MD's Racer-The Flying Brick

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OzMidnight
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Re: MD's Racer-The Flying Brick

Post by OzMidnight » Tue Oct 07, 2008 12:45 pm

Bad luck about more breakages - although good news on the BMW guibo being better. Doesn't make me feel all that super about things I have to "look forward" to. Even though you used only 3 gears, what did you feel your times would have been like?
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MD
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Re: MD's Racer-The Flying Brick

Post by MD » Tue Oct 07, 2008 1:08 pm

The co-driver did 2:59's around the middle circuitat Morgan Park and Andrew was doing 2.56's I believe.
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Re: MD's Racer-The Flying Brick

Post by kevin » Tue Oct 07, 2008 1:57 pm

MD, remember my problem with the crack in the clutch housing was caused by the vibration from chip tooth in crown and pinion. In the eighties they used to weld extra webs in clutch housing on GTV 3.0l. Recheck balance on clutch unit.
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Re: MD's Racer-The Flying Brick

Post by MD » Sat Oct 11, 2008 3:22 pm

Kevin,

Thanks for the feedback. Love to know how they did the bracing up if you got pics.
My view at the moment is that to weld here would cause distortion and even if you overcome this, now that the housing front is stronger, it is simply likely to break the gearbox side of the housing so its just changing deckchairs on the Titanic. Maybe your guys do have the solution. Love to find out if you know.
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Cracked front clutch housing.jpg
Cracked front clutch housing.jpg (116.98 KiB) Viewed 3349 times
Last edited by MD on Sat Oct 11, 2008 4:00 pm, edited 1 time in total.
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Re: MD's Racer-The Flying Brick

Post by kevin » Sat Oct 11, 2008 3:45 pm

MD, what I gather from most of the racing chaps here is any sort of vibration or inbalance leads to clutch housing failure. Dawies naturally aspirated race car has 270kw with same setup as us except for cv's as couplings and has not burst a housing so i dont think its a power thing. Its could also be a longitudanal movement relatedbut Im sure your box has bolted mountings. I have kept the rubber doughnut options on my car with cages to help dissipitate some of the shock. The proof will be in the next two races. car is taking far mor abuse on slicks. Will ask around for more opinions from the gurus here.
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Re: MD's Racer-The Flying Brick

Post by MD » Sat Oct 11, 2008 3:59 pm

Giuliettaevo2

Yes I do have some pics of the front conversion. I hope you can figure out the sequence of assembly from the pics. Basically it requires a change of PCD because the Alfa bolts do not line up to the new donut. The second problem is that the bolts sizes are larger for the new coupling so you have two choices. Either make sleeves to convert from 10>12mm or use bigger bolts.

I used bigger bolts .

Notice that the shaft still centres on the original centre locator bearing however it is a completly new shaft and the Alfa end has been grafted onto it. It is necessary to weld onto the driveshaft, the converter plate. The photo does not show welds. Care must be taken to avoid distortion (hence alignments after).

In hindsight, instead of making conversion PCD plates, it would be better to simply make a complete new flywheel out of billet steel, shrink the starter ring onto it and have the correct PCD's on the new flywheel to fit the new donut. You would still have to do a conversion on the driveshaft itself as well of course.

Presently my current shaft uses this at the front followed by two universal joints. This is about to receive its final and third modification to eliminate the rear universal and covert it to a similar type of donut as is in the front. This is not necessary but I just want to take a precaution against any further stresses on the clutch housing from alignment and vibration issues which are almost impossible to eliminate altogether. Putting the front one on made a huge difference to quieten down the noise from the transmission during idle . The final mod should complete the picture in our driveshaft development.

The only other improvement I can see is a change to a CV joint in the middle instead of a universal one in my set up which may yet be done if needed.

Finally, if you wanted the ultimate, go the the composite one piece shaft and BMW donuts at both ends.
Attachments
Front shaft removed studs 1.jpg
Front shaft removed studs 1.jpg (134.88 KiB) Viewed 3326 times
New coupling on flywheel 1.jpg
New coupling on flywheel 1.jpg (111.52 KiB) Viewed 3328 times
Flywheel converter side view 1.jpg
Flywheel converter side view 1.jpg (110.09 KiB) Viewed 3330 times
New coupling on driveshaft 2.jpg
New coupling on driveshaft 2.jpg (117.27 KiB) Viewed 3329 times
Flywheel PCD Conversion 1.jpg
Flywheel PCD Conversion 1.jpg (119.52 KiB) Viewed 3327 times
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Re: MD's Racer-The Flying Brick

Post by MD » Sun Oct 12, 2008 2:02 am

OzMidnight.

Can you confirm receiving my last two PM replies as I don't think my PM's are working. They are getting to the Outbox and then sitting around gathering dust..
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Re: MD's Racer-The Flying Brick

Post by PietereQ » Sun Oct 12, 2008 8:39 am

MD is there any noticeable change in power/torque transfer to the wheels with two cv joints over stock setup? - just wondering.
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Re: MD's Racer-The Flying Brick

Post by MD » Sun Oct 12, 2008 1:20 pm

Pete,
I have no data for this only a perception and my perception is that the difference is negligible. I certainly would not advocate changing over for faster lap times. The changeover is more about reliability and dependability. Having said that many owners report having no problems at all. That is not been my experience because I have broken donuts on every Alfa Ihave ever had and in one case I broke all three at the same time !!! The fact that you have to fit cans on the Alfa donuts is more evidence of their vulnerability.

With regard to your car and the idea for another topic set. Well it could have been anybody's car . It is just a coincidence that I thought of the idea at the time. By the look of it, you are working through your problems very well anyhow.
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Re: MD's Racer-The Flying Brick

Post by TS_turbo » Wed Oct 15, 2008 12:16 pm

from what bmw model is that rubber? small 4 cyl middle most of 6 cyl ..big and fat ones from v8 and big sixies ?
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Re: MD's Racer-The Flying Brick

Post by MD » Thu Oct 16, 2008 1:14 am

Ah, TS_Turbo i'd love to be able to say which model it comes from but I didn't pick it from seeing any BMW cars. I went to the new spare parts place and picked one from their racks that I thought would suit(and it does).
Best I can do is to tell you the brand and the part number and maybe you can do something with that. Remember that is is not a direct changeover. Must change the mount PCD's.
Make : Lemforder P/N 26 111227 869-(78/12mm).

For a V6 engine flywheel and driveshaft coupling this item would be useless.

One of the criteria for selecting a cetain diameter coupling is the need to be able to install it via the rear engine mount when it is already fixed to the driveshaft. There are beefier couplings but too large in diameter etc. for the 4 cylinder rear engine mount aperture.
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Re: MD's Racer-The Flying Brick

Post by OzMidnight » Sun Oct 19, 2008 4:37 pm

I got your pm's thanks....just haven't been online to receive them! Very informative, as usual!
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Re: MD's Racer-The Flying Brick

Post by MD » Fri Oct 24, 2008 2:56 am

Well, our development work continues and we have just finished making some more refinements to our prop. shaft and drive shafts, gearbox and clutch. Got it all pretty much stitched up and running again in prep for next week end at Queensalnd Raceway. Notwithstanding the failures that we have had along the way, the car is getting better and better and we are getting more and more in tune with it as well as you would expect.

Our pitfalls have been related to some adventurous design mods that better qualified engineers may have foreseen that certain things may fail in certain combinations but like most do it yourself types that hang out on this Forum, we just blasted on to oblivion until it brakes !! :D Nah not really but it sure is a serious way to learn mechanics. For example,we broke the LHS CV joint. Essentially nobody had an exact idea of why this was so as it is not that common a fault. However in our case a number of factors came together to bring it all undone.
1The car is lower than a turtle's arse. This runs the driveshaft totally horizontal.
2 The suspension travel is very small and so the shaft spends most of its time horizontal which it normally doesn't.
3 The track corners we use are mostly right handed causing most of the lateral forces to be applied to the left axle.
4 Combined with the increased negative camber of our rear wheels and the lowering, it has caused the shaft to have so little end float that it rotates on it very edge of the internal ball cage where it should not be.
5 End result, you guessed it, el breako finito !

..and so we learned another valuable lesson which Iam sharing with you. If you are going to lower you car to the shithouse and give it bags of negative camber and minimal suspension travel, please ensure you have the shafts machined shorter so they have some end float. Between 5-10mm will do it.

See what I mean about having good intentions but no experience ! It's costly I can tell you that much.
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Re: MD's Racer-The Flying Brick

Post by ar4me » Fri Oct 24, 2008 7:02 am

MD wrote:..and so we learned another valuable lesson which Iam sharing with you. If you are going to lower you car to the shithouse and give it bags of negative camber and minimal suspension travel, please ensure you have the shafts machined shorter so they have some end float. Between 5-10mm will do it.
Hmm, that description fits my race car pretty well, although I have not had any problems - pic attached. I will check the float. How much negative camber do you have at the rear?

I know Mats runs a lot on his Alfatta GT - I'm guessing more than -4 degrees. I have about -4 degrees on mine, and I believe it is too much. Very, very hard on tires. Braking suffers too due to little straight-line traction and with some tires it has gotten extremely squirmy (requiring significant steering correction) during hard braking, using one hand while down-shifting. I'm going to do another Dedion with about -2.5 degrees - just have to find the time...

Jes
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Re: MD's Racer-The Flying Brick

Post by Zamani » Fri Oct 24, 2008 8:38 am

Jes,

Your car looks like it has more camber in the back. So the front must be around -2? Maybe it's just the photos? My car has -3 Front and -0.5 rear.
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