driveshaft conversion

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75evo
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Re: driveshaft conversion

Post by 75evo »

I guess I could do the same for the BMW guibo, just cut the old three flanged connection and weld one that suites the BMW Guibo.

Ozzies are so smart.

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MD
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Re: driveshaft conversion

Post by MD »

Ozzies are so smart.
Yeah and they have big dicks too. I am getting naturalised next week. I am hoping it will help with my credentials.

...ah not so fast Zeefa, a CV joint is centered within the mounting cup of the new adaptor and the original Alfa rear donut has a centering bearing. However, unless you come up with a way of centering the BMW job, you may develop vibration issues and wind up with one of these:
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Transaxle Alfas Haul More Arse

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SydneyJules
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Re: driveshaft conversion

Post by SydneyJules »

This has been the most enjoying topic to read through!

After destroying my front donut (fitted about 13 years ago when I did my 2.5 screamer conversion- obviously an original Pirelli part, because I regularly changed gears at 8000 and never had an issue until it exploded), I've digested everything here in preparation for my (modified) GTA transplant.

Z's idea of three BMW couplings seems like a cost effective solution, with ease of maintenance bonuses down the track, however, I'm wondering about getting a custom shaft made of aluminium at the same time. It's done regularly here because of guys running two piece shafts in old GM drag racers (VL Commodores as duk posted s while back).

Single piece seems ridiculous for the length of shaft on a street driven car.

MD proposes: donut (to take the low Rpm firing irregularities with harmonics out of the shaft), CV centre and Uj rear and talks of experience with finding a sweet spot without rattles).... And there is everything in between...

Do I just have to suck it and see?

Kevin- as always, you've had a red hot go- how is your Aston inspired tail shaft treating you!?

Ps... Hoping for a uk visit this year to pick up some throttle bodies
Fixing it bit by bit....

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MD
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Re: driveshaft conversion

Post by MD »

Hey Big Jules !

If I knew then what I know now, this is what I would do:-

1 Use the Torsion Resilient Propshaft Tube concept as suggested by Kevin. May only be required for front shaft.
2 Modify the flywheel and the clutch input shaft to accommodate CV centering
3 Use 3 CVs.

If at all possible, whoever is balancing the shaft, it should be balanced fully assembled and preferably at the fundamental resonant vibration frequency (ie maximum actual revolutions at which it is to be used) and not at some lower harmonic rpm.

Most local balancers never use such high rpm for balancing and use a harmonic value to predict the state of balance at the fundamental higher up.

General result: Crap.

I recommend Beninca in Melbourne for balancing.
http://www.beninca.com.au/
Transaxle Alfas Haul More Arse

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SydneyJules
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Re: driveshaft conversion

Post by SydneyJules »

Beninca balanced my current tail shaft and it has never given me any issues until now.
I think the ends of the bolts holding the front donut on have started to splay out from all the "g" Ive put them under over the years... I had to laugh when it blew!

Now, I'm worried more about torque than revs, but still wanting to see about 7,000 out of this GTA engine.

Keen to hear the kevin's experience and considering having a run of tail shafts built if it's successful... Especially considering how low the kangaroo currency is.

I'll start investigating and speaking to the guys that build stuff for drag cars, and Belinda themselves as well.
Fixing it bit by bit....

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75evo
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Re: driveshaft conversion

Post by 75evo »

SydneyJules wrote: I'll start investigating and speaking to the guys that build stuff for drag cars, and Belinda themselves as well.
Who is this Belinda you speak of? Is she blonde? Does she do driveshafts? :shock: #Autrocrrect

BTW, I'm interested in a setup like MD's. The center donut can easily be converted to BMW. The front needs an adapter for a BMW unit. But the rear, I'm inclined to adopt MD's setup.

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SydneyJules
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Re: driveshaft conversion

Post by SydneyJules »

Ahh Belinda! So many stories, so little time :)
I'll see what I can come up with in. Our banana republic dollars!
Fixing it bit by bit....

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75evo
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Re: driveshaft conversion

Post by 75evo »

Mate,

Remember when the AUD was 2:1 to the USD? That was about 15 years ago. I was super happy then, buying stuff from Beninca like no tomorrow.

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Re: driveshaft conversion

Post by Duk »

I think knowing more about how carbon fiber behaves in a propshaft roll would be very helpful.
The R35 GTR uses a CF propshaft with a unijoint and a CV joint and no apparent rubber damping. Same for the Mazda RX8, but obviously they aren't a transaxle car. But given that 99% of RWD cars in the last 15 odd years have some sort of rubber damped tailshaft, I think that CF must have some benefits in noise transfer.
I'm guessing that CF would have a very different natural frequency than a suitable piece of steel tube.
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Re: driveshaft conversion

Post by MR2 Zig »

Cf definitely damps out vibration....at least with a softball bat!
We had been using aluminum bats and then someone brought out a Carbon Fiber one. That had the deadest thunk when you hit the ball with it and it didn't send the ball as far. That was almost 30 years ago though.

(spelling edit)
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SydneyJules
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Re: driveshaft conversion

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After much discussion, we are planning to fabricate a tail shaft with two BMW donuts up front/middle and an Alfa one at the rear, as the sacrificial link. Construction material to be determined.
Will probably require a custom flywheel up front.

I can't find PCD info for either our, or the BMW donuts. Does anyone know where I can find the info for our donuts?

My mate with a modded E46 CSL race car has changed his twice in 8 years. He used to live in the UK. He took regular trips to the 'Ring and he drives it pretty hard when he races.

There's the whole issue with "our" hitting max tail shaft revs every gear change, but I figure, if it's good enough for a modded M3, it should be ok behind my 3.2.

I like the idea of keeping some vibration damping in the tail shaft. And in the long run, replacement of parts will be easier- there are lots of suppliers for BMW stuff and they're obviously a lot tougher than our parts!
Fixing it bit by bit....

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Mats
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Re: driveshaft conversion

Post by Mats »

On the other hand the BMW ones gets the massive torque because they're after the gearbox...
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SydneyJules
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Re: driveshaft conversion

Post by SydneyJules »

That's a fair point. Even more reason to have the engine flywheel adapted to take one.

I can't see any downsides to having three BMW ones.

MD has had luck with his arrangement of three different joints and others have with other combinations as well, but I see this solution as OEM+ rather than an out and out race set up.

Time will tell- I'll know after a few track days how they are hanging on. These are the last of the mods I will do to my GTV6- I just want to drive and maintain it, and start building my turbo stepnose 105!
Fixing it bit by bit....

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75evo
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Re: driveshaft conversion

Post by 75evo »

Jules,

Have you asked Beninca? I asked him and he can do it, but he told me to get a couple of mates to do a group buy. I think he is THE driveshaft guy in Aus. Unfortunately he is in Melbourne not Sydney. But MD sent his driveshaft there after the local guys couldn't do a proper job for him.

The type of driveshaft I talked with Joe was similar to yours. Something like 2 rubber (OEM from another brand like maybe BMW) and a CV at the clutch end. I wouldn't mind ALL being BMW giubos though.

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Re: driveshaft conversion

Post by PietereQ »

Just to let you know the new Giulia will come with CF driveshaft. And no not just the QV, every goddam Giulia will have one :D

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