The Great Wheel Weigh In

[Azureblue52]

Hi Guys,

After a chat with Fabian about Empi 5 Spoke fitting to Porsche 356 Drum Brakes I thought I'd get one of each wheel I've got kicking around and do a weigh in and fit guide. Here are the subjects on the front lawn, we've got an original 356 steel wheel, a Speedwell BRM, an early Empi 5 spoke and a late Empi 5 spoke. For our fit guide we've also go a 356A drum and a 356B drum:



Here's the 356A Drum with the BRM, no fit problems with a decent amount of air space between the drum and the wheel.



Here's the BRM with the 356B Drum. I think it looks good with the 356B drums, they look like something from Flash Gordon!



Here's a shot from the back of each:





Next up is the early Empi 5 Spoke. This is where the fit problems start because the 356 drum is almost 13 inches in diameter. Fabian is using 356A drums with an 8mm spacer. This is the gap left without the spacer:



Here's the interference problem (the webs on the rear of the wheel also creates a problem)



The 356B drum makes the problem worse due to its cooling fins:





The problem is worse still with the late Empi 5 due to additional strengthening webs on the rear half of te wheel:



There was no point in taking a photo of a 356 wheel on a 356 drum, because it was obviously designed to fit it. Next comes the weigh in with amazing results:

Speedwell BRM - 4.2 kgs
Early Empi 5 spoke - 7.9 kgs
Late Empi 5 spoke - 8.1 kgs
356 Steel wheel - approx 9 kgs!

The front half of the early Empi 5 spoke weighs just about the same as a whole BRM!

Just on another note. Here's the improvement Empi made to the 5 Spoke in an effort to stop them from cracking across the spoke. As you can see on the early version the back of the spoke has a rectangular cut out with square edges causing a stress raiser right from the corner. The later version as a curved cut out and additional strengthening webs at the back of the spoke. It's easy to tell the difference from the front because the late version uses the same top hat inserts that the BRM uses. The early Empi 5's were known to crack right across the lug hole.





I hope everyone will find this useful.

Cheers
David

[speedwell]

Very good comparative    , like that more nobody will make a crack in these wheel 
rgd
fabian 

[John Rayburn]

EMPI actually made a 5 spoke version to fit the 356 drum brakes.The wheel half studs and bolts were low profile and the ribs on the back halves were configured differently. I used to run a set on my 356b drums. My spare wheel was not for 356 , but I was able to clearance everything so it bolted up with no problem at all.

[jick]

yeah, those are the type i have john, with the straight lug hole, not the ball socket type....

they bolt right up.....

interesting stuff david & nice stuff you have there!

[Frank LUX]

Very Cool Idea...!!!

Looks like a Period Cal-Look Tech Feature...

Frank

[John Rayburn]

My 5's were interesting because I had bought them from the original owner back in '79. They had the ball socket lug hole and he'd told me he converted them to run the lightweight 911 lugs, which I ran for many years along with the trick 911 wheel locks that leave the washer flush in the wheel; so originaly they also had the straight lug hole.

[nicolas]

very nice work! that helps a lot.

[SOB/RFH]

John, those Empi 5's ended up here in Sweden. Sadly the new owner died about 2 months ago......I do not if they are sold or not right now, but they were supposed to go on a 54 Karman with 356A brakes....cool wheels and a cool story on how they were modified.

[Azureblue52]

EMPI actually made a 5 spoke version to fit the 356 drum brakes.The wheel half studs and bolts were low profile and the ribs on the back halves were configured differently. I used to run a set on my 356b drums. My spare wheel was not for 356 , but I was able to clearance everything so it bolted up with no problem at all.

Hi John, do you have a photo of the back of your old wheels? I've never seen a 356 brake specific Empi 5 spoke before.

Has anyone else got a set of those wheels? Any pics?

Cheers
David

[empicolector]

good idea

[John Rayburn]

I'm really sorry to hear about the fellow that received my wheels, what makes it even sadder was that my friend Mark Herbert was the one that brought the deal around. U nfortunatelly I have no photos of the back half of one. but I just remembered I think I still have a broken back half in the garage that I can take a photo of and post . I'll take a look today. There's a scary story that goes with it that I'll post with the photo if I can find it.... Also , I forgot to mention earlier in the thread that EMPI also did a version for bus that had real beefy ribs on the inners...Kinda cool.

[John Rayburn]

Here's a shot that shows the differences. The lack of ribbing and extra countersink. Also the extra clearancing where the ribbing is near the drum.This wheel also takes a low profile nylock nut.

[John Rayburn]

So here's the story, Ihad spent my typical Wednesday night racing at OCIR , and it was now the following day cruising down Orangethorpe. I heard this huge bang and the car got all squirrley on me , luckily I was only going about 40. I pulled over to find a rear back half had exploded and completely grenaded my rear fender!!! Iwas running around the busy street picking up pieces of my beloved wheel when it dawned on me that this couldve happened last night at speed through the traps at the track. People wonder these days why I choose to go the steel wheel route. This is my answer.Kinda scary stuff, huh?

[John Rayburn]

I forgot to mention earlier that the front half mating studs are very short and don't extend past the low profile nylocks that hold the halves together. So , to modify , you have to cut the studs down as well as duplicate all you see in the picture I posted.( Except for the explosion part of course)

[Black Sheep]

Kind of makes you wonder about the sanity of using 30-40 year old mag/alloy wheels on our car's when most of us are pumping out 150+ bhp . Ive got a mate in the aviation industry who maintains that the use of these alloys at this age are a accident waiting to happen .

[63 ripper]

i think this is the 5 spoke written about in Hot VWs. exploded whilst inflating a newly fitted tyre

[Shubee2 (DSK)]

i think this is the 5 spoke written about in Hot VWs. exploded whilst inflating a newly fitted tyre

Luke has a Back half for that wheel for Sale on the Lounge

[John Rayburn]

These wheels do indeed scare me , I kept pestering Bill Schwimmer , when he got his, not to run them at the track; I finally showed him the back half I showed you all, and I think that made the difference. Don't want anyone to get hurt. But they are just such cool wheels!

[Cornpanzer]

i think this is the 5 spoke written about in Hot VWs. exploded whilst inflating a newly fitted tyre

As I heard the story, the back half of that wheel ended up imbeded in the neighbors roof soffit.  Makes you wonder how much air pressure was being applied to explode the wheel to that extent. 

[louisb]

There was a white '55 featured in one of the HVW Cal-look issues with original Empi fives. After that article came out there was a short insert in another issue where one of the wheels came apart. They are cool, but I think I would leave them on display in the garage myself.

--louis

[WCB Hitler's Hot Rod]

There was a white '55 featured in one of the HVW Cal-look issues with original Empi fives. After that article came out there was a short insert in another issue where one of the wheels came apart. They are cool, but I think I would leave them on display in the garage myself.

--louis

That was Andy Splikoman. He's lucky to be alive as it damn near blew up in his face.

[Azureblue52]

There's some scarey looking photos here for sure, thanks for everyone's contribution.

I think it'd be cool if anyone else wants to add a period wheel weight and photo, this would be good comparison.

[Black Sheep]

I think If you want to put some proper power down on the black top its best to stay away from split rim 40 year old wheels . Don't get me wrong they look the bomb but for racing I think you would be safer with a pair of new erco's .
I don't think back in the late 60's and 70's anyone ever envisaged the amount of power people would be putting through these wheels 40 years later .
I think if you have to have a period wheel and give it some abuse you cant go far wrong with a early fuch , these wheels were designed to take proper amounts of power and have the added advantage of being made by the over engineering crazy German's.

[Diederick/DVK]

That one is a very nice example of a beautiful breed of wheels