Lexus IS Forum banner

41 - 47 of 47 Posts

·
Registered
Joined
·
1,609 Posts
Keeping in mind that the car ran fine up to a few weeks ago and for the sake of record keeping here goes:

• Car starts shaking at around 40mph (10% of the time), 65mph(10% of the time) and 60mph (80% of the time)
• Shaking can be felt through the drivetrain (i.e. shifter knob and seats) but not the steering wheel nor any of the plastic trim around the shifter nor the hand brake. These items DO NOT shake at all.
• It will start shaking at mentioned speeds when rolling down a hill in neutral.
• Driveshaft has been uninstalled, re-balanced, and re-installed to no avail.
• Wheels were verified to be balanced.
• Put it up on lift and torqued everything down. Nothing seemed to be obviously broken on the rear end and diff mounts seemed in good condition.

Next step would be taking axles out and checking everything thoroughly but need time and more important, the space for this. Or just drop a bunch of cash on an, at best, $5,000 car. At the same time I cannot go over 50ish on the highway so I might have to burn some vacation on the stupid car.
 

·
Registered
Joined
·
189 Posts
Discussion Starter #44
Update:

I had the driveshaft modified to have a longer splined section where it telescopes in and out. This helped SIGNIFICANTLY, and allowed me to drive the car up to 80mph with MUCH less vibration.

After 80mph, the vibration gets bad, but As a daily driver, this was "good enough" to hold me off for the time being, until the school year is over.

It seems that because of the AR5's in and out thrust at the output shaft, the driveshaft needs to be able to accomodate for this plunge. Im guessing this is why the factory Solstice used a CV at the transmission end, and a rubber guibo at the differential flange.


What does this mean?

It looks like it will be necessary to use a plunging CV Joint at the transmission end, and in theory, this SHOULD fix the issue.

The problem is there are no high quality / high performance CV flanges available that fit into the Solstice/Sky AR5 output shaft.

The only brand I have found is Dorman. I am hesistant to use them as they are a standard parts store brand, and I have seen many parts store brand axle CV's fail within 6 months.

Here is a link to the kit, which includes info on the dimensions, spline count, etc.

https://www.dormanproducts.com/p-46711-932-108.aspx

I do not trust it to last for more than a few months, so I am still looking for a better solution before making any decisions. I am also hesistant to weld a used factory Solstice driveshaft CV, as I don't know what kind of life span to expect from it.

I have emailed DSS and am waiting to see if they can get any high performance CV's for the AR5 output flange.

Fingers crossed that I eventually find a solution for this. Any additional input welcomed

Attached is a picture of my current driveshaft
 

Attachments

·
Registered
Joined
·
576 Posts
Honestly, with all of the extra stress from this issue I would be going back to a two piece driveshaft. Take your stock one in to a local driveshaft shop and see if they can replicate it but with new replaceable GM u-joints and of course the needed AR5 guibo on the front end.
 

·
Registered
Joined
·
189 Posts
Discussion Starter #46
Honestly, with all of the extra stress from this issue I would be going back to a two piece driveshaft. Take your stock one in to a local driveshaft shop and see if they can replicate it but with new replaceable GM u-joints and of course the needed AR5 guibo on the front end.
This is pretty much what we are going to do. I spent some time talking to the guy at the local driveshaft shop today, and after exchanging ideas, we determined a 2 piece will be the best route to go.

Being a proper 2 piece with carrier bearing should automatically result in less vibration. On top of this, it will put a lot less stress on the CV joint.

Finding a suitable CV was the iffy part. I was considering retaining the 1350 adaptor, just as a 2 piece setup. I was hesitant to use any aftermarket CV other than GKN which is a high quality OEM supplier. He was able to find a matching CV from Powertrain Industries, which he says does not sell poor quality parts, so fingers are crossed that its a quality piece that's up for the task.

It will take a few weeks to gather the parts and get everything together, so I will report back once the driveshaft is complete and I install it.
 

·
Registered
Joined
·
189 Posts
Discussion Starter #47
UPDATE:

The 2 piece driveshaft with the CV flange did the trick, and there is no vibration anymore.

I am not sure if its having the CV end, having 2 pieces, or both, that solved the issue. So I can’t say if just doing one or the other would also work.

Having 2 shorter driveshafts lessens the load on the parts, and reduces the chances of vibration. This should make for a stronger shaft, and less stress on the CV portion as well, which seems to also be necessary.

Keep in mind I am only NA with bolt ons, but I have had the driveshaft on since March, and the CV has held up fine to numerous many dumps in 1st gear, and a good amount of clutch kicks in 2nd gear.

Proshaft is the company I worked with that was able to make the custom 2 piece CV driveshaft for me. Justin was very knowledgeable, helpful, and patient throughout the journey of trying to find a driveshaft solution that would solve the vibration issues.

Here is is website:
https://www.proshaftllc.com/

The cost is in the neighborhood of $800, so it is a little cheaper than the driveshaft shop or driftmotion shaft, and you do not need to worry about purchasing the aluminum adapter.

The rear section is identical to a stock IS300 manual rear shaft, so you could potentially re use that to save cost, however you would need to send that to him so the unit can be balanced as a whole.


Attached is a photo of the 2 piece CV shaft on the bottom, with the single piece on top.

I hope this helps someone, and saves them from the nightmare I went through!
 

Attachments

41 - 47 of 47 Posts
Top