TheSamba.com :: View topic - Porsche 944 axles and 944 CV's for Vanagons

Mon Jun 25, 2012 11:26 am

To the best of my knowledge the Porsche 944 axle is 21.25", and a direct replacement for a Vanagon rear axle. 14" Vanagon 2wd and 4wd rear axles and Cvs are the same.

here is my empi axle next to the 944 axle. Empi is on the bottom.

I am personally running 944 axles in the rear, with 944 CV's. I have only about 200 miles on them, no problem so far.

I chose to use a CV with greater than the maximum 17 degree operating angle of stock CV's because at maximum droop, my axles are at 19 degrees. My fox shocks allow an extra inch of droop.

The 944 CV is rated for a max angle of 22 degrees, based on this site:
http://blindchickenracing.com/How_to/CVJoints_Axles/cv_joints_101.htm

we took some measurements of shaft diameters

Empi axle 24mm
944 axle 25mm at the narrow point near the end, 26mm in the middle of the shaft
stock axle 27mm

backstory:
I believe 930 CV's are the strongest option for a Vanagon. They are also the most expensive.

I learned of an intermediate upgrade beyond stock, and tested it. I found the Empi Type 2 Offroad CV's (rated for 25 degree max angle) too loose and noisy for my taste, and they got looser and pitted after a trip to Death Valley, so I had the CV's replaced with Lobro Type 4 cv's (Porsche 944), then the empi axle broke (the CV's and axles were not assembled correctly, so I then went to Porsche 944 axles):
The info about Type 2 Off Road CV's came from a post by DK Comet which gave this supplier link, and part numbers:

---
from http://autos.groups.yahoo.com/group/Syncro/message/48433
Guys,
The Empi race-prepped CVs & Axles I have been testing with success are in the
stock 100mm size, not moving up to the 930s. This means no new stub axles or
tranny flanges & fully interchangeable with stock sized parts, if you do manage
to break one. This is the stuff I tried to get a group purchase going for, but I
only had 6 interested people & needed 50+, but prices are very reasonable at
this well liked online vendor:

http://www.dansperformanceparts.com/buggy/susp/buggysusp%20IRS.htm

1st scan down to the 3rd item - IRS Race Axles. The size that fits our 14"
syncros is:
01-16-2212-0 21 3/8" AXLES,33 SPLINE, T-1 & 2 CV JOINTS, PR
To make these work better on a syncro, I recommend having an inner snap ring
groove added so they don't rub on your stub axles over time.

Then scan down to the 5th item - Type 2 Off-road CV Joints. There's only one
choice. The description is short, but looking these up in the Empi catalogue,
they are hardened steel outer & balls with chromoly cages. These have much
better max angle than stock & even better than the 930s.

Originally, I bought the full type 2 race kit (2nd item down), which is not
available in the length we need & then bought separate axles. However, I really
hate the racing boots & have since switched back to stock style. Those are shown
a few items further down - IRS CV Boots W/FLANGE.

If you buy all the parts that you need from here, including boots, bolts & snap
rings, the total is $424 + shipping. I have found these exact parts on the Samba
classifieds by Dan's & one other vendor, often for slightly cheaper.

This race prepped CV also works great as a front inner, but there is no front
outer or front axles that I have found in the chomoly twisting style. I'm
planning to tear into a front outer to see if it has cages that are the same as
the inner. I've never opened one up, but in that case, cages are available
separately & could be swapped in to reduce breaking. I have not checked yet. If
anyone knows, please let me know!

I really didn't want to change out stub axles & tranny flanges, so I thought I'd
try this stock sized set up to see if it could handle hard off-roading that
usually breaks these parts. Call me lazy. Call me cheap. I just could not see
springing for the lovely 930 set ups & then still having to change out stub
axles & flanges, then having to buy at least one more full axle set to carry as
a spare. So this is my compromise. These CVs have proven to be super strong &
these twisting axles really take some of the force that would normally shatter
the cages or snap the axle (or possibly damage the tranny). I have put these
through the most difficult terrain I have ever conquered & really tried to break
them, launching out of the pits at Mogfest (over & over)using full throttle with
a van full of passengers & the front end 10 feet in the air.

Mon Jun 25, 2012 12:07 pm

Good info jon, now find me some direct replacments for my 2wd.

Mon Jun 25, 2012 1:42 pm

In the first photo, it looks like the splines have beeen twisted. It might be an illusion, but if they are in fact twisted, I doubt the axle will last for long before it snaps.

Mon Jun 25, 2012 1:55 pm

I just checked Napa's part numbers for the vanagon axle assembly and compared it against the 944 and the part numbers are the same.

Maybe I'm missing something but they look to be the same part. some aftermarket axles may have slightly different dimensions like you've measured, I've noticed differences on axles I've changed before.

Mon Jun 25, 2012 2:43 pm

> In the first photo, it looks like the splines have beeen twisted.

correct, that is the empi axle

here is the one that broke,

after being installed incorrectly. The axle originally on the Driver Rear was mistakenly moved to passenger rear, without flipping the axle, and with the CV joint on the axle backwards, and the innboard circlip groove that belongs on the wheel side installed on the transmission side.

contributing factors to the failure include reverse twisting the axle, and reverse installation of the CV joint

explanation, my empi axles were prepped and installed by Burley. He added one additional circlip groove on only one end of the axles. That groove is to retain the axle shaft from sliding through the CV joint and riding on the wheels stub axle.

There is no provision to prevent the axle from sliding through the CV on the transmission side. Arguably it would be better to prevent the axle from sliding through the CV into the transmission also. DK Comet has experienced problems with the lack of groove on the transmission side, and recommends grooving both ends.

The use of grooves is controversial, and is part of a more in depth exploration of 930 axles covered here:
http://www.thesamba.com/vw/forum/viewtopic.php?t=417210

stock do not have circlip grooves cut into the inboard side of the axle. stock axles have flared splines and the axle cannot slide in and out of the CV joint star like empi or sway away axles do.

I see no merit to the Empi Type 2 Offroad CV's with torsional axle setup.

My purpose is to share the information, thanks to tdwesty, that it is a direct swap to put a 944 axle and 944 CV.. on the rear of a Vanagon.

I will report back if I manage to break one. I have heard of no one breaking a 944 axle yet. I do have reports of breaking 944 CV cages. I will confirm when I accomplish that.

Mon Jun 25, 2012 5:16 pm

Since these are solid axles like stock isn't the shock load transferred to the tranny?
The race axles are supposed to have some give and spool up to avoid that issue- obviously yours weren't up to the task though.
What is the advantage of going to 944 axles?
Porsches weigh in at half of the curb weight but twice the HP, their wheel rotating mass is half or less.
I am interested in how this lasts over time. Thanks for the post.

Mon Jun 25, 2012 6:08 pm

Interesting post ... thanks Jon.

Mon Jun 25, 2012 7:48 pm

Weird to see this post today. Yesterday I replaced the inner spacers and stock cvs on the front axles with 944 units. I pulled them from one of my parts cars and besides the boots they looked un-used.

I'm focusing on a engine swap right now so my money's tight. Thanks for informing, us Jon. I'll have some upgraded units to put on rear of my van until I can afford 930s.

Mon Jun 25, 2012 7:51 pm

syncrodoka wrote: Since these are solid axles like stock isn't the shock load transferred to the tranny?
The race axles are supposed to have some give and spool up to avoid that issue- obviously yours weren't up to the task though.
What is the advantage of going to 944 axles?
Porsches weigh in at half of the curb weight but twice the HP, their wheel rotating mass is half or less.
I am interested in how this lasts over time. Thanks for the post.

Torsional flexation saves expensive transmission repairs.

I could see using 944 parts with waterboxer powered vans, but any converted vans and especially diesel, H6 or turbo charged vans would be better equipped with 930s.

I personally have over 100,000 miles on 944 rears in my 91 Syncro base model, still wbx powered.
All my converted vans have 930s in the rear, some have them up front if running upgraded suspension.

Mon Jun 25, 2012 8:23 pm

> Since these are solid axles like stock isn't the shock load transferred to the tranny?

maybe the shock goes to the tranny, but I hope the shock load finds the 944 CV cage to be the weak link, before the tranny.

> What is the advantage of going to 944 axles?

for me personally the advantages were that they were a gift, they don't have the groove that failed on the Empi, and they work with the Lobro 944 CV's, I had just bought and installed on the empi axle before it snapped.

For the general public the advantage of 944 axles is that you can buy completely assembled 944 axles with CVs and boots installed, that have higher than the maximum operating angles that syncro axles achieve, for half the cost of 930 axles and CV's.

disclaimer, nobody I know of seems to have broken a 930 CV nor with one exception a 930 axle. If you want unbreakable, consider the 930 option. I personally would be concerned about the transmission breaking if the 930 system does not.

I am not in any way saying the 944 CV is stronger than stock, I don't know if it is or not, just that it allows more angle.

My interest in angle was initially because I though higher ride heights increased CV angle beyond the max operating angle of the stock Vanagon CV joint. That was not correct, ride height is not, imho, the main cause of high CV angles.

The highest CV angles will always be at full droop, which is not affected by ride height. What does affect full droop is the use of non stock shocks.

Besides the max operation angle of a CV, the torsional feature of the Empi axle I tried interested me, until I saw the twisted splines, and the snapped axle shaft.

I dont know if the torsional feature of a 930 axle is protective for situations like the one that broke my torsional Type 2 axle.

I will update with any new developments in my use of the 944 axles and CV's

Mon Jun 25, 2012 8:35 pm

I'll be a guinea pig too, ordering some 944 axles as my current ones are on the last leg.... Soon

Mon Jun 25, 2012 8:39 pm

Jon_slider wrote:
> What is the advantage of going to 944 axles?

for me personally the advantages were that they were a gift, they don't have the groove that failed on the Empi, and they work with the Lobro 944 CV's, I had just bought and installed on the empi axle before it snapped.

For the general public the advantage of 944 axles is that you can buy completely assembled 944 axles with CVs and boots installed, that have higher than the maximum operating angles that syncro axles achieve, for half the cost of 930 axles and CV's.

I ran the 944 CVs on stock axles for some time, I was just wondering if the porsche axles were somehow better than vanagon axles. I have them sitting around still wondering what to do with them.
I always have reservations about using rebuilt units rather than a known axle with new CVs- cheaper has to come from somewhere.
I converted to the 930 setup for the torsional properties of the axles.

Mon Jun 25, 2012 8:46 pm

> I'll be a guinea pig too

yay, someone to share my misery, or.. joy

> I was just wondering if the porsche axles were somehow better than vanagon axles.

I dont know if the 944 is a better axle than a stock axle. I did not have a pair of stock axles available or I would have put the 944 CVs on stock axles, like you did.

Tue Jun 26, 2012 2:49 am

I'm using stock Vanagon axles.

Tue Jun 26, 2012 7:09 pm

Interesting stuff right here 8)

Quote: The axle originally on the Driver Rear was mistakenly moved to passenger rear, without flipping the axle, and with the CV joint on the axle backwards , and the innboard circlip groove that belongs on the wheel side installed on the transmission side.

Hey,Jon,

Can you explain to me what's in red,I don't understand why this is an issue:I'm confused;was the Cv joint mounted backwards on the axle shaft itself,or it's just because the whole axle have been moved from driver side to passenger side?

Thanks for your input ;-)

Alex

Tue Jun 26, 2012 8:25 pm

Jon's 944 CV joint was both mounted backwards on the axle shaft itself and the empi torsional axle was moved from driver side to passenger side by mistake. Unfortunately he didn't find that out till the axle snapped. The empi axle snapped do to the revolutions being reversed from its natural state! Thats why that picture shows twisted splines! Ouch! Make sure your CV joints and tortinal axles are installed right and pay cation not to mix up left and right axle assembly's when they are removed. I won't even get into clocking CV's....

Tue Jun 26, 2012 8:34 pm

VWhead wrote: Jon's 944 CV joint was both mounted backwards on the axle shaft itself and the empi torsional axle was moved from driver side to passenger side by mistake. Unfortunately he didn't find that out till the axle snapped. The empi axle snapped do to the revolutions being reversed from its natural state! Thats why that picture shows twisted splines! Ouch! Make sure your CV joints and tortinal axles are installed right and pay cation not to mix up left and right axle assembly's when they are removed. I won't even get into clocking CV's....

Yup, that"ll f'em up for sure.
I take a Blue Point engraving pen to the axles and CVs when new to mark them.

Tue Jun 26, 2012 10:35 pm

Thank you guys!

So,once new,the shafts are installed a certain way,it doesn't matter right?

That's only because of stress that we shouldn't move them from side to side without reversing them,correct?

Thanks for your clarification :D

Tue Jun 26, 2012 10:35 pm

> with the CV joint on the axle backwards

This first pcture shows the cv installed wrong. The shoulder of the star belongs on the boot side, not as pictured, on the flange side aka axle end. In addition the Cv cage is flipped wrong side out, and the boot side of the outer ring was flipped wrong, facing the axle end

This next pic shows the star correctly installed, the cage facing correctly

and the outer ring oriented properly, with single groove towards axle end

Note the B for big, in the above pic, refering to the wide shoulder in the outer cv ring, in anticiparion of clocking the Cv installed on the other end of the axle shaft, by lineing up the small shoulder on one end to the big shoulder on the other end, when sliding the Cv onto the axle splines

Almost every possible assembly error was made

Tue Jun 26, 2012 10:41 pm

Dang, I need to pay closer attention to my axles....I believe i'm gulty of such act. :oops: