HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Wore out my drive shaft

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Re: Wore out my drive shaft

Post  xschop on Wed Mar 16, 2011 7:04 pm

Once again..... What is the actual spline length of that "upgraded" clutch disc? The pic I got of the Spec clutch from Endernet's gallery shows about half the spline length of even the 944T clutch disc.
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Re: Wore out my drive shaft

Post  DVC on Wed Mar 16, 2011 7:10 pm

fliermike45 wrote:Constantine just stopped by my house to pick up my old TT (He's going to recycle the outer tube as the shaft is shot).
We discussed the picture of the DVC's worn shaft. [/url]


Good timing Mike, you're correct. Look at the pic I posted above.

V8 Carrera-My adapter is 16.26mm.
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Re: Wore out my drive shaft

Post  xschop on Wed Mar 16, 2011 7:51 pm

Just got back from Autozone with a mic in hand....

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Last edited by xschop on Wed Oct 19, 2011 4:12 pm; edited 2 times in total
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Re: Wore out my drive shaft

Post  v8carreragts on Wed Mar 16, 2011 7:56 pm

That's the same as I have on mine, 1"

I assembled everything on the floor without the pressure plate so I could see how everything lined up.
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Re: Wore out my drive shaft

Post  xschop on Wed Mar 16, 2011 8:00 pm

So you're telling me that the red ? in the pic is 24mm spline length?

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Re: Wore out my drive shaft

Post  robstah on Wed Mar 16, 2011 8:16 pm

When talking to Gregory at Gripforce about the clutch setup, this is what he had to say (I linked him to the roadrunner clutch):

Rob,

The disc in the link you gave me would not work for your application.
It has all the correct dimensions but the shape of the Chrysler
input shaft is different from Porsche input shaft.

Here's the custom built clutch from Gripforce:

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There is at least an inch worth there.

All I know is that I have heard of nightmares when it comes to Spec and that is mainly from the Porsche and BMW crowd.

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Re: Wore out my drive shaft

Post  v8carreragts on Wed Mar 16, 2011 8:43 pm

I don't know about the Spec disc. I have a Borg Warner disc and the splines in the hub are 1" long. It also fits just like the 944 disc did. The 944 disc I had was a Ferodo spring center disc. It also had a 1" spline in the hub.

I also used a Mustang disc in my last 924 (79 n/a) that was turbocharged. I added a 944 TT and transaxle and since the 924 (early) n/a uses a 13/16 x 24 spline and was 215mm diameter, I couldn't use the 944 disc. I had over 60,000 miles of hard driving on it and it still looks usable.

Before I sold it I put the 944 engine from my car in it. That's why I still have the disc.

I wonder if hubs from some manufactures are looser than others.
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Re: Wore out my drive shaft

Post  948 on Wed Mar 16, 2011 9:05 pm

It looks like you already have an idea of what went wrong....lack of engagement.
But I'll throw my $0.02 in also.
I have seen this type of wear in gas turbine thrust reverser spline drives, when there is excessive axial movement. Since the tip of the spline shaft is at or close to over center and not fully engaged , as it relates to the hub, the hub is able to wobble and cause fretting wear over time.
Two other things:
Firstly, try to avoid the Chrysler female spline on a male Porsche spline. The Chrysler is ever so slightly larger and can also promote fretting wear.
Secondly, don't try and "harden" the spline. It would require that you know what material you have and what its current hardness is. Some steels don't respond to flame hardening/oil water quenching as they don't have enough carbon content to convert to martensite. If the shaft has a lower carbon content, like say 8620 steel, then you would need to introduce carbon to the steel after heating it, carburizing it. BTW you could try and carburize a low carbon steel by repeatedly heating and quenching it in motor oil, because of the carbon content in the oil.

I think that with a new shaft and proper engagement you should be a-okay.

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Re: Wore out my drive shaft

Post  DVC on Wed Mar 16, 2011 9:19 pm

948 wrote:
I have seen this type of wear in gas turbine thrust reverser spline drives, when there is excessive axial movement. Since the tip of the spline shaft is at or close to over center and not fully engaged , as it relates to the hub, the hub is able to wobble and cause fretting wear over time.

Very well said. This was a Chrysler disc as well.

I'm very disappointed the builder didn't check drive shaft engagement. He claims out of the 25 swaps he's completed, mine is the 2nd to do this. I'm really surprised mine lasted 4 years as my daily driver, when it had maybe 70% engagement. BTW, he blamed using a high mileage TT combined with lots of power, and driving the car hard.

I guess on the bright side, it gave me an excuse to get Constantine bearings and aluminum clutch components.
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Re: Wore out my drive shaft

Post  xschop on Wed Mar 16, 2011 9:34 pm

The method I did was carburizing. It infuses carbon at the molecular level during the quench with a high carbon substrate into the steel a few mm's. I've done this many times to various parts. The old timers call it "case hardening". I also retempered it (stress relieved it) by reheating it to a bluish color, the quenching with water. Now that I see the spline engagement issue, I don't belive this is what's needed, but simply a longer spline engagement. I've heard it stated many times about the Chysler spline pattern being slightly looser than the male Porsche pattern, But that Dodge disk had the same minute play as the 944 disc I removed.
That being said, I remember clearly that the Chrysler inner spline ridges were taller than the Porsche inner spline ridges between the two discs and wondered if the posts about the spline patterns were ever actually measured on the 944 or just assumed they were metric. Just as I've found that these spindles and Hubs are NOT METRIC. Even the outer tie-rod ends are not metric, but 1" TPF and hubs/spindles all have ENGLISH bearings.
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Re: Wore out my drive shaft

Post  xschop on Wed Mar 16, 2011 10:10 pm

I'll take a 1.0" Chrysler spline engagement over a 0.7" Porsche spline engagement any day. The surface area contact is a huge difference.
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Re: Wore out my drive shaft

Post  948 on Wed Mar 16, 2011 10:33 pm

On an involute spline the only way to really determine its size is by measuring key characteristics, like the circular pitch / pitch diameter (neither are easy on an unknown). The outside diameter means practically nothing.....
Years ago I had a conversation with Red Roberts, founder of Mcleod Clutches, about getting a GM disc with a Porsche spline....he assured me that his manufacturing tool for the Porsche spline was different than the Chrysler.
Regarding case hardening: I must have mis-read the post as I thought you mentioned that you oil quenched. Oil quenching, on a low carbon steel, will not really case harden....if yours changed hardness then the steel must have a higher carbon content with which to convert the surface to martensite.

Does anyone know what the material is?

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My Mcleod dual friction clutch with 1 inch wide Porsche spline hub....
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Re: Wore out my drive shaft

Post  robstah on Wed Mar 16, 2011 11:00 pm

Wow, purdy disc you got there. Very Happy

That hub looks identical to the one on mine.

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Re: Wore out my drive shaft

Post  xschop on Thu Mar 17, 2011 7:59 am

Until spline surface area calcs are done between the various "upgraded" discs, I'm not buying it...literally.
What would put an end to the debate/problem is a 1.5" length spline engagement with the proper spline pattern, whatever that may be. At that engagement I wouldn't bother hardening the splines.
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Sample

Post  fliermike45 on Thu Mar 17, 2011 10:38 pm

Here are some pics of my clutch plate and my alignment tool.

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Re: Wore out my drive shaft

Post  robstah on Fri Mar 18, 2011 1:44 am

I still don't know why people are running the shorter sealed bearing setup. I followed what Rob (xschop) said to use, and sure, it does stick out about 2 mil, but it definitely guarantees that the shaft does not jump out on load or any other situation. So far, the guy seems to be on the ball with everything so far.

This is my main reason why developing a source of information from scratch would be worthwhile to the new guys on the block.

Hell, I still don't know what to do with the coolant temp setup.

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Re: Wore out my drive shaft

Post  948 on Fri Mar 18, 2011 6:51 am

xschop wrote:Until spline surface area calcs are done between the various "upgraded" discs, I'm not buying it...literally.
What would put an end to the debate/problem is a 1.5" length spline engagement with the proper spline pattern, whatever that may be. At that engagement I wouldn't bother hardening the splines.

Really??? The worn spline, in this case, has nothing to do with the overall length of the spline hub. Re-read my post for the explanation. Rolling Eyes
Even a spline hub 5/8" long, fully engaged with the male spline, would handle the kind of torque typically found in these engines, it would however have a shorter fatigue life; maybe a factor of 10 instead of 12 Laughing

1.5 inches?? Why not just say 2.0" that's just as good a guess.....if you can determine PD, material tensile, whether it was hobbed or precision cut, and pressure angle I'll do the yield calcs for you.

The moral of the story is: Always make sure your clutch hub is fully engaged to the drive spline.


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Re: Wore out my drive shaft

Post  948 on Fri Mar 18, 2011 6:53 am

fliermike45,
That sure does look like the hub is not fully engaged???
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Re: Wore out my drive shaft

Post  DVC on Fri Mar 18, 2011 9:54 am

I've yet to find anyone who's stripped the splines with a properly installed drive shaft, regardless of hub length. Here is an old (but VERY good) post from Marc A on the old hybrid board:

The position of the drive shaft in the torque tube is set by the factory. At the rear end of the torque tube the drive shaft is notched, as is the main shaft of the transmission, and the two joined by a coupler. The gap between the drive shaft and main shaft from the factory is less than a match book cover wide. I originally installed the clutch and pressure plate on the flywheel of the LS1 without even thinking to check whether the drive shaft was going to be positioned properly into the pilot bearing. This was my first mistake and caused the clutch hub/drive shaft failure mentioned above.

LESSON #1 - Install engine WITHOUT clutch and pressure plate FIRST and then bolt up bell housing with torque tube connected. This way you can see the position of the drive shaft "nose" as it relates to the pilot bearing. If you find the same thing that I did the drive shaft will have to be gently tapped forward (from the rear of the torque tube) until the nose of the drive shaft is fully engaged in the pilot bearing. I had to move my drive shaft about 1/4" forward. Moving the drive shaft forward requires the drive shaft to be "notched" so that the coupler can be installed with the new location of the drive shaft. The drive shaft is not hardened so a drill can be used to make the notch.

At this point connect the transmission to the bell housing, properly tightening the four mounting bolts. Slide the collar onto the drive shaft until the notch in the main shaft is aligned with the rear through hole of the coupler and install the allen head bolt all the way. Now check the position of the drive shaft nose to make sure it is still in the proper location. MAKE SURE THE CAMFER BEHIND THE NOSE DOES NOT TOUCH THE PILOT BEARING.

If all is in order, drill the drive shaft using the coupler as the die. Do not drill too far as you will hit the threads on the top side of the coupler. Once drilled install the allen head and check the nose one more time.

Now remove the transmission and back the torque tube out of the bell housing. Install the clutch and pressure plate and then re-attach the torque tube and transmission.
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Re: Wore out my drive shaft

Post  xschop on Fri Mar 18, 2011 10:53 am

Thanks for the pic Mike.
Puts an end to the debate for me.
13/16" = 0.8125
I measured a new 944T disc at Autozone last night, actual spline length is 24mm AND it is offset towards the rear 5mm to guaratee 100% TT spline engagement...What ya know the P engrs got something right!

As for 948 "upgraded" dscs.....Doesn't take an eng. degree to decipher the problem....
Hmmm..... Stick in double the power and torque and go down in spline engagement contact area....


Last edited by xschop on Fri Mar 18, 2011 1:23 pm; edited 1 time in total
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Re: Wore out my drive shaft

Post  robstah on Fri Mar 18, 2011 10:55 am

xschop wrote:Thanks for the pic Mike.
Puts an end to the debate for me.
13/16" = 0.8125
I measured a new 944T disc at Autozone last night, actual spline length is 24mm AND it is offset towards the rear 5mm to guaratee 100% TT spline engagement...What ya know the P engrs got something right!

As for 948 "upgraded" dscs.....Doesn't take an eng. degree to decipher the problem....
Hmmm..... Stick in double the power and torque and go down in spline engagement contact area....

The -P- engineers did design the majority of it. Razz

I don't know why people are re-notching their driveshafts either. This shouldn't be needed, right?

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Re: Wore out my drive shaft

Post  xschop on Fri Mar 18, 2011 10:58 am

robstah wrote:
xschop wrote:Thanks for the pic Mike.
Puts an end to the debate for me.
13/16" = 0.8125
I measured a new 944T disc at Autozone last night, actual spline length is 24mm AND it is offset towards the rear 5mm to guaratee 100% TT spline engagement...What ya know the P engrs got something right!

As for 948 "upgraded" dscs.....Doesn't take an eng. degree to decipher the problem....
Hmmm..... Stick in double the power and torque and go down in spline engagement contact area....

The -P- engineers did design the majority of it. Razz

I don't know why people are re-notching their driveshafts either. This shouldn't be needed, right?

No, a properly designed Clutch disc is needed.

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Re: Wore out my drive shaft

Post  Porch on Fri Mar 18, 2011 12:18 pm

The notching has nothing to do with the clutch disc, it has to do with how far the TT shaft goes into the pilot bearing. It isn't really a question of whether you should or shouldn't do it, it's a matter of whether or not you have to.

I didn't have to re-notch mine, but i did have to move it forward a few mm.
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Re: Wore out my drive shaft

Post  xschop on Fri Mar 18, 2011 12:33 pm

Porch wrote:The notching has nothing to do with the clutch disc, it has to do with how far the TT shaft goes into the pilot bearing. It isn't really a question of whether you should or shouldn't do it, it's a matter of whether or not you have to.

I didn't have to re-notch mine, but i did have to move it forward a few mm.

Actually Yes it does, unless you are using a clutch disc that has the same 944T hub dimensions. For the newcomers, people were notching the TT shaft at the rear coupler to get the 15mm dia. shaft tip to fully insert into the factory 15x35x11 bearing because it was wearing the tip prematurely (very little shaft tip was inserted), this is true. But as a side effect they were gaining a little more spline enagement, but still no cigar.
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Re: Wore out my drive shaft

Post  xschop on Fri Mar 18, 2011 12:52 pm

This will be the last I have to say about this "issue".... The rear hub spline shot tells the story....

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