Yet another 5-lug rear conversion, some questions Options

[Richard Casto]

I forgot to mention above, that I agree 100% with the above comments about the stop block. It should NOT be welded to the backing plate. It should be welded to the arm as shown in the photos above. People have been welding it to the backing plate and not having issues, but in my opinion it's a matter of time before someone runs into trouble with that setup.

[TonyAKAVW]

Wow, Richard that is a GREAT resource!!! I think that many will find that very very useful, thanks for putting that together!

Now I wonder whether I have 944 or 911 stub axles. Is there a characteristic feature of each?

I will see to it that I get the stop block welded to the arm. It does make sense to have it attached there. I will have to see what angle the parking brake needs to be pulled by and give sufficient clearance for that. For access, I could weld on a block with tapped hole and have a bolt-in stop block. hmmm.

-Tony

[jaxdream]

Sorry about the mix up on the backing plate, I didn't catch the 914 e-brake holder tab in the 3rd pic of the first set, the pics didn't show the whole arm, Richard is on a very good track on the e-brake setup , there is a thread titled " A different way to hook up 911 e-brakes" it's a merged thread , should be able to search it out , check out the thread , you will get the I have three e-brake cabling spreader setups , 911 , 944 , 928 , I've worked all three around , I was going with the 928 spreader setup , but changed mind because it requires a stright pull from a cable similar to the 911, the 944 uses a pull by cable but at an angle from the backplate which I feel can be setup and executed a lot more easily than the other two because the cable would have to make a 90 deg bend going back to the hand brake lever , the 944 will just use a slightly angled setup , no need to 90 it and keep the cables out of the exhaust's way and not melt them .Richard is also right about the stop tab , it needs to be anchored to the casting , think about the drum brakes on American cars , the brake shoes butt up against the anchor pin that the springs attach to , this keeps the shoes from rotating around the hub in case of emergency handbrake pull ,Porscheses ( Porshi ??) are no different in this respect.You all the parts in the pics , except for calipers, caliper spacers ( don't forget them ) rotors, rotor holding screws, and pads. The studs should be decided upon depending on your wheel choice and the need or not to use wheel spacers . The stud thing should be done to the hubs before they are pressed into the bearings , unless you come up with a way to press them out and reinstall different length while the hub is mounted in the bearing.
Good luck , it can get crazy with the possibilities available ( $$$$$ ) (IMG:style_emoticons/default/headbang.gif)

Jaxdream

[PRS914-6]

it's a matter of time before someone runs into trouble with that setup.

Yep, the reason it has worked is nobody has had a flow blown emergency. When the stop is welded to the sheetmetal and the brake is pulled hard at speed, the sheetmetal will wrap up like a pretzel. It works fine for holding your car in the driveway. Can you imagine stopping a 2000# car and expecting a piece of sheetmetal to take the force during an emergency stop? The thought scares me...... (IMG:style_emoticons/default/w00t.gif)

[jaxdream]

it's a matter of time before someone runs into trouble with that setup.

Yep, the reason it has worked is nobody has had a flow blown emergency. When the stop is welded to the sheetmetal and the brake is pulled hard at speed, the sheetmetal will wrap up like a pretzel. It works fine for holding your car in the driveway. Can you imagine stopping a 2000# car and expecting a piece of sheetmetal to take the force during an emergency stop? The thought scares me...... (IMG:style_emoticons/default/w00t.gif)

Yeah and when it does wrap up it will lock up and do a flat spin , like Tom Cruise in Top Gun , ziz ziz ziiz splat os something similarly baaaaddd ! (IMG:style_emoticons/default/hissyfit.gif)

[charliew]

I bought some aluminum rear trailing arm assemblies for a dune buggy application before I started working on the 914. One was bought as a 74 and the axle stub is flat where the cv bolts on. It uses the straight pull spreader. It also uses a narrower wheel. The second set was sold to me as turbo arms and they will hold a 11 inch wheel. They were sold as 84 year arms. They have the angle spreaders but the stub axle has a lip that goes over the edge of the cv. They are both 100mm axles. Also they both are hubcentric. AS a last resort if someone wants the latest parts the boxter has the same rear bearing as the 914 and the same eb parts as the 84 on 911/944. Brad has some pictures on a thread on the club forum. I also bought a stub axle assembly on ebay and the outercv is part of the axle stub, it was sold as a 944 stub. The stub axle spline and the cv outer case is one piece.

[Wes V]

Tony;

Just a heads-up on using a "single pull" spreader (944 and BMW) and not a "push-pull" spreader (911 type).

As I understand it (standard disclaimer), the "single pull" spreaders function by bearing on a section of the backing plate or main hub.

It's simpler to talk about the straight pull ones but the function is the same with angle pull ones, so I'm just going to refer to the straight "single-pull" spreader.

As the cable pulls toward the center of the car, it pulls the spreader with it, toward the center of the car. What stops this (in the original car the parts are from) are the two bearing areas on the backing plate (or hub flange). If the backing plate wasn't there, the whole spreader assembly could move toward the center of the car. (this is partially resisted by the brake shoes, but that wasn't how it was designed or intended)

As the cable pulls the spreader and forces it against the backing plate, the spreader spreads.


So, what I'm getting at is that for you to use this type spreader (as intended by the factory), you also have to provide the bearing area for it. As with that 40mm wide spacer, I feel it should be welded to the hub.

Although I've read threads where people talk about using the angle "single pull" spreaders (and I like the idea!), I've yet seen anybody do it in a fashion that fully addresses all of the issues that are part of the factory design.

Wes

[jaxdream]

[attachmentid=179
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Top pic shows lft 944 spreader =angle pull , rgt 928 spreader slight straight/angle pull -requires a 90 deg bend in cable.
2nd pid shows 928 rear hub WITH steel shoe liner.
3rd pic shows liner - notice the factory welded on rubing block for the spreader.
5th pic shows where I layed the 928 liner on top of a early 911 shoe plate , marked to cut , did so , welded ( mig ) the 928 section onto the 911 section ( I am a very novice welder and this turned out Gr8 , but DA didn't take pics )
4th pic shows plate , shoes , spreader , cable mounted studing for the best angle to fab up a holder for the cable tube to mount the cable in, and fab the shoe stop / anchor tab.

Look these over , think what you want, maybe try it yourself.

944 spreader seems to be the ticket !!

Jaxdream

[Wes V]

Good job!!!

It looks like you are covering all the bases.

Wes

[TonyAKAVW]

This is excellent info! I will definitely put in the bearing plate for the angled 944 puller. I will also check to see if the PO had changed the location of the cable mount to account for the proper angle.


-Tony

[TonyAKAVW]

Turns out the PO installed 'rubbing pads' on the brake frame...

[charliew]

Tony there is a chance that your backing plate is thicker than the early 911 backing plate. The one you have looks different from the 68 plate I have. If yours is thicker it may be alright. Those may be off of a boxter or later porsche. On the early 911 backing plate the opening is a lot bigger. At any rate I will just cut a piece of 1.5x1.5x .250 angleiron and fit it in the hole and let it do both jobs and weld it to the arm casting.

I have thought about it and I don't think the backing plate will twist up. I don't think it is that far out from the center. I think the tires will break loose first, but the block was always on the casting so thats where we should also put it.

[Richard Casto]

Tony, just beware of the wiki info right now. I am still editing it and it probably has some incorrect info. I am hoping that I can get a handful of people to review it in the near future. I would hate to have someone spend $$$ on parts and then find they don't match up. But I will say it is probably mostly accurate and probably better than trying to peice together info from 20 different threads.

Jaxdream, I am also looking to do that same single/side pull spreader. My biggest issue yet (I still don't have all of the parts yet) is that the spreader fits into a notch on the shoes that doesn't exist on the 911 shoe. So it looks like you either have to use 944 shoes (which have the notch), but they mount on a slightly different style pin on the 944 backing plate. Or you have to notch the 911 shoes.

I am hoping to come to a parts combo that does not require modification to the consumable. Particularly trying to use the 944 shoes on the 911 backing plate.

[charliew]

Brads thread, boxter parts look a little familiar?
http://www.914club.com/bbs2/index.php?show...emergency+brake

Also I have both the 911 early shoes and the 944 versions and they are pretty much interchangeable on the backing plate, you might need to drill a coupla holes in the plate. In the case of the boxter, the shoes look narrower, But they are probably the right size for the lighter car.

Of course you still gotta do the support/rubbing block deal on the 914 casting. And on the boxter I don't think the backing plate will fit on the 914 casting but it might.

[Wes V]

Charliew; (and others)

Just a word of caution; be careful about repeating stuff that Brad posts. (not to start a cross-site war!)

In that string he posts up a bunch of photos and aludes to the fact that it should work. If it was as straight forward as he would have you think, he would already be selling a kit.

The photos are worth looking at, but be careful on how you read what he says.

(for the record, I've been visiting both sites for about a year and a half and this is the first time I've done brad-bashing)

Wes V

[charliew]

I think the backing plate and the initial parts cost is their holdup. Not enough profit margin I'm sure. It could be Brads having too much fun racing right now too.

[davesprinkle]

Charliew; (and others)

Just a word of caution; be careful about repeating stuff that Brad posts. (not to start a cross-site war!)

In that string he posts up a bunch of photos and aludes to the fact that it should work. If it was as straight forward as he would have you think, he would already be selling a kit.

The photos are worth looking at, but be careful on how you read what he says.

(for the record, I've been visiting both sites for about a year and a half and this is the first time I've done brad-bashing)

Wes V

In Brad's defense, he's mostly focused on Boxster stuff right now. He loves 914s, but his priorities have recently shifted to making a living.

So the lack of a kit shouldn't infer anything regarding suitability. As I mentioned, BR just hasn't had the time to look at this in depth. I suspect (without having seen the pieces in person) that there will be enough advantages to the Boxster setup to make it a worthwhile pursuit. At the very least, it will be as functional as using any of the other, similarly designed (ie. 944), angle-pull spreaders.

On a slightly related topic, in the same thread, BR alluded to the Boxster's use of the 914 rear wheel bearing and suggested that as a result of this, the Boxster hubs and stubs would work in a 914 trailing arm.

Intriguing. Seductive, even. A new option to be added to the Rear Hub Conversion Parts Matrix? Anybody have any comments?

[jaxdream]

Boxster hubs on a 914 ?? That's GR8 - even more choices to choose from giving a wider field of parts availability to select to fab with (IMG:style_emoticons/default/piratenanner.gif) (IMG:style_emoticons/default/piratenanner.gif)

Jaxdream

[Richard Casto]

On a slightly related topic, in the same thread, BR alluded to the Boxster's use of the 914 rear wheel bearing and suggested that as a result of this, the Boxster hubs and stubs would work in a 914 trailing arm.

Intriguing. Seductive, even. A new option to be added to the Rear Hub Conversion Parts Matrix? Anybody have any comments?

If the Boxster uses the same wheel bearing, that means the OD and length of the mating surface on the hub is the same as the 914. Questions that remain are...

1. How far out is the hub mounting surface? Point being can you mount a rotor to it and still have it centered on the caliper correctly? If so, it might be an improvement over the 911 hub-centric hubs which require the custom 5mm spacer.

2. What is the spline count and diameter inside the hub? Or another way of saying this, what stub axle will work with that hub? Will only the Boxster stub axle work, or will others?

3. If only the Boxster stub axle works, then what is the CV joint situation with the Boxster stub axle?

Unless the Boxster stuff is cheaper than the current options, I am not sure what it will do to help. (IMG:style_emoticons/default/confused24.gif) But I think it's something worth researching.

One last thing to mention. Brad may know something beyond what is listed in PET, but I just looked up the part number for the 986 and 987 and as far as I can tell they list a different part number for the bearing than they do for the 914. Frankly I would be suprised if they used the 914 bearing. They increased the bearing size in later cars (probably due to load from increased weight and performance of the newer cars) and I would not expect them to go backwards with the Boxster. But I don't know any more than what I can see in PET.

[craig downs]

I've adapted the 944 e-brake spreader to my car and have been using it for 3 months now it it works great.