Any transaxle dampener on our Grennies?

[Leonidas]

On my old Land Rover, I have a rubber coupling which dampens shocks and vibrations
I did also have one (smaller() on my Kia Sportage GTline AWD
Looking under the car I cannot see any such dampener
Is the same objective achieved through other means ?

 

[Dokatd]

Well, the Grenadier doesn't have a Transaxle so.... I'm not sure what you're asking. The engine has isolation mounts, as does the transfer case. On the IG they went with very firm isolators to help retain the drivetrain in rough conditions and over time.

I sheared all for of mine in my Defender 90 while rock crawling. Whole engine and trans was sitting at about a 3° angle. Had to drive 45min home like that.

 

[C-Mack]

If you’re referring to rubber flex-discs or Guibo joints on any of the drive shafts or transfer case outputs or differential inputs no everything is a solid in the driveline.

 

[Zimm]

On the IG they went with very firm isolators to help retain the drivetrain in rough conditions and over time.

Where did you hear this? I've heard this repeated here, but I've never actually read it anywhere, and I've never had other mounts catastrophically fail on a plethora of other cars, or cause damage to the engines or drive train. I've never actually heard of a condition where traditional mounting methods and materials caused drive train damage. I've been confused by this, because softer isolators would seem to provide more shock and NVH isolation in both directions. I would think if harder was better, you'd just just bolt everything to the frame. I thought the trade off of engine and transmission mounts was to be as soft as needed while limiting as much wear on the actual mount as possible.

 

[Leonidas]

If you’re referring to rubber flex-discs or Guibo joints on any of the drive shafts or transfer case outputs or differential inputs no everything is a solid in the driveline.

Don't you think Guido joints are a good idea to protect transmission from shocks?

 

[C-Mack]

Don't you think Guido joints are a good idea to protect transmission from shocks?

They are indeed very good at reducing NVH in drivelines but can present maintenance and reliability issues for 4x4s where high torque/loads are expected. For sure, I’ve had them on old Land Rovers and it didn’t take long for them to crack or tear/vibrate and in the end switch them out for traditional u-joints for added reliability.

Also, flex-discs can only tolerate very shallow running angles and none of the CV joints or input/output flanges on a Grenadier driveline are straight enough relative to each other to use a flex-disc in place of a CV joint. In fact, most of the CV joint angles are “compound” meaning they have both a vertical and horizontal angle which would tear apart a flex-disc in no time.

 

[Zimm]

Don't you think Guido joints are a good idea to protect transmission from shocks?

I thought they were for a small degree lateral of flex, not really for shock.

 

[Leonidas]

I thought they were for a small degree lateral of flex, not really for shock.

Probably both? otherwise ,,with a cv joint all of the impact is transmitted=not good!

 

[Bruce B]

Where did you hear this? I've heard this repeated here, but I've never actually read it anywhere, and I've never had other mounts catastrophically fail on a plethora of other cars, or cause damage to the engines or drive train. I've never actually heard of a condition where traditional mounting methods and materials caused drive train damage. I've been confused by this, because softer isolators would seem to provide more shock and NVH isolation in both directions. I would think if harder was better, you'd just just bolt everything to the frame. I thought the trade off of engine and transmission mounts was to be as soft as needed while limiting as much wear on the actual mount as possible.

I have changed many, many engine mounts in my life in the automotive business. Front wheel drive vehicles, rear wheel drive vehicles and all wheel drive vehicles have failed mounts sometimes. Some failed because of their age, some were obviously subjected to years of oil leaking and failed for that reason and of course, the mounts that were subjected to brutality could fail at any time.
As for stiffness of a mount, I can only offer this. On our trawler with a Cummins QSB 6.7 liter Diesel, we chased noise and vibration for a few years. It is a long story but I finally turned to an engineer who specializes in marine vibration abatement and paid him to help us solve the issue. He recommended a set of mounts that reduced interior noise by 10 dBA! He explained that the trick with boat engine mounts is to find the weight you need to support and then to specify a mount that hits as close to the middle of that with its weight range. That apparently is the sweet spot for noise abatement. Of course different mount designs handle different kinds of loads too. As far as I understand, it is a complex subject.

 

[Bruce B]

I thought they were for a small degree lateral of flex, not really for shock.

Giubo - Wikipedia

en.m.wikipedia.org

 

[Zimm]

Giubo - Wikipedia

en.m.wikipedia.org

NVH is one thing, but wouldn't "shock" be backlash?

 

[Zimm]

I have changed many, many engine mounts in my life in the automotive business. Front wheel drive vehicles, rear wheel drive vehicles and all wheel drive vehicles have failed mounts sometimes. Some failed because of their age, some were obviously subjected to years of oil leaking and failed for that reason and of course, the mounts that were subjected to brutality could fail at any time.
As for stiffness of a mount, I can only offer this. On our trawler with a Cummins QSB 6.7 liter Diesel, we chased noise and vibration for a few years. It is a long story but I finally turned to an engineer who specializes in marine vibration abatement and paid him to help us solve the issue. He recommended a set of mounts that reduced interior noise by 10 dBA! He explained that the trick with boat engine mounts is to find the weight you need to support and then to specify a mount that hits as close to the middle of that with its weight range. That apparently is the sweet spot for noise abatement. Of course different mount designs handle different kinds of loads too. As far as I understand, it is a complex subject.

I'm sure all true. But he was writing that ineos says they are stiffer than normal to help retain the drive train. I'm not sure what they are referring to. They must be stiffer than something, so I guess that's stiffer than other light duty trucks, and just didn't know there was ever an issue with say, a traditional silverado ls engine mount.

 

[255/85]

Where did you hear this? I've heard this repeated here, but I've never actually read it anywhere, and I've never had other mounts catastrophically fail on a plethora of other cars, or cause damage to the engines or drive train. I've never actually heard of a condition where traditional mounting methods and materials caused drive train damage. I've been confused by this, because softer isolators would seem to provide more shock and NVH isolation in both directions. I would think if harder was better, you'd just just bolt everything to the frame. I thought the trade off of engine and transmission mounts was to be as soft as needed while limiting as much wear on the actual mount as possible.

My experience has been with vehicles that have flexible frames/chassis like my 70s era Chevy pickup or older Land Cruisers. I've cracked aluminum-cased transmissions nearly in half on our 3/4 ton truck from being twisted up off road. General Motors/Chevrolet added many improvements and bracings through the '73-'87 year vehicles to help mitigate the issue.

With the riveted frames on FJ/BJ40 series Toyotas the chassis were so flexible that for the first 18 years of production (1960-1978) the transmissions and transfer cases were literally hung off the back of the engine without any bushings or support of any kind. Where people get into trouble is with drivetrain swaps that require fabbing up some sort of overly solid bracketry at the t-case end and then start cracking the aluminum housings when they're in the rocks.

My very unscientific assessment of the Grenadier is that the frame is so stiff that Ineos was able to use whatever durometer rubber it wanted for the engine and transmission mounts because they aren't worried about frame twist jeopardizing the all aluminium drive train. The engine mounts, in particular, seemed quite firm on the prototype I poked around which kind of reinforces the idea of a low flex under carriage.

 

[Bruce B]

I'm sure all true. But he was writing that ineos says they are stiffer than normal to help retain the drive train. I'm not sure what they are referring to. They must be stiffer than something, so I guess that's stiffer than other light duty trucks, and just didn't know there was ever an issue with say, a traditional silverado ls engine mount.

I of course am not an engineer so…
My guess is, as in many of these situations, the answer is simplified for the audience (us non engineers) and there is something lost in the process.
I was a little surprised with the engine vibration I saw in the brief 300 miles I drove one. It was not offensive but it was a little surprising. It would not surprise me to learn that in the name of handling the gear multiplied torque, in various off-road conditions, vibration took a second seat to strength. Again, that’s just a guess.

 

[Zimm]

I of course am not an engineer so…
My guess is, as in many of these situations, the answer is simplified for the audience (us non engineers) and there is something lost in the process.
I was a little surprised with the engine vibration I saw in the brief 300 miles I drove one. It was not offensive but it was a little surprising. It would not surprise me to learn that in the name of handling the gear multiplied torque, in various off-road conditions, vibration took a second seat to strength. Again, that’s just a guess.

there's definitely some NVH i wasn't expecting from a straight 6, especially a drone in 8th at 2000rpm'ish, but that may be partly due to the exhaust, as it dissipates if you downshift to 7th. engine /tranny mounts seem like a reasonable culprit. the original supposition still seems a bit counterintuitive to me, as i would think a little more movement prevents stress on the mounts.

 

[Bruce B]

there's definitely some NVH i wasn't expecting from a straight 6, especially a drone in 8th at 2000rpm'ish, but that may be partly due to the exhaust, as it dissipates if you downshift to 7th. engine /tranny mounts seem like a reasonable culprit. the original supposition still seems a bit counterintuitive to me, as i would think a little more movement prevents stress on the mounts.

Again, I am not an engineer but doesnt movement in a mount mean that the mount must then stop the mass at the end of the movement? I believe that the more movement you allow the higher the forces generated when things reach the end of the allowed movement or F=MA???

 

[Zimm]

Again, I am not an engineer but doesnt movement in a mount mean that the mount must then stop the mass at the end of the movement? I believe that the more movement you allow the higher the forces generated when things reach the end of the allowed movement or F=MA???

the material is elastic and it acts like a shock absorber. stopping with a slow push and stopping with an impact isn't the same acceleration.

 

[Dokatd]

Zimm, I will admit to parroting a bit on my original post in regards to why the IG is built as is.

But! It is a real thing in the off-road world at large. For instance the 2000's model Gwagons have very dedicated mounts to account for off-road use. Otherwise they would have used the standard C-class mounts to smooth things out.

Most heavy duty off-road trucks have much more retained mounting schemes to prevent the drive train from twisting to much in the chassis if a rubber mount fails. This is of course to allow you to continue on until you can find parts.

Personally I would have been fine with normal mounts on my IG so as to smooth it out a bit, but meh I don't care that much about it.

90's rovers did like to spit out their isolators if they weren't replaced regularly. And I had an Ashcroft Crawler box that made things worse. And on the Rover design the whole engine could be dislodged if the mounts cracked. The whole damn thing was loose at that point.

So the reality is largely maintain your junk, but if you're going to build a truck with the mind set that Ineos took then you overbuild it to account for stupid stuff. This is evident in many parts of the IG....annnd not so much in others.

 

[Zimm]

Zimm, I will admit to parroting a bit on my original post in regards to why the IG is built as is.

But! It is a real thing in the off-road world at large. For instance the 2000's model Gwagons have very dedicated mounts to account for off-road use. Otherwise they would have used the standard C-class mounts to smooth things out.

Most heavy duty off-road trucks have much more retained mounting schemes to prevent the drive train from twisting to much in the chassis if a rubber mount fails. This is of course to allow you to continue on until you can find parts.

Personally I would have been fine with normal mounts on my IG so as to smooth it out a bit, but meh I don't care that much about it.

90's rovers did like to spit out their isolators if they weren't replaced regularly. And I had an Ashcroft Crawler box that made things worse. And on the Rover design the whole engine could be dislodged if the mounts cracked. The whole damn thing was loose at that point.

So the reality is largely maintain your junk, but if you're going to build a truck with the mind set that Ineos took then you overbuild it to account for stupid stuff. This is evident in many parts of the IG....annnd not so much in others.

i guess thats kinda my confusion. it's only 300hp in a light duty truck. it aint like they dropped a twin turbo 6.0 ls in to twist it off it's moorings. sometimes i think shit is done just for marketing hype. kinda like ads i saw with vw discussing how strong their car hinges are, because, you know, the rash of hinge failures in the car world is lately.

 

[Dokatd]

i guess thats kinda my confusion. it's only 300hp in a light duty truck. it aint like they dropped a twin turbo 6.0 ls in to twist it off it's moorings. sometimes i think shit is done just for marketing hype. kinda like ads i saw with vw discussing how strong their car hinges are, because, you know, the rash of hinge failures in the car world is lately.

The 3.9L in the D90 is IIRCC 185hp. It took out mounts easily enough if they were more than a few years old.

HP or torque is irrelevant unless you factor in the scale of the isolator/mount. Sure you can just beef up the regular rubber mount but then packaging may be a problem.