Punisher cvd;s

[adrian ss]

I hope someone can help. After reading the long thread regarding the lower arms on the mt, I feel I need to bring this to someones attention, and this seems to be the place to do it.
Ok I have a standard width Punisher into which I have tried to fit the front cvd;s, as I have lost the front driveshaft a couple of times.
At first I thought the new shafts were too long, but having read the mt thread regarding lower arm lengths ( thanks cabbie ) I now wonder if the Punisher is suffering from a similar problem.
I hope someone can help me with a solution, cause at the moment I have a set of cvd;s that are next to useless :damn:

[RCKIWI]

I have sold a few CVd's for TB2 and n ot had any problems, if you think there is a length problem as per the MT please post your length centers from pin to pin!

[adrian ss]

Bryan, The measurement from centre to centre is 116mm.

[mradlin]

That's the same measurement on mine. And the CVD's fit tight on mine also. Perhaps the internal out drive spring in the diff makes it feel like the cvd fits tight.

[adrian ss]

When the standard dog bones are fitted and the car is sat on its wheels, there is about 4mm of movement on the outdrive cup in and out against the spring in the diff.
When the cvd;s are fitted under exactly the same conditions, the outdrive cups are forced hard against the diff and there is no movement at all.
My first thoughts were that the shafts were too long :going insane:

[Freeprawn]

I gotta admit the front CVD's that came with my PRO TB II looked as if they were too long. My initial reaction was they are like 3 or 4 mm too long

The scary thing about them is the front of the chassis won't bottom out as the shafts of the cvd's bind on the diff output cups. Not to mention the fact the cvd's as Adrian says are pushing hard on the diff.

I put this down to being new and not run in. It's interesting you are seeing the same problem Adrian.

Nige

[roccos_van]

The MT arms are longer the the FTX ones. Maybe you accidentaly got a set of MT CVD's?

[Freeprawn]

Hmmm what are the lengths of them so I can check, anyone know?

Nige

[adrian ss]

Nige, sorry to hear that you are having a similar problem, but on the other hand I am glad its not just me, if that makes sence LOL

I guess its possible we have got mt cvd;s instead of punisher ones, I might take a trip to MMR later and see if they have got any more on the shelf so I can compare. They must be wrong cause they wont even fit in the back, they stop the suspension compressing as you described in your post.

Hopefully between us we can find a solution
Fingers crossed Ade

[RCKIWI]

Bryan, The measurement from centre to centre is 116mm.

Guys no way will MT CVD's even look at fitting in a TB2 they are heaps longer not just a few mm's!

For those that have CVD's for RTR TB2 yes they are a bit tighter fitting than std dogbones but you have to remember they do not move in and out like dogbones so they will feel tighter.
As long as there is no binding with your suspension up-down travel without a shock fitted you will be fine!

[Nutech Ethan]

http://i755.photobucket.com/albums/xx199/nutechracing/DSC00028.jpg?t=1271408570

http://i755.photobucket.com/albums/xx199/nutechracing/DSC00026.jpg?t=1271408616

http://i755.photobucket.com/albums/xx199/nutechracing/DSC00023.jpg?t=1271408644

From the pictures, you will find out that there is no question on the Arms and CVDs, thank you

[adrian ss]

Guys no way will MT CVD's even look at fitting in a TB2 they are heaps longer not just a few mm's!

For those that have CVD's for RTR TB2 yes they are a bit tighter fitting than std dogbones but you have to remember they do not move in and out like dogbones so they will feel tighter.
As long as there is no binding with your suspension up-down travel without a shock fitted you will be fine!

That is exactly the point, they do bind when the suspension goes up and down. if I run them like this I am going to cause premature wear to the diff outdrive cups for sure, if not damage to the diff internals :going insane:

[RCKIWI]

I have just tried a new set on a brand new car and they are fine! sorry but I don't understand why you are having problems?

[adrian ss]

Im very greatfull to those people that have taken the time to try and offer me solutions to my problem.
I also accept the fact that some people are using them without a problem, thats great for them.
But please try and see it from my point of view, I have spent £50 sterling for something that, for whatever reason, I cannot use.

The fault wherever it may lie, is not with me. I have been a mechanic for the last 20+ years so I think I can manage to fit a set of driveshafts to a model car.

The cvd;s are 3-4mm longer than the total lenght of the dogbone and drivecup which I took out. This I believe is the problem. Must be honest, not very happy now :damn:

[mooman007uk]

please measure the total length from end to end of the cvd so it can be compared with others...as mentioned the cvd's are slightly longer than the dogbone/outdrive they replace and are a tighter fit...how much neg camber are you running?

[adrian ss]

please measure the total length from end to end of the cvd so it can be compared with others...as mentioned the cvd's are slightly longer than the dogbone/outdrive they replace and are a tighter fit...how much neg camber are you running?

From the flange part that sits against the inner bearing in the hub,to the ball end of the shaft is 115mm.

I am not able to run any neg camber, in fact to stop them from binding, I have to run slight pos camber.

To be honest I have taken them out and thrown them in the tool box. :mad:

[Freeprawn]

I'm seeing the same thing as Adrian too. It's not just him.

With the PRo TB II as it comes out of the box. I removed the front shocks to check suspension travel and the front of the chassis wouldn't bottom out because the dog bones of the cvds were binding on the diff output cups and pushing in on them.

if this binding is stopping the chassis from bottoming out then the part stopping it from doing so is gonna break.

The cvds are just a little too long.

N xx

[Pipeous]

I haven't tried to fit mine yet, so interesting read... I get a few days off this week finally and was going to strip mine and do the dirty work. too many projects.

[adrian ss]

I haven't tried to fit mine yet, so interesting read... I get a few days off this week finally and was going to strip mine and do the dirty work. too many projects.

I hope you have more joy than I am having.
I need to have 2-3mm machined off each cvd before I have any chance of them fitting properly.

[bentley marshall]

the axle lenth is the same as whats in my car and they fit fine ....another thing to check is that your bearing is seated in the hub right ..i found the spacer between the bearing to wide and the bearing wasint seating right in the hub

allso photos might help sort this out

[mooman007uk]

now that it's been established the cvd's are correct and the arms are it must be something unrelated to these items, with the MT cvd's they were a nice very tight fit in the bearings...but they caught me out first one i put in..it also seemed too long but i knew the measurements were correct so took a closer look...it took a good shove to get them in the last few mm into the knuckle bearings

Bentley also has a good point with the bearing seat ...it can only be something simple as everything else is correct and one is a pro and one a standard

pics will dfinitely help if the 2 above solutions don't work

[grfilipp]

i am guessing that arms and cvds are ok (very strange to make a mistake there).
2 things i would check
the spring mechanism in the diff. is it going all the way in or does it bind and as a result locks the suspension.
second is the shims in the diff. maybe the diff has shims that put the more diff to one side and then shims that bring the pinion closer to the crown to cover the gap.
as i said just guessing.

[bentley marshall]

yeah im picking its the pin slot in side the diff thats worn and stoping the cup going all the way in
it needs to go all the way in till if hits the bearing on the diff

[adrian ss]

Thankyou gents, certainly another couple of interesting possibilities to try.
Will keep you posted as to my findings

[Andi]

I'd like to add my 2p's worth and agree that the CVD's are too long.
I have to run 2 degree pos camber so as to allow free movement of the suspension and to avoid the drive cups from pushing hard against the Dif bearings.
I actually mounted the wheel without the grub screws to pull on the drive shaft and they were pulled as tight as they would go. had a look and they were seated nicely against the bearing.

Sorry to crap on you rose garden but they are too long...

[bentley marshall]

so why do they fit my car with not probs at all ?????

[Freeprawn]

Can you push the front of your car down with 0 degree camber without feeling any binding before the chassis touches the floor?

Nige

[bentley marshall]

yep been running it with cvds for about 10 tanks .....but i have broken the pin in one cvd but that hapened when i hit a post at fill speed

[Andi]

@ Freeprawn,
I cannot push the front down. It stops as it's pushing against the diff bearings.
I'm goinf to take another look at it this weekend. There are a possible few others coming to the local track with Punishers so I will see if there is anything to compare by.

If I do have any finding, be sure I will post pix and any possible resolutions.

[Freeprawn]

Ok, Proof the CVD's are too long.:rifle:

http://i761.photobucket.com/albums/xx256/freeprawn/th_L1020275.jpg (http://s761.photobucket.com/albums/xx256/freeprawn/?action=view&current=L1020275.flv)

Forgot to mention, That is with 2 degrees positive camber set too!!!

[Pipeous]

That's odd and shouldn't bind like that. and the dif cups are in as far as they go?

[adrian ss]

Great vid Nige, shows exactly what we have been trying to describe.
Be interesting to see what the powers that be say now, what cant speak cant lie.
Mine are away at an machinist to see if they can be shortened in any way, will keep you up to date with any progress.

[mradlin]

I wonder if the slot in the cup would need to be deeper?

[Freeprawn]

@pipe - Yes the drive cups are pushing in all the way, thats the problem ;)

@mradlin - Yes, slot deeper, drive shafts shorter either need to be done.

[mooman007uk]

That's interesting and nice vid to expain, instead of trying to shorten the cvd the easiest solution would be to use a thinner inner bearing in the hub so the cvd can move 1mm further out to the wheel...it's a 7mm wide bearing...if you got a 6mm handy see if 1mm thinner is enough to fix it.

[mradlin]

That's a good idea Moo.

[Freeprawn]

The drive cups are pressing on the ends of the diff not the diff bearings though so i don't think that will help. :(

Ahhh my mistake, in the hubs you said. Hmmm might work, seems a bit pikey though. Also we need 4-5mm not just 1 mm though. Don't forget in the video the hubs are set with 2 degrees camber, so 1mm will help but not solve the problem :(

[mradlin]

The drive cups are pressing on the ends of the diff not the diff bearings though so i don't think that will help. :(

it should shift the entire drive shaft outward by 1 mm

[mooman007uk]

try a 5mm bearing, that should give you enough to dial in neg camber as the top moves at double the centre in distance when you turn in the upper arm turnbuckle so you got 4mm to play with at the turnbuckle...a 5mm wide bearing it'll move the entire shaft over 2mm...get a decent sealed one and i don't think it'll change durability as most of the weight is taken by the outer bearing when sitting on it's wheels

[Pipeous]

is there even enough meat in the drive cup to file it back a few mm without causing structural problems? I'll have my front end off this afternoon and be able to see myself... I just have some tweaking to do to my on roads... I dig the buggy but honestly on road is my thing

[Andi]

Thats exactly the problem I have.
Cheers Nige.. Thought :going insane:

[andyw]

I just bought a TB2 Pro a couple of days ago and have noticed the same problem.
The only way to stop the binding is to run positive camber, which is less than ideal.
Shorter CVD shaft is required rather than having to mess around with other parts.

[mradlin]

I just bought a TB2 Pro a couple of days ago and have noticed the same problem.
The only way to stop the binding is to run positive camber, which is less than ideal.
Shorter CVD shaft is required rather than having to mess around with other parts.

Ideal yes, available...not yet. Perhaps Moo's idea of a skinnier bearing on the inside would help aleaviate this problem until it is addressed by Nutech.

[RCKIWI]

I noticed when watching the video the drive cups were not moving at all! are they pushed all the way in on the video?

[andyw]

Yes Brian the drive cup is being forced hard up against the end of the diff housing hence the binding, there is just no clearance left for the dogbone as the suspension travels upward reducing the distance between hub and diff.

[RCKIWI]

Ok I have done my own testing today to report back to factory!

First the length of std dogbone to CVD length is 5mm longer in CVD.

http://i885.photobucket.com/albums/ac58/Nutech-NZ/Testing/TB2cvd1sm.jpg

http://i885.photobucket.com/albums/ac58/Nutech-NZ/Testing/TB2cvd2sm.jpg

Here is video I did also. Camber is set to 0deg!

http://i885.photobucket.com/albums/ac58/Nutech-NZ/Testing/th_CVDtesting.jpg (http://s885.photobucket.com/albums/ac58/Nutech-NZ/Testing/?action=view&current=CVDtesting.flv)

I still think there is not a problem after re-checking it myself, as you can see in the video there is no binding until the wheel is starting to go past the height of the chassis, which means if the chassis is bottoming out on the ground there is no binding! But this would change if you wanted to run higher camber angles, so I have recommended to the factory to shorten there new CVD's.

[roccos_van]

Excellent work.

[andyw]

Well done Brian, very thorough.
As you say there is not really much of a problem at 0 degree camber but ideally most people would like to run with some negative camber, which presents a problem.
Lets hope the factory take this on board and deliver us some shorter CVD's.
Cheers
Andy

[Freeprawn]

Great video Bryan.

Perfectly shows what is going on.

The 5mm difference between CVD's and standard dogbones is the most interesting bit.

Although with 2 degrees pos camber my chassis in not bottoming out properly.

Shame really they are fantastic CVD's, very well made. I'm still gonna run them I just hope they take it on board for future producion runs of them.

Nige

[mooman007uk]

great way to show what's happening...so the cvd's need to be 5mm shorter...even though the chassis bottoms out with zero camber as said most like the option of being able to run neg camber...also i like the extra bit of travel past the chassis bottoming out is good for when landing on one side or one wheel

[Freeprawn]

Sums up my thoughts exactly :)

Nige

[RCKIWI]

Obvious the travel length of the shocks would also limit whether the wheel will go past the point of chassis bottoming out, I didnot try a shock on the car without spring to see the fully compressed shock limit! When I get time I will see what it is!

Oh and on my off road 4wd cars I always run front 0deg camber and rear 0-2deg

[mooman007uk]

I'm running about 2-3deg neg on the front and same on the rear and find...with the MT, it hooks up better at the back and steers way better up front but the MT tires do roll alot in the corners so i'd guess lots of neg camber somewhat compensates for it