: Carbon Fiber DSS Driveshaft installed



barrok69
09-01-13, 12:33 PM
My oem carrier bearing bushing was shot and made the vehicle buck real bad on in-gear off-throttle decel type maneuvers which drove me to buy this nice one piece DS to eliminate the nonsense. The bearing itself felt ok, but i was getting some grainy noise coming through the cabin with the oem shaft also.

From a weight perspective the CF drive was 27lbs including billet couplers. The oem was slightly heavier at ~10lbs more than the CF (guesstimate).

I Just completed installing my new CF DSS Driveshaft the other day. It was relatively painless other than having to deal with allen key bolts in tight spots. Dropping the Corsa exhaust was pretty easy. Everything came apart real nice without any drama. I undid the clamps at the backside of the cats and took the muffler hangers off and dropped the entire thing all together.

I painted the areas of the exhaust with some blue VHT ceramic header paint and also wrapped the rear section near the diff with DEI titanium wrap for heat management purpose.

The last part was applying some omega label temperature stickers to the critical bond areas of the shaft to monitor the temperatures in those areas. DSS recommended temp cannot exceed 300F at the bond.

With this 3.25" Driveshaft It still has enough clearance as to not smack the bottom of my Katech shifter, which is nice. There isn't a ton of room between, but i wouldn't recommend a 1piece shaft any wider.

I took it out for a drive and wow. Noticeable difference in power delivery and driveline tightness. The car feels much smoother off the line and the laggy feeling of wind up is completely gone. My coastdown issue is also resolved and no more bucking is present. The grainy cabin noise was also eliminated. I'll be keeping an eye on the temperature stickies I attached to the parts to ensure temps stay within recommended values.

Great Product DSS !

Here is the website to get the temp stickers if anybody is interested. They are great for putting on shocks to monitor temps and other places!
http://www.omega.com/toc_asp/subsectionSC.asp?subsection=F02&book=Temperature

pics!
Side by side of Driveshaft Shop CF 1piece Driveshaft next to used 38k oem 2piece shaft
http://i169.photobucket.com/albums/u240/barrok69/oldoemvsnewCFDSS_zps1f31142c.jpeg (http://s169.photobucket.com/user/barrok69/media/oldoemvsnewCFDSS_zps1f31142c.jpeg.html)

installed
http://i169.photobucket.com/albums/u240/barrok69/CFDSSinstalled_zpsf8312353.jpeg (http://s169.photobucket.com/user/barrok69/media/CFDSSinstalled_zpsf8312353.jpeg.html)

Katech Shifter clearence
http://i169.photobucket.com/albums/u240/barrok69/ClearancetoKatechsfhiter_zpseb602c23.jpeg (http://s169.photobucket.com/user/barrok69/media/ClearancetoKatechsfhiter_zpseb602c23.jpeg.html)

Trans side pic
http://i169.photobucket.com/albums/u240/barrok69/frontcoupler_zps0c036a7e.jpeg (http://s169.photobucket.com/user/barrok69/media/frontcoupler_zps0c036a7e.jpeg.html)

Diff side pic
http://i169.photobucket.com/albums/u240/barrok69/rearcoupler_zpsb8c56dbd.jpeg (http://s169.photobucket.com/user/barrok69/media/rearcoupler_zpsb8c56dbd.jpeg.html)

rand49er
09-01-13, 12:45 PM
Wow ... nice! Good pics, too.


Two ques:
1) Did it get rid of any driveline clunking you may have had before the install?
2) Cost, if I may be so bold to ask?

heavymetals
09-01-13, 12:59 PM
Told ya so.

Pretty neat huh?

barrok69
09-01-13, 01:18 PM
Wow ... nice! Good pics, too.


Two ques:
1) Did it get rid of any driveline clunking you may have had before the install?
2) Cost, if I may be so bold to ask?

1- Driveline clunk is much better. I have the stock clutch/flywheel so I still have a clunk if I don't push in my clutch the right way. When I had everything apart i was turning the diff by hand and noticed that just turning by hand it clunks when it engages the gears. There appears to be about 10-15 of lash in there and its not exactly quiet. So short answer any kind of clunk I'm hearing is most likely gear engagement now that I have replaced with CS motormounts, trans mount, diff bushing&block, revshift cradle bushings and lastly CF DS. It's not as loud as it was, so that's a plus, but in order to completely eliminate it I believe a different diff is required aka 8.8 possibly. I'm quite content at this point until my diff blows up. My diff was replaced in 2008 under warranty according my warranty report, so I'm not sure what vintage diff I have (should have looked when i was doing bushing). It only has slight whine after extended romping sessions and I also have a bmr pinion brace which i believe helps keep the diff material deformation in check. I don't launch the car any more than 2500rpm/off-idle but I do shift under redline wot conditions burning tires through the gears. This was only possible with the cradle bushing swap though.

2- $1300 shipped. I needed a new DS regardless, so $1000 for stock, or + $300 for something that will actually last. It was kind of a no brainer for me. I looked at the aluminum shaft for a couple seconds but realized that when I had my car at the track doing 140+mph the critical speeds of the shaft versus the speed the car is capable of achieving would become an issue.

Hope that helps :)

I was kinda bummed when I found out that after I placed my DS order that Creative Steels CS 8.8 would be getting CF DS option. But then again, I'm not ready for a full rear end with the power I'm making. Am I on borrowed time? unsure. But I know there is a solution if I do blowout this diff. Then I'd sell this DS, since it won't fit with an 8.8 kit due to being too long.


Told ya so.

Pretty neat huh?

Indeed! Even though I had already bought it, I was glad I got to drive yours before I installed mine.

ctsv247
09-01-13, 03:11 PM
Is there no way to shorten a cf driveshaft? Sure would make investing 1300 bucks in a driveshaft a little easier to swallow if I could reuse it latter....

heavymetals
09-01-13, 03:17 PM
Is there no way to shorten a cf driveshaft? Sure would make investing 1300 bucks in a driveshaft a little easier to swallow if I could reuse it latter....

They can shorten, but cannot lengthen.

Junior1
09-01-13, 04:30 PM
Keep me/us posted on the heat please. Thats the only hold back for me at this point.
Nonetheless its still on my list for upgrades/weight reduction...

rand49er
09-01-13, 07:16 PM
... Then I'd sell this DS ...If that happens, keep me in mind. You wouldn't have to ship the thing, either.

2007V
09-03-13, 12:20 AM
If that insulation doesn't do it, then this will: http://www.aircraftspruce.com/catalog/appages/fiberfrax.php


Keep me/us posted on the heat please. Thats the only hold back for me at this point.
Nonetheless its still on my list for upgrades/weight reduction...

AAIIIC
10-01-13, 01:12 PM
Any data on temperatures yet, barrok69? I get a decent amount of in gear, off throttle "trailer hitching", much like you described in your initial post. I think having a lightweight flywheel just highlights the inherent driveline sloppiness.

barrok69
10-01-13, 02:17 PM
Any data on temperatures yet, barrok69? I get a decent amount of in gear, off throttle "trailer hitching", much like you described in your initial post. I think having a lightweight flywheel just highlights the inherent driveline sloppiness.
The temperatures haven't registered above 190F on the temp stickers. I'm going to put a lower temp threshold sticker on next time I'm under there and see what temps it is actually seeing. After a few spirited drives of nothing but WOT pulls I checked and things were nice and toasty underneath, but not enough to set off the stickers. The VHT paint and DEI titanium are definitely doing their job. I'm guessing that since it was "hot to the touch" it's right around the 140-150F mark. New stickers will confirm this.

The "trailer-hitching" isn't as bad as it was with the old DS, it definitely mellowed out by removing the 2piece driveshaft bouncing up and down. It is still there, but much smoother.

I noticed when I had everything all apart that just turning input shaft/pinion by hand on the diff and then turning the trans output shaft by hand there is significant lash to the system. Both clunk when turning by hand independently (no DS installed). Adding the 1piece driveshaft in between definitely will give you less of the clunk. But if you really want to get rid of the clunks/trailer hitching It'll be by using a different model/brand transmission and diff. Or just simply driving around it, ie, not leaving vehicle in high gears when coming to stops or coasting, which is pretty BS in my opinion. I'm going to be working with my tuner in the near future to see how much he can tune out with DFCO.

Having poly motor mounts, trans, diff bushing, cradle bushings, etc probably isn't helping any for sound isolation, but they are a must for other driveability concerns!

I'm having quite the love/hate relationship with this car. Just wish it was engineered a little better from the factory.

StretchASU
10-01-13, 05:30 PM
I noticed when I had everything all apart that just turning input shaft/pinion by hand on the diff and then turning the trans output shaft by hand there is significant lash to the system. Both clunk when turning by hand independently (no DS installed). Adding the 1piece driveshaft in between definitely will give you less of the clunk. But if you really want to get rid of the clunks/trailer hitching It'll be by using a different model/brand transmission and diff. Or just simply driving around it, ie, not leaving vehicle in high gears when coming to stops or coasting, which is pretty BS in my opinion.

I'm having quite the love/hate relationship with this car. Just wish it was engineered a little better from the factory.

This is probably the biggest thing I have noticed with these cars, all of them, that I have looked at and even the one I ended up buying. There is considerably more slop in the ring and pinion setup than in any other vehicle I have been around. For whatever reason, I have yet to figure out because these diff's obviously arent worth overhauling when something lets go. There is something to be said for how much the diff bushing/block mods account for fixing the issue of the case moving, but much of the parade clunk can be attributed to piss poor ring/pinion tolerances. The torque and weight transfer in these cars only magnifies the poor setups IMO. Not trying to say that a better ring/pinion setup would fix the issues with these rear diffs, because we know there are other weak areas, but I would be willing to bet that one with less backlash and a better engagement pattern would drastically reduce the failure rate for the average V owner.

On an OT note though, that driveshaft is nice. I am interested to see how it holds up at speed on the track and if it develops any vibes or issues as it is used at higher speeds. This will be something that will have to be replaced at some point, but none of the other options make me feel confident that they will hold up in the long run for a car that is tracked.

Heavybody
10-02-13, 12:45 AM
Any data on temperatures yet, barrok69? I get a decent amount of in gear, off throttle "trailer hitching", much like you described in your initial post. I think having a lightweight flywheel just highlights the inherent driveline sloppiness.

Trailer hitching is exactly what my car does !! I just couldn't think of an accurate term to describe it but that is the exact feeling I get more often than I would like...
Very frustrating condition especially in a Cadillac it might make more sense if I had the truck motor ...

barrock how much has that feeling gone away with the one piece drive shaft?

AAIIIC
10-03-13, 11:28 AM
The temperatures haven't registered above 190F on the temp stickers. I'm going to put a lower temp threshold sticker on next time I'm under there and see what temps it is actually seeing. After a few spirited drives of nothing but WOT pulls I checked and things were nice and toasty underneath, but not enough to set off the stickers. The VHT paint and DEI titanium are definitely doing their job. I'm guessing that since it was "hot to the touch" it's right around the 140-150F mark. New stickers will confirm this.

The "trailer-hitching" isn't as bad as it was with the old DS, it definitely mellowed out by removing the 2piece driveshaft bouncing up and down. It is still there, but much smoother.
Thanks for the feedback. I'll probably get around to doing this in the next few months.


I noticed when I had everything all apart that just turning input shaft/pinion by hand on the diff and then turning the trans output shaft by hand there is significant lash to the system. Both clunk when turning by hand independently (no DS installed). Adding the 1piece driveshaft in between definitely will give you less of the clunk. But if you really want to get rid of the clunks/trailer hitching It'll be by using a different model/brand transmission and diff.
I've had my diff replaced a couple of times due to noise issues. The first time, the tech at the dealer popped the rear cover off and showed me the gears. I wish I had had a camera to take a picture of it, because the wear pattern was clearly AFU. I think a combination of housing flex + poor gear setup were to blame (based on my vast experience with such things :p). Of course, the diffs aren't serviceable, so the dealer can't adjust backlash or pinion depth - they just install the diff as it comes out of the box.

Naf
10-04-13, 07:19 AM
I had rpm rebuild both of mine. One has stock 3.73 the other is 3.42 for more traction...

They changed the clutches and all the needed work...

barrok69
10-04-13, 09:41 AM
I had rpm rebuild both of mine. One has stock 3.73 the other is 3.42 for more traction...

They changed the clutches and all the needed work...

How did they turn out? Do you still have a ton of lash like everybody has been complaining about?

AAIIIC
10-04-13, 10:15 AM
I had rpm rebuild both of mine. One has stock 3.73 the other is 3.42 for more traction...

They changed the clutches and all the needed work...
And how much did that cost you?

Perhaps I should've been more specific in my post - the diffs are serviceable, but not by GM with GM parts. You have to source the parts from Getrag. The Corvette shop that tuned my car offered me a V diff (with 3.90 gears) that they had built for a guy that was road racing his V. They said getting all of the shims and clutches and everything from Getrag was $$$$.

Naf
10-04-13, 12:30 PM
I dont remember how much i dropped on each diff upgrade. Never had a slop issue before.

My car is still on jacks for the dry sump tank. So dont know how it runs

HAMSTAR
10-09-13, 08:31 AM
I wonder how much RWHP you will gain back after eliminating some drivetrain loss...

barrok69
10-09-13, 11:17 AM
I wonder how much RWHP you will gain back after eliminating some drivetrain loss...

There could be some improvement from reducing the rotating mass and making the system slightly more solid. But I didn't do it for those reasons and I don't have a before or after dyno to compare. If anything, whatever the current power levels are, it should be put to the ground sooner during a launch from less drivetrain wind-up.

FuzzyLogic
10-09-13, 09:24 PM
There probably won't be an improvement due to inertia. The rotating inertia of a cylinder is essentially L*m*r^2 (the moment of inertia of a thick-walled cylinder is much more complicated, but the principal is the same). Length remains the same, and mass might be decreased, but diameter definitely went up, offsetting the mass reduction.

VincentT
10-09-13, 11:22 PM
Length isn't a variable in the calculation of the moment of inertia of a thin-walled cylinder.

I would think that reduced friction from the loss of a carrier bearing and mid-shaft joint in combination with reduced mass would overcome the increased radius.

FuzzyLogic
10-09-13, 11:50 PM
Length isn't a variable in the calculation of the moment of inertia of a thin-walled cylinder.

I would think that reduced friction from the loss of a carrier bearing and mid-shaft joint in combination with reduced mass would overcome the increased radius.

This isn't a thin-walled cylinder, however ("thin-walled" means that the wall thickness is effectively zero), and there's really not a lot of losses in the carrier bearing unless the bearing is very old/worn.

As far as I know, the significant inertial gains can be had at the flywheel, the wheels, and the rotors. In my opinion, it's worth going with a carbon fiber driveshaft for a) the high critical speed and b) the reduction in drivetrain slop.

VincentT
10-09-13, 11:56 PM
This isn't a thin-walled cylinder, however ("thin-walled" means that the wall thickness is effectively zero), and there's really not a lot of losses in the carrier bearing unless the bearing is very old/worn.

As far as I know, the significant inertial gains can be had at the flywheel, the wheels, and the rotors. In my opinion, it's worth going with a carbon fiber driveshaft for a) the high critical speed and b) the reduction in drivetrain slop.

I agree with all of that.

sssnake
10-10-13, 02:42 PM
What is the critical speed of this driveshaft? I may replacing mine soon and was going to go two piece for the critical speed advantage it offered over the one piece aluminums I've seen offered.

barrok69
10-10-13, 02:59 PM
What is the critical speed of this driveshaft? I may replacing mine soon and was going to go two piece for the critical speed advantage it offered over the one piece aluminums I've seen offered.

250mph. More than our cars can ever dream of seeing. I've hit 140+mph at track days so going with the 1 piece aluminum was not a good option (150mph crit speed). I also wasn't interested in going the two piece route again. Also the aluminum shafts are 3.5" in diameter and can cause clearance issues with certain shifters. The CF is 3.25" and clears my Katech shifter with room to spare.

With respect to the intertia calculations. It is quite a bit more complex than doing a cylinder. The CF driveshaft would fall under thin walled cylinder or could be considered a point mass due to the almost weightlessness of the material. you'd have to add the inertias of each section of the stock DS to do comparable calculations.
It is very awkward to hold the CF driveshaft because the middle literally has no heft to it. All the weight is on the ends in the CV and coupler. You get a real fun gyroscopic effect when moving it around.

If you want to get more detailed you can also include the couplers, solid vs. flexjoint and add those to the overall inertia. If I get some spare time one of these days I might go an measure everything and do the calculations.

Based on a few rough initial calculations with guesstimates of stock DS sizes I was doing last night it looks like the CF one might actually come out to be slightly less than the stock. We shall see.

At the end of the day, it feels great and is working better than what it replaced :)

rand49er
10-10-13, 05:46 PM
Am I the only one who gets some great big ol' rectangle where Fuzzy's avatar should be?

Sorry ... I know this is way off subject.

HAMSTAR
10-10-13, 09:20 PM
There are avatars? I don't see any at all.

fweasel
10-10-13, 10:03 PM
FWIW, a lightweight flywheel on my 300ZX was a hugely noticeable modification to the driveline. The carbon fiber driveshaft I installed made no noticeable change to how the car drove or responded to throttle input. Yes, completely different platform, but still a heavy OEM piece was replaced with something more lightweight and the inertial difference wasn't measurable from the seat of the pants.

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There are avatars? I don't see any at all.turn them on in your user settings

FuzzyLogic
10-13-13, 03:51 PM
Hey, I'm under my car right now, looking at clearances between the driveshaft and the bottom of my Katech shifter.

I accidentally flipped my nylon shifter cup over when I last had the transmission out, and I just measured only 0.60" clearance between the stock 2.00" driveshaft. When I flip the nylon back to the correct orientation, I'll measure again, but I doubt I'll like the results. All of this (including Barrok69's pictures on the previous page) makes me wonder whether G-Force has tested or sold one of their 3.75" carbon fiber driveshafts for use in this car.