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Old 11-21-2016, 09:23 PM   #11 (permalink)
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Originally Posted by hydroressources View Post
Tks Fabulist for this input. That is very impressive how the engineers of Fisker did it wrong. That remain very basic mechanics, calculate the torque, the HP, acceleration and shear strength of metal parts. Rotation and torque are common stuff in several applications such as pumps and impeller.

However, according to what I saw on previous post, noise on decel is more associated with the drivetrain. That is what I noticed before it broke. So that make sense to believe it is the drivetrain.
Not trying to make excuses for Fisker engineers, but I think Fisker leaned very heavily on suppliers to design a lot of the sub-systems. But of course, that decision itself has consequences also.

Your diagnosis is logical, I was just wanted to make you aware of this issue to look into it while you have the RDM apart, because it has been some time since we had discussed it on the forum, and you may not have seen it. One solution applies prophylactically by Fisker service techs was to apply Loctite at the interface to reduce the lash between the gears.

Some of the experts have also tried working with machinists to forge and make hardened steel parts to prevent damage. Check with @FiskerPhilly and @Harleyguy about that.
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Old 11-23-2016, 05:47 PM   #12 (permalink)
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One more questions regarding this topic: I started opening all my car. However, I noticed a series of cooling line. There is one linked to the combustible engine, one or a bunch linked to the inverters and the batteries and one linked to the drivetrain. Of course, I will have to disconnect at least one at some point.

Any advise regarding this aspect ? What is the effect of air in the cooling system ? Before to touch it, I would like to have some feedback.

Tks again
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Old 11-30-2016, 01:19 PM   #13 (permalink)
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Originally Posted by PowerSource View Post
Are you just swapping out a complete RDM unit with motors or are you rebuiding the motors and RDM?
Finally, I got everything out of my car, and as you and Fabulist was thinking, the problem is due to erosion of the splines of the traction motors. Of course the male part of the spline in the RDM is also affected.

Regarding the motors, I think I can rebuilt it. We just have to remove the splines and replace by new one. However, I read many post on hard and soft spline. To what I understand, Soft spline are related to soft steel, and hard to tempered steel. Many noticed that soft and hard splines failed, which is normal. Tempered steel does not have higher torsion and shear resistance: it is just harder in terms of hardness. It is then probably less susceptible to erosion, but it will shear if the torque is too high.

I would like to know if some of you succeed to rebuit the RDM and the motors and/or if some of you have something to offer. In terms of splines, the best is to rebuilt with duplex stainless steel alloy (17-4PH) this alloy is about 3 times more resistant for torsion. This what I intend to do with the motor. However, for the RDM, if someone has stuff to propose, I would like to hear about. Rebuilding it might be more complex.

Cheers
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Old 11-30-2016, 01:34 PM   #14 (permalink)
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Originally Posted by hydroressources View Post
Finally, I got everything out of my car, and as you and Fabulist was thinking, the problem is due to erosion of the splines of the traction motors. Of course the male part of the spline in the RDM is also affected.

Regarding the motors, I think I can rebuilt it. We just have to remove the splines and replace by new one. However, I read many post on hard and soft spline. To what I understand, Soft spline are related to soft steel, and hard to tempered steel. Many noticed that soft and hard splines failed, which is normal. Tempered steel does not have higher torsion and shear resistance: it is just harder in terms of hardness. It is then probably less susceptible to erosion, but it will shear if the torque is too high.

I would like to know if some of you succeed to rebuit the RDM and the motors and/or if some of you have something to offer. In terms of splines, the best is to rebuilt with duplex stainless steel alloy (17-4PH) this alloy is about 3 times more resistant for torsion. This what I intend to do with the motor. However, for the RDM, if someone has stuff to propose, I would like to hear about. Rebuilding it might be more complex.

Cheers

Try 58-62 HRC made out of 8625h cold rolled if possible
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