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1G Driveshaft shop 1G 3.25" one piece carbon driveshaft, installation / review / impression.

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DSMPT

DSM Wiseman
2,796
2,498
Jun 12, 2014
Japan / Mexico, Arizona
I just wanted to let people in this forum know about this driveshaft. Driveshaft shop state on their site as the driveshaft is for DSM, but it actually comes with a non DSM rear flange. (I guess it is a 3000GT/Stealth flange. The centering pilot diameter is the same as DSM but the flange itself is slightly larger than DSM, with different bolt pattern and M10 bolt holes instead of DSM M8 holes). So if you are planning to order this driveshaft, just note that this driveshaft is not direct bolt-on, if you have a DSM rear diff. It requires some modifications to install.

I reported them that the flange is not for DSM and asked them to replace the flange to a right flange (as I am the one who asked them to list this driveshaft on their site to make it possible to order in January of this year), but they didn't admit it nor cover their fault.
They didn't pay attention to what I was telling them, even I provided infos about DSM rear diff flange. they just kept telling me that the flange they supplied me with the driveshaft is the right one for 1G DSM and "my DSM" has a different flange somehow (I have several 1G rear diffs and all have the same dimension, of course...). also told me that the best way to solve the issue would be drilling my DSM rear diff flange pattern onto the flange they supplied me (to make M8 holes) or drilling the driveshaft flange pattern onto my DSM flange (to make M10 holes). and that is the only flange they have for DSM, EVO and 3000GT. Their flange catalog doesn't have any flange that has the dimension of DSM which I provided...

Installation: (Pics attached)
Actually drilling DSM pattern onto the flange they supplied me (to make M8 holes) was the only choice. Since there won't be enough material left on the edge of DSM flange if drill to make M10 holes.

After you drill M8 holes with DSM pattern onto the flange on the driveshaft, you require to remove the rear diff flange from rear diff and trim the dust cover part to let the bolts pass through from rear diff side to driveshaft side. because you will require to put the bolts from rear side to front side since bolts can't pass through from driveshaft side to rear diff side (original direction) due to contact the u-joint. And also the bolt strength, if you set the bolts as the original direction, only threads part of bolts will remain in rear diff flange due to the thicker flange on the driveshaft.
When you put back the flange to the rear diff, first you set the bolts on the flange and then put the flange back to rear diff. otherwise bolts won't pass through after the flange is installed due to no room. (Maybe replace the drive pinion oil seal at the same time is a good idea, if you have never replaced it)

Review:
I was concerned about vibration because of the difference of angle between t-case and rear diff. and I haven't run in the track yet so it is hard to tell. but with a couple of easy pulls on the street, so far vibration is less than I expected. Actually I didn't notice much difference. maybe because all engine mounts are metal solid and they are already giving me a bit of harsh driving feeling. and I noticed the throttle response is more direct and much quicker than when it had the stock 3 piece driveshaft.
I made a quick comparison of weight. It is scaled by a bath scale, so it is not that accurate.

- 1G Stock driveshaft with carrier bearings : approximately 16.2kg (35.7 lbs)
- Driveshaft Shop 1 piece 3.25" carbon fiber driveshaft : approximately 7.4kg (16.3 lbs)

Impression:
As everyone knows, their product's quality is very high and well made. I am very impressed, happy and have absolutely no doubt about it, but I am not impressed with their after-sales customer support. That should be improved more.
Hope they would realize that their catalog of flange is misinformed, and would revise it ASAP to produce a right flange for DSM to avoid this issue with further customers.

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So you couldnt take the Dsm flange and install it on their driveshaft?
No, you can't install the stock flange on their driveshaft. The dimension is different. Also you will need to re-balance the driveshaft if you change the flange or the yoke.

Oh sorry. donniekak already answered while I was writing.
 
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Interesting. I have their aluminum one and it’s direct bolt-on.
As @OH91awd said.
And this shaft wasn't their off the shelf product when I ordered it in the late 2017 to the early 2018. It was only for a custom made. I guess the last person who ordered this shaft before me probably made for a 3000gt rear diff on a dsm, that's why DSS believed the 3000gt flange was the same as DSM flange.

Great write up, did you measure driveshaft angle, to me that is Suuuuuper important.
Before I ordered I was concerned a lot about it, too. So I confirmed about it with a DSS rep before ordering. and they just told me it won't be a big deal with this shaft (I imagine that's why the shaft is 3.25", not 3.5" like the 2 piece one). Well I am definitely not drivetrain expert and I got confused by reading too much in the internet, so I decided to experiment it myself. That's the easiest way to know the answer.

I forgot to mention in the original post that I made new bolt holes on the front engine mount below the original bolt holes. Because I have a driveshaft loop but the shaft wasn't centered in the loop tunnel. But I am not sure if this was the angle difference or the fitment issue of a tubular crossmember in a 90.

I haven't used this shaft for many years yet, so I can't say how long it lasts or maybe there would be some unknown issues in the future.
But so far I haven't had any issues. I don't have any unusual vibrations at 140mph range, I haven't exceeded 150mph though.
 
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How did you drill the 8mm holes in the d/s flange and keep it centered? Seems like that would be crucial.
That is a long sucker to be 1 piece. I don’t really know squat about carbon driveshafts, but maybe they dampen vibrations better than metals. A slight angle in the joints is not a problem as long as the diff and xfer pinions are parallel. A conventional u joint (cardan) at each end will self-cancel the torsional vibrations, so long as they are 90 degrees out of phase. I never could understand why Mitsubishi went with 3 cardan and one c.v. (Lobro).
 
How did you drill the 8mm holes in the d/s flange and keep it centered? Seems like that would be crucial.
That is a long sucker to be 1 piece. I don’t really know squat about carbon driveshafts, but maybe they dampen vibrations better than metals. A slight angle in the joints is not a problem as long as the diff and xfer pinions are parallel. A conventional u joint (cardan) at each end will self-cancel the torsional vibrations, so long as they are 90 degrees out of phase.
The centering pilot diameter is the same between the two flanges. So it would be centralized. I believe it makes more vibration than the stock but I haven't seen any noticeable issues yet.
I never could understand why Mitsubishi went with 3 cardan and one c.v. (Lobro).
Maybe because of serviceability/longevity/comfortability/cost.
 
The centering pilot diameter is the same between the two flanges. So it would be centralized. I believe it makes more vibration than the stock but I haven't seen any noticeable issues yet.

Maybe because of serviceability/longevity/comfortability/cost.

Hi, Hiroshi.
I'm curious to see what you opinion of the 1 piece carbon shaft is long term.
Thoughts, opinions, and otherwise.
I’m considering going this route. It would be a needle in a haystack, but it sure would be awesome to find one used!

Thanks!
 
Hi, Hiroshi.
I'm curious to see what you opinion of the 1 piece carbon shaft is long term.
Thoughts, opinions, and otherwise.
I’m considering going this route. It would be a needle in a haystack, but it sure would be awesome to find one used!

Thanks!
Since the car is not daily, I still don't have many miles on it. So I can't tell about its longevity. But it's still on my 1g and I haven't seen any issue so far. I personally like it, obviously the car responds more directly/quickly and accelerates faster.
 
Since the car is not daily, I still don't have many miles on it. So I can't tell about its longevity. But it's still on my 1g and I haven't seen any issue so far. I personally like it, obviously the car responds more directly/quickly and accelerates faster.
Any chance you could measure the length from u-joint to u-joint? I am trying to have one made. Thanks
 
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