Big Rock GPM rear driveshafts / car vibrates

[SECT]

Guys, I have a problem with my GPM driveshafts. Since the installation, the rear of the car starts to vibrate very loudly at a certain speed. The hubs have no play and the connections are greased. It doesn't matter which tires I use either. The entire back also vibrates with the Badlands with adapters. The only thing that helps is when the arms move towards a horizontal position. I'm really bummed. These GPM driveshafts feel really solid. The connection to the differential is also well constructed. Who can help me with this problem? Or who else has experienced this and hopefully resolved it?

I was planning to upload a video but that doesn't seem to work?

 

[Tex Koder]

Guys, I have a problem with my GPM driveshafts. Since the installation, the rear of the car starts to vibrate very loudly at a certain speed. The hubs have no play and the connections are greased. It doesn't matter which tires I use either. The entire back also vibrates with the Badlands with adapters. The only thing that helps is when the arms move towards a horizontal position. I'm really bummed. These GPM driveshafts feel really solid. The connection to the differential is also well constructed. Who can help me with this problem? Or who else has experienced this and hopefully resolved it?

I was planning to upload a video but that doesn't seem to work?

View attachment 327643

You may want to check the shafts for straightness..
Take the driveshafts Off and roll them on a flat surface.

 

[Camaroboy383]

You may also want to check the phasing of the shafts.. if the yokes are misaligned it will cause major vibration... can you show us pictures of the shafts as they are on the rig..

 

[SrC]

Guys, I have a problem with my GPM driveshafts. Since the installation, the rear of the car starts to vibrate very loudly at a certain speed. The hubs have no play and the connections are greased. It doesn't matter which tires I use either. The entire back also vibrates with the Badlands with adapters. The only thing that helps is when the arms move towards a horizontal position. I'm really bummed. These GPM driveshafts feel really solid. The connection to the differential is also well constructed. Who can help me with this problem? Or who else has experienced this and hopefully resolved it?

I was planning to upload a video but that doesn't seem to work?

View attachment 327643

Dumb question:
Do you balance your wheels at all?
Driveshafts can cause vibration if damaged/bent. But new ones?? IDK. They should not.
If you never balanced your wheels, any of them. I would look into that first. If you already do balance them and know they are good, disregard.
Some wheels come balanced well enough out the package, yet most don't. I check and balance all of mine. It reduces vibration very much.
Have you tried testing for vibration with the Wheels completely off the rig????
I would do that first. Then look for vibration again.
That aside...many say GPM stuff is not all that.

 

[LibertyMKiii]

This always comes to mind with GPM parts where cheap is always one of your (2) pre-selected for you.

 

[slick2500]

You may also want to check the phasing of the shafts.. if the yokes are misaligned it will cause major vibration... can you show us pictures of the shafts as they are on the rig..

Iirc the GPM units are cv style.

This always comes to mind with GPM parts where cheap is always one of your (2) pre-selected for you.

View attachment 327653

This is what happens when you have zero QC with your products.

 

[slick2500]

@SECT put the stock drive shafts back in does it still vibrate? Do you run in wet conditions, sand or really fine dirt? Have you ever vented your tires?

 

[Camaroboy383]

Iirc the GPM units are cv style.


This is what happens when you have zero QC with your products.

Keep in mind these are not true cv style joints.. true cv style joints use ball and groove.. if it has cross pins it's still a u joint, just an encapsulated one with a little more articulation..

Pay close attention to the way they are portrayed in the manuals, or exploded views.. I'm sure it's not by accident every one you see the pins are parallel in an assembled view..

For instance, mip trx4 center shafts of fake cv style.. part of Thier marketing boasts of keyed splines so the ends are in phase always... definitely not by accident..

Another indicator it's the joints of the shaft is he states the only thing that makes it better is making the shafts horizontal to the chassis.. as well as stating tire choice makes no difference..

I'm not familiar with the gpm shafts, so if it's just a standard multi tooth spline, it would be easy to have the shafts oriented in the wrong manner..

Some say it may not matter, some say it does.. but it's not an accident that every shaft out there portrays a visual of the pins being parallel.. arrma shows the same in exploded views..

It's definitely worth a look for the o.p..

 

[SrC]

Keep in mind these are not true cv style joints.. true cv style joints use ball and groove.. if it has cross pins it's still a u joint, just an encapsulated one with a little more articulation..

Pay close attention to the way they are portrayed in the manuals, or exploded views.. I'm sure it's not by accident every one you see the pins are parallel in an assembled view..

For instance, mip trx4 center shafts of fake cv style.. part of Thier marketing boasts of keyed splines so the ends are in phase always... definitely not by accident..

Another indicator it's the joints of the shaft is he states the only thing that makes it better is making the shafts horizontal to the chassis.. as well as stating tire choice makes no difference..

I'm not familiar with the gpm shafts, so if it's just a standard multi tooth spline, it would be easy to have the shafts oriented in the wrong manner..

Some say it may not matter, some say it does.. but it's not an accident that every shaft out there portrays a visual of the pins being parallel.. arrma shows the same in exploded views..

It's definitely worth a look for the o.p..

View attachment 327836

+1
Correct about what a True Constant Velocity Drive is. Found on scale vehicles. Rarely found in RC's.
Yeah Indexing multipiece shafts are a thing. Doing this right technically matters. Worth a try?

 

[slick2500]

Keep in mind these are not true cv style joints.. true cv style joints use ball and groove.. if it has cross pins it's still a u joint, just an encapsulated one with a little more articulation..

Pay close attention to the way they are portrayed in the manuals, or exploded views.. I'm sure it's not by accident every one you see the pins are parallel in an assembled view..

For instance, mip trx4 center shafts of fake cv style.. part of Thier marketing boasts of keyed splines so the ends are in phase always... definitely not by accident..

Another indicator it's the joints of the shaft is he states the only thing that makes it better is making the shafts horizontal to the chassis.. as well as stating tire choice makes no difference..

I'm not familiar with the gpm shafts, so if it's just a standard multi tooth spline, it would be easy to have the shafts oriented in the wrong manner..

Some say it may not matter, some say it does.. but it's not an accident that every shaft out there portrays a visual of the pins being parallel.. arrma shows the same in exploded views..

It's definitely worth a look for the o.p..

View attachment 327836

They look like this. Top one is GPM bottom one is RCAWD which is basically the same crap.

 

[SrC]

You may also want to check the phasing of the shafts.. if the yokes are misaligned it will cause major vibration... can you show us pictures of the shafts as they are on the rig..

+1
Also called Indexing the shafts halves.

 

[SECT]

I took it apart again. While disassembling the drive shafts, checked at various times whether the parts were still wobbly. I discovered that the differential outdrives themselves wobble. These are from the Metal Gear F/R Transmission Module Set (ARA311156). This is probably the cause of the vibration of the rear drive. But what goes wrong here? I don't think I even put a lot of strain on this Metal Gear Transmission Module set because the composite drive shafts kept coming loose.

 

[SrC]

Diff outdrives wobbling can be bad or worn out BB's and/or diff(s) need shimmimg. If not simply bad outrdrives.

 

[SECT]

You may also want to check the phasing of the shafts.. if the yokes are misaligned it will cause major vibration... can you show us pictures of the shafts as they are on the rig..

Something like this?

You may want to check the shafts for straightness..
Take the driveshafts Off and roll them on a flat surface.

The tube part is straight. I rolled them over a straight stone windowsill.

You may also want to check the phasing of the shafts.. if the yokes are misaligned it will cause major vibration... can you show us pictures of the shafts as they are on the rig..

I watched a YouTube video about phasing. I'll definitely try that. There's logic in it. Thanks!

@SECT put the stock drive shafts back in does it still vibrate? Do you run in wet conditions, sand or really fine dirt? Have you ever vented your tires?

I also tested this with the original ventilated tires from Arrma. That made no difference unfortunately, but it was worth a try.

 

[SECT]

Dumb question:
Do you balance your wheels at all?
Driveshafts can cause vibration if damaged/bent. But new ones?? IDK. They should not.
If you never balanced your wheels, any of them. I would look into that first. If you already do balance them and know they are good, disregard.
Some wheels come balanced well enough out the package, yet most don't. I check and balance all of mine. It reduces vibration very much.
Have you tried testing for vibration with the Wheels completely off the rig????
I would do that first. Then look for vibration again.
That aside...many say GPM stuff is not all that.

I once discussed balancing bash wheels with my local hobby shop manager. He had never heard of it and only uses it for RC speed runs and on race tracks. Do you have any tips or tricks for me?

 

[SrC]

Your LHS can't be all that.
Balancing RC wheels of any type has been a thing for Decades. Place your rig on a stand and throttle up your MT wheels. You will see extreme imbalance and vibration, observed throughout the Arms and all. Balancing the wheels will remove that. Just a fact, not an Opinion. Many don't balance them. And let their wheels explode and rig drives horrible, Drivetrain and ST servo wear becomes exacerbated as well. Most Basher MT wheels are very poorly made in general and come NIB way out of balance. Despite the high asking prices. It's just a thing.
The choice is always yours. Tires are a costly part of this hobby.
>>Proper venting of the tires is also important. And I'm sure your LHS also says otherwise. Your LHS just wants to sell you more $Tires$. They just sell stuff and don't run what they sell 99% of the time.
Not hating ALL LHS's. Just it has been a thing I seen for 35+ years now. Most LHS's are far from Hobbyists. It's just a business, like any other.

Edited.

 

[SrC]

Get yourself a Team Associated wheel balancer and some Non Hardening Hobby Craft Clay. Watch a few videos. Balancing is not that hard to do. The results are obvious IMHO. Check gluing of your wheels beads first, add CA as needed. Many new wheels have poor gluing right out the package.
>>Make 1/8" vent holes at 2 or 3 places at the tires tread area and tape off any inner wheel vent holes before balancing.
"Some" Arrma wheels are already done this way. Check first.

 

[SECT]

I've solved the problem. It was probably a combination of circumstances. Tires ventilated. There was water in the Badlands. I aligned the ends of the driveshaft with each other. After this it was still not resolved. I also installed new RPM suspension arms. The original wishbones were very bent. I also installed new hubs. It doesn't vibrate at all anymore. Even on the work block it looks very stable when accelerating. Thanks for your help and advice!

 

[SrC]

Hopefully you balance your wheels also.
And never run in the wet. If you do, make sure to vent them at the tread.
But foams getting wet will always fall apart and cause an imblanced tire/ wheel. I found that 99% of the time, poorly balanced wheels causes all the vibration. All else assumed in proper working order. New out the package, most every Tire is poorly balanced. A thing.