Author Topic: Transaxle weakness's  (Read 10654 times)

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MD

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Re: Transaxle weakness's
« Reply #15 on: December 20, 2015, 12:56:52 PM »
Doing some lateral thinking of your CF concept, if it was possible to source a billet of CF, I dare say you could machine out the casing and make the entire casing components from CF.

At this point I am looking over my shoulder for a couple of guys in white coats moving a mobile stretcher with long tie down straps and if I am not mistaken, one of them is carrying a large hypodermic labelled "sedative". I'll keep you posted on my 4G network connection while I make a bolt for it.....

..to be continued.
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105gta

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Re: Transaxle weakness's
« Reply #16 on: December 20, 2015, 01:32:52 PM »
Haha MD, I think few should all be looking over our shoulders just owning there cars :/

Duk, I have already been thinking if a similar process for other parts of the car but in the case of the trans I have concerns bout the expansion rate of the alloy and the vastly differing temps at which it works. From my experience of the carbon fibre I have worked with it really really really I mean REALLY!! Does not like to flex, bend or move in any way. A great idea i agree. It used in the same way to strengthen bridges and other structural items with great success but only in items the have a slow, steady and minimal rate of expansion.  My issue would be on a usual day in Brisbane the case would be say 15deg and working in a relatively short time could reach 100deg. With alloy's expansion rate it would be pushing the limits of the carbon's resin. Once it cracked it would then become a costly, time consuming but very cool looking heat containing cover around the gearbox.
It may work but would need to confirm with an plastics engineer to confirm.

Ben
1967 Giulia Sprint GT Veloce (WIP)
1985 GTV6 (WIP)

Duk

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Re: Transaxle weakness's
« Reply #17 on: December 20, 2015, 03:11:01 PM »
Aluminium's rate of expansion (please note that there are heaps of ALLOY steels) is considerable. But rember, the alloy block engines use cast iron sleeves and the rate of thermal expansion is still kept safe enough that gaskets and seals stay in 1 piece. And if it is that bad, then the growth of the parts of the case that locate the shafts relative to each other, would cause enough change (and probably can) that the contact between the gears would change. In this case, both reduction (by temperature control) and restraint of the the thermal expansion should be considered.
High temperature resin would still be a good idea, to maintain stability. As would an alloy steel centre plate.
And as mentioned, CF is a pretty good thermal conductor and you should already have an external oil cooler by this stage.
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105gta

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Re: Transaxle weakness's
« Reply #18 on: December 20, 2015, 04:06:08 PM »
I get what you mean Duk. In the case of the engine having cast iron liners with an alloy/aluminium case, the liners are machined to actually stick proud of the block. Even though the liners are cast iron with a relatively low expansion, they are also subjected to a few hundred degrees more heat than the cylinder block. Combustion temps exposed to the liners compared to the block which only sees the coolant temp, yet it as still required to have the liners longer than the block to maintain an acceptable sealing surface at operating temp due to the blocks growth in length compared to the liners growth in length.
As for the shafts moving away from each other.. They do. Even though there is only approx a couple of millimeters between the the bearings, but more so because of the axial forces involved and the bearings being so far apart on the same shaft. Int flange at one end and pinion bearing so far away. Leaving long shafts with no real support in midway. That in itself there is a cure well 2 actually.
So strengthening the case will have little to no effect for that issue.
1967 Giulia Sprint GT Veloce (WIP)
1985 GTV6 (WIP)