Need answers to aluminum driveshaft questions

[jdub]

I have no doubt David your driveshafts can handle the HP...my aluminum shaft has been working out well too. Nor am I implying your shafts would have any safety issues. It's extended high speed...the Mk III is a heavy touring car, not a drag car (though some guys make them that way). The track time I look at for fun is an oval or Grand Prix type course...that where shaft critical speed comes into play.

As far as safety loops goes, it's not that I'm expecting the shaft to fail...but I am taking precautions, because if it does, it can really tear the car up. IMO, if you run a high HP car, you should use safety loops on *any* driveshaft. I've got way too much $$$ in this car...lets call it "cheap insurance"

 

[shaftmasters]

It took some time but after reading this entire thread I have learned allot. I currently have an aluminum driveshaft on my daily driver, got it indirectly from Jawsgear. I don’t think I will be going 120+ to work every day so I am not worried about it falling apart.

I can say that I get a tiny vibration at 70 and its gone at 80. It hits my exhaust when it vibrates. However a HUGE pothole that was filled with water at my bank bent my downpipe a bit, now there is allot less clearance between the exhaust and the DS. It rubs a tiny bit when it vibrates. I assume I will need a new downpipe when I can afford one..

A custom 2-piece sounds interesting.

If your driveshaft is running that close to your exhaust I wouldn't wait any longer to do something about it. I have had to retube many driveshafts, both steel and aluminum that were sawed in half because of them rubbing on exhaust clamps, emergency brake cables etc.
Robert

 

[starscream5000]

Hasn't it been mentioned that the AL DS's can fatigue from twisting over time to the point where they become a danger to continue using? The steel DS's don't have this problem, correct?

I'm highly interested in a fully balanced two peice steel DS with upgraded U-Joints and center bearing. Is a poly center carrier bearing feasible? Or should you stick with the rubber for it's dampning properties?

 

[shaftmasters]

Hasn't it been mentioned that the AL DS's can fatigue from twisting over time to the point where they become a danger to continue using? The steel DS's don't have this problem, correct?

I'm highly interested in a fully balanced two peice steel DS with upgraded U-Joints and center bearing. Is a poly center carrier bearing feasible? Or should you stick with the rubber for it's dampning properties?

Steel driveshafts can fatigue, become bent, twist and rust in-half. I retube many steel driveshafts every week because of these reasons. Here are a few things to consider for those of you that are so down on the use of aluminum driveshafts. Crown Victoria police cars all use aluminum driveshafts in them. Talk about being used in extreme condtions. Many late model pickup triucks and vans also come from the factory with aluminum driveshafts in them. Don't the engineers who designed these know what they are doing or is it only that Toyota engineers know what they are doing?

 

[starscream5000]

I like my steel DS thanks.

Think of how old the cars are already. The steel DS is going to outlast the supra as is anyways...

 

[supraguru05]

guys i think we need to show a little more support here this guy is doing amazing leg work here figureing stuff out we need to show that we would indeed buy aluminum driveshafts if he made them because i know some would

so what we are looking for is

a durable al driveshaft
a two piece steel driveshaft with upgraded joints

i personally would purchase the AL unit because i plan on continueing to road race and the driveshaft is point free weight reduction i will however run a super beefy loop

 

[JMDigital]

If your driveshaft is running that close to your exhaust I wouldn't wait any longer to do something about it. I have had to retube many driveshafts, both steel and aluminum that were sawed in half because of them rubbing on exhaust clamps, emergency brake cables etc.
Robert

Its my next repair. It does not rub unless it vibrates. I have looked and I can not see any marks. It hits for about 2-5 sec. when it vibrates then it stops and all is well. I am going to get it fixed asap tho.

 

[jdub]

guys i think we need to show a little more support here this guy is doing amazing leg work here figureing stuff out we need to show that we would indeed buy aluminum driveshafts if he made them because i know some would

so what we are looking for is

a durable al driveshaft
a two piece steel driveshaft with upgraded joints

i personally would purchase the AL unit because i plan on continueing to road race and the driveshaft is point free weight reduction i will however run a super beefy loop

I agree...there's a place for both types of driveshaft.

David - I appreciate you looking into the 2 piece upgraded shaft. There's guys here that will want the aluminum shaft as well. I look forward to what you come up with

 

[starscream5000]

Crown Victoria police cars all use aluminum driveshafts in them. Talk about being used in extreme condtions. Many late model pickup triucks and vans also come from the factory with aluminum driveshafts in them. Don't the engineers who designed these know what they are doing or is it only that Toyota engineers know what they are doing?

I'm not sure about the Vans or Crown Vics, but have you noticed that there is plenty of space around the drive shaft on trucks? The angle down to the differential and have lots of room to vibrate about once they reach that certain speed, which in supras seems to be around 60-70ish, that they start resonating at.

This isn't so with the supra. The driveshaft is tucked up tight to the car, it's above the exhaust, and held in place by the center carrier bearing.

Like some have already mentioned on here, who by the way already are running AL driveshafts, they vibrate and have confirmed that they are making contact with other objects, be it the exhaust, or the body of the car, when they resonate at that speed, which happens to be right around normal driving speed.

That's why I want a two piece Driveshaft.

 

[Mr. Sinister]

Just to add here, I currently have a 1 piece AL driveshaft and have had zero vibrations up to ~90. Haven't gone faster than that (don't plan on it either any time soon). Point is, driveshafts will vibrate at different speeds on different cars.

 

[IJ.]

We do not see how a 2 piece aluminum is possible. There are no aluminum stubs and you can't weld a steel stub into aluminum tubing. As far as an exchange program for 2 piece steel shafts we do not feel comfortable making people send in their existing shaft and then waiting for us to build a new one and then shipping it back. We know you have 2 shafts but not everyone does. We would not feel comfortable starting a core program and relying on getting good cores back. Just give us a little time and we will come up with pricing for a brand new 2 piece assembly with high performance ujoints and a good quality center support bearing.

As I said earlier I could design one but it's not going to be "affordable" for most of the guys, I tend to overbuild parts as my end use is a little different to most and I break parts constantly.

In 99% of cases an Aluminium shaft is going to be fine it's when you run a shaft fast for sustained periods that it will rapidly fatigue and fail NOT 7>10 seconds at a time on a strip.

 

[supraguru05]

so should my stock driveshaft be a concern for track days considering in one day alone it gets 80 minutes of track time 20 minutes at a time. ive done one track day but ill be doing 5+ next year i might need to install a loop incase

nevermind i just realized your just worried about a long AL shaft not the stock short ones

BTW IJ offtopic i took those mkI rabbit koni bodies you told me about a turned them into 8212s lol

 

[IJ.]

SG: If it's in good condition with no dings or scratches and the Uni's and CB are good it should be fine. (Never heard of a Group A having a failure and you don't get much more extreme than that)

Part of why I put 3.5 diff gears in the IRS 9" was to drop shaft speed on the top end.

 

[IJ.]

Another thing I thought I'd add is it looks like you're all fired up to dyno test the difference between a steel 2 piece and and aluminium 1 piece?

A couple of points to keep in mind the stock shaft is actually 3 piece with a bonded rear section, in time these can debond and run out of phase and this WILL suck power.

For the tests you need a 2 piece in very good condition, having said this there isn't going to be a huge difference other than the 1 piece will have a slightly lower PMoI and this will let it ramp a touch quicker on the dyno and this will show as a power gain (it isn't really it's just the way dyno's work)

The whole "Frees up power" thing isn't quite right it will "feel" more powerful as it lets it accelerate sooner but xx power is xx power it doesn't care how you transmit it as long as there's no parasitic drag in the system.

 

[TurboStreetCar]

Another thing I thought I'd add is it looks like you're all fired up to dyno test the difference between a steel 2 piece and and aluminium 1 piece?

A couple of points to keep in mind the stock shaft is actually 3 piece with a bonded rear section, in time these can debond and run out of phase and this WILL suck power.

For the tests you need a 2 piece in very good condition, having said this there isn't going to be a huge difference other than the 1 piece will have a slightly lower PMoI and this will let it ramp a touch quicker on the dyno and this will show as a power gain (it isn't really it's just the way dyno's work)

The whole "Frees up power" thing isn't quite right it will "feel" more powerful as it lets it accelerate sooner but xx power is xx power it doesn't care how you transmit it as long as there's no parasitic drag in the system.

Load Bearing Dyno owns Inertia Dyno for accuracy because of exactly that.

 

[Poodles]

also why lightweight flywheels show gains on the dyno...

 

[808mkiiisupra]

wait dont we have some kind of driveshaft loop from the factory...? or is that just a weak brace?

 

[Poodles]

it's a brace...

Driveshaft loop goes all the way around the driveshaft in strong steel so that if it does break at spead it doesn't cut through the car body...

hopefully

 

[IJ.]

(easier for us as you don't have to allow room for up/down movement)

 

[LordLo]

1 piece ds vibrate at certain speeds. It's not like a horrible vibration, but it resonates the cabin... I would only use it in a race only car.

The 1 ps alu driveshaft does help. It makes the car feel nimble and light. The stock driveshaft makes the car feel like a tank, but it is no doubt more comfortable.