CVD's vs Dogbones - General Thoughts, Problems, Solutions

[ohsnap]

I run a variety of parts on several Savages, and when I originally installed CVD;s it was first to replace a dogbone that broke, and I'm willing to admit that the thought "hey, these are an upgrade - they must be better" probably crossed my mind to justify the cost.

Looking back, CVD's are currently my most consistent failure point, and that being the pin backing out.
And yes, I am familiar with the concepts of thread-lock and prep...
90% of the time, the grub is tight. 10% of the failures are probably on me.

I've run Hot Bodies, MIP, and even titanium ones.
I have some CVD's that never give me a problem.

The TI's were by far the worst.
With the TI's, it wasn't a question of whether or not that the pin would back out, but when.
I had one Savage with them down the centerline and out to the four corners.
Both the front and center drive ones were the worst.
At one point I HAD to deal with one of them and under the circumstances - both, every week, but eventually one of corners would also let go.
Yanked them all out.

As a general trend, regardless of manufacturer, the front and center CVDs seem to be the worst offenders.
I replaced an old Hot Bodies CVD that went bad on me earlier this year. I noticed that the slot in which the pin rode was worn so that it was more "S" shaped than parallel.
Given how the pin interacts with that slot, I can see how it screwed itself out of position.
The only fix was to replace the worn part (or in this case the while unit).
I couldn't get two tanks through it before the pin was wedged under the motor mount plate and locked things up.

I have also noticed that the pins in the newer MIP rebuild kits are notched out in the center, while their older pins are not.

I don't seem to have this issue with the CVD's on other trucks like Revos or Hellfires.
Now watch, they'll act up.

I did have to replace a right front dogbone in the past year, but its demise given the hit is understandable.
It snapped, but it was also older than dirt...
Thoughts, tricks, opinions?
What do you run and why?

 

[Horatio]

I run a variety of parts on several Savages, and when I originally installed CVD;s it was first to replace a dogbone that broke, and I'm willing to admit that the thought "hey, these are an upgrade - they must be better" probably crossed my mind to justify the cost.

Looking back, CVD's are currently my most consistent failure point, and that being the pin backing out.
And yes, I am familiar with the concepts of thread-lock and prep...
90% of the time, the grub is tight. 10% of the failures are probably on me.

I've run Hot Bodies, MIP, and even titanium ones.
I have some CVD's that never give me a problem.

The TI's were by far the worst.
With the TI's, it wasn't a question of whether or not that the pin would back out, but when.
I had one Savage with them down the centerline and out to the four corners.
Both the front and center drive ones were the worst.
At one point I HAD to deal with one of them and under the circumstances - both, every week, but eventually one of corners would also let go.
Yanked them all out.

As a general trend, regardless of manufacturer, the front and center CVDs seem to be the worst offenders.
I replaced an old Hot Bodies CVD that went bad on me earlier this year. I noticed that the slot in which the pin rode was worn so that it was more "S" shaped than parallel.
Given how the pin interacts with that slot, I can see how it screwed itself out of position.
The only fix was to replace the worn part (or in this case the while unit).
I couldn't get two tanks through it before the pin was wedged under the motor mount plate and locked things up.

I have also noticed that the pins in the newer MIP rebuild kits are notched out in the center, while their older pins are not.

I don't seem to have this issue with the CVD's on other trucks like Revos or Hellfires.
Now watch, they'll act up.

I did have to replace a right front dogbone in the past year, but its demise given the hit is understandable.
It snapped, but it was also older than dirt...
Thoughts, tricks, opinions?
What do you run and why?

CVD's are merely re-buildable, single cardan joints. They are definitely smoother than dogbones and can be kept operational for a very long time if well looked after.

For nitro use, they shouldn't pose too many issues, provided you find high quality items and use PTFE dry lube.

Centre drive for me is dogbones only. Mine are dead straight and level anyway - so pointless introducing CVD's.

 

[Jam 1]

I prefer Dog Bones and cups on my Savage, it is easier to find those parts separate in most cases, I only have the one Savage and stocked up on a few spares after I got the rig... although I do have MIP Shiney CVD drives on both my T Maxx and E Maxx caz I got a deal on them when my hobby shop sold a bunch of stuff on his sidewalk sale a few years back, kind of a tossup on how badly you plan on Bashing with your rigs I guess...Most of my Nitro stuff has been on the shelf because I just prefer electric stuff these days for me...

 

[Horatio]

At one time, there were plenty of options when it came to universal joints and re-buildable joints. Some were significantly better than others. Obviously, the weak point is the pin.

For my Savage, I required smooth, accurate steering along with precise response - so I sourced hardened 'CVD's'.

Whilst given the acronym Constant Velocity, they definitely aren't, but they certainly smoother than dogbones and less likely to jam or pop out.

Options on the centre driveline were always much more limited. Anyone using aftermarket TVP's are limited to the length of front & centre bone lengths determined by the chassis selected for use.

Another major limitation was the brake hub. Alloy variants used to get chewed up in next to no time. Crazy nut used to offer a hardened 7075 brake hub that was lighter than the steel items, but reasonably hard wearing. I'd get half a season out of one.

Dog bones are reasonably quick and cheap to replace, inputs/outputs and axles on the other hand - not so much.


And everyone says my rig is a shelf queen and never gets dirty! 😝

I have managed with 'CVD's' on just the front, but dogbones everywhere else. When racing hard, the front end was problematic with dogbones. Cornering hard, powering out of turns on bumpy tracks could sometimes result in a bone popping out, or jamming up.

I can't recall what these are - I think they might be HPI hardened items. 🤔

 

[ohsnap]

"I can't recall what these are - I think they might be HPI hardened items."

Those appear to be HPI's "Heavy Duty" dog bones (86134)
Who made those trick steering knuckles?

 

[Horatio]

"I can't recall what these are - I think they might be HPI hardened items."

Those appear to be HPI's "Heavy Duty" dog bones (86134)

Nope - they're CVD's, but they're hardened and shiny silver

Who made those trick steering knuckles?

The brand isn't known unfortunately. I bought them second hand in 2019 - just as COVID was kicking off....



I run the Proline 23mm hexes



And 40 series velocity 23mm hex wheels.

When I was first racing the Savage, wheel choice was difficult. The original 14mm hexes used to strip or warp. Warping in many ways was worse, because it resulted in serious wobble and damage to other parts.

I got some fabulous alloy wheels CNC machined by a firm called Ramtech in the USA. The wheels were called Vipers.


The wheels were heavy, but worked with 40 series tyres. The combined weight of the alloy wheels with 40 series tyres was less than the stock wheel/tyre combo that came with the SS! 😅



After some porting mods, my Nitro Star engine was out performing fancy picco engines and was still working well after 15 gallons of fuel. 😎

The extra rip was appreciated with the alloy wheels.

When Proline came out with the 23mm hex 40 series wheels/tyres, it was a game changer. I know 17mm hexes became the standard on the Savage, but 23mm hexes are definitely sturdier. Obviously, 17mm hexes have much more choice of wheels and tyres, but the 40 series - bowties - are so good.

Integy seem to be the only company still producing these 40 series, 23 mm hex wheels.

23mm 40 Series Wheels

There was no going back for me. Proline obviously stopped making them, but the Integy items are decent and near identical.

Perhaps one day I'll try some Truggy wheels using some 17mm hexes, but for now - it's 23mm wheels.