ALFAGTV6.COM

[MD]

Fedezyl

Two suggestions:

1 You edit my quote above to reduce it down to just the item relevant to you as it seem pointless as it is immediately preceding your post.

2 Wait for my new shaft to be completed as I am not happy with the existing one and I will post the photos in my own topic of my race car.

[kterkkila]

None of the cars using UJ's etc. have ever broken any cranks here. They dont of course make anywhere near 190Kw either. Mine has broken the flywheel bolts but that is for a different reason. The bolts bottomed out in the crank and didn't make sufficient tension on the flywheel.

Having said all that, I will experiment to try and remove the nosie nuisance by adding a better quality single donut just behind the front flywheel as part of the flywheel mount repairs. This will require some serious mods to the mounting arrangment for it. I am hoping that it will dampen the noise out and provide a little cushening to gear changes which wont hurt at all.

Glad to hear that you found obvioius reason for flywheel bolt failure, great

Sometimes transaxles makes all kind of noise even with std rubber setup, what a race car feeling.

There's plenty of donuts out there, which are designed for high speed and torgue, so finding good alternative shoudn't be a problem.

[fedezyl]

Fedezyl

Two suggestions:

1 You edit my quote above to reduce it down to just the item relevant to you as it seem pointless as it is immediately preceding your post.

2 Wait for my new shaft to be completed as I am not happy with the existing one and I will post the photos in my own topic of my race car.

Sorry for the inconvenience, will do next time.
I'll make sure to follow up on your drive shaft evolution...cheers

[Mats]

Mats, the problems I have seen is where a CV is used and it breaks it always results in crank breaking. Not crank breaking as a result of using cv(definately not good english here).
Mats, good question why do we need any rubber in prop(for racing). Surely some of the shock must be taken up on the drive train with the movemnt of gearbox under braking(longitudanal), changing gears(rotational).
Mabybe the only GTV I have seen with solid prop(cv and unversals) that always broke was because the motor was 190kw on wheels-3.7L which was to strong for that set up in extreme racing conditions.

CVJ's are incredibly strong and the only issue is the low angle (lubrication) and the rpm (boot + heat buildup). Almost all CVJs are plunge type, there are fixed ones as well for halfshafts for instance but they are rarely used in props, one CVJ with plunge will easily deal with the change in length of our system, we're talking mm's here.
Strange that you/your friends have had issuses with breakage, any more info on this?

My race car presently has three universal joints and no rubber couplings. Generally the balance is better than with rubber couplings however this combo has an annoying minor failing. It causes a "hammering" sound in the drive train during idle and up to 15-1600 rpm. After that the noise disappears. This is due to the cummulative impacts in the entire driveline moving in response to the engine turning over.. At first I thought there was something loose but after talking to two other owners with similar set ups, it appears that the problem is the same. The other cars use a variation of mine such a 2 UJ + 1 CV. Sometimes the CV is behind the crankshaft and sometimes it is in the middle.

You can readily see why the Alfa factory decided to use rubber couplings because they had no choice !! They would never have sold ANY cars if they made that much transmission noise.

This is an NVH issue and is as you said the reason why they built it with donuts, Porsche moved the clutch and used a torque tube instead to minimize vibrations. Not a problem on a racecar but gearbox rattle is not a sexy sound and will shorten the life of the gearbox (again not applicable in racing)
Probably it can be solved with a tuned torsional damper or sprung clutch-plates.

In the past I have read a lot of boloney about never using univesral joints because they resulted in vibration but that is just rubbish. The real problem for street cars is the idle noise. For racing purposes, you dont seem to spend too much time at idle that I seem to recall, heheee.

They only cause vibrations if you use then at an unappropriate angle. 0.4<1.6 is a good envelope to start with, also phasing is important when having two or more in the system.

Having said all that, I will experiment to try and remove the nosie nuisance by adding a better quality single donut just behind the front flywheel as part of the flywheel mount repairs. This will require some serious mods to the mounting arrangment for it. I am hoping that it will dampen the noise out and provide a little cushening to gear changes which wont hurt at all.

Good plan, typical BMW setup. They have the clutch and gearbox to help to dampen the vibrations though but on an automatic with engaged lockup it is solid, lots of mass still but it is solid between the engine and gearbox and still no rattle.
Have you got an aftermarket ECU on there? Maybe playing with timing advance can help soften the amplitude of the engine firing?


Hmm, a lot of non-racing stuff...
But what are you going to do? It's interesting enough.

[kevin]

Very interesting discussion. mats what do you use in your car. When my front donut explodes I am going to make a solid donut(aluminium) with rubber inserts. Just had some chaps do my engine mounts for me and they are perfect. Made a few extra sets with different shor hardness from 55 to 70. Softer ones for road car. I must say we are extremely lucky here in SA as you can get nearly anything made at a decent price very quickly. My engine mounts cost me R250 (25 pounds) and the quality is excellent BUT they are also chaps who make rubbish so have to be aware.
Got a pic from Saturdays race showing some more bad driving skills. Lock up in the corner due to trying to hard to make up ground. I guess racing is just like any sport as the harder you try the more tense you get, higher your heart rate which all impacts on your balance.(In pro golf if your heart beat goes up you imediatley add extra yards to that club . Probably thats why they do drug testing in golf to check for stimulants to regulate your heart beat).

[MD]

Hey Kevin !! That photo is hotter than the sunny side of Mars man !!

GO KEVIN !!!

[la_strega_nera]

another

I like the rear caliper access panels...

[Mats]

Very interesting discussion. mats what do you use in your car.

Maybe 10yo (I don't know but they are not mint, that's for sure) std donuts, got a few bits n pieces laying around the garage though...
Looking to make a CVJ-cardan-CVJ shaft actually. Just offset the center bearing a tad to get some angles in there. Even got a CVJ flange to modify for the clutch side which is nice.
Maybe I'll redo the entire flywheel on the engine to make a nice setup at the front but I haven't decided yet.

[MD]

If you want to see my current shaft look here:

http://alfagtv6.com/bb/viewtopic.php?p= ... bd8a#31612

[fedezyl]

Thanks MD, by the way Kevin, nice pictures, wich tires are you using?? glad to see an Alfa being pushed to the limit and beyond!

[kevin]

Fed, using bridgestone re55 semislicks. MD, Mats there are a few here looking at your pics and reading your comments. Mtas that race car here sheared the CVj off the flywheel. the bolts were correct lenght. Maybe to much power as mentioned before however having said that there are a few Twin turbo set ups here that have more power but are not driven in race conditions which use cv upfront. I still think it could be a shock issue ??

[kevin]

Fed, using bridgestone re55 semislicks. MD, Mats there are a few here looking at your pics and reading your comments. Mtas that race car here sheared the CVj off the flywheel. the bolts were correct lenght. Maybe to much power as mentioned before however having said that there are a few Twin turbo set ups here that have more power but are not driven in race conditions which use cv upfront. I still think it could be a shock issue ??

[kevin]

Fed, using bridgestone re55 semislicks. MD, Mats there are a few here looking at your pics and reading your comments. Mtas that race car here sheared the CVj off the flywheel. the bolts were correct lenght. Maybe to much power as mentioned before however having said that there are a few Twin turbo set ups here that have more power but are not driven in race conditions which use cv upfront. I still think it could be a shock issue ??

[kevin]

Fed, using bridgestone re55 semislicks. MD, Mats there are a few here looking at your pics and reading your comments. Mtas that race car here sheared the CVj off the flywheel. the bolts were correct lenght. Maybe to much power as mentioned before however having said that there are a few Twin turbo set ups here that have more power but are not driven in race conditions which use cv upfront. I still think it could be a shock issue ??

[kevin]

Fed, using bridgestone re55 semislicks. MD, Mats there are a few here looking at your pics and reading your comments. Mtas that race car here sheared the CVj off the flywheel. the bolts were correct lenght. Maybe to much power as mentioned before however having said that there are a few Twin turbo set ups here that have more power but are not driven in race conditions which use cv upfront. I still think it could be a shock issue ??