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+--- Thread: Flex disks. (/showthread.php?tid=254)
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Flex disks. - winmutt - 02-23-2009
Could have sworn there was a thread on this. I need stronger flex disks, my less than year old ones are cracked. Suggestions?
RE: Flex disks. - ForcedInduction - 02-23-2009
(02-23-2009, 03:15 PM)winmutt Could have sworn there was a thread on this. I need stronger flex disks, my less than year old ones are cracked. Suggestions?
I don't think I've ever seen anyone try to upgrade to the larger ones. If the diff flange can be converted to the smaller one, any reason why it wouldn't work the other way around and with the transmission too?
RE: Flex disks. - winmutt - 02-23-2009
(02-23-2009, 05:42 PM)ForcedInduction(02-23-2009, 03:15 PM)winmutt Could have sworn there was a thread on this. I need stronger flex disks, my less than year old ones are cracked. Suggestions?
I don't think I've ever seen anyone try to upgrade to the larger ones. If the diff flange can be converted to the smaller one, any reason why it wouldn't work the other way around and with the transmission too?
The ds would have to be replaced as well. Are there not thicker ones, not just bigger diameter (2nd gen 126)?
RE: Flex disks. - bgkast - 02-27-2009
Maybe try OEM ones. I believe they used these same flex discs on V8s so they should be strong enough
RE: Flex disks. - winmutt - 02-28-2009
(02-27-2009, 02:36 AM)bgkast Maybe try OEM ones. I believe they used these same flex discs on V8s so they should be strong enough
Pretty sure these are OEM.
RE: Flex disks. - DeliveryValve - 03-01-2009
The w126 gasser flex disks are thicker as well obviously larger in diameter. If your beating up disks like that, then a w126 upgrade may be the answer. 1st gen and 2nd gen use the same disks. Even the 560SEL with the LSD uses the same disks as the 380SE.
RE: Flex disks. - ForcedInduction - 03-01-2009
My small flex's have a 126 part number.
RE: Flex disks. - DeliveryValve - 03-01-2009
(03-01-2009, 05:19 PM)ForcedInduction My small flex's have a 126 part number.
That's because it is the same flex disk. w123 and w126 Diesels use the same stuff.
RE: Flex disks. - larry perkins - 03-02-2009
i am told that the weak link is the front disk,also am told that the rear one will fit into the front and is much stronger.
will try the plan as soon as i lose a front one.
larry perkins
RE: Flex disks. - ForcedInduction - 03-03-2009
Front and rear are the same. The rear lasts longer since it doesn't have as much shock stress with the front disc and driveline absorbing it.
RE: Flex disks. - larry perkins - 03-03-2009
fi,it looks to me like it depends upon your chassie number and your serial number,german star has different part numbers for 123 and 124 cars.
larry perkins
RE: Flex disks. - winmutt - 01-07-2011
Check out this solution for BMW :
![[Image: e30guibo.jpg]](http://www.revshift.com/shop/images/uploads/e30guibo.jpg)
http://www.revshift.com/shop/index.php?_a=viewProd&productId=76
RE: Flex disks. - Biohazard - 01-07-2011
^^^ That is sexy! ^^^
You may want to have your driveshaft rebalanced as well. If its off a bit, it could be causing the discs to wear prematurely.
Also, I wonder if it would be possible to swap to standard u-joints and eliminate the flex discs all together on your model. I know that there is the option on the W123 & W126.
RE: Flex disks. - willbhere4u - 01-07-2011
that looks simple enough to make one!
RE: Flex disks. - Captain America - 01-07-2011
I'm pretty sure that Rudolf upgraded the Flex discs on his car....
RE: Flex disks. - 300D50 - 01-08-2011
I could look into punching out a bushing holder like the revshift one if you want Rolf, you'd just need to find the bushings you wanted.
Price would be much less as well, I can assure you.
RE: Flex disks. - okto - 02-04-2011
(01-07-2011, 02:21 PM)Biohazard Also, I wonder if it would be possible to swap to standard u-joints and eliminate the flex discs all together on your model. I know that there is the option on the W123 & W126.The W124 has a U-joint in the driveshaft, the flex disks apparently function as drivetrain vibration dampers.
RE: Flex disks. - winmutt - 02-06-2011
(02-04-2011, 04:05 PM)oktoI am pretty sure most of them have a u joint. It is not like a normal u joint, the angle of deflection should be very minimal most of the time.(01-07-2011, 02:21 PM)Biohazard Also, I wonder if it would be possible to swap to standard u-joints and eliminate the flex discs all together on your model. I know that there is the option on the W123 & W126.The W124 has a U-joint in the driveshaft, the flex disks apparently function as drivetrain vibration dampers.
RE: Flex disks. - jeemu - 02-13-2011
Put rear solid flex disk front and rear, they is strong enough.
If not there is something wrong about drive shaft. Balance, bushing?
RE: Flex disks. - Biohazard - 02-14-2011
(02-06-2011, 10:49 PM)winmutt(02-04-2011, 04:05 PM)oktoI am pretty sure most of them have a u joint. It is not like a normal u joint, the angle of deflection should be very minimal most of the time.(01-07-2011, 02:21 PM)Biohazard Also, I wonder if it would be possible to swap to standard u-joints and eliminate the flex discs all together on your model. I know that there is the option on the W123 & W126.The W124 has a U-joint in the driveshaft, the flex disks apparently function as drivetrain vibration dampers.
Suppose I should have referenced this thread:
http://www.superturbodiesel.com/std/no-more-flex-discs-t-783.html
I meant eliminating the flex discs all together and running standard style u-joints front and rear. Just a thought.
RE: Flex disks. - winmutt - 02-15-2011
Oh. The flex disk keeps undo pressure of the hard parts of the drivetrain. I believe this to be a good and probably necessary setup.
RE: Flex disks. - Biohazard - 02-15-2011
Gotcha. I thought their main function was absorbing vibrations and/or making the car drive smoother like a Benz should drive? I've got the parts already to eliminate the flex discs. Just waiting for my house to close so I can have a garage again and make some progress finally.
Converting to u-joints just happens to be one of the projects waiting to get finished. If I wasn't going with the u-joints, I would probably be pretty interested in those aluminum ones with the bushings, look like they would be pretty stout.
RE: Flex disks. - winmutt - 02-15-2011
(02-15-2011, 10:29 AM)Biohazard Gotcha. I thought their main function was absorbing vibrations and/or making the car drive smoother like a Benz should drive?
All the above. With U joints you have to take into consideration the strain additional strain you will be putting on the entire drivetrain, it could significantly reduce the life span of trans and rear diff.
RE: Flex disks. - Biohazard - 02-15-2011
Ok, thanks Winmutt. I hadn't heard that before. I may end up being the guinea pig on this one then. I have spare diffs in different ratio's, but no spare trans just yet. I think I found a 4 speed for 175 bucks, may need to stash that under a work bench soon.
RE: Flex disks. - winmutt - 05-04-2012
I reached out to revshift to see how much it will take to get one of these. Also going to call prothane tomorrow.
RE: Flex disks. - Torkey - 05-16-2012
Dying to hear what you found out. I'm considering something similar.
RE: Flex disks. - aaa - 05-29-2012
Well it took a few weeks but I got my Thailand disk. $147 shipped.
RE: Flex disks. - lgreeley83 - 02-09-2013
How you liking the disk?
RE: Flex disks. - aaa - 02-27-2013
Haven't had opportunity to use it. Turbo mods are proceeding slowly, then I will do a 5 speed swap and see if if the disk will fit into the driveshaft equation.
RE: Flex disks. - sassparilla_kid - 02-27-2013
I'm thinking about getting some made, maybe after the 4-speed swap is done. I grabbed a new looking flex disk I found laying under a w123 at the junkyard so I now have something to use for dimensions and what not
RE: Flex disks. - raysorenson - 02-28-2013
(05-29-2012, 03:45 PM)aaa Well it took a few weeks but I got my Thailand disk. $147 shipped.
The metal sleeves that go through the urethane bushings are thicker than what Revshift uses. I've seen a pic of a used Revshift guibo and some of the sleeves were either distorted or just smashed. Where did you get this?
RE: Flex disks. - sassparilla_kid - 04-04-2013
Yeah where did this beast come from???
RE: Flex disks. - winmutt - 04-05-2013
$147 for one or 2?
RE: Flex disks. - Simpler=Better - 04-05-2013
EDH Performance just uses steel:
![[Image: IMG_4086.jpg]](http://i3.photobucket.com/albums/y66/volvoturbopower/W201/IMG_4086.jpg)
RE: Flex disks. - Druk - 04-06-2013
Druk just uses steel too...
![[Image: 1_zps1e656b4b.gif]](http://i62.photobucket.com/albums/h112/a10ruk/300TD/1_zps1e656b4b.gif)
http://www.youtube.com/watch?v=TCP62uc_Cmc
![[Image: propshaft012_zpsd13022b9.jpg]](http://i62.photobucket.com/albums/h112/a10ruk/300TD/propshaft012_zpsd13022b9.jpg)
trial fitting.
![[Image: propshaft009_zps4cbfeb8c.jpg]](http://i62.photobucket.com/albums/h112/a10ruk/300TD/propshaft009_zps4cbfeb8c.jpg)
.
RE: Flex disks. - aaa - 04-06-2013
(04-04-2013, 11:02 PM)sassparilla_kid Yeah where did this beast come from???
It was designed and rolled out somewhere in the middle of this thread:
http://190rev.net/forums/showthread.php?t=35434
$147 for one, $218 for two. The second one in a set of two was thinner for some reason.
RE: Flex disks. - Torkey - 04-06-2013
How do you get access to that site?? I've been trying to get an account for over a week so I could look at that post. I've gone through the registration process AND emailed the admin multiple times. nothing
RE: Flex disks. - raysorenson - 04-06-2013
That there is some serious bling blang Druk.
Does it work well? Is this a daily driver? I don't buy the argument that there must be a flex disc in a Mercedes driveline or it will explode, but what about alignment? Surely the pinion angle tilts up and down just a bit and the motor jumps around some too.
RE: Flex disks. - Druk - 04-06-2013
(04-06-2013, 04:44 PM)raysorenson That there is some serious bling blang Druk.
Does it work well? Is this a daily driver? I don't buy the argument that there must be a flex disc in a Mercedes driveline or it will explode, but what about alignment? Surely the pinion angle tilts up and down just a bit and the motor jumps around some too.
Not quite on the road yet. Maybe another month. Had to go for Spicer joints because of mis-alignment of engine/box. Flex discs wouldn't cope with the amount it's out. It's all parallel, just an 1" high. It's the same arangement that's in a G Wagen and the axle/engine jumps about quite a lot in that. It's a one piece shaft..no center bearing, 52"oa X 3" heavy wall tube custom built. One friend did the cad/cam and brother-in-law machined the flanges.
Here's what I made for the speedo pick-up..
![[Image: propshaft016_zps067f0d9a.jpg]](http://i62.photobucket.com/albums/h112/a10ruk/300TD/propshaft016_zps067f0d9a.jpg)
And bolted up..front
![[Image: propshaft032_zps32f02000.jpg]](http://i62.photobucket.com/albums/h112/a10ruk/300TD/propshaft032_zps32f02000.jpg)
and rear..
![[Image: propshaft031_zps396cf3f4.jpg]](http://i62.photobucket.com/albums/h112/a10ruk/300TD/propshaft031_zps396cf3f4.jpg)
.
RE: Flex disks. - raysorenson - 04-06-2013
The perfect solution. Very nice work.
RE: Flex disks. - winmutt - 04-06-2013
The problem with the solid steel is that it will cause additional strain on the drivetrain and severely shorten the life span.
I am *fairly* certain that there are cheaper alternatives stateside for poly/metal flex disks from the MB owned Chrysler years.
aaa dont you have a manual trans with the smaller yoke on the front and the larger 603 yoke on the back like I do?
RE: Flex disks. - aaa - 04-07-2013
The smaller yoke is the plan, I have a manual transmission and matching driveshaft half, they are just not installed in the car
. Still auto.
RE: Flex disks. - Druk - 04-07-2013
(04-06-2013, 08:31 PM)winmutt The problem with the solid steel is that it will cause additional strain on the drivetrain and severely shorten the life span.
I can understand this were the car to be driven at the limits, as is the case with some of the superturbo/big element cars featured in the YouTube vids: but surely if it's driven in a normal and sympathetic manner then there'll be no more strain than on any of the everyday RWD propshaft cars that have been trundling about our world for the last 80 yrs or so? I'll not be doing 2000rev take-offs or doughnuts in Tesco's carpark.
I accept the thing may have a slightly harsher 'feel' compared to original...but "severely shorten"??
Unless you have evidence to the contrary?
.
RE: Flex disks. - raysorenson - 04-07-2013
(04-06-2013, 08:31 PM)winmutt The problem with the solid steel is that it will cause additional strain on the drivetrain and severely shorten the life span.
I consider this a forum perpetuated myth. The flex discs exist to reduce NVH. There is nothing unique about the Merc diffs or transmissions that would require a flex disc over a u-joint.
Quote:I am *fairly* certain that there are cheaper alternatives stateside for poly/metal flex disks from the MB owned Chrysler years.
I'm not sure about cheap, but Revshift told me that the '05/'06 Pontiac GTO/G8 flex disc couplers will fit the W124. They don't have anything for the smaller 190e stuff. I assumed aaa's coupler came from the 190rev board, that's why I was interested. Plus it looks like better stuff than revshift's.
RE: Flex disks. - Mark_M - 04-07-2013
I think there is some confusion here. Replacing the flex disk with solid steel/original shaft is a bad idea, you will break something even if it is all perfectly in line unless you solid mount the engine, gearbox and diff. However replacing it with steel and using a UJ like Druk has done is a perfect solution. Your clutch plate or DMF has all the damping needed to take the shock loads out.
RE: Flex disks. - mach4 - 04-07-2013
(04-06-2013, 08:31 PM)winmutt The problem with the solid steel is that it will cause additional strain on the drivetrain and severely shorten the life span.
I don't doubt that there are additional stresses on the drivetrain with a system without flex discs as opposed to a system with flex discs. But the question is are these stresses significant enough to adversely affect drivability (so called NVH) or shorten the life of components to a significant degree.
First, we do know that there are huge differences in the torsional load, This stems from the reality that in an internal combustion engine the cylinder pressure goes from 0 to a large maximum within a few degrees of crank rotation, and just as quickly drop off to zero as the cylinder goes from power stroke to exhaust stroke. I follow the trials and tribulations of experimental aviation pilots who use Subaru engines in their planes. They have huge problems with props and PSRU (Prop Speed Reduction Units) providing extremely short useful life and even self destructing, sometimes catastrophically. Many different strategies are being designed and tested to deal with the torsional loads including belts, disc, inserts, as well as larger flywheels and so forth.
So obviously, there are inherent issues with internal combustion engines and drivetrain. We know that solid steel drivelines have been used since the beginning of the automobile and are still in use.
What are the factors that create huge problems for aircraft but seem to not affect autos and trucks?
1- One factor, at least for the current discussion is the number of cylinders. The more cylinders, the more overlap in power strokes and the less significant the maximum and minimum torsional loads are.
2- Another factor is the weight of the flywheel. Aircraft strive for minimum weight flywheels for obvious reasons - cars, not so much. The heavier the flywheel, the less torsional load change that is transmitted out of the engine.
3- Yet another factor is the use profile. Aircraft engines operate in pretty much 3 conditions - full power for climb out, 75% power for cruise and idle for descent. Cars on the otherhand, rarely operate at full throttle for more than a few seconds. At 60mph cruise, a MB 300SD diesel is running at 20kw (full power is about 92kw) so that's about 22% power
4- Aircraft engines because of their use profile, run at substantially higher RPM than a comparable car engine. This fact makes it easier on all components in the system.
Cars are generally over-engineered allowing a comfortable margin between max design strength and normal operating envelope.
For all these reasons it's clear that despite the fact that we can point to significant torsional stresses and even the presence of harmonics that can damage power train components, it's rarely if ever a significant factor to consider.
Bottom line - well designed, solid steel driveshafts are not a problem in normal use. Are flex disc systems better? Probably yes, but can we say that solid steel ones are bad and destructive? Probably not.
RE: Flex disks. - Simpler=Better - 04-08-2013
Druk, any reason you didn't go with wheel studs? I'm impressed with the machining, but cutting out hex recesses seems complicated.
RE: Flex disks. - Druk - 04-08-2013
(04-08-2013, 07:55 AM)Simpler=Better Druk, any reason you didn't go with wheel studs? I'm impressed with the machining, but cutting out hex recesses seems complicated.
We had lots of options including studs and cap screw recesses but seeing as how I already had the fine thread bolts and Brother-in-Law who did the machining said it didn't matter either way once the CNC mill was set-up I just went with bolts. I wished I'd used capscrews for the six flange bolts because I had great difficulty getting the correct grade metric fine bolts we designed the thing for. Should've looked further into that aspect before we did the drawings.
Mach4 eloquently summed up my thoughts regarding all steel drivelines. Time will tell.
Hey-ho.
.
RE: Flex disks. - TheDon - 04-14-2013
I like you method for the spedo pickup.
RE: Flex disks. - Eric78 - 04-15-2013
Just wondering, if someone were to sandwich the standard flex disks between steel plates would it be effective at taking extra abuse without sacrificing too much vibration dampening?