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RGS Paul Samba Member
Joined: April 20, 2007 Posts: 662 Location: Los Alamos, NM
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Posted: Fri Sep 17, 2021 5:11 am Post subject: Stud advice for Epytec hubs |
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I need some advice on a set of hubs I'm trying to get setup for my Syncro.
I'm in the process of converting to rear disks using the Epytec adapters for the Eurovan calipers and disks. Since I was ordering parts from Germany I went ahead and also ordered the Epytec rear hubs so I didn't have to bother machining my old hubs. The Epytec hubs come with 35 mm wheel studs and I need to change them out for longer ones since the disks are thicker than the drum.
My issue is that the Epytec hubs are bored for a ~15mm (0.590") spline diameter on the stud and stock studs for the Vanagon are 14.88 mm (~0.586"). Bugger. So my options as I see them are:
1) Ditch the Epytec hubs, have my hubs turned down and press in the stock studs. I had hoped to have my old hubs available for my brother or Dad to use for this conversion in a few years but it's not a show stopper. The buggest negative is I'll have to have the van apart for several weeks again and I'd really like to have her back on the road. The van has been out of service since May getting the front suspension rebuilt and we're getting a little stir crazy.
2) I found some M14 studs with a 0.620" spline section. I can have the Epytec hubs reamed to accept these studs. It's a pretty small change in diameter, the one thing I need to check is how much material I have on the need to go measure how much material I have on the outside diameter. I'm sure it's fine but I want to double check. The advantage here is I have fresh hub material for the stud splines to grab, the negative is I'll have odd-ball studs in the back.
3) Get a set of used hubs and have them turned and press in the new studs. I searched for used hubs a few months ago and didn't see any I was willing to buy. This might have changed in recent months though.
None of the other replacement studs I can find the right size splines for the Epytec hubs. I'm checking with the vendor in Germany but I'm not optimistic they will have an answer. Am I missing any alternatives and do people have thoughts on pros/cons of each of the above?
Thanks in advance!
Paul _________________ '87 Syncro 7-Pass. Adventure Touring Vehicle
"Simplicate, then add lightness." Colin Chapman |
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Jake de Villiers Samba Member
Joined: October 24, 2007 Posts: 5911 Location: Tsawwassen, BC
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pjn_wyo Samba Member
Joined: April 22, 2019 Posts: 181 Location: Bellingham, WA
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Posted: Fri Sep 17, 2021 7:57 am Post subject: Re: Stud advice for Epytec hubs |
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Are you sure you need to change the studs? What is the length of the studs? Didn't epytec consider then length of the studs on the hubs for disk conversion already? |
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RGS Paul Samba Member
Joined: April 20, 2007 Posts: 662 Location: Los Alamos, NM
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Posted: Fri Sep 17, 2021 4:36 pm Post subject: Re: Stud advice for Epytec hubs |
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Ok, more data.
There's no way to hold them square and in center for a weld, so I think that's off the table. Welding a grade 10.9 stud also sounds dubious.
I'm a little miffed they put in the stock length 35 mm studs in a hub that's intended for a rear disk conversion. They should at least add the 5-6 mm extra meat for the disk thickness. As it is, with my SA 16" steel wheels, I only have about 9 mm of stud engagement in the wheel nut. It might work, but it doesn't leave any margin for thicker wheels in the future and I'd prefer at least one stud diameter of engagement.
I just measured and I have about 0.358" on the outside ligament of the hub from the stud. That should be enough to accommodate the extra hole diameter. Right now I'm leaning towards reaming the holes and getting the fatter studs.
For the record, everything else about the Epytec parts looks brilliant. I got mill specs for the steel they used, everything was nicely packaged, and the hub centering rings work nicely with the disks to keep everything in line. If they had used a 45 mm stud they would have knocked it out of the park. Hopefully the installation is as nice as the parts are looking.
Thanks for the thoughts and peer review,
Paul _________________ '87 Syncro 7-Pass. Adventure Touring Vehicle
"Simplicate, then add lightness." Colin Chapman |
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Franklinstower Samba Member
Joined: September 21, 2006 Posts: 1892 Location: PNW
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Posted: Sat Sep 18, 2021 1:40 pm Post subject: Re: Stud advice for Epytec hubs |
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Jake de Villiers wrote: |
Hey Paul, as long as the smaller studs centre properly in the hubs you could just tack weld them in place, no? |
That's what I would do too. Draw them in with a spacer and tighten down all 5 with lug nuts then tack em in place. _________________ '89 Westy - EJ25/22 Frank 4.44 5mt
'75 Miami Blue Sunroof FI Standard Bug |
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Sodo Samba Member
Joined: July 06, 2007 Posts: 9521 Location: Western WA
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Posted: Sun Sep 19, 2021 9:52 am Post subject: Re: Stud advice for Epytec hubs |
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This “.590 hole vs .586 stud knurl”
Is this ‘measured’ or a listed spec?
Did you ask Epytec about using .586 studs?
If the studs draw in tight with spacers as Jake/Franklins suggested, they will be as square as any wheel stud in the history of wheel studs since time immemorial.
Squarer than even meaurable.
Even squarer than ream-able for that matter.
And reaming will be fine too, but then you have adapted to “special studs”.
Which is not the end of the world either.
A tack weld is just for the anti-rotation.
The tack won’t be ‘flexed’. All tacks are brittle anyway, and they work for this.
If you’re concerned, use two tack-welds per stud.
This is a specialty antique vehicle.
It won’t get parked in the weeds for 20 years letting the nuts get stuck & spin the studs where ya gotta burn them off with a torch etc.
Agreed on the 1D minimum. But I’d put the longer studs too just ‘cuz it would bug me everytime I saw the end of the stud below the lugnut surface.
All just “shop talk” here, actually all of the options seem fine. _________________
'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb |
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