Rear hub with 928 bearing and increased offset, 928 Hybrid trailing arm, 944 brakes, extended hub offset, parking brak Options

[Wilhelm]

Few pics of a project I'm working on to break up the misery or paint, bondo and rust removal on my V-8 SBC conversion. I'm going to do the sheridan body work on my car and found these wheels which I liked.




The problem is the wheels are 10 inches wide with an offset of 2 inches. In searching the web site it seems that most people with this combo have gone with 3" spacers. This seemed like it would put a lot of force on the bearing and I still would not have many other rear brake options. So.... I found some rear 928 hubs on ebay. the bearings are much larger: 85mm diameter and 47mm wide (versus stock 75mm diameter x 37mm long) and this would provide me with other 5 lug rear brake options. So off to the barn.



First, put a piece of 5 inch 1.25 inch wall DOM(Drawn Over Mandrel steel tubing) in the lathe.

[Wilhelm]

Cut off everything that didn't look like rear hub.........




Cut the sides off for the 928 brake shoe backing plates.




And was left with new hub that could hold a larger (928) bearing. Sure is purty at this point. I'm finally getting the hang of turning parts. The 2 critical dimensions in this hub are the diameter of the bearing bore and the length of the bearing bore back to the its front which is a large circlip. I was confident I got these within 1/1000. Everything else can be done in hundreths.

[Wilhelm]

Found a some 11 gauge 4.75" outside diameter tubing, cut it to length and beveled one end.




Then pressed it into place.



Then practiced the TIG welding. Sure like that alot, no mess, no spatter but a steeper learning curve than mig. If you look closely, you'll see some bung welds about 5/8" down from the main weld. Just being a bit anal retentive. Doubt this was necessary as I put the press to the limit shoving the hub into the tubing.

[iamchappy]

Impressive!....

[Wilhelm]

Cut the old hub out of a 914 swing arm and than welded in my new 928 hub assembly. Made a jig to keep the alignment all the same. The new exterior bearing surface is 3" farther out than the old 914 stock face.




Had a 944 turbo brake disc that dropped right onto the 928 hub without any issues.




Here is how the new wheel will sit on the widened hub without a spacer.




Advantages:
Bigger bearing
Bearing is moved to center of wheel for less angular loading on bearing.
Should be able to handle the SBC V-8
Bigger brakes
Parking brakes
Takes my mind off my troubles and pesky body repair

Disadvantages:
More weight (will do a comparative weighing- will be using aluminum caliper)
Time

To do:
Finish the parking brake
Add brake caliper bracket
Add some reinforcement
Powdercoat the arm
Make an axle spacer

[SirAndy]

(IMG:style_emoticons/default/smilie_pokal.gif)


how does the brake attach?
(IMG:style_emoticons/default/idea.gif) Andy

[Wilhelm]

(IMG:style_emoticons/default/smilie_pokal.gif)


how does the brake attach?
(IMG:style_emoticons/default/idea.gif) Andy

More pics and explanation to follow. Basically it will be like the 914, but instead of "ears" for the caliper there will be a plate with a 4.75" hemicircle cut out of one end and 2 holes 3.5" apart on the other end. This will be welded perpendicular to the 4.75" tubing and the caliper will bolt to this.

[sww914]

What you've done looks great! Good ideas for sure.
My only concern now is all the extra torque that distance will put on the stock trailing arm. Do you plan to reinforce it somehow or deal with that problem if it arises?

[Mikey914]

Nice. Saw a set of turbo twisties on CL locally and had the same thought, but knew it was beyond what I was capable of. Kind of wild, having the same idea... nice to see someone execute it as nicely as you have.

[neo914-6]

Excellent work and great idea!

[Wilhelm]

What you've done looks great! Good ideas for sure.
My only concern now is all the extra torque that distance will put on the stock trailing arm. Do you plan to reinforce it somehow or deal with that problem if it arises?

Doubt moving the bearing outward transmits any additional torque to the trailing arm compared to a stock arm with a 3" spacer and this same wheel or a stock arm with a deep offset wide wheel and no spacer. This design puts a lot less torque on the bearing compared to a spacer setup. Plus the bearing is substantially hurkier. Certainly comparing this trailing arm to a stock one with a stock wheel there will be additional torque applied to the arm. I have a set of stock sheet metal arm reinforcements shells I can weld on, but my hunch is they are better at adding weight than strength. I did a search on arm reinforcements where tubes were welded across the insides of the trailing arms. Unfortunately the pics of this thread are all gone. Guess it was a proprietary secret? Think most likely I will run a diagonal from the hub adjacent to the back of the parking brake plate forward at 45 degrees to the outside of the trailing arm keeping it inside of the wheel rim. Anyone have better ideas?

[Wilhelm]

Since I can add the brake bracket for my caliper essentially anywhere over 360 degrees, can anyone state a sound reason why I shouldn't point it straight up rather than tipped forward at about 100 degrees like the 914?

[PeeGreen 914]

What you've done looks great! Good ideas for sure.
My only concern now is all the extra torque that distance will put on the stock trailing arm. Do you plan to reinforce it somehow or deal with that problem if it arises?

Doubt moving the bearing outward transmits any additional torque to the trailing arm compared to a stock arm with a 3" spacer and this same wheel or a stock arm with a deep offset wide wheel and no spacer. This design puts a lot less torque on the bearing compared to a spacer setup. Plus the bearing is substantially hurkier. Certainly comparing this trailing arm to a stock one with a stock wheel there will be additional torque applied to the arm. I have a set of stock sheet metal arm reinforcements shells I can weld on, but my hunch is they are better at adding weight than strength. I did a search on arm reinforcements where tubes were welded across the insides of the trailing arms. Unfortunately the pics of this thread are all gone. Guess it was a proprietary secret? Think most likely I will run a diagonal from the hub adjacent to the back of the parking brake plate forward at 45 degrees to the outside of the trailing arm keeping it inside of the wheel rim. Anyone have better ideas?

Eric Shea does the tubes that strengthen the arms. I would think you would be well advised to do something like that as you are putting more stress on the arm. The bearing I am sure is fine but the arm is now the weak point. May be fine as it is though. Nice work (IMG:style_emoticons/default/aktion035.gif)

[Rick_Eberle]

Since I can add the brake bracket for my caliper essentially anywhere over 360 degrees, can anyone state a sound reason why I shouldn't point it straight up rather than tipped forward at about 100 degrees like the 914?

That is a nice job!

As to the brakes, won't having the caliper horizontal make bleeding difficult?

[roadster fan]

Nice work, wish I had some of those tools (IMG:style_emoticons/default/pray.gif)

Here is a pic of the trailing arms with the reinforcements like you described, cant remember who did these (Shea (IMG:style_emoticons/default/confused24.gif) ). Chris Foley was doing the reinforcement by cutting/sectioning the arm and welding in a plate....kinda hard to describe.



Keep us posted on the progress,

Jim

[Wilhelm]

Thanks for the info on the reinforcements!

The trailing arm build continues. It was 108 F here Saturday, the shop was 120 F inside and wasn't able to do anything till today. Here is a drawing of the adaptor flange. From my measurements it will work with the caliper I choose with it's adapter or a 944 turbo caliper as a direct bolt on.




Here is the flange cut out of some plate.



Flange welded onto the new trailing arm.




With the backer to support the parking brakes.



And with the brake shoe carrier

[Wilhelm]

Here are the parking brakes set in place without the cable and gizmos to make it work.




928 hub put in for trial fit.




944 turbo disc put onto 928 hub




Detail of adapter for the new brake caliper as seen from the back.

[r_towle]

awesome work...

I agree that what you did will add the same if not less stress to the trailing arm than the guys with 3 inch spacers...

Rich

[Krieger]

Nice work. Do you think the axles are going to hit the inside of the new trailing arm tubes you fabbed, or have you figured this out too?

[John]

Wow!

That is some excellent thinking.

Are you going to have some sort of bolt on bearing retainer or are you relying on the press fit of the bearing? I think the bearing will be big enough.

I would consider stiffening the trailing arm a bit (but not too much). You DON'T want to make the suspension console the weak point in the rear suspension. It would be a bitch if you ripped that off the car instead of bending an arm.

It looks good so far. Expensive machine work, but it sure looks good.

just my $0.02