Front Drive Shaft Update

[C-Mack]

Looks like well built driveshafts and curious if their out of phase u-joints (old LR/RRC approach) on the front actually worked? Also, how did they determine the amount of phase they used? I could see it reducing the resonance/vibration but probably not eliminating it completely. Hopefully the owner will post their impressions somewhere?

 

[TCMColorado]

View: https://youtu.be/K8sqKSf-kMw?si=APZ1mYPwKkHHxoQi

This prop shaft is materially no different than the one sold by Agile Off Road and will suffer from the same vibrations at certain shaft rpm and torque load. The Agile shaft is also out of phase. This improves but does not eliminate the vibrations given the joint angles of the Grenadier.

 

[Dokatd]

Ultimately you're still left with a drive shaft that has joints well out of operating spec. But I am not sure there is a real way around this issue.

 

[Lexx]

These U-joint type shafts remind me of the ones on big work trucks. And I do recall that those trucks tend to have some sort of grinding sound as they speed up or slow down. Perhaps that's a similar type of harmonic issues that the Agile Offroad and UK propshafts have?

 

[DenisM]

I lived with the UJ vibration issue in a RR P38 for years, especially if it was running ever so slightly higher ground clearance than spec with the air suspension. A single Cardan joint is not a true "CV"...never can be.. that's basic engineering physics. Indeed, increasing the drive angle on a single Cardan joint worsens the out of phase induced vibration.
At one stage I was tempted to import a Tom Wood double cardan shaft from the UK.... the $$$ curbed my enthusiasm.... dropping the ride height 18mm at cruising speed almost eliminated the vibration. Who knew??!
A double Cardan joint pretty much solves the vibration issues, eg. as employed on the Grenadier front axle! I was surprised that the chap in the video dismissed the double Cardan joint arrangement out of hand.
Surely the issue might just be to redesign the existing CV boot to allow more flexibility....

 

[Tom D]

Interesting, I take it the owner is not on here? I'd love some feedback... given the cost is likely quite high its not something you'd want to buy just to see if it works.

I might give them a call though.. My original shaft is still fine after nearly 60k miles.. i'm just wary of it going bang one day..

 

[Tom D]

I just had a long chat with the guy. Really nice chap. there is some resonance on that shaft, but the G it was fitted to has a 3" lift apparently... They are still playing with the design so I'll talk to him again in a few weeks and see how that have got on.

 

[Logsplitter]

I just had a long chat with the guy. Really nice chap. there is some resonance on that shaft, but the G it was fitted to has a 3" lift apparently... They are still playing with the design so I'll talk to him again in a few weeks and see how that have got on.

If it works ok then that resolves the only major concern I have with the vehicle.

 

[Tom D]

We had a long chat. one thing he did say was that any uj or dc joint can have harmonic resonance especially when operating at wider angles. So they can play around with the off set on the yolks to try and push the resonant point around. For example if it's resonant at 50mph, changing the angle might make it resonant at 65mph. So ideally they could just push it past 80 mph which would be less annoying (for me) as I don't often go that fast..
The problem is what works on a 3" lift will be different to what works on a 1" lift which will be different to stock..

He even said that on old defenders he has made the same shaft and put it on two identical cars and only one had resonance issues. even a tiny amount of play in either the pinion or the output on the transfer case can change the resonant point...

 

[Krabby]

I just had a long chat with the guy. Really nice chap. there is some resonance on that shaft, but the G it was fitted to has a 3" lift apparently... They are still playing with the design so I'll talk to him again in a few weeks and see how that have got on.

Ask if they could pass along our forum information to the owner. I doubt they’d give you his contact info but if we could get them on here we could hopefully get real world feedback.

 

[Tom D]

I'm tempted to get one for overland trips just for peace of mind. I'd be happy to put the factory one back on once back home and close to a dealer. I could live with resonance on a trip, especially if it only occurs at high speed as I'll likely be travelling slower anyway.

 

[Tom D]

His feedback on the factory shaft was that the slip joint was not a particularly good unit, and that seized slip joints were likely responsible for the few that had ripped the spline out of the CV...

 

[Tom D]

@Logsplitter was that what happened to yours? was the slip joint free? or jammed?

 

[Logsplitter]

@Logsplitter was that what happened to yours? was the slip joint free? or jammed?

Not sure about the slip joint. I was told the cause was a failed C clip. I didn’t get to inspect the prop shaft myself as when it failed there was gearbox oil everywhere

 

[Tom D]

Not sure about the slip joint. I was told the cause was a failed C clip. I didn’t get to inspect the prop shaft myself as when it failed there was gearbox oil everywhere

The guy reckoned a seized slip joint would put so much pressure on the circlip that it would ping it off.... makes sense..

 

[Logsplitter]

The guy reckoned a seized slip joint would put so much pressure on the circlip that it would ping it off.... makes sense..

Definitely makes sense.
Please keep us informed of what you hear about the driveshaft.
I have emailed Ineos about the issue but they have not responded with any details about a fix for the problem.