Almost All You Ever Wanted to Know about..., Rear Hubs and 5-Lug Conversions Options

[Eric_Shea]

There’s been a lot of questions lately about 5-lug conversions; What hubs to use? Can I use a standard -4 hub? Should I use the early -4 hub with the bosses? Should I get expensive 914-6 stub axles and use an early 911 hub? How about the 944 hub conversion? All great questions; the idea behind this post is to put it all together in one thread with a few pictures.

First, let’s take a look at the two basic styles of -4 hubs. The first series of hubs for a 914 were on the 1970 cars. They were a little different as the factory had bosses formed in the casting for not only 4-lug configuration but 5-lug as well. The 4-lug bosses were predominant as they sat at 11.75mm while the remaining 5-lug bosses sat at 7.5mm. These are very popular with people who are doing their own conversion to 5-lug because they simply had to take them to a machine shop and request a 5x130mm pattern.

Here’s a picture of an early 1970 -4 hub that has been drilled for the 5x130mm pattern (courtesy Mike Ginter). These hubs have been replated to make them shiny new (IMG:style_emoticons/default/wink.gif)



The following is a picture of the standard -4 hub that you will find on most cars. From MY 1971 on, all 914 hubs looked like this.



There are basically three things that can be done with these “914” hubs.

1. If you have the early hubs you can, as above, take them to a machine shop and have them drilled to a 5x130mm pattern.
2. If you have a later hub you can take it to a machine shop and have it spot faced (where they make the stud surface level) and drilled to the 5x130mm pattern, and
3. You can have them spot faced with the 5x130mm pattern, have ring bosses made up to bring the stud engagement back up to the 11mm depth. Press the studs in and weld the bosses on.

I think all are good choices. Regardless of what you hear out there, I’ve yet to see a -4 hub that’s been "properly" drilled fail. I’ve seen one picture posted here of someone who basically drilled out their hub with a hand drill and didn’t spot face it. The studs worked loose and buggered everything up but, I’ve never seen one done right fail.

I’ll add to that; I’ve never seen a stud fail. You can purchase inexpensive studs from EMPI at www.cip1.com. If they’re installed properly they will probably outlive you. I do like the factory Verbus studs because of full thread engagement and “consistency”. They are extremely consistent across all sizes and various studs in a batch. If you want custom length studs Porsche has probably tried them all on various vehicles so again, Verbus will be your only choice if you are using adapters etc. Be prepared… they are expensive. Some coming in at $10-15.00 EACH! (IMG:style_emoticons/default/ohmy.gif)