Yet another 5-lug rear conversion, some questions Options

[TonyAKAVW]

I've been reading up on lots of threads about the rear conversion, CV joints, etc. etc. I'm not 100% clear on everything, but more importantly I'm not exactly sure what I have...

A few years ago I picked up a roller that was in the early stages of a -6 conversion. The owner worked at a Porsche shop here in socal, and had put a 1987 SC front end on the car, and started to do the 5-lug rear conversion.

So what I have are a pair of trailing arms with some stuff installed. From what I can tell from the other threads, I have a 74+ hubcentric wheel flange, early 911 stub axles, and on one of the trailing arms, a partially complete 911 handbrake. The other trailing arm has the dust shield portion installed, but no shoes, etc. The stub axle flanges measure 100 mm across in total diameter (edge to edge).

Now for the questions:

1. There were several threads about spacers required for the hubcentric wheel flanges, but I couldn't figure out where these spacers are supposed to go. Second, is there a way I can tell if this setup has them or not?

2. I'm hoping to use the 944 CV joints, 914 axle, and 911 coarse splined output flanges. Based on what I have are there any issues?

3. Brakes. I currently have the A calipers on the front and stock 914 rear calipers. When I finish this rear 5-lug conversion I will have to choose between upgrading the rears to the V-calipers or moving my A calipers to the rear, and using Boxster calipers on the front. As far as I can tell, there is little to convince me to go with the V-caliper. A set of Boxster calipers is ~$300 off ebay, and I figure I should be able to make a set of adapters on my milling machine. The V-calipers are nearly $600 and offer no change in pad size on the rear. I realize that fora narrow bodied car, the setup I'm proposing is overkill, but if in the future I decide to flare, I'd have the brakes already done. I have a 165 HP Subaru motor, and I'm sitting at about 1900 lb right now, with some weight still to come off. So the question here is any suggestions/opinions?

4. If I do put the A calipers on the back, are they strictly bolt-on or will I need to modify anything?

-Tony

[TonyAKAVW]

Here's my understanding of what the CV joint/axle stackup looks like. Is this correct, and where does this spacer that I mentioned go?

[jaxdream]

The spacer goes on the hub that the studs stick out of and the brake rotor and wheel bolt to . The spacer goes on the shaft that goes into the bearing, it is on the wheel side of the bearing and presses up against the inner bearing race. It has been figured out by earlier crafters that the thickness of the spacer should be 5mm and can be had probably from some of the folks here , I got a set from an outside entity and was disappointed that the QUALITY control dept was on break when the set I got was made- 5.07 mm going around the ring to 5.87mm on the other side. These spacer rings need to be a little more consistant as they press against the race and when the stub shaft is installed and tourqued down a certain amount of squish happens giving your bearing a preload similar to preloading the front bearings but is not adjustable because of the rear stub axle / hub setup, SO make sure that the spacer rings you get are uniform in thickness around the circumference to get the disired preload. Hope this helps ther are threads here about this particular subject.

Jaxdream

[TonyAKAVW]

Is there a way for me to know if I have such a spacer installed? I'm not sure but if I have to tear this apart to inspect do I ruin the bearings? Is there a measurement I could take, say between the face of the flange and the brake mounting ears?

Without the spacer, does the system bolt together properly or would there be some slack somewhere?

Thanks for the description of the location.

-Tony

[jaxdream]

If there was no spacer the flange and the stub axle being bolted together would flop around, what I see from your pics is the backing plate being installed upside down from waht others have executed for a 911 e-brake setup , you didn't show pics of the top side of the arm. You seem to have all the parts required to convert to 5 lug with the hubcentric flange I feel is a plus ( opinions vary ) just might look into the e-brake setup and how you will get it operational. Hopfully someone may have an idea as to getting that done as I'm sure you have pondered this also. It would be a shame to dismantle it to turn the backing plate 180 deg to get the pull bowtie setup to the bottom of the trailingarm , also look to get a block setup that goes between the shoes that sits above the actuating hrdwre , this is a must for safety reasons as it stops the shoes from rotating around if used for an emergency brake in whcih case with no stop , the whole shebang spins with the disc / drum. There are sevaral threads on here for this setup , use search for 911 parking brake conversion.Good luck and like I said search is your friend.

Jaxdream

p.s YES if it is taken apart the bearing is usually destroyed hence my mention about it being a shame to take it apart to rotate the backing plate.

[SirAndy]

Without the spacer, does the system bolt together properly or would there be some slack somewhere?

Depends on your setup. If you have the correct year 911 hub and stub axle combo, the bearing surface is the same as on a stock 914 and you won't need any spacers.
(IMG:style_emoticons/default/shades.gif) Andy

[jaxdream]

Without the spacer, does the system bolt together properly or would there be some slack somewhere?

Depends on your setup. If you have the correct year 911 hub and stub axle combo, the bearing surface is the same as on a stock 914 and you won't need any spacers.
(IMG:style_emoticons/default/shades.gif) Andy

Hi Andy , look at the pics he posted , he has some arms he acquired with the 74+ hubs with the hubcentric ears and should already have the spacers installed , the ones you speak of are from the earlier than 74 911's . check out the pics of the arms .

Jaxdream

[jaxdream]

Hi Tony , one of your questions were about the calipers for the rear , your front A calipers won't fit , they have a 3.50 inch bolt spread and the 914 arm hasa 3.00 inch bolt spread.A lot of guys use the rear M type caliper ( up to 83) with the 20 mm thick rotor . The calipers require a 5mm spacer in between the caliper and the mounting ears on the 914 arm both bolts.This gives you the correct spacing for the caliper with pads over the 20 mm thick Vented rotor. This will give a Gr8 rear disc setup once you get the e-brake operational and there is no modification to the arms other than the 5mm spacer addition to bolt the calipers on. Some one on here is selling some M calipers ,IIRC correctly , check out the classifieds.
Look it over , post your thoughts.

I am in the process of doing the same as you , 5 lug conversion with 944 cv conversion.

Jaxdream

[Wes V]

One word of caution in regards to the hub being able to "flop around" if the spacer wasn't installed, in a configuration where it should be.

It will not flop around due to the friction (inward and outward) on the inner race of the wheel bearing. Keep in mind that the hub needs to be pressed into place (plus removing it can do damage to the bearing).

Not having the spacer (where needed) will lead to problems due to the fact that the axle stub isn't adding compression to the bearing and the fact that under heavy side loading, the assembly could move outward.

Now this is all nit-picking on the wording "flop around", but I wouldn't want you to use that to indicate if the spacer is there or not. Even with the stub axle removed, the hub wouldn't flop around, unless the bearings were trashed.

You have no idea what the PO did. Take it apart to make sure.

(as a side note; don't tow your car with the (stub) axles removed.)

Wes

[PRS914-6]

Without the spacer, does the system bolt together properly or would there be some slack somewhere?

Depends on your setup. If you have the correct year 911 hub and stub axle combo, the bearing surface is the same as on a stock 914 and you won't need any spacers.
(IMG:style_emoticons/default/shades.gif) Andy

If my memory is correct (old age), Porsche went to a wider bearing when they went hub-centric. If I'm correct, all hub-centric flanges need spacers and perhaps they are installed already. If the flanges are flat face (like 69) no spacer is needed. Double check this info though.

jaxdream is correct on the spacers, if not properly machined, they cause problems. I machined some for a few members requesting them but several never sent payment so if you need a set PM me as I have two sets remaining.

Stop blocks are ESSENTIAL and must be welded on. There are numerous threads on this. Leave the old bearing in while you do the welding to prevent any distortion.

Numerous ways to do the axles. I used and prefer getting the proper length axles from Sway-a-Way but it cost a little more.

I hate it when people respond with "do a search" but in this case there are tons of threads with all the info and pics you need with plenty of different options for your budget.

Good luck, it's a worthy conversion.

[Rotary'14]

Hi Tony,

You need to use a spacer to keep the rotor centered relative to the caliper. A spacer under the rotor will increase the track of the rear of the car. This can be a problem if your trying to squeeze 16 x 7 under the stock body work. If you space the caliper instead, you'll have an easier time fitting big meats under stock body work.

-Rob

oops,, different spacer you guys are talking about. My bad.

[SirAndy]

If my memory is correct (old age), Porsche went to a wider bearing when they went hub-centric. If I'm correct, all hub-centric flanges need spacers and perhaps they are installed already. If the flanges are flat face (like 69) no spacer is needed. Double check this info though.

You're probably right. I don't recall the exact year when they went to the wider setup, but i'm pretty sure his '74 hubs need the spacers ...
(IMG:style_emoticons/default/bye1.gif) Andy

[TonyAKAVW]

Okay, so essentially the answer is that there is no way to know if the spacers are installed because the friction between the bearings and the stub axle and flanges would prevent any axial sliding (or what I was calling flop around). It sounds like there's nothing I can do besides sacrfice one set of bearings on one side to inspect. (Assuming that both sides were done the same way)

I will have to do more reading about the parking brake installation to see whether I hould have the cable enter at the top or the bottom and how to do this stop block.

Sounds like the M calipers for the rear are the way to go.

Thanks for all the info. Hopefully today I can get one side opened up and see how it was done. I'll post pics.

-Tony

[TonyAKAVW]

Okay so I tore apart one trailing arm and I figured out a way to determine whether there is a spacer on the other side. I will measure the exposed threads on the stub axle on the other side, and if it comes up the same as on the side I tore apart, then I know there is a spacer.

I also discovered that the PO had a great idea with regards to the stopping plate for the parking brake. The pictures below illustrate that...

Another interesting detail on the parking brake is that instead of the expanding butterfly style, this one uses a compound lever (that's the best way I can figure out how to explain it) You pull on this tab that comes out and the shoes expand. In the end its the same effect, but with a different mechanism and does not seem to require the special cable that uses the sheath as part of the compression system.
(Is that confusing or what?)

So, back to the original purpose of tearing this apart... There is a spacer in the stackup, and it measures 4.92 mm thick and seems to be made of stainless steel (not magnetic) and has a nicely machined curved inner radius to fit against the radiused flange surface.

Patrick Motorsports' website says that there is an inner and outer spacer, and that both must be used. I have not seen anywhere else, mention of this. Anyone know about that?

-Tony

[TonyAKAVW]

First picture showing the stop block installation

[TonyAKAVW]

axle stuff

[SirAndy]

(IMG:style_emoticons/default/smilie_pokal.gif)


Now, while you have it apart, get some longer wheel studs ...
(IMG:style_emoticons/default/biggrin.gif) Andy

[charliew]

Tony you've got most of the parts. The stop block really should be welded on the arm casting as it would be a lot stronger than being on the backing plate. The block should be 40mm wide. The spreader you have looks like the 84 up 944 spreader and it will work from a angled cable. I call it a angled spreader. They are even on bmw's. There is a earlier one that is straight but very similiar. Then there is the one you referred to as the one (butterfly) that needs the sheath to work properly. That's where the backing plates came from (65-68 steel arm 911) You could actually make a short extension from the 914 cable to reach the spreader. You will need to rotate the cable mount that anchors the 914 cable. It may already have been done. The spacer you checked on was because the 911 bearing is wider than the 914 bearing and the flange is cut back more to allow for it. The stop block is part of the aluminum housing on the 944, not part of the backing plate. Your backing plates seem to be on right to me the spreader goes on the same side as the emer. brake cables. As yours appear to be. Brad on the club has pictures of a boxter eb assembly and it is also nearly identical. The shoes may be narrower though.

I think I remember the part about the inner spacer as being one that spaces the cv out to allow for the 911 axles that are "almost long enough".

[PRS914-6]

Yep, the stop block needs to be welded to the arm. On a 911 it is cast in. Here is a picture of a cast 911 and my 914.

[Richard Casto]

Patrick Motorsports' website says that there is an inner and outer spacer, and that both must be used. I have not seen anywhere else, mention of this. Anyone know about that?

Tony, I am in the middle of collecting parts for this myself. I have tried to read and study every thread on this topic that I can find. To answer your question about the two spacers...

The one you have is for the hub-centric 911 hub. The other (what I think Patrick calls the "inner") is to be used if you use a 944 stub axle. If you have the 911 stub axle, you don't need the other spacer.

I have also been working on a 914 wiki article on this entire subject. The article is not done (missing some info and has some errors that needs to be cleaned up), but here is it's current state...

http://www.roadglue.com/wiki/index.php?tit...sion_conversion

One thing I want to do for the article is to create various diagrams like you have above. Along with the diagram, I want to include actual Porsche part numbers and where to source them (i.e. what year range of 911, 944, etc.)

Richard