shock tower
904-045 top of shock tower
Stoopes 904 -3.jpg (354.18 KiB) Viewed 5719 times
front of prototype bulkhead
front of prototype bulkhead
Rear bulkhead 8.jpg (368.75 KiB) Viewed 5719 times
So far so good and I am pleased with the progress.

On another front, I head down to San Diego on Sunday to spend a few days at Jacques LeFriant's shop helping reassemble the 4 cam motor for the car. Gregory Campbell is coming too. A future post will cover engine reassembly.

Then on Friday March 1st we will drive up to LA and tour some of the restoration shops before going to the Lit meet on Saturday and Sunday. Hope to see many friends there!

Thanks for following along!
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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George Hussey
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Re: Building a 904

#23 Post by George Hussey »

Is Barry still building these 904s? I had one built
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Re: Building a 904

#24 Post by George Hussey »

Had one built back in 2006, but maybe want another one
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Bill Sargent
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Building a 904

#25 Post by Bill Sargent »

Hi George - the answer is yes and no. Yes, Barrie is still building 904s. He has 6 in the build queue after mine. But he stopped taking orders for new builds a year or two ago. Barrie is 71 and it he completes on average one car every12 - 18 months.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Bill Sargent
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Building a 904

#26 Post by Bill Sargent »

Been a while since I have posted progress on this thread, but there is finally progress to report 😁!

The chassis is now complete, painted and the body has been bonded on. It is now awaiting a slot at Robinson Race Cars to have the FIA roll cage installed. Below are several photos of the chassis as it was being constructed.

Progress has been slow due to Covid and the work to design and fabricate the correct rear bulkhead.
Setting the steering column location
Setting the steering column location
Checking body fit with steering column
Checking body fit with steering column
Press for making rear bulkhead parts
Press for making rear bulkhead parts
Freshly pressed rear bulkhead parts
Freshly pressed rear bulkhead parts
Rear bulkhead assembly
Rear bulkhead assembly
Trial fit of dummy transmission
Trial fit of dummy transmission
Chassis coming together
Chassis coming together
Nearly complete chassis
Nearly complete chassis
Corner piece is reinforcement called for in Porsche 904 Tech bulletin #4
Corner piece is reinforcement called for in Porsche 904 Tech bulletin #4
Detail of oil lines to cooler exiting at the front of the chassis.
Detail of oil lines to cooler exiting at the front of the chassis.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Bill Sargent
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Building a 904

#27 Post by Bill Sargent »

While waiting on the chassis to be constructed I decided to reverse engineer and produce the quarter turn hood and rear compartment latches as well as the side window latches. Tim Kyuser, who owns 904014 has been very helpful and giving of his time in supplying many measurements and photos.

The original latches look like the photo below and have not been available since the late 60s.
Front hood latch
Front hood latch
Rear compartment latch
Rear compartment latch
The knobs and the front hood knob holder were aluminum while the front receiver and the rear receiver parts were press formed steel. To simplify manufacture I decided to make everything from aluminum using CNC machining. The first step was to obtain measurements and photos of original parts, which Tim Kyuser was kind enough to provide. I then made CAD models of each piece of the latches using Autodesk Inventor software. Below are some screen shots of the CAD models.
Front latch cross section
Front latch cross section
Rear latch screen shot of CAD model
Rear latch screen shot of CAD model
After the CAD models were complete prototype parts were 3D printed in nylon and installed on Gregory Campbell’s 904 replica.
3D printed prototype front and rear latches
3D printed prototype front and rear latches
Prototype front latch installed
Prototype front latch installed
Once the prototype parts were perfected (it took two tries) the next step was to get the production parts made. I chose to use an on line CNC machining service called “Hubs” (www.hubs.com). The process is simple. You upload your files, the site error checks them for problems, you specify materials and machining tolerances and supply a technical drawing. Then pay and wait about 3 weeks.

When the parts arrive they have a fairly bright machined finish. To make them look more “period” I tumbled the parts visible on the outside of the car to give them a slight patina matt sheen.
Front latch knobs as machined
Front latch knobs as machined
Front latch knob.  As machined on bottom, tumbled on top
Front latch knob. As machined on bottom, tumbled on top
While the parts were being produced I used the factory 904 parts book to determine the correct hardware. Amazingly, I sourced all of it from Amazon! Then came the tedious job of assembling the latch sets. To make only 1 latch set would have cost about $1200. So I found buyers for 15 sets and made a first run of 18 sets to allow for problems. The CNC machining quality was excellent and I ended up with 18 good sets. Below is a photo of a set ready to ship.
Hood and rear compartment latch set ready to ship
Hood and rear compartment latch set ready to ship
The window latches were made in a similar manner. Below is a photo of the window latch in an original car.
Original Window latch
Original Window latch
559C7B41-FBF6-42FB-99FB-3A7EDCCB1B45.jpeg (77.63 KiB) Viewed 4120 times
I have hit the 10 photo limit so will continue in the next post.

Thanks for following along.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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Bill Sargent
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Building a 904

#28 Post by Bill Sargent »

My last post left off with a photo of an original window latch. Below is the CAD model.
Window latch CAD model
Window latch CAD model
After a 3D plastic prototype was produced and tested I made a run of 25 sets.
Window latch parts - lots of them!
Window latch parts - lots of them!
Window latch set ready to ship
Window latch set ready to ship
As with the hood and rear compartment latch sets, I sold 18 sets to buyers all over the world. Now, 2 years after selling the first run of hood and rear compartment latch sets I had enough demand to make a second run. Who knew? A couple of sets have gone on original cars but the majority have gone on replicas from several different manufacturers - mainly M&W, Beck, Rock West.

In the next post I will return to the chassis and body assembly.

Thanks for following along!
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

Dave Erickson
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Re: Building a 904

#29 Post by Dave Erickson »

Nice work, Bill. Its cool that you can go from CAD to finished product via an online CNC service.

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Bill Sargent
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Building a 904

#30 Post by Bill Sargent »

Prior to the chassis legs and other box sections being welded closed they were epoxy primed and painted inside. After the chassis was mechanically complete it was epoxy primed and painted black.
Chassis front view
Chassis front view
Chassis rear view (upside down)
Chassis rear view (upside down)
Chassis - press formed parts around transmission. Some of it is a box section.
Chassis - press formed parts around transmission. Some of it is a box section.
Detail shot of tray that carries shift linkage, fuel line, parking brake and throttle cables.
Detail shot of tray that carries shift linkage, fuel line, parking brake and throttle cables.
When the chassis gets to this stage the body is bonded on. Areas where the fiberglass is to be bonded to the chassis are scuffed and then the previously made fiberglass parts are bonded to the chassis with additional resin and cloth.
Main passenger cabin being bonded.
Main passenger cabin being bonded.
Close up of passenger cabin being bonded
Close up of passenger cabin being bonded
View from the rear.  Chassis is upside down and rear of seat backs can be seen.
View from the rear. Chassis is upside down and rear of seat backs can be seen.
The chassis is then turned right side up and the front fenders and roof are bonded on. It is starting to look like a car at this point!
Fenders and roof bonded on
Fenders and roof bonded on
View of front trunk area
View of front trunk area
View from the rear.
View from the rear.
With these parts bonded to the chassis it can now be sent to have the FIA spec roll cage installed. Once that is complete I will make a trip to the UK for a “fitting”. I am 6’2” so we need to alter the driver’s seat fiberglass so I can comfortably drive the car. This will involve lowering the seat by about 1 inch and moving the seat back about 2 - 3 inches. This is possible as a 4 cam motor will be used and there is space behind the driver’s seat. This has all been discussed with the roll cage fabricator and he will, within the scope of the FIA regulations, allow as much space behind the seat as possible between it and the cage.

While the car is getting the roll cage fitted things like the front hood, rear clamshell and other fiberglass parts are being readied for installation.

My next post will discuss suspension parts. Thanks for following along.
Regards,

Bill Sargent
#151489 59A Cab - Faux Cam
#159176 64C Cab
#460603 67 912
904 clone in the works

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