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Posted by: 914Sixer Nov 19 2014, 06:10 PM

We all know that 69-73 911 rear hubs are getting scarce and pricey. I went out on a limb and bought a whole rear 99 Boxster assembly for $41 delivered on EBAY. It is a well known fact that the 914 and the Boxster use the same wheel bearing. So I figured it would be an easy swap. I drove the hub out of the bearing and started the comparison of the two hubs. I had a 69-73 911 rear hub and a -6 stub axle to use as a baseline. The Boxster hub has the same splines as the 911/914-6 stub axle so it was a drop in fit. One down, so I put them side by side to find out they are the same height. Now have two down, the last check was to set the rotors on both hubs to see where we were at. Bingo, they matched up. So the stub, the hub and the height are all the same. HOWEVER, there is one area to be addressed. the -6 stub sticks up about 5mm past the center of the hub. It is going to require a spacer to fill in the area so the washer and nut will tighten down. I am thinking that the one that Patrick Motor sports will do the trick. I think it will be worth trying because I am using Boxster wheels.

Tell me what you think.


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Posted by: ClayPerrine Nov 19 2014, 07:00 PM

IIRC, the Boxster stub axle is a 6 bolt that is the same size as a 944 turbo CV joint. Use the Boxster hub and stub, and then use the 944 CV conversion procedure.

Should be a complete bolt on for a 914.

Posted by: r_towle Nov 19 2014, 07:10 PM

Because I have a set of early 911 trailing arms in the back of a very cold barn....
Could you explain what I might be able to use from an old 911 trailing arm to help me switch to five lugs?

Posted by: 914Sixer Nov 19 2014, 07:14 PM

So, you need to disassemble the axle from the Boxster and get the stub off then. I will see if I can find one. I like the idea of using the 944 CV conversion.

Posted by: 914Sixer Nov 19 2014, 07:17 PM

The trailing arms need to be 69 or later to be used for the 5 lug conversion. You will need to take the 5 lug hubs out of the swing arm. If you have the stub axle from the axle you can use them too.

Posted by: Series9 Nov 19 2014, 07:19 PM

This could be a very productive thread. Nice job.

Posted by: r_towle Nov 19 2014, 07:58 PM

QUOTE(914Sixer @ Nov 19 2014, 08:17 PM)

Posted by: 914Sixer Nov 19 2014, 08:33 PM

Early 65-68 arms have a long stub axle and long hub. 74-Up are aluminum. Go to ebay for early 911 trailing arms or rear hubs and look at the images. Hope this helps.

Posted by: Woody Nov 19 2014, 09:08 PM

QUOTE(Series9 @ Nov 19 2014, 07:19 PM)

Posted by: 396 Nov 19 2014, 10:05 PM

Excellent work.

One quick question...what year / years were those Boxster rear hubs?

Posted by: 914Sixer Nov 19 2014, 10:25 PM

I used a 97-04 boxster rear hub. Part number 996.341.605.54 on the hub. I just ordered a Boxster axle to check out what Clay said about getting the stub off and using a 944 CV Joint.

Posted by: rick 918-S Nov 19 2014, 11:06 PM

Nice!

Posted by: McMark Nov 20 2014, 12:47 PM

Watching with interest.

Posted by: nsyr Nov 20 2014, 07:07 PM

This would be a nice option for a subaru engine/trans conversion. Use the boxster axles and respline them to except the subaru cv on the trans side.

Posted by: 914Sixer Nov 21 2014, 10:36 PM

New interesting development about the axle. I paid $60 for a used one and I could have gotten a NEW aftermarket one for $81 shipped with new bolts,straps and axle nut. I am guessing they are the same as some part used on the the VW/Audi line of cars. It will be Tues or Wed before used axle shows up.

Posted by: El Vikingo Tropical Nov 22 2014, 12:23 AM

A good and productiv thread

Posted by: davep Nov 22 2014, 08:46 PM

I agree, this is an interesting development. I have all the original parts for the six, but when the time comes to replace the CV's this system looks to have great potential.

Posted by: McMark Dec 12 2014, 12:34 PM

Any updates?

Posted by: SirAndy Dec 12 2014, 12:48 PM

QUOTE(McMark @ Dec 12 2014, 10:34 AM)

Any updates?

Posted by: 914Sixer Dec 12 2014, 06:24 PM

I will be working on a update for this weekend. Boxster axles came in but they do not look promising. -6 rotor will require new holes to hold rotor on boxster hub.

Posted by: 914Sixer Dec 12 2014, 06:46 PM

The 964 front hub looks like it may be another option as it uses the same wheel bearing. It would be a matter of finding out what stub axle will work though. It may be an area from some one else to explore.


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Posted by: pcar916 Dec 12 2014, 06:55 PM

Very cool thread.

Posted by: Mueller Dec 13 2014, 08:32 AM

QUOTE(914Sixer @ Dec 12 2014, 04:46 PM)

Posted by: a914622 Dec 13 2014, 10:21 AM

964 with splines in front should be c4

Posted by: porsche913b_sp Dec 15 2014, 02:41 PM

Great job, keep it coming

Posted by: 914Sixer Dec 15 2014, 04:24 PM

I am not going to make it to the shop until this coming weekend. I sprained my wrist and hyper extended my thumb. It does not look like the Boxster axle or stub will be an option. Might be a source for used 110mm cv joints though.

Posted by: Amenson Dec 15 2014, 07:22 PM

QUOTE(914Sixer @ Nov 19 2014, 04:10 PM)

Posted by: Amenson Dec 15 2014, 10:22 PM

Really jonesing so I went looking for more info and found this:

http://www.thesamba.com/vw/classifieds/detail.php?id=1457201

No mention of spacers or machining.
Does this really work?

Cheers,
Scott

Posted by: 914Sixer Dec 16 2014, 04:57 PM

Yes, the 911 stub axle sticks up the same amount as the -6 stub.

Posted by: 3d914 Dec 16 2014, 09:34 PM

Great job. Thanks. Keep the details coming!

Posted by: El Vikingo Tropical Dec 17 2014, 02:34 AM

You can see her what you will need:
http://www.patrickmotorsports.com/part/914-901-carrera-drive-axle-conversion-kit/

Posted by: Amenson Dec 17 2014, 08:43 AM

I had thought that also but Patrick Motorsports has the note:
"THIS ITEM IS DESIGNED FOR USE WITH 5 LUG CARRERA AXLE FLANGE"

My understanding is that the Carrera uses a differnt (wider) bearing and therefore requires the spacers for preload and to put the brake rotor in the correct plane.

http://www.914world.com/bbs2/index.php?act=ST&f=2&t=234009

Isn't the advantage of the Boxster part that it uses the same bearing and therefore could be used w/o spacers?

So much information in so many different places.

Cheers,
Scott

Posted by: CptTripps Dec 17 2014, 08:58 AM

Just a question: Are the Boxster parts better/cheaper than the Carrera parts? There seems to be no shortage of them out there.

Posted by: 914Sixer Dec 17 2014, 03:30 PM

Whole rear Boxster hub assemblies can be had for less that $50 shipped on Ebay. You will have about 5 lbs of scrap aluminum when you are done.

Posted by: 914Sixer Jan 26 2015, 08:30 PM

Ok, here is the last of what I have found out using the Boxster and later 993 axles. The 911 and Boxster axle are the same length, are hollow tubed and use a 28 spline. The 911 axle is 32 mm thick and the Boxster is 28mm thick. Both are to long for 914 use. The Boxster S inner CV is a 911.332.030.01 , 108mm and 32mm thick. It is used in bunch of Porsche applications including the 930 Turbo. The 911 inner CV only had a Lobro part 7253150199001 and it is only 28mm thick. Both CV's used a 928.332.293.02 boot.

I had some 110mm 911 stub axles so I bolted the CV's up. I see no reason why the CV would not work for this application with joint gasket.

The outer stubs are a completely different item. The flanges are crimped on and no replacements are available. CV joint cup could be machined off and holes drilled. Not cost effective to use them. The overall height is the same but each is machined differently.

In summation the only useable part would be the Boxster hub. The 914-6 rotor would have to be drilled and screw holes countersunk to allow the hub to be screwed to the hub. The 911/944 stub axle will required a 8mm spacer at the top of the stub axle so it can be tightened down.

So, I spent some money and learned some new information. It seemed like a good plan at the time but NOT worth the cost of modification required to make it all work.


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Posted by: CptTripps Jan 27 2015, 09:40 AM

Thanks for the intel Mark. Looks like we can put this one to bed then.

Posted by: Randal Jan 27 2015, 10:24 AM

QUOTE(Woody @ Nov 19 2014, 07:08 PM)

QUOTE(Series9 @ Nov 19 2014, 07:19 PM)

This could be a very productive thread. Nice job.

Posted by: Amenson Jan 27 2015, 10:44 AM

I am still planning to use the hubs. Still cheaper than tracking down early 911 hubs plus the hub centric benefit.

Posted by: 914GTSTI Jan 27 2015, 12:50 PM

I know i'm going to get flamed but will the 4 lug wheel, cv stub fit into the boxer hub ? I know this would not give the bigger CV. I have not pulled down one yet to look at the stub.
Thanks,Randy

Posted by: Mark Garriott Jan 27 2015, 01:03 PM

There are some variations on this:
The 986/996 use the same hub at the front with a stub axle. That front stub axle is not drilled for CV, it just has the ABS reluctor/exciter sawtooth cuts. That would be a better starting point for conversion item (i.e. welding on a 6 bolt CV flange)

Patrick Motorsports used to sell a set of washers to use the wider, later 911 hubs/stubs in a 914 trailing arm. The P/Ns were something like PMPCSPI and PMPCSPO. I don't know if that changes the CV or brake rotor offsets.

Apparently, you can use the later hubs and the wider axle bearing in the 914 trailing arm, you need a specially machined bearing retainer plate that is countersunk to deal with the excess width. Maybe Patrick makes something for that, too. (Same disclaimer about CV and rotor offsets)

Posted by: blackmoon Jan 27 2015, 01:09 PM

QUOTE(McMark @ Nov 20 2014, 10:47 AM)

Watching with interest.

Posted by: Larmo63 Jan 27 2015, 08:05 PM

Or, you can just use real 914-6 hubs/stubs for your conversion.

Posted by: 914GTSTI Feb 3 2015, 01:26 PM

I ordered in some Box outer hubs.


If I read this post right. I need a 911 axle/stub, drill and tap for a rotor mount and a spacer .?

With my build being a Subaru motor and trans , what outer CV will be needed ? Being new to this it looks like a 911? Is it the same as the 944 CV ?

My plan is to use the axles from ColdWater914. Subaru on the trans and it looks like 914 or 944 on the axle.

With this in mind ,if I go with a 911 rear vented rotor with 911 parking brake and kit. What will this change ? What will I also need ?

Please take it easy on me,I'm old.
Randy

Posted by: 914GTSTI Feb 10 2015, 12:43 PM

Here is a little add to using the Boxster hub. I made a small cut on the stubs to make resesed in the 108mm hub. Don't forget the radius when cutting the stub . And to reuse the nut and the holes in the stub I made a washer/spacer.

Posted by: Mueller Feb 10 2015, 01:02 PM

^Looks good, instead of cutting the stub axle I would have just added a chamfer or radius or counterbore to the spacer.

Posted by: 914GTSTI Feb 10 2015, 02:11 PM

Yep, I looked at that but wanted just a little more contact . Like .007, LOL .

Posted by: Harpo Feb 10 2015, 04:28 PM

Make sure your spacer is as hard as your nut (HRC) or you will have gaulling on your bearing surface and end up with a lot les clamp load in your joint.

David

Posted by: 914GTSTI Feb 10 2015, 08:16 PM

Thanks David,I will keep a eye on that.

So it will not be plug and play. The the hub will need to be cut to clear the bearing flange. If you look at the green paint ,its missing.









Going to be tight in their with the 108's !



And I stopped at Patrick Racing and got the trailing arm stiffeners. Welding in the AM.



One last thing,I don't think it will need any cutting on the stub shaft. More in the AM. But I have a set !

Posted by: Amenson Feb 10 2015, 08:46 PM

QUOTE(914GTSTI @ Feb 10 2015, 06:16 PM)

Posted by: 914GTSTI Feb 10 2015, 09:01 PM

Good idea. I will look at it tomorrow. But I don't think so. It is a non-symmetrical pattern on the Boxster.

If I built a holder I could cut down the bearing flange shoulder ? Maybe in the field it could just be ground down ?

I will cut one of the stubs and see what clearance will be needed. Need to take a look at the 130x4 hub.

Posted by: 914GTSTI Feb 11 2015, 12:33 PM

Huston we have launch ! It will work,but it takes some modification. The big problem will be the bearing retainer. The in side lip will need to be cut down. I used my mill but it could be done with a die grinder. Next will be the cut on the hub. At this time I do not think a cut on the stub will be necessary. (I cut both of mine but a step in the new spacer could take care of that.

With a Boxster hub and a 911 28 spline 108mm stub you can have 5x130. But you will need access to a lath,mill,some steel and time.

Because I will be using a Subaru trans I can't help with the link between the 108mm flange and the trans flange ? Sorry, I'm sure someone here can help with that. Their maybe other ways but this is the way I went.







Gets kind a close !







Randy

Posted by: Jeff Hail Feb 12 2015, 01:18 AM

Order 4 911 rear bearing covers so they are doubled up ( 2 stacked) on each side. It will give you an extra 1/2 inch space over the 914 bearing retainer between the hub.
The run $9-10 bucks a piece.


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Posted by: 914GTSTI Feb 12 2015, 10:41 AM

Here is what I found.

The 911 flange is .090 thick with a .213 flange. To thin and to tall for the cut Box hub. This was used as a backup to the parking brake hat. (note this hub could not be used if you were going to use a 911 parking brake system)

Box retainer is .212 . To thick for the cut Box hub.

914 is .115 thick and has a cut flange of .210 ( this is the inside flange ) clears the cut Box hub by .030+-. And it has the outside flange witch is a big plus.

I still feel this is the best IMO.



Randy

Posted by: Mueller Feb 12 2015, 10:57 AM

Did you measure the wheel mating surface compared to the original one?

Meaning will the wheel be in the same place or stick out further or less relative to the fender or inside trunk wall? I guess the track would be the correct term?

Posted by: 914GTSTI Feb 12 2015, 11:03 AM

The way I looked at it, the brake caliper is in the same position (no spacers stock mount) and its the 914-4 rotor. This should make every thing the same. IMO
Right ?

Posted by: Mueller Feb 12 2015, 11:06 AM

QUOTE(914GTSTI @ Feb 12 2015, 09:03 AM)

The way I looked at it, the brake caliper is in the same position (no spacers stock mount) and its the 914-4 rotor. This should make every thing the same. IMO
Right ?

Posted by: 914GTSTI Feb 12 2015, 11:28 AM

No Problem !

All it takes is tools,parts,time,money,more time,more money,more money, some more time and voila all better.

Posted by: pete000 Feb 12 2015, 12:24 PM

Might this be an option for the flange hitting the hub?

These are lighter and flat.

Tangerine Racing





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Posted by: 914GTSTI Feb 12 2015, 12:36 PM

Yes this will work but may need to be chamfered ?

Posted by: Amenson Feb 12 2015, 09:25 PM

I got in touch with Chris Foley today and the diameter of the hole in his bearing retainer is 2.75". I measured the boxter retainer and it is 2.71. Thickness of the boxter plate is 0.196", CFR's is a bit thinner. There should be no reason it will not work so I just ordered a pair. I think that the issue with the 914 retainer is the smaller diameter opening combined with the raised lip.

Posted by: 914GTSTI Feb 12 2015, 10:53 PM

Scott. The retainers from my Boxster hubs will not work. The hole pattern is wrong. If you want mine you can have them but stop you order.

Yes the hole is bigger but wrong pattern.

I will send you a drawing of the two I have so you can see. It will AM, need to get to the shop.

Oh, I have the trailing arm apart for painting and I will recheck the cut I made on the 914-4 retainer,AM.

Randy

Posted by: Amenson Feb 13 2015, 06:59 AM

QUOTE(914GTSTI @ Feb 12 2015, 08:53 PM)

Posted by: 914GTSTI Feb 13 2015, 08:28 AM

It mite be open enough . When I get to the shop I will take a look. the hole is 2.95" ?

Posted by: 914GTSTI Feb 13 2015, 11:45 AM

The Box center hole is 2.72" +-. The 914-4 is 2.383" and the cut lip is .210" +- So the CFR flange with a chamfer should fit. Maybe with out a chamfer ?

Posted by: 914GTSTI Feb 16 2015, 12:43 PM

All installed. 930 CV, cut Boxster Hub, and a 108 MM stub. Stock brake caliper and rotor drilled 5x130.







Randy

Posted by: djb Mar 18 2018, 10:15 PM

First, incredible thread, thank you! I have recently purchased a 1975 914 with GT flairs but still 4 lug and hideous wheels.

Will the stock 914 stub axle work with the Boxster outer hub. Can I simply use the Boxster out hub and keep all the rest 914 parts?

I understand the bearing retainer may need to be modified or replaced.

David

Posted by: 914Sixer Mar 19 2018, 09:47 PM

I have a set of Boxster hubs for sale if some one need them.

Posted by: djb Mar 20 2018, 10:24 PM

QUOTE(914Sixer @ Mar 19 2018, 08:47 PM)

Posted by: 914Sixer Mar 21 2018, 07:11 AM

$74 shipped. The thread pretty much covers it. Stock bearing retainer could easily be ground off too. The axle has to be a 944 or 911 splined one.