gearbox output flange weldable?

[KTL]

You should be able to find a set of outer 100mm stub axles quite easily. They are very plentiful on the used market. I don't think the 100mm CVs are necessarily the weak link. It's the M8 bolts and their relatively low torque that often loosens the connection. That said, with proper attention they should hold up OK. Our old MotoDelta 1970 911 GTS4 car had a 248RWHP 3.3L short stroke in it and used the SC axles for a number of years before eventually switching to a G50 (problematic 915 had to finally be abandoned) and in that time the car never had a problem with axle failure. Low ride height, sticky radial slicks and fast = a lot of load put thru those 100mm CV axles every time it hit the track. Never had an axle fail in ~7 years of running those axles. Key was ensuring the bolts were tight during regular nut & bolt check plus annual regreasing.

That said, a 3.6L is a torquier engine and the car you're running is considerably heavier than our old 1970 car. 108mm axles are not a bad idea for a 3.6 car considering that's how the factory 3.6 cars are equipped by Porsche

[Shaun @ Tru6]

Originally Posted by ClickClickBoom

The flange, if it were to fail would most likely be under load, 6000RPM means a foot full of gas, any sudden decrease in loading while under that amount of power would cause the engine to accelerate instantly, into an over rev situation, enough over rev will cause valve float.

That's funny.

[356RS]

I had a set of 68 stub axles on the 68 IRS arm modified to accept 930 CV joints. This was mated to an early 915 trans. 5 years of hard driving so far.

[KTL]

Mark,

Could you elaborate a bit how you modified the '68 stub axles to fit the 930 CV? Reason I ask is because I think the later CV has more articulation and that's why the later stub axles have the "reliefs" cut in them to clear the joint balls?

[ClickClickBoom]

Originally Posted by Shaun 84 Targa

That's funny.

Not getting the funny part....unless its someone else's motorsheister motor.

[356RS]

Kevin, I used a set of early 108mm 4 bolt/2 pin stubs, cut off the CV flange section. I then cut off the 68 IRS stub axle CV section and mated the 108mm section to it. Careful measurements were made and the mating surfaces were carefully shaped before any welding was done. I had to make up a set of gaskets for the 930 CV's. On the 68 IRS arm I had to relocate the emergency brake cable hole so to clear the 930 CV.

[Dodge Man]

69-73 have the same BC as the 84-86 Carrera & M10 bolts/thru holes. Try to buy hubs that "bolt on" because welding, stress relieving, and machining can be more costly. Hubs are machined castings and welding castings is not always easy. Since mine had the sand grain texture from the cores I called it a casting. Forged parts I have seen generally have a smooth surface from the forging die and generally do not have a sand texture on the surface. Maybe Check the splines on early 84-86 Carrera hubs and you may have what you are seeking. Check the trans info charts here on Pelican. Same axles were used from 69(901)-73(915) so you should not have length issues.

911-332-033-09-M60

Complete Axle With CV Joints And Boots (bolts not included) (2 per car, sold individually), 911 (1969-73), Each
Brand: GKN Loebro Original Equipment Manufacturer at the time of the vehicle's assembly [More Info]

I actually use the 1973 new replacement Loebro 911 axles from Pelican which are basically 84-86 Carrera replacement axles with the roll pins installed. I just knocked out the roll pins on the trans side and bolted right up. Be sure to get the factory tin grease cups for the inner CV joints to make the install a lot easier/cleaner. Gaskets are a PITA and break easily. I have a 915/72(ROW) with the fine splines and large BC. Replacement axle shaft diameter is large enough for your 300HP racing/sport purpose. Doubled the shaft OD of my 73 axles. Replacements are the same price of just 1 replacement 1973 CV joint kit. A bit of homework but worth the effort.

[Matt Monson]

Just a slightly off topic pet peeve but I hate when people make blanket statements about forging being better than casting. Technically, forging is a form of casting. They use dies. They cast the materials at various temperatures and in different ways. But cast doesn't mean that something is automatically done in pot metal using some rough hewn die that produces an inferior part.

Just like forging doesn't guarantee quality. A forging is only as good as the material used and the balance of the process (like heat treating or finish grinding).

Sorry, just a pet peeve of mine. Most of what we make is from billet, but that again doesn't mean that our stuff is automatically better than something forged (or cast). The Japanese are the masters of selling the merits of forged automotive parts, and some of the stuff they produce is utter junk.

[chris_seven]

Originally Posted by Matt Monson

Just a slightly off topic pet peeve but I hate when people make blanket statements about forging being better than casting. Technically, forging is a form of casting. They use dies. They cast the materials at various temperatures and in different ways. But cast doesn't mean that something is automatically done in pot metal using some rough hewn die that produces an inferior part.

Just like forging doesn't guarantee quality. A forging is only as good as the material used and the balance of the process (like heat treating or finish grinding).

Sorry, just a pet peeve of mine. Most of what we make is from billet, but that again doesn't mean that our stuff is automatically better than something forged (or cast). The Japanese are the masters of selling the merits of forged automotive parts, and some of the stuff they produce is utter junk.

How can you describe forging as a type of casting? The two processes have no similarity at all other than to produce shapes.


Forging is a 'solid' phase process and casting is a liquid phase process.

There are basic differences in resulting microstructures that will have a significant influence on mechanical properties.

This is a very basic explanation

http://www.atcgroup.com.au/CustomCastingForging/TheDifferenceBetweenCastingForging.aspx

[KTL]

Originally Posted by 356RS

Kevin, I used a set of early 108mm 4 bolt/2 pin stubs, cut off the CV flange section. I then cut off the 68 IRS stub axle CV section and mated the 108mm section to it. Careful measurements were made and the mating surfaces were carefully shaped before any welding was done. I had to make up a set of gaskets for the 930 CV's. On the 68 IRS arm I had to relocate the emergency brake cable hole so to clear the 930 CV.

Thanks for the clarification on how you did it Mark.

And Mark's not the only one to attempt this. In my hunting on VW off road sites, i've found some other welded parts

Race Ready > 930 Conversion Stub Axles

Also found in my hunting that there are virtually no VW or 914 stubs/flanges with the CV reliefs in them. So I really can't understand why Porsche chose to have their stubs relieved for clearance. Some people have said the reliefs are to allow the metal end cap to fit onto the stub. That makes sense. But recall that the smaller 100mm stubs used from 75 thru 85 have the reliefs in them and those small stubs do not use the metal end caps. They use the pesky gaskets.

[yundar]

Hey There... I have been reading this thread because I am replacing the CV boots on my (mostly) stock 74. Should the drive axles come off the car without having to remove the stub axles? I am able to remove them from the tranny drive flanges but they do not want to come off the stub axle side. Should I remove them as a unit with the stub axles? They are the four bolt style with retainers.
Also, can the tranny drive flanges be removed by pulling the center bolt? There is an oil leak around the drive flanges where they come out of the transmission and I would like to replace these seals. Can they be replaced by simply removing the drive flanges?

On a less technical note... I removed the Koni shocks for cleaning and I accidentally cleaned some of the paint off! Is there a close enough color or brand of spray paint that I can use to repaint them. Does Koni make or sell the paint. What do restoration people use?

Thanks, Andy.

[KTL]

Yep the axles should come off the trailing arm stubs as easily as the transmission stubs. Years of crud and dried grease most likely has them stuck on there. A good whack with a hammer and wooden dowel should knock them free. The four bolt style with the pins does a good job of holding the CV onto the stub.

Yes the trans stubs come out simply by removing the center bolt. Use a couple of old CV screws installed in the stub. Slide a bar between the screws to use as a counterholding bar and that'll allow you to loosen the stub center bolt.

Dupli-Color or Plasti-Kote "School Bus Yellow" seems to be a good match for people.

[yundar]

Thanks for the response!