Stock Two-Piece Driveshaft Upgrade

[chikinhed]

One mine, it was the three bolt flange on the stock driveshaft that twisted and cracked, the transmission flange was fine. I think if a disc style flange, instead of the three finger style, was used with the stock guibo it would probably be fine..... and way more enjoyable to drive with.

[pbonsalb]

I twisted the front half of one stock shaft in 2 and very visibly twisted the splined section joining the 2 halves in another. My guess is the cracked flanges come from repeated flex in the guibo.

Never broken a DSS one piece shaft, but the lack of a front flex disk probably contributes significantly to the added NVH. My current DSS is foam filled, which slightly reduced the singing that probably comes in part from the solid side mount and 75D rear mounts of the 210 diff. The vibration is reduced since I shortened the shaft as part of the GS6-53 conversion. Vibration that used to be almost intolerable above 100 is lessened noticeably.

I think I would prefer a 2 piece shaft with flex disk that is strong enough if someone starts making them for a reasonable price.

I wonder whether a front CV on the DSS in place of the u joint would be an improvement?

[m3boost]

I twisted the front half of one stock shaft in 2 and very visibly twisted the splined section joining the 2 halves in another. My guess is the cracked flanges come from repeated flex in the guibo.

Never broken a DSS one piece shaft, but the lack of a front flex disk probably contributes significantly to the added NVH. My current DSS is foam filled, which slightly reduced the singing that probably comes in part from the solid side mount and 75D rear mounts of the 210 diff. The vibration is reduced since I shortened the shaft as part of the GS6-53 conversion. Vibration that used to be almost intolerable above 100 is lessened noticeably.

I think I would prefer a 2 piece shaft with flex disk that is strong enough if someone starts making them for a reasonable price.

I wonder whether a front CV on the DSS in place of the u joint would be an improvement?

Did you get another dss for your new set-up? or did you shorten your previous dss? I currently have a dss drive shaft for the 210mm diff and 320 trans. I'm about to do the gs6 trans swap and debating on just selling my current dss and ordering the dss that is a match with the gs6 and 210mm or getting my current one shorten. I guess when I'm there, I'll find out which route is more cost effective.

[pbonsalb]

The new shaft was not available at the time I did mine. I was the guy who took all the measurements for John, who fave them to DSS, but they were non responsive at the time and after waiting a month with no timeline from DSS, I gave up. John later said they were now available.

I shortened mine and used the 96mm to 105mm front adapter sold by drifthq in FL. I could have instead modified the driveshaft to a 1310 u joint and 105 flange but did not see any need. Seems to work fine and cost me a total of about $200. Tested to 160 mph. The shorter 6 speed shaft really helps reduce the vibration I experienced with the 5 speed shaft length. Not gone but way better.

If DSS was doing the new shaft with a front CV, that might be more tempting. They make shafts for other BMW with front and rear CV.

My biggest complaint about the conversion is that the LTW flywheel and HD 2 disk clutch is really noisy at idle and low rpm. Really noisy. Obnoxiously noisy. I had an AA LTW flywheel years ago and it was not nearly as bad. I drained 1L a few days ago and replaced it with 75W140NS but the noise is only slightly reduced. Prior to that, I thought it was the TOB, so I changed that and there was no difference. Also, the ceramic disk version is practically an on off switch in 1st. I have driven the competition twin ceramic for the ZF320 and it is like stock in comparison for both noise and engagement, but it is steel and the whole assembly weighs 50% more.

[m3boost]

Do you think it will reduce the noise if the idle is raised to 1k rpm?

[pbonsalb]

Mine is at 900. 1000 should be a tiny bit better but I don’t think it will be enough. Between the LTW flywheel and the DSS shaft, I am enjoying driving the car a lot less unfortunately.

[R.Thomas]

Do you have to run a LTW flywheel? Also, what about adding weights to the driveshaft and then having it re-balanced. If it's a resonance vibration issue that may help.

[pbonsalb]

I have to run a LTW flywheel with the GS6-53 conversion because it’s the only type offered that accommodates the bell housing adapter.

Everyone with DSS shafts and 5 speeds complains. I had 3 different ones and all vibrated. Others have had them rebalanced and still had issues. Maybe there is someone out there who has no issues. The shorter length really helps. Someone with a science background can explain why — I don’t recall the terms.

[someguy2800]

Shaft critical speed. There is a certain speed with any length shaft where centrifugal force will overcome the stiffness of the shaft and it will start going around like a jump rope. A 3” one piece shaft of the length needed for an E36 is way too long.

[budgetbmw3]

I think part of the issue is also that the geometry is off also unless you are changing your pinion angle when converting to a 1 piece.

[jakermac]

I think part of the issue is also that the geometry is off also unless you are changing your pinion angle when converting to a 1 piece.

I checked drivetrain angles accurately as a part of my build and came to the conclusion (measured) that the crankshaft and diff pinion are pretty much perfectly parallel vertically (within 1 degree or less) and their respective heights are within 1/4" of each other. I have not been able to check the horizontal relationship yet. Gotta buy a laser level. I suspect it's all down to critical speed. And that should be an embarrassment for Drive Shaft Shop.