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Maurizio
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Re: driveshaft conversion

Post by Maurizio »

Also a total PITA to tune correctly, the one in my daily driver is driving me nuts because the clutch judder is magnified by a factor of around 50 or so.
:mrgreen:
so I'm not the only one who hates the system and then they also installed a pressure release valve in de clutch hydraulics.
It really took me some while to learn myself to drive off without slipping or vibrating clutch....
As it is a daily driver, I live with it. But a real fast take off is almost impossible.
Banned.. ? ;-) Daily donky.. ==> BMW 325d Image
E36M3 (3.0) Ringtool :twisted: ==> definitely BANNED!

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Mats
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Re: driveshaft conversion

Post by Mats »

Needs LOTS of revs or a veeery controlled clutch engagement. :?
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kevin
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Re: driveshaft conversion

Post by kevin »

MD , thought I would post some pics of a torsion resilient propshaft tube that's used on Aston Martins etc ( and my car ha ha) . These cut away pics show rubber strips which are bonded to the inner tube . The outer is compressed over this with severe pressure and friction creates the bond to the outer . These hold up 1000nm easily . They are different size tubes for different applications . There are a few transaxle GTV running this set up with no couplings but just using this bonded rubber to absorbs all the harmonics .
Even with a copper clutch I don't have clutch shudder in my race car . Think it was just luck that mine turned out perfectly .
Some pics explain this concept better of steel tube within a tube .
The blue prop is for a marina but its same size used on the GTV .
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75evo
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Re: driveshaft conversion

Post by 75evo »

Kev,

Whats't the advantage of this if you use rubber giubos? Reduce vibration even more? I wonder if this setup will allow me to use a 2 giubo system or rubber gibe + CV joint.

I think for your setup with UJs it has a big advantage in terms of vibration reduction right?

Looks like all I really need is a section of pipe which has the bonded rubber. I can put the end couplings over here in the US.
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Re: driveshaft conversion

Post by kevin »

You use this set up when you're racing with big power and very high rpm and you're not taking and chances with rubber guibos ( doughnuts) . Or even simply an 8000rpm 2.5 screamer . You normally run three universals with this set up . This pic is on the GTV and has just the last section with the torsion resilient tube .
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Joemart
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Re: driveshaft conversion

Post by Joemart »

oooooo..... nice... so what would this setup cost?
squadragrunn
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Re: driveshaft conversion

Post by squadragrunn »

looks a lot like the driveshaft from my maserati biturbo.....
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75evo
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Re: driveshaft conversion

Post by 75evo »

Will a front CV or UV or avoid this sort of catastrophy?

https://www.youtube.com/watch?v=sfrtta3dmNw

This is scary!

I'm seriously considering a different front donut, you can literraly lose you feet if this happens. I will also strengthen the sheet metal there.
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Re: driveshaft conversion

Post by kevin »

Just put a coupling cage on and you're safe unless the prop breaks at the weld .
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75evo
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Re: driveshaft conversion

Post by 75evo »

Hey Kev,

Did you have any luck with the Aston style drive shaft with the built in rubberized material? I think all I need are a 1 sections of that shaft, then I can eliminate 1 or even 2 rubber couplings. Thinking of a front CV joint, AM shaft, center BMW rubber coupling and rear CV joint.

Maybe I will ask Beninca's to design me a lightened driveshaft and have them balance it since MD has had excellent luck with them.
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Re: driveshaft conversion

Post by kevin »

My prop is different to yours however the torsion resilient tube section has taken away all harshness and works well in terms of uj noise etc .
There is a transaxle car that runs this type of set up with no rubber couplings but just uj 's ( cardan joints ) and section of the TRT section as photographed previously and no issues . It does sound a bit noisy on idle though .
From my limited research and experience ( hopefully Mats can help ) the us of CV joints is frowned upon amongst the big prop designers as they generate to much heat and do fail from this hence the use of UJ which handle this better ie less friction at angles . Surely if they have perfected UJ for the side shafts in modern motoring then they would have one for the propshaft that can handle this friction .
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75evo
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Re: driveshaft conversion

Post by 75evo »

Actually now I'm seriously thinking of just adapting an E36 M3 driveshaft to the 75. All I need is the front guibo adapter, and rear CV joint adapter. Center bearing mount can easily be drilled to the chassis.

Parts would be super easy to get!
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Re: driveshaft conversion

Post by Jim K »

Your best bet in this case is to also get all surrounding parts i.e. the entire M3 and drive a real car for a change! :wink: :mrgreen: :wall:
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Re: driveshaft conversion

Post by kevin »

I'm not sure why you want to replace entire driveshaft . I had really good success for a few seasons with the standard driveshaft with a coupling cage on the front coupling . I used this set up when the car was 3.0 24v and also when it was 3.7 24v BUT I did modify the engine alignment( ie lasered it down to gearbox) with custom engine mounts and an engine stay to keep it in position . You're bell housing bush also needs to be modified to cater for the straight engine .
Their is another two liter GTV in SA the revs to 8500rpm and he has also perfectly aligned engine and has no failures on driveshaft .
Personally I would not change the prop .
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Giuliettaevo2
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Re: driveshaft conversion

Post by Giuliettaevo2 »

Cv joints are commonly used nowadays. Most beemers have at least one in the propshaft. Audi quattro uses at least two and also on the rs4 and rs6 model.

Should not really be a problem i think.

Aligning the engine is a good idea,also looks a lot better. For a racer i would also use stiffer mounts for the engine.
Drive it like you stole it...
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