STD Tuning Drivetrain Custom Flex disks or Uni joints?

Custom Flex disks or Uni joints?

Custom Flex disks or Uni joints?

 
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Eric78
GT2559V

198
02-14-2014, 02:07 AM #1
So I'll need a modded or custom built drive shaft when the 722.636 goes in my w201 anyway so which is the better option? Custom flex disks like those aluminium/polyurethane ones or just replace them uni joints?

I'v seen people argue against uni joints before but can't remember why.
Eric78
02-14-2014, 02:07 AM #1

So I'll need a modded or custom built drive shaft when the 722.636 goes in my w201 anyway so which is the better option? Custom flex disks like those aluminium/polyurethane ones or just replace them uni joints?

I'v seen people argue against uni joints before but can't remember why.

john
GTA2056V

90
02-16-2014, 05:59 AM #2
So, i am thinking the same.
My problem is that i have gs6 bmw tranny with huge flexdisk and have to mate it to 123 flexdisk.

Ujoints... i am thinking that u cant run it with 3 joints on one shaft. 2 custom and center bearing one. I think it will get to woobly. So the option is to erase the centerbearing and run a straight shaft directly to the diff i think.

If you still whant centerbearing you could just bolt the flanges together?? The steershaft in gearbox/diff and the bearing in the propshaft doesnt allow any play sideways anyway when new. Its only for distrubaring the force moore sooftly to the diff. When ading ujoints you erase the softyness anyway.

Am i thinking correctly now??

Holset power!
john
02-16-2014, 05:59 AM #2

So, i am thinking the same.
My problem is that i have gs6 bmw tranny with huge flexdisk and have to mate it to 123 flexdisk.

Ujoints... i am thinking that u cant run it with 3 joints on one shaft. 2 custom and center bearing one. I think it will get to woobly. So the option is to erase the centerbearing and run a straight shaft directly to the diff i think.

If you still whant centerbearing you could just bolt the flanges together?? The steershaft in gearbox/diff and the bearing in the propshaft doesnt allow any play sideways anyway when new. Its only for distrubaring the force moore sooftly to the diff. When ading ujoints you erase the softyness anyway.

Am i thinking correctly now??


Holset power!

Druk
Holset

297
02-16-2014, 06:33 AM #3
Nothin wrong with uni-joints, they work fine although a one piece shaft has to have a large section tube to stop whip. And some means of connecting the joint flanges to the spiders.

[Image: propshaft031_zps396cf3f4.jpg]

[Image: propshaft032_zps32f02000.jpg]

[Image: propshaft011_zpsf82d7f42.jpg]

[Image: propshaft012_zpsd13022b9.jpg]


.
This post was last modified: 02-16-2014, 06:35 AM by Druk.
Druk
02-16-2014, 06:33 AM #3

Nothin wrong with uni-joints, they work fine although a one piece shaft has to have a large section tube to stop whip. And some means of connecting the joint flanges to the spiders.

[Image: propshaft031_zps396cf3f4.jpg]

[Image: propshaft032_zps32f02000.jpg]

[Image: propshaft011_zpsf82d7f42.jpg]

[Image: propshaft012_zpsd13022b9.jpg]


.

raysorenson
Superturbo

1,162
02-16-2014, 09:55 AM #4
3 joints are the typical thing on 2 piece driveshafts. You try to set it up so that there's a minimal operating angle at the output shaft joint and you can do whatever with the operating angles after the hanger bearing. Think of the first half of the driveshaft as an extension of the trans.

I'm having a 2 piece w/3 joints fabbed up for my W124. When discussing the possibility of a one piece, the guy asked if I had room for 4"/100mm tubing. I didn't. Even if I did have room, with the length of the shaft required he said 4" tubing with wide diameter spline and sleeve would have still been a compromise.
raysorenson
02-16-2014, 09:55 AM #4

3 joints are the typical thing on 2 piece driveshafts. You try to set it up so that there's a minimal operating angle at the output shaft joint and you can do whatever with the operating angles after the hanger bearing. Think of the first half of the driveshaft as an extension of the trans.

I'm having a 2 piece w/3 joints fabbed up for my W124. When discussing the possibility of a one piece, the guy asked if I had room for 4"/100mm tubing. I didn't. Even if I did have room, with the length of the shaft required he said 4" tubing with wide diameter spline and sleeve would have still been a compromise.

john
GTA2056V

90
02-16-2014, 03:24 PM #5
Ok. I see. But why have joints then? Why not just bolt the 3 point flange together if the purpose is to make it strong.

Holset power!
john
02-16-2014, 03:24 PM #5

Ok. I see. But why have joints then? Why not just bolt the 3 point flange together if the purpose is to make it strong.


Holset power!

raysorenson
Superturbo

1,162
02-16-2014, 05:13 PM #6
(02-16-2014, 03:24 PM)john Ok. I see. But why have joints then? Why not just bolt the 3 point flange together if the purpose is to make it strong.

Because the engine/trans and the diff move around. The diff being the worst. It's soft mounted to mounted to a rubber mounted subframe. It gets moved by cornering and acceleration forces. Accel makes the pinion tilt up and decel makes it tilt down.
raysorenson
02-16-2014, 05:13 PM #6

(02-16-2014, 03:24 PM)john Ok. I see. But why have joints then? Why not just bolt the 3 point flange together if the purpose is to make it strong.

Because the engine/trans and the diff move around. The diff being the worst. It's soft mounted to mounted to a rubber mounted subframe. It gets moved by cornering and acceleration forces. Accel makes the pinion tilt up and decel makes it tilt down.

john
GTA2056V

90
02-17-2014, 02:53 PM #7
yeah. but it has ha a centerbushing in the prop that is 16mm. the pin in the diff/trans is 16mm. that means no sideflex, only rotating flex. this is my point, its a fixed alignment.

Holset power!
john
02-17-2014, 02:53 PM #7

yeah. but it has ha a centerbushing in the prop that is 16mm. the pin in the diff/trans is 16mm. that means no sideflex, only rotating flex. this is my point, its a fixed alignment.


Holset power!

raysorenson
Superturbo

1,162
02-18-2014, 02:23 PM #8
John, I just checked this since I've got a pinion gear here on the bench and a driveshaft in the corner. There is a lot of slop. I guess it more or less centers the driveshaft but you can tilt it at least 10*.
raysorenson
02-18-2014, 02:23 PM #8

John, I just checked this since I've got a pinion gear here on the bench and a driveshaft in the corner. There is a lot of slop. I guess it more or less centers the driveshaft but you can tilt it at least 10*.

Eric78
GT2559V

198
02-19-2014, 12:27 AM #9
(02-16-2014, 06:33 AM)Druk [Image: propshaft011_zpsf82d7f42.jpg]

[Image: propshaft012_zpsd13022b9.jpg]

Where would I find adaptors like those?
Eric78
02-19-2014, 12:27 AM #9

(02-16-2014, 06:33 AM)Druk [Image: propshaft011_zpsf82d7f42.jpg]

[Image: propshaft012_zpsd13022b9.jpg]

Where would I find adaptors like those?

Druk
Holset

297
02-19-2014, 09:31 AM #10
^ These were my own interpretation of a similar set-up seen on here

this...
[Image: flange_zps6b0e0a94.jpg]

I got friends to CadCam them for me to suit my own application but they wouldn't need to be so complicated to work just as well. My point was that ordinary UJs will work perfectly well with a standard sliding splined shaft.



.
This post was last modified: 02-19-2014, 09:33 AM by Druk.
Druk
02-19-2014, 09:31 AM #10

^ These were my own interpretation of a similar set-up seen on here

this...
[Image: flange_zps6b0e0a94.jpg]

I got friends to CadCam them for me to suit my own application but they wouldn't need to be so complicated to work just as well. My point was that ordinary UJs will work perfectly well with a standard sliding splined shaft.



.

winmutt
bitbanger

3,468
02-19-2014, 11:25 AM #11
Why solid? Ake and a few others make solid with poly bushes. You need SOME give in there.

1987 300D Sturmmachine
1991 300D Nearly Perfect
1985 300D Weekend/Camping/Dog car
1974 L508D Motoroam Monarch "NightMare"
OBK #42
winmutt
02-19-2014, 11:25 AM #11

Why solid? Ake and a few others make solid with poly bushes. You need SOME give in there.


1987 300D Sturmmachine
1991 300D Nearly Perfect
1985 300D Weekend/Camping/Dog car
1974 L508D Motoroam Monarch "NightMare"
OBK #42

Druk
Holset

297
02-19-2014, 07:09 PM #12
The designer of my driveshaft advised against having flexible mounts at each end because of possible whip in the shaft. As he explained the UJ flanges need to be rigidly affixed otherwise you effectively have a double joint at each end. The center tube could end up proscribing an elliptical orbit instead of simply rotating.

I accept that Merc and BMW prefer to have a degree of flexibility in the driveline but they're almost alone in that. Most other cars/trucks including Mercedes Sprinters have the same set-up as me and things seem to get along just fine like that. Simple is best I think?
Druk
02-19-2014, 07:09 PM #12

The designer of my driveshaft advised against having flexible mounts at each end because of possible whip in the shaft. As he explained the UJ flanges need to be rigidly affixed otherwise you effectively have a double joint at each end. The center tube could end up proscribing an elliptical orbit instead of simply rotating.

I accept that Merc and BMW prefer to have a degree of flexibility in the driveline but they're almost alone in that. Most other cars/trucks including Mercedes Sprinters have the same set-up as me and things seem to get along just fine like that. Simple is best I think?

winmutt
bitbanger

3,468
02-25-2014, 02:02 PM #13
Spent alot of time looking at Jeep's lately for a new project and they have something they call a Slip Yoke Eliminator. Can't help but think that they look AWFULL like our DS. How many splines on ours? I think there are 2 diff sizes?

1987 300D Sturmmachine
1991 300D Nearly Perfect
1985 300D Weekend/Camping/Dog car
1974 L508D Motoroam Monarch "NightMare"
OBK #42
winmutt
02-25-2014, 02:02 PM #13

Spent alot of time looking at Jeep's lately for a new project and they have something they call a Slip Yoke Eliminator. Can't help but think that they look AWFULL like our DS. How many splines on ours? I think there are 2 diff sizes?


1987 300D Sturmmachine
1991 300D Nearly Perfect
1985 300D Weekend/Camping/Dog car
1974 L508D Motoroam Monarch "NightMare"
OBK #42

Simpler=Better
PORTED HEAD

2,127
02-25-2014, 02:18 PM #14
(02-25-2014, 02:02 PM)winmutt Spent alot of time looking at Jeep's lately for a new project and they have something they call a Slip Yoke Eliminator. Can't help but think that they look AWFULL like our DS. How many splines on ours? I think there are 2 diff sizes?

When you want a DJ5 I might know a farmer with 3 in his back yard. Sold me mine for scrap value +$50

Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?
Simpler=Better
02-25-2014, 02:18 PM #14

(02-25-2014, 02:02 PM)winmutt Spent alot of time looking at Jeep's lately for a new project and they have something they call a Slip Yoke Eliminator. Can't help but think that they look AWFULL like our DS. How many splines on ours? I think there are 2 diff sizes?

When you want a DJ5 I might know a farmer with 3 in his back yard. Sold me mine for scrap value +$50


Newbie-read this: Cheap Tricks
617.952-220k-Getting built up
larsalan I guess I need to look at this stupid ass drip shit. What you have to like mess with those elements on the pump? What a fucking hassle. then use some wire to hold the throttle open or some shit?

raysorenson
Superturbo

1,162
02-25-2014, 03:16 PM #15
From memory, both diffs has 27 splines. I know for sure the little diff has 27 splines. To verify, check the pinion flange part# from a v8 and all other w124's, they should be the same.
The 717 manual trans output shaft will have the same diameter and spline# as the pinion. The autos will not have the same spline count.

The aluminum/poly guibos should be just fine. The only reason I had a u-joint driveshaft built was to keep driveline windup to an absolute minimum. 1st gear "trailer hitching" is pretty bad in my car, probably because my engine is not equipped with Mercedes' "anti-jerk control" that the manual trans equipped diesels got. I'm assuming that eliminating driveshaft torsional flex will reduce the trailer hitching.
raysorenson
02-25-2014, 03:16 PM #15

From memory, both diffs has 27 splines. I know for sure the little diff has 27 splines. To verify, check the pinion flange part# from a v8 and all other w124's, they should be the same.
The 717 manual trans output shaft will have the same diameter and spline# as the pinion. The autos will not have the same spline count.

The aluminum/poly guibos should be just fine. The only reason I had a u-joint driveshaft built was to keep driveline windup to an absolute minimum. 1st gear "trailer hitching" is pretty bad in my car, probably because my engine is not equipped with Mercedes' "anti-jerk control" that the manual trans equipped diesels got. I'm assuming that eliminating driveshaft torsional flex will reduce the trailer hitching.

 
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