Factory LSD installation into 915 - stub axle issue - Page 2

jager911 · 01-19-2014, 12:34 PM

Quote:

Originally Posted by mreid

Steve, the hubs appear to be the same 74-89:

Pelican Parts - Product Information: 911-331-065-33-M260

.

Mark,
Thanks for the info. Checked part# also and it appears the hubs are the same so hopefully I can swap axles without worrying about machining.

jager911 · 01-19-2014, 12:47 PM

Quote:

Originally Posted by newms

Hi Steve. I'm looking forward to your feedback after you get the LSD sorted. I found an alarming amount of noise and vibration at first. I also have wevo blue mounts which adds to it. I've gotten used to it and think its obvious in my car as I have no sound deadening anywhere. Also I am interested to hear your thoughts on the performance of the LSD. For me (I have a US 915 from an 83 with factory LSD). I'm not completely sure my track times are better but I do feel way more stability and safety in braking and trail braking turn in. And on the autox course ,where I have been known to go, an incredible improvement in off throttle stability and high speed decreasing radius entry. So overall I love it but not convinced my track times are a lot better. Maybe see you at pocono and we can compare notes.
Rick

Hi Rick,
I find my car wiggles the rear end under hard braking from 140 at Pocono and I can't get on the gas early in tight turns so hoping the LSD helps with both of those issues. Did you need to rebuild your LSD before installation? Gary Fairbanks is telling me they are pretty hardy. Definitely looking forward to chasing you again as our old cars are in the minority among the herd of GT3s. I may even make it out to an autox this year to give you some competition but I'm rusty having been away from it since 1999.

newms · 01-19-2014, 02:59 PM

I did not rebuild the LSD. It was tested and deemed not necessary during the Trans rebuild. Yes the braking stability and slow speed wheel spin much improved. Places like entering the octopus at Thunderbolt you can really feel the diff locking up and keeping everything quiet. Who is setting it up for you?

jager911 · 01-19-2014, 03:14 PM

I spoke to Gary Fairbanks on Friday, I'm planning to have him do it as he's the tranny guru on the East Coast. BTW, having a problem with finding 2nd gear in tight left hand turns (Pocono CCW, Devils' Elbow), are the Wevo mounts semi-solid? Alex also recommended them. I have no sound deadening either, but who cares when you're on track.

KTL · 01-20-2014, 10:14 AM

Steve,

Can you measure your axle length? I can measure my 915 axles to get you in the same ballpark. Tom's great thread link (I have that saved in my list of links about axles/CVs) did a nice job of getting Tom Butler to put together those part numbers and dimensions!

The outer stub axles are indeed the same from 74-85. The 6 bolt stub axles are P/N 923.332.232.01 and this same stub part number shows up in the '85 diagram. The complete CV axle is also the same from 74-85, if the CV is the small 100mm joint with six M8 bolts. Part number 923.332.033.02

Note that the outer hub (the female splined hub containing the lug studs) is the same from 74-89 for the narrowbody/non-turbo body cars. So your hubs are splined just fine and of a proper "depth" to receive whatever axle stubs you acquire.

As far as the trans output flanges, that's a challenge to figure out. I would see if someone can compare a set of their fine spline flanges with the dimensions of yours. You need to measure the shoulder, the shaft length, spline length and if there is a recess at the end of the shaft. There's a good topic on the 914world forum that talks about the output flanges and what to look out for.

914World.com - The fastest growing online 914 community!

I know their issue on the 914 forum is the fitment in the 901 trans. But its still a good comparison to see how the flanges can seem the same but really are not.

Matt Monson · 01-20-2014, 11:17 AM

KTL,
Just be aware that the 914 differential is not a 901 differential. It is a 911/914 differential which happens to be the same as the '72-74 915 differential for 7:31 cars.

Haven't clicked over there so don't know if they are trying to go earlier or later on their installs but each has its own challenges. This is why we make 5 different LSDs for '64-86.

KTL · 01-20-2014, 11:53 AM

I hear what you're saying Matt. Was just using the 914world topic as a reference point to demonstrate the importance of correct output flanges.

When going simply by part numbers, the CV axles and outboard trailing arm stub axles are very easy to define. But the trans output flanges varied over the years depending on the diff, so I didn't want to state any sort of definitive choice from a certain year to seek out. Seems best approach is to measure what Steve's got in hand with his fine spline '74 108mm flanges and then see what later 100mm flanges match up with that?

I only have coarse spline flanges on hand, one set of '79 SC 100mm CV size, one set of 108mm CV size (four M10 holes, two roll pin holes) of unknown origin that matches the dimensions of my '79 set. My trans setup is iffy for comparison purposes since my FrankenPorsche racecar chassis is a '79 SC but the trans is an '84 915. A 915 with an unknown make of performance diff that uses the coarse splines.

Guard Diff OMG!

mreid · 01-20-2014, 03:14 PM

Steve, just picked up my 915 with the new Guard LSD and Matt was exactly right. He switched the gears in the LSD to match the flanges in my 74 (early type with 4 bolts and 2 studs). Good luck!

jager911 · 01-20-2014, 04:23 PM

Thanks Kevin and Mark for the follow up. I can't really measure anything right now, car is put away in winter storage. Just gathering parts for spring project.
A buddy with '78 SC had the opposite issue installing a Quaife with coarse splines so he has his fine spline stub axles available. I figure I'll pick up 6-bolt SC axles and in theory, this should work.
Thanks all for the input, I will report back with my findings.

jager911 · 02:33 PM

After speaking with Gary Fairbanks, he put me in touch with Tom Conway at CarQuip. After a long chat with Tom who seems like a really nice guy as he patiently explained ramp-up % to me, I'm now leaning to a new KAAZ LSD with 60% ramp. It has more clutch plates than the factory ZF (i.e. less prone to wear), would be brand-new, bolt-in to my coarse-spline stub axles without monkeying around with changing stub axles, CVs, and hub axles.
I have not heard much about this option. At $1500, it's a better deal than rebuilding an unknown used LSD. There is a nice LSD parts explosion here showing 6 clutch plates per side, for a total of 12 plates:
KAAZ USA | Technical Intro
I assume the people on this thread have looked at all the options, what's your opinion of KAAZ? Any anecdotal or personal experience welcomed!

KTL · 01-22-2014, 02:11 PM

Do a search on the forums for Kaaz and form your own opinion. I gather the "made in Japan" quality they tout is still not entirely accurate today. This is based on comments from other forum participants that actually know the specifics around manfacturing a quality LSD.

sig_a · 04:17 PM

KAAZ is manufactured in Japan. I have one installed in my G50 and it works fantastic. There's an overabundance of BS posted about LSD's on this BB. Call Ray at KAAZ USA. He is the president of KAAZ USA, and will explain the history of the company and his background in performance motorsport as both a race car driver and author.

KAAZ is a Japanese agricultural machinery manufacturer of large tractor-type bush hog mowers down to small engine grass trimmers. The disc clutch technology used in the wide variety of KAAZ LSD models is similar to that of the disc type clutch systems found in their agricultural mowing machinery. You would be a wise man to listen to what Ray has to say about KAAZ JAPAN and KAAZ USA before you make a decision. I believe he told me he moved to California from Japan to establish KAAZ USA in 1995. Very interesting fellow with no need to BS anyone.

jager911 · 01-26-2014, 07:03 AM

Quote:

Originally Posted by sig_a

KAAZ is manufactured in Japan. I have one installed in my G50 and it works fantastic. There's an overabundance of BS posted about LSD's on this BB. Call Ray at KAAZ USA. He is the president of KAAZ USA, and will explain the history of the company and his background in performance motorsport as both a race car driver and author.

KAAZ is a Japanese agricultural machinery manufacturer of large tractor-type bush hog mowers down to small engine grass trimmers. The disc clutch technology used in the wide variety of KAAZ LSD models is similar to that of the disc type clutch systems found in their agricultural mowing machinery. You would be a wise man to listen to what Ray has to say about KAAZ JAPAN and KAAZ USA before you make a decision. I believe he told me he moved to California from Japan to establish KAAZ USA in 1995. Very interesting fellow with no need to BS anyone.

Thanks for the feedback, I read conflicting reports about made in China vs made in Japan and after much research was all set to go with OS Giken but the KAAZ price is very attractive and Car-quip recommends them also. Right now, it's either OS Giken or KAAZ and happy to hear a positive report about KAAZ. How long have you had it installed and how is the car used? I need to know if it will stand up to severe track use. A local highly-regarded race shop runs Giken in their personal race cars, 3 race seasons so far without a rebuild needed.

sig_a · 08:46 AM

Installed in January 2012 by a Porsche dealer with 3.2 liter engine and G50 removed. I drive HPDE's at mid Ohio and Putnam Park, but I've done dozens of days before and after the KAAZ install. I, like you, considered ZF, Guard and OS Giken, and many others. I was willing to pay up for the Guard or Giken. But I spoke to a well regarded "Porsche Transaxle Specialist" (BMC&G) who preferred the Porsche Motorsport factory LSD over Guard or Giken. So everyone has their own opinion and bias. You have to talk to everyone who really knows LSD's. Don't limit yourself to non-experts like myself or many others posting on these motorsport BB's.

I made up my mind after a number of long and informative conversations with Ray, KAAZ USA president. Other 911 drivers I've recommended the KAAZ brand to have also contacted Ray with questions and set-up advise, and are now satisfied with their KAAZ installation. I bought my SuperQ direct from KAAZ. He set it up so that lockup is limited to 80% on acceleration, and up to 100% on deceleration. This set-up configuration is "reversed" and unique to rear-engine 911's because of the 40/60 weight distribution.

As with any LSD out there, the amount of wear and failure rate depends primarily on how well it matches horsepower, torque and the demand put on it by driver style. Some guys overdrive their cars to a point where they tear up the best and most expensive machinery available. As far as I know Guard makes a very strong chrome moly cased LSD unit. But a 200 hp 1987 Carrera will never break the ring gear flange off the face of my KAAZ SuperQ.

As for performance; it's the most impactful handling modification I've made to date. Your 911 will not be nearly as prone to oversteering as before the installation. Hard braking induced rear axle shimmy is gone. You will enjoy learning a new corner entry and exit line with more understeer than before the install.

And don't listen to me, just call Ray.

jager911 · 01-26-2014, 09:02 AM

Thanks for the detailed feedback, that is exactly the problem I'm trying to solve, the high speed 'tail wagging the dog' and inability to trail-brake late into corners then get back on gas. I have a stock '85 3.2l with just bolt-on stuff, making estimated 220ish HP so don't expect too much load on R&P. I do need to update my early mag case side-cover to later model 915 alum side cover.
Yes, I've talked to 4 different transmission specialists and I agree, each has his own bias based on his personal experience but want to get good value for my buck so KAAZ is still on my short-list based on your feedback. I will PM you as I prefer hearing about actual user experience more than the marketing pitch from anyone selling their product.

Matt Monson · 01-26-2014, 09:15 AM

My Boxster Racing Car Project

The Gikens are doing the same thing. Search 6speed and RL and you will find examples on a number of makes and models. RL has a thread called "gotta get a Giken".

jager911 · 01-26-2014, 09:33 AM

Quote:

Originally Posted by Matt Monson

My Boxster Racing Car Project

The Gikens are doing the same thing. Search 6speed and RL and you will find examples on a number of makes and models. RL has a thread called "gotta get a Giken".

Thanks Matt, that's very nice of you, restraining from promoting Guard and even mentioning the competition.

Matt Monson · 01-26-2014, 10:05 AM

Quote:

. But I spoke to a well regarded "Porsche Transaxle Specialist" (BMC&G) who preferred the Porsche Motorsport factory LSD over Guard or OS Giken.

In the interest of disclosure many people don't know that until about 90 days ago Brian was a PMNA employee/subcontractor. His opinion is almost as biased as mine. He was paid to promote their brand.

Matt Monson · 01-26-2014, 10:10 AM

Quote:

Thanks Matt, that's very nice of you, restraining from promoting Guard and even mentioning the competition.

I'm sorry if I have offended you and you feel like I am trying to sell you something. Review my posts on this board and you will see that's not my intended approach to anything. I'll recuse myself from your thread and let you get the balance of your feedback from your peers.

jager911 · 01-26-2014, 10:17 AM

Quote:

Originally Posted by Matt Monson

I'm sorry if I have offended you and you feel like I am trying to sell you something. Review my posts on this board and you will see that's not my intended approach to anything. I'll recuse myself from your thread and let you get the balance of your feedback from your peers.

I was giving you a compliment, no offense taken at all, I genuinely appreciate your input, not sure if my comment was taken the wrong way. I would prefer to hear all sides of the ongoing discussion about LSDs.