driveshaft conversion

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75evo
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Re: driveshaft conversion

Post by 75evo »

Part of reason is parts availability and quality. Some giubos blow up within a few hundred miles and can cost upto $270/each. I think to service the whole shaft it could possibly be around $500 - $600 and there is absolutely no guarantee on parts availability and quality.

If I take the initial hit on adapting the BMW shaft, or any universal parts based shaft, the issue of quality and parts availability won't be much of an issue down the line. Especially if were to use something as popular as an E36.

I think within 10 years manufacturers will think 10 times before producing giubos for the dwindling demands of the transaxle crowd.

BTW, the owner of the GTV6 which blew the prop clarified that the shaft failed not the giubo.

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Re: driveshaft conversion

Post by kevin »

To keep thinks simple then just import a prop from Richard Melvin . Its the one pictured on previous page with the TRT section on the rear part. Its made by the same company who made my prop .
Search for Richard on face book and contact him . They have done all the home work . Your other alternative is send your prop to the US company Spicer and tell them you want a TRT section on rear with uj designed to spin to 8000rpm . Design theory is different between M3 and the GTV as the only time the M3 will spin its prop like a GTV /75 is in fifth as its got a 1:1 fifth gear other than that it does not see any of the abuse the transaxle prop gets .
Watch on youtube the same chap who broke his prop in the clip you posted on his other race . On that track theirs a section when he is in third gear holding the loud pedal down then backing off then applying power repeatedly . This is a prop killer especially when using standard engine alignment set up . The front of the prop will be moving like a happy dogs tail ! Soon the front pivot bearing will break off .... Seen it .

Now if only I could find a cv that will work reliably at high rpm and operate at uneven opposing angles between front and rear .

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Re: driveshaft conversion

Post by Duk »

Silly question time........................ :wall:

While I love Kevin's approach to the tailshaft saga, what is stopping someone from making their own rubber couplings of a more durable design and perhaps with some internal Kevlar reinforcement?

The big problem that I see is the actual rubber itself.
2 part RTV silicone rubbers are available, but as Mats has mentioned in the past, natural rubber is much more durable than just about everything else.
But you can buy RTV silicone rubbers easily (note that I'm talking about creating such things on a very low scale (personal level) production), but being able to find information about about 'where to get' and 'how to work with' natural rubber(s) in smallish quantities, is proving much harder. :shock:

kevin
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Re: driveshaft conversion

Post by kevin »

Duk , that's the best solution - proper made couplings . When I bought a rubber coupling for the BM ZF box I had a choice of two as their was one specifically for the M3 . A friend of mine here has had the original Pirelli couplings on his 3.5 GTV for 17years and does at least five trackdays and a ring trip a year . Yep I could not believe it either but makes sense as the quality was far better then . This particular car is garaged all year when not in use with temperature control .
So the big question is who can make this reinforced coupling that can do in limited numbers .

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Re: driveshaft conversion

Post by Duk »

After a bit more Goggling it's pretty obvious that an RTV silicone is completely unsuitable. It kinda, sorta doesn't stick to much other than itself............... :oops:

The way I was thinking about it, each coupling would have 2 interlacing steel structures that provide the majority of the strength.
Then the rubber would link the 2 together and provide the dampening. A strip of Kevlar tape could be used around the outside of the internal steel structures, but inside the outer edge of the rubber, to help add strength to the rubber and prevent it from flying appart at high revs.

Yep, a drawing would help explain it a lot, but I'm shizen-housen at drawing. :P

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75evo
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Re: driveshaft conversion

Post by 75evo »

Kev is right, the older couplings were much superior in quality thant the one we can (with some difficulty) get today. I wouldn't mind paying for 2 sets of very high quality custom rubber coupling with improved quality over the original OE (which was already good and last 10+ years). I'm pretty sure if the quality was great, just aligning the driveshaft could easily its useful life of 10-15 years even with a 3.2 24V.

So if we can find a manufacturer who can make a run for us, that would be good.

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Re: driveshaft conversion

Post by kevin »

Z , here is name of guys who can make a replica Alfa prop with torsion resilient tube and universals . They said when I was at their shop Itbwould cost about £450 . You then need to make adaptors to flywheel .
However ... Just use the coupling cage on std prop with new front coupling , BMW centre coupling and Alfa rear with cage when you break something let me know but I doubt you will . Save a lot of time . :wall:
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Mats
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Re: driveshaft conversion

Post by Mats »

Just replaced all the guibos on my "other brand car", what a joy it was. No overlapping studs, no expanded rubber that needs o be compressed to be able to fit it. Just put the disc in place and insert the screws and torque to spec. Done.
Mats Strandberg
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GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!

hexen
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Re: driveshaft conversion

Post by hexen »

PietereQ wrote:Using Mats concept as a guideline, I have had the rear flange manufactured recently, it still needs fabrication though to fit the CVJ :x
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Hello,

I search the profil of the clutch spline shaft to draw and made a CV joint rear flange.

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MD
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Re: driveshaft conversion

Post by MD »

After that you need this:

Note the welded up vent opening for extra rigidity at the circumference. You can Swiss cheese the the actual inserted plate for ventilation if you wish.

There are 4 brace version of this but for most applications, just 2 will do.

You have to machine the housing front to create a smooth and perfect circle. Then heat expand the braced ring first and install it on the machined nose piece. Once cooled, there will be no play.

...end of cracked clutch housings.

(Ignore the modification fitted to the clutch input shaft end, It has nothing to do with this and it was an attempt to modify the centering requirement for a foreign rear coupling.)
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75evo
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Re: driveshaft conversion

Post by 75evo »

Salut Hexen,

Do you have any info on the BMW guibo adapter flange which Yannick had on his Facebook page? What I'd like to do is convert all 3 of the guibos to a single BMW style guibo.

Reason? Very easy to buy, avaialble almost anywhere and price is relatively cheap. Sometimes the Alfa guibos are out of stock and you have to wait a long time for it to be available. Especially if you have the thick center guibo and non-slip joint driveshaft.

hexen
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Re: driveshaft conversion

Post by hexen »

Yannick take a transmision from BMW série 3, He cut the front tripode, cut the driveshaft in the good dimension. Next he put a new tripod machined (it's me who draw it), and the driveshaft was welded and balanced.

For the rear the adaptateur is machined too, but machined 2 times because I don't have the profil of the clutch shaft.
The spline was made not by a local machineer, but by a machineer who know the exact profil.

So I search the profil to do a compléte drawing.

Actualy I have a driveshaft with font 75 turbo and rear from a front range rover driveshaft. It's heavy, so I made a new with bmw 530 driveshat with a CV joint.

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75evo
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Re: driveshaft conversion

Post by 75evo »

Salut Hexen,

Est-il possible pour vous de partager le CAD fail pour le CNC, sil vous plait? Je pense en utilisant la guibo de BMW est un bon choix. Bon marche and et facile à acheter.

Merci beaucoup ( pardon mon français est tres mauvais :( )

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MD
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Re: driveshaft conversion

Post by MD »

I don't have the profil of the clutch shaft.
Yes you do.
What you do is use the existing three flanged connection yoke of the clutch input shaft and cut the front flanges off.

You then weld on the new CV adaptor/locator mount onto the original rear cut off section of the joke that has the splines inside it.

Once the two are joined and balanced, you have a CV connection with the original splined shaft centre. No spline details required. You already have them.
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hexen
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Re: driveshaft conversion

Post by hexen »

It's what I plan to do it. But i's better if I can can make it in on part.

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