ALFAGTV6.COM

[Duk]

Structurally reinforcing the transaxle to keep clearances correct, does sound like 1 of the most important thing that can be done.
Making the main bearing plate from a block of alloy steel like 4140, me thinks, would be a very good idea.
Having a pumped oil supply with, at a minimum, a feed line for the ring gear and pinion, would help a lot.
Adding a feed for the output shafts main bearing would also be a good idea.

[MD]

Some structural updates. The photos should be self explanatory. Any questions, fire away...

[MD]

A few more..

[MD]

Buttressed to the sheithouse clutch cover as version 2 of my original design. Don't try this at home unless you are an expert aluminium welder and want to avoid massive distortions. A lot of skill set required to do this.

[MD]

The Dashboard. A work in progress awaiting instrumentation panel cut-outs.

[KevinR]

You certainly have been really busy ! Small things like central jacking point on the front that strong and low enough for low nose Jack make life easy unless you have inbuilt gas jacks .
You don’t really worry about rain into bulkhead in Oz . On the current turbo project we need engine bay bracing but need to make sure no hot air comes into cabin and water drains away .. welcome to racing mostly in the rain !

Dash layout looking !
Sure you got enough braces on clutch . Your spider version is working well on all my mates cars . I even laser cut the whole set up for simplicity .
Regarding gearbox, my mate has already made up a reinforced sandwich plate ! Just need to find a supply of bearings !

What’s your crown pinion ratio going to be on this ?

[MD]

Hi Kevin,
We mustn't neglect the contribution from our long standing contributor to this Forum namely the Dukster. Always a good lateral thinker. Thanks Duk for the steel billet sandwich plate idea. If someone can get me the CNC software drawings for it, I would be willing to give it a go.

That revised clutch cover was a job and a half. I had to make templates for each rib and then hand shape all the actual rib contours so each rib would fit the curves of the cover. It has to be thoroughly clamped down and fully preheated prior to any welding. And of course the crappy original casting isn't exactly the ideal material to weld either. Like I said, I just wanted to show that I did make an improvement on my original design but I am not going to make another one !!!

Regarding the bulkhead opening, it is not intended that it remains open like all the other firewall holes all over the place, they will all be sealed off prior to commissioning the vehicle. I am just showing work in progress rather that work totally completed.

Regarding the final drive ratio. I expect to have some reasonable torque available so I am planning to experiment with the original ratio and the transaxle used by Alfa themselves in the 75 turbo which has a final drive of 3.9:1 If the motor can handle the load, it should haul ass. We'll see.

[Duk]

MD, I think there also needs to be emphasis on a pumped oil supply for the ring and pinion gears, rather than relying on conventional splash/carry lubrication.
Same thing for the main output shaft bearing that wears the thrust load from the pinion gear.

[Zamani]

Interested in the pumped gearbox solution. Might actually help cool some parts in there as well especially if there are multiple oil jets spraying at strategic places

[MD]

Well guys, there is merit in those suggestions especially in distance motorsport of some sort like rally or 24hr events mainly to address serious wear issues. My experience has not been a wear issue and when stripping down the boxes, there are no adverse wear indicators to warrant such measures.

My problems are more to do with torque, material capability, ring to crown leverage and casing flexing, pinion and crown walking. Anotherwords and to be blunt, materials fit for the purpose. Is my Alfa transaxle fit for the track work I expect of it, probably not.
No amount of extra lubrication is going to address that. There is a good reason for the famous Ford 9" diff.(or the equivalent.)

My track work when I can get there are 15 minute sessions at most and the box is just getting nice and warm even a cooler is not warranted.

Like they say, horses for courses...I need to figure out a ZF to Nissan transaxle swap

[Zamani]

One of our members (gtv-racer) here from Denmark already has that CAD file for the billet bearing plate. He is the guy from Denmark with the supercharged 75 3.0.

http://myalbum.com/photo/LaAsgWQpcCeg/720.jpg

[MD]

Geez Zamani, you're worth your weight in Googleberries.

We shall make the approach and see how long the garden path is. Email dispatched.

[KevinR]

MD , when I made drastic changes to my gear box cooling and moving to redline oil I significantly reduced the breakages . So more cooling in my 40mins races means better crown /pinion tolerances …. I think .. it was not mere coincidence but really did have an impact

[MD]

Hi Kevin,
I cannot believe I completely forgot about the extended reporting from gtv-racer** about the custom bearing block. I blame it on tight underwear that shrank in the last wash.

Back on track.. Let's look at the two very different times of use: 15vs40 minutes. The heat build up would be substantially different. If that resulted in greater expansion and possibly walking clearance, you've got a crown wheel dental cavity in the making. So the prescriptions for keeping the parts, lubricants and casings cool would take on much more importance.

How much part the Redline product played in the that role is potentially interesting but it would need to be repeatable to make it valid. I think most of the factors contributing to failures were discussed in detail 5 or more years ago. The factors mostly concentrated on the hardware.

** I don't recollect seeing the final testing results of the revised appointments to the transaxle. If anyone knows of this info, please fill me in. Cheers.

[Zamani]

MD,

You know what they say, never air dirty laundry in public, especially if they're a man's pink panties

I've sent gtv-racer an email, let's see what he says. He did put in a lot of effort into it, so I expect he would want some of it back.