911 Race stength rear wheel hub flange available?

[silver911rdb]

Does anyone know if a forged/ heavy duty rear wheel hub for a 1984 911 is available? I broke my rear wheel hub at the track and was wondering if there was something better? Multiple searches come up empty. Thanks

[KTL]

I think you just had a rare occurrence. A lot of people here have been tracking these cars for a long time. Rear hub failures are not at all common.

[Cory M]

I've broken one too, but that was about 9 years ago on a widebody car with big sticky hoosiers and i haven't broken one since so i think they are pretty durable. Good idea to crack check the replacement before installing.

[KTL]

Incidentally I think the hubs actually are forged? Pretty high strength high quality part on the car. But hey, these cars aren't getting any younger and nothing lasts forever?

[Mahler9th]

A friend identified these after he broke a 930 hub. He opted not to buy them.

No experience with the parts or the company that makes and/or sells them.

[chris_seven]

We have had a number of hub failures on SWB Race Cars mainly due to fatigue cracks in the region shown on the above photograph.

The cost of producing new forging dies is prohibitive so we have re-manufactured these parts using a modern Ultraclean High Strength Steel.

We selected 300MVAR heat treated to around 42HRC.

They are stress relieved prior to final grinding.

We have been using them regularly for around 6 years now.

[silver911rdb]

Thanks guys good info. I'll look into them. I have a 1984 911 Wide body track car with wide sticky hoosiers and non turbo trailing arms. The hub broke through a pretty high speed corner at Watkins Glen.

[silver911rdb]

Chris Seven...any more info on the wheel hub? Is this something you make or can you point me in the right direction to the mfg

Thanks

[Kraftwerk]

Aftermarket hubs: Looks like a good place to have extra strength.

[chris_seven]

We have manufactured them locally - our design and material selection but local machine shop with a 5 axis capacity carried out the machining from our 3-D Model.

We plan to make other variations but time is short.

[Tom '74 911]

I'm digging up this older thread because I recently broke a rear wheel hub in my 1976 911 CUP race car - running Hoosiers. Mine broke exactly where Chris_Seven indicates in his post. It's a little weird because I never noticed it during my last 3-day race weekend or unloading the car at home afterwards etc... I was just completing an engine-out service and was re-torquing the CV bolts to the transmission and noticed the rear hub flopping around. At first I thought the rear wheel bearing had blown up (which it basically had) but further investigation showed that the rear hub was broken too. I don't know how I missed that when I removed the rear wheel for the engine out service... or even when I was driving the car to the hoist bay in my shop... Yikes!

It sounds like this isn't a regular occurrence, but I do need a replacement now so thought I'd look into options. New ones are available from our host, but are quite expensive ($450-950). A used one is probably safe, but the key word there is "probably"... I'm curious if anyone has located and tried out any aftermarket alternatives mentioned earlier in this thread?

Thanks,
Tom

[Mahler9th]

Hi there.

I never tried an aftermarket hub, but I would encourage you to consider trying to hunt down such a product and learn as much as you can before pulling the trigger.

My wife was in #2 at a PCA DE at Thunderhill in June 2009 when she had a right rear hub/stub axle failure at about 90 mph under load.



Lots of damage and could have been worse.

My friend Scott had a 930 hub failure we discovered in the paddock at Thunderhill at a different event. Lucky.

Jerry W. told us he hadn't seen many.

But everything is getting old.

I bought some light use replacement spares from Partsheaven and had them crack tested... just gave away my final such spare to one of your competitors.

I suggest considering replacement of both sides at some point, and I'd consider replacing the stub axle or at least close inspection on the side where the hub failed.

Feel free to send me a PM.

[Mahler9th]

[Tom '74 911]

Originally Posted by Mahler9th

Mahler9th -

Yup, that's what mine looks like except the short end section is still stuck in the rear wheel bearing...

Fortunately, the flange end with the wheel studs has some splines left in it so I was able to get the axle nut off - although it was still a battle... : ) : )

If I can find good replacements, I will definitely replace both sides... Those old stock parts are getting up there in years and hours - especially those used on race cars. I'm glad to hear that it's not a super common failure point although if it was, I suppose there'd be more aftermarket alternatives.

Thanks,
Tom

[KTL]

CMS makes the transaxle output flanges. So it might be worth an ask if they ever considered making the hub?

https://californiamotorsports.net/collections/porsche-915-transmission-parts

[Tom '74 911]

Originally Posted by KTL

CMS makes the transaxle output flanges. So it might be worth an ask if they ever considered making the hub?

https://californiamotorsports.net/collections/porsche-915-transmission-parts

Thanks for the idea! I'll shoot them a note...

Here's my broken hub...

[Mahler9th]

Yikes.

We could not tell if the hub failed first or the stub axle failed first. When ours broke, the right rear wheel and tired took off for turn 3. They knocked off the oil suction hose before they left, and a bunch of oil left the tank and hit the headers.

The oil caught fire on the headers.

The right rear caliper broke and the rotor was disintegrated.

The right rear quarter panel was ripped in half, as was the bumper.

Both were FRP parts.

Luckily my wife shut the engine down pretty fast and the fire went out by itself.

This was at about 11 am on a Friday am in early June. After the car was towed in, we could not load it into the trailer easily.

As I tried to figure out what I was going to do, a track worker brought over the wheel/tire from turn 3.

Then, in early June at Thunderhill... it started raining.

Thankfully it was more of a cloud burst.

I knew a friend was headed down from the Tahoe area for activities the next day, and I knew he might just have a hub and stub axle.

So I called him. He was able to bring the parts down.

So that enabled me to load the car on Saturday morning.

The friend that brought me the parts actually built my car and had a lot of experience. He had seen a few failures back in his IMSA/SCCA racing days.

My wife's accident got some attention and folks in my little racing circle were extra careful to ensure their stub axle nuts were torqued properly.

I had just a couple of weeks to get the car back together for a race.

I went to Partsheaven and bought a bunch of spares.

My friend Hayden (WEVO; RIP) suggested a place for crack testing, so I had all my spares fluxed.

Could have been a lot worse.

So all of this reminds me... to the extent you get around a lot of other Cup/Spec 911 drivers... please remind them to keep an eye on rear wheel bearings, and consider changing out hubs and stub axles if they believe their accumulated use (street/track/race) has been high.


I'd take a hard look at aftermarket parts these days... remember my accident was in 2009. The 70's and 80's used parts are a lot older now, and it was probably easier to hand pick low mileage used parts like I was able to do at Partsheaven.

[Mahler9th]

For cross reference:

https://forums.pelicanparts.com/porsche-911-technical-forum/1137657-broke-driveshaft-outer-axle.html

[Matt Monson]

If you find an aftermarket variant, it will not be less expensive than the new ones Pelican is selling. I’d buy the original one, and be done with it.

[Tom '74 911]

Originally Posted by Matt Monson

If you find an aftermarket variant, it will not be less expensive than the new ones Pelican is selling. I’d buy the original one, and be done with it.

Hi Matt,

I'd assumed that any aftermarket option would be more expensive than an original. But I'd be willing to pay more, if they are stronger and more durable... where the price difference meets value, I don't know. But I think it's worth investigating. I'd not be surprised if I come up empty with aftermarket options anyway...

Thanks,
Tom