Transaxle/Engine Mis-Alignment; Custom Drive-shaft!

[alfaspence]

looking good folks, some really good viable ideas! i did wonder about caged type guibos as this would limit the disstortment under high rpm and torque loading, as i work for volvo trucks, i spent all day (well, what i can get away with) looking at various designs volvo use! B10M bus's have a hydraulic cooling fan setup driven by propshaft direct off crank, with a u/j one end and a guibo the other!
the early guibos used to fail quite often (similar to milano type), so volvo modified them to a more hexagon style with big cast ally segments.

[Craig]

G'Day Jon,

Seems to me like you have to allow for some forward/aft movement of the gearbox during acceleration/braking as these forces will be transfered through the gearbox to the chassis. May not be much but it will be there.

[BigSwede]

Couple of notes...

If you use CV joints you need a slight misalignment similar to a U-joint or they will have accelerated wear.
There is some changes in total length due to gearbox/engine windup, should however not be a problem if you use a plungeing CVJ in one of the positions (Rear would be my bet).
Single tube will have to be very large dia or there will be excitation issues due to engine firing, especially on V6 cars. runout/whip would be an issue too.
CVJs will be of much larger dia for the specified torque then U-joints.
U-joints and CVJs will need very little angle for them to work, typically down to 0.2 to 0.4 and a U-joint will work up to ~4 degrees if you can play with the weld angles and CVJs comfortably go up to ~8 degrees.
If you go for CVJs you will need the J-style boot duer to propshaft speed, the bellow boots doesn't like speed over ~4000rpm and definetly not together with heat (tunnel + exhaust), also there would not be an issue with the clamps since there are no large dia clamps on the J-boots.

For the record I believe the engine is shifted in the way it is to make it line up under load and the swaging is there for the package issue with the shifter rather then the crash feature (this is from the seventies, nobody crashed then. Or it was not a design issue anyway. )

[slyalfa]

just a note:
the thong in the back of the motor it so the motor can rotate on the front mounts.
there is a fair amount of rotatation as the exhaust pipe heats and gets longer.
the motor is rotated down in the front when cold and as it heats the front moves up.

I found out about this when I had a clearance problem with the alternator and the power steering hydraulic line. there is a lot of movment there.

[loach1]

I know JJ is allergic to Giubos, but rubber couplings have come a long way since the Milano. They achieve everything needed in the Milano - vibration absorbsion, slight articulation, easy to correct unbalance (no moving parts), high torque capacity (yes, really!) and they can be readily adapted to the input and output flanges. It's most tempting to put a UJ in the middle, but that doesn't seem to be a problem area.

Here's what I'm talking about:
http://www.visteon.com/products/auto...ropshaft.shtml
The picture is exactly what I mean. Read the .pdf for more background, pity there's no torque capacities for flexible couplings.

Here's a link to the coupling supplier preferred by my last company (GKN):
http://www.sgf.de/uploads/media/Antr...huere_E_01.pdf

Coincidently they also show the type of driveshaft that I think is the best combination for almost any road car...

[5yearplan]

The problem I have with guibos, or rubber driveshaft couplings is that by the time I get these cars they are completely trashed, and have never been replaced. On my old e30 BMW I broke a few of the bolts that hold the center guibo in. It hadn't been serviced in awhile, and may have been stock for all I know. Needless to say, none have them had been treated with thread-lock or anti seize, so the middle of the bolts were froze to the metal pieces pressed in the rubber. I then had to cut/burn out the guibo to get everything out. Pesky things.

[BigSwede]

loach1, interesting. tnx for the links.
about the torque capacity, the E34 M5 has a rubber coupling in the first position. That's after the gearbox with a 3.3 first gear or something...

Engine rotating due to exhaust elongation? Not very likely, you would have loads of NVH issues if you had hangers tight enough to move the engine and the flexipipes are there to help with the decoupling of the exhaust forces.

[PSk]

Quote:

Originally Posted by loach1 I know JJ is allergic to Giubos, but rubber couplings have come a long way since the Milano. They achieve everything needed in the Milano - vibration absorbsion, slight articulation, easy to correct unbalance (no moving parts), high torque capacity (yes, really!) and they can be readily adapted to the input and output flanges. It's most tempting to put a UJ in the middle, but that doesn't seem to be a problem area. Here's what I'm talking about: http://www.visteon.com/products/auto...ropshaft.shtml The picture is exactly what I mean. Read the .pdf for more background, pity there's no torque capacities for flexible couplings. Here's a link to the coupling supplier preferred by my last company (GKN): http://www.sgf.de/uploads/media/Antr...huere_E_01.pdf Coincidently they also show the type of driveshaft that I think is the best combination for almost any road car...

[alfaspence]

Quote:

Originally Posted by PSk This is the correct solution, redesign the driveshaft to use modern and readily available rubber couplings. Pete

[BigSwede]

The new ones use three legged flanges too. Why do you want a cage? The cage is useless on a properly designed system and will only be there to catch the parts that break loose, they will add nothing in terms of durability.

[DaveH]

I have to agree with the above. Respec the donuts! Just imagine, new, more advanced composition rubber....

Perhaps a lead: MTU driveshafts in Charleston, SC make giubos for BMWs. Can't find a website, but here's a patent filing on a driveshaft: http://www.wipo.int/pctdb/en/wo.jsp?...DISPLAY=STATUS

Also, some the E34 could be a donor for parts (front donut?). I think Barry might be able to shed some light on this. IIRC, the tricky part was some machining was required to accommodate the internal guide bearing.

Stay away from cages. I know they have been available for donuts, but whats the point? If the M5 can run a donut in its driveshaft, why can't a 116 car?

Also, I recall reading a thread that the bolts in a giubo/spider arrangement can splay outwards under centrifugal force - I don't believe this for a moment. The front and rear donuts/giubos are not just lumps of rubber. They have internal spiders formed by 3 radial members sprouting from a central sleeve, picking up 3 outer sleeves that the bolts go thru. The other 3 adjacent bolts also pass thru donut sleeves that are well landed on the opposing driveshaft section's yoke. The thread's suggestion was to make up a sheetmetal plate to pick up the end of the bolts so that they would not be able to splay. I don't believe the M5 employs such a plate.

[alfaspence]

with regards to cages, ok you may not need them, its just what ive heard from various sources thats all.
what we need to know is are these new joints available in our size (and center brg) ? sorry to be pushy but i'd like to know if this solution is likely to happen before i invest in the crappy old skool route!

[BigSwede]

That's a crash feature right there, a spline with shear pins. Nothing to do with rubber couplings.

[DaveH]

FFS Mats, read the post fully.

[BigSwede]

I did, again, still don't understand why you posted a link to a patent regarding a crash feature?

Edit: Or did you mean you can't find an online site? They have changed name I think, here's the overall site but mostly for Diesel engines MTU