E28: Eggenberger Group A E28 Tribute Build Thread

[downforce22]

he sold it 2/11/19

https://stanceworks.com/2019/02/the-...or-a-new-home/

[Eric]

It's been a few years and 2020 is nuts, how is this car?

[kronus]

I think the thing I miss the most about my M5 is the sound of the S38. Have any sound clips? I bet it sounds mean.

[SpasticDwarf]

Sorry I didn't continue to update this thread! I got sidetracked, and well... that's just how it goes sometimes. :D

For the engine side of the build, it's honestly not all too interesting, partly because I didn't take any photos of the process, save for a few.

I think I touched on it before, but one of the liberties I took in building my Group A replica was that I didn't really want to use the 2.8 M30. While it would have been the correct engine, I've always endeared the M5, and so I wanted to build the Gr. A M5 that never was. So, under the sheet metal, the "Parts Car" is all M5.

I bought a donor car that had a complete M5 driveline - the PO originally owned an M5, wrecked it, bought another car, and swapped everything over, including things like the black headliner, door sills, and other tidbits. He was very thorough. As such, I was essentially buying an M5 donor car, minus the vin. The driveline had 124k miles and fantastic compression numbers when I pulled it from the driving donor. It ran great, and I didn't have a real reason to tear it down other than I wanted to do some maintenance while the engine was out of the car.

Chloe was there to help.


Maintenance began as "I want to do all of the timing components. So I ordered everything to the tune of a few thousand dollars (S38 problems) and got to work.



However, in order to do the S38 timing components correctly, you need to pull the head. And since I had it off, I figured why not redo it. So I sent the head out and had it completely rebuilt, with new valves, seals, etc.



As far as performance changes, I wanted to keep in mind what an M5 Group A car would have been like. The 528is were not that hopped up, as the FIA rules didn't allow much more than cam changes and a .6mm overbore. I thought about making changes according to the rulebook, but decided on keeping it simple: since the S38 was never homologated, I wanted to run it in factory trim. The only modifications came in the form of a lightweight JB Racing flywheel, a ClutchMasters 6 puck clutch, and euro headers.



The transmission is of course the M5 G280, as fragile as it may be. Everything I could convert to M5 has been. Aside from the VIN, I'd call my car as thorough as they come, for the most part.



I didn't want to paint the bay or anything like that, since I figure I'll be working in it a lot and don't want to worry about nicking the paint or silly things like that. Overall, the bay is in great shape as is, although it could use a detail.
We did go through and refinish all of the engine bits while they were off the car, which helped.

[SpasticDwarf]

I also find your most recent builds more to my taste than the older/slammed cars from before. Not that I dislike the Model A, E9, Rusty(post crash), or the E36, just meat/function is more my style.

Glad to see some of your content on r3v again. It's been too long.

I remember I met you once at Bimmerfest 2009, it's been a mintue. Awesome build!

Thank you both!

[SpasticDwarf]

Hi Mike,

No, not referring to the center spindle/nut that you had custom machined.
I am referring to the drive pins and their method of attachment to the wheel hub.

Are they through bolted with a nut on the backside of the hub (FAG piece), or simply bolted INTO the existing threads on the wheel hub where you would normally screw in lug bolts (photo of the FAG bearing above)?

If the later, they will fail. What material you had the drive spindle made out of has zero bearing on this.

-Chris

The material the pins are made out of does have an effect, as a stronger material means less flexure, especially within the threads. Also, mechanically, the load on the FAG hub isn't largely different than a wheel mounted with an 18mm spacer and extended lugs. Those aren't tearing off hubs regularly.

With that said, I too would like to see pictures of the failed part, if possible.

Nicely done! So damn cool to see such dedication put into making a faithful replica like this. Was there also a motor build to go along with it? I'd love to see that documented too! Also thanks for posting up detailed photos of the cage construction. That tar/adhesive scares me just looking at it.

Thank you! Yes, there's more posts to come.

[theneek]

Hi Mike,

No, not referring to the center spindle/nut that you had custom machined.
I am referring to the drive pins and their method of attachment to the wheel hub.

Are they through bolted with a nut on the backside of the hub (FAG piece), or simply bolted INTO the existing threads on the wheel hub where you would normally screw in lug bolts (photo of the FAG bearing above)?

If the later, they will fail. What material you had the drive spindle made out of has zero bearing on this.

-Chris

Chris, do you have photos of the failed unit(s)? I'm curious to see it. Sounds like a scary situation.

[Sh3rpak!ng]

Nicely done! So damn cool to see such dedication put into making a faithful replica like this. Was there also a motor build to go along with it? I'd love to see that documented too! Also thanks for posting up detailed photos of the cage construction. That tar/adhesive scares me just looking at it.

[UNHCLL]

You also mention pulling the pins from the "hub" (I assume you mean the centerlock hub, not the E28 hub itself), which is impossible, because my drive pins do not thread into it. They pass through it.

Hi Mike,

No, not referring to the center spindle/nut that you had custom machined.
I am referring to the drive pins and their method of attachment to the wheel hub.

Are they through bolted with a nut on the backside of the hub (FAG piece), or simply bolted INTO the existing threads on the wheel hub where you would normally screw in lug bolts (photo of the FAG bearing above)?

If the later, they will fail. What material you had the drive spindle made out of has zero bearing on this.

-Chris

[pandaboo911]

I remember I met you once at Bimmerfest 2009, it's been a mintue. Awesome build!

[Northern]

I also find your most recent builds more to my taste than the older/slammed cars from before. Not that I dislike the Model A, E9, Rusty(post crash), or the E36, just meat/function is more my style.

Glad to see some of your content on r3v again. It's been too long.

[SpasticDwarf]

Mike,

Having just gone through this, with a car weighing less than your E28, I can tell you with 100% assurance that using the drive pins to hold those front hub adapters to the hub will result in failure.
The front wheel hubs are NOT strong enough to support the load of the wheel under actual track use/racing conditions. It will pull the drive pins from the aluminum of the hub.

The "vendor" who sold us the identical setup to what you have created claimed the same. Just bolt them on using drive pins. It doesn't work.
Been there, tried that.

If you plan on using the car any more than just a nice show piece for parade laps, you need to revisit the front spindle connection method.

Also, you might want to check your driveshaft angle on that wrap! ;)

-Chris

Chris,

With all due respect, your setup can not be "identical" because mine is not from a vendor, but instead was designed specifically for this project by an aerospace mechanical engineer using FEA software to establish a safety factor of 2.5 using the dynamic loads from a respected name in the wheel industry. My components are also made from 7075 aircraft alloy, which is about 60% stronger than 6061 T6 forged aluminum; if you used an aluminum part, it was made from that. My pins are built to Grade 8 specifications.

It will pull the drive pins from the aluminum of the hub.s

You also mention pulling the pins from the "hub" (I assume you mean the centerlock hub, not the E28 hub itself), which is impossible, because my drive pins do not thread into it. They pass through it.

With all of that said, and considering that's how the Group A cars were run:







And considering they didn't have problems:


I'm going to assume mine will be alright. I have, and will continue inspecting the parts after each track day to confirm integrity. Two track days so far and there's no sign of a problem.

Furthermore, I assume the other setup you are referring to is akin to the steel hub and either steel or titanium drive pins provided by a certain E30 M3 fabricator. The designer of my setup noticed that the hex-key arrangement in the drive pin tips seems to complicate the torquing process of the pins into the hub. The flats designed into my drive pins and many other drive pin setups we have seen (including the GrpA parts) makes torquing the pins to an appropriate value much more consistent and less fraught with error.

As far as driveshaft angles go, someone get BMW on the phone! We've gotta fix their car too :D

[UNHCLL]

For our hub, we did add some lightening holes (as also used on the original hub I own, but not as seen on the Gr. A E28s in the pic above), however, they do use the drive pins to affix to the car - they’re not a dual-bolt style “adapter”. It’s as close to the factory centerlock hubs as we could venture.

Mike,

Having just gone through this, with a car weighing less than your E28, I can tell you with 100% assurance that using the drive pins to hold those front hub adapters to the hub will result in failure.
The front wheel hubs are NOT strong enough to support the load of the wheel under actual track use/racing conditions. It will pull the drive pins from the aluminum of the hub.

The "vendor" who sold us the identical setup to what you have created claimed the same. Just bolt them on using drive pins. It doesn't work.
Been there, tried that.

If you plan on using the car any more than just a nice show piece for parade laps, you need to revisit the front spindle connection method.

Also, you might want to check your driveshaft angle on that wrap! ;)

-Chris

[SpasticDwarf]

Great build! Just curious how long the entire build took from car purchase to track ready?

4 months to the day, exactly. It was an after-hours and weekend project only.

[Powling]

Great build! Just curious how long the entire build took from car purchase to track ready?