Outdrives - Weak point or bad luck?
 

Down Newbury last night there seemed to be a little bit of a problem with outdrives on the CATs. As far as I was aware 3 CAT SX's were racing (not bad going) and all 3 broke outdrives. Two of which (mine included) had limiters on to stop the driveshafts fouling the cups. Oddly I broke a front out-drive and on the front my driveshafts are well clear of getting stuck.

I think mine can be put down to impact perhaps, but still you would expect a wishbone or something to snap before the differential outdrive - so very odd. The other two cats snapped rear outdrives, so appears to be a case of driveshaft causing the damage.

I just found it very odd that on mine, with the setup on the front my driveshafts should have been well clear of getting stuck, yet I still broke an outdrive yet not anything else.

After doing some modifications I ran the rest of the evening rwd - good news is that the CAT handles fine in rear wheel drive mode :o:)

It's a strange one really. The reason i say this is I haven't broken one all year, don't think Si or Grant have either - so it wasn't on the radar at all when the car was launched.

So for me on a personal level there isn't an issue, but clearly there are odd people that are suffering, and i'll be honest and say i don't understand how. I think it is probably a collection of "small" things - as was listed at the top of the built tips thread.

Don't think that answers the question!! I believe they are looking at making modifications for the next batch to try and eradicate, but we'll see i guess.

I was one of the drivers whos rear output cup broke on Friday and mine went when I had a car hit me from the side very hard as he came over the table top and missed the down ramp! My car was his buffer for a soft landing!! :lol: I was running one o-ring on the shaft to stop the drive shaft from hitting the cup but think that I may have to run two or even run a 2mm limiter from my Losi xx-4 to stop this from happening again. I also have one of the other drivers diff which also went and have noticed that the two diffs I have here that have failed are the female output cups U3336. Glypo did your female side go as well?

Upon examination it also looks as though the output cups may have been hardened too much as the metal has fractured straight across where the slot has been machined for the dogbone and there is also tiny amounts of metal that have fractured off where the dogbone pin runs inside the slot. I have included some pictures in this post.

http://www.ukdirtmasters.co.uk/catsx/IMG_1151.jpg

http://www.ukdirtmasters.co.uk/catsx/IMG_1152.jpg

Looks like mine fractured differently to yours.

http://www.glypo.com/reviews/catsx/diff.jpg

This is the male side as well. Does look to be a brittle fracture, so over hardening is certainly likely - and explains why team drivers like Matt have no experienced problems.

Hmm, I didn't have any issues with mine at all on my first run with it. And I'm not running any limiters. For some reason, straight out of the box, mine didn't catch on the outdrives.

Maybe with cars hitting them, it a problem when they have force applied from an unfamiliar direction?


Strange

My cat was fine first time out too. It was still awesome handling last night until it went snap. Mine was a definite impact situation rather than the driveshaft catching on it. Sounds like Grant has a similar issue judging by what he said above.

I just found it odd that the outdrive could snap but not something like a wishbone which you would expect to go didn't. Well... not until I smashed a wishbone when my cat was in rear wheel drive mode lol.

When I look at one of mine there is a simiar fracture on the side that is still left from the lightening hole to the outer edge of the out drive very similar to yours Jason. I cannot tell from the picture that you posted but has yours failed on the same side as where the screw is?

Have a look at your driveshafts, if they are marked on the shaft near the bone end, then they have fouled on the outdrive.

I know you have said that the shocks have been limited, and all should be fine. But the thing is, the car on the track is under a lot more stress than the car in the hand and there may be the chance that it has still touched. Especially if you are running extreme camber change as per the manual setup - rather than one of the setup sheets in the rear.

I may be wrong with all that, but do look at it and then we can rule out the driveshaft touching.

That picture of the outdrive snapped in half, I have never seen one go like that, usually it is just a 1/4 of the outdrive that goes. I say usually, I have done 1 and I have seen lil' Ben do 1 like that too - but now we have limited the shocks up travel and seems to be fine again.

I ran Mossy's worksop setup with the short rear cf plate and long camber arms, shocks in the centre hole in the front and rear towers. I only had one o-ring on the rear but it does seem like the shafts have still managed to touch the outdrives. I may have to go to two o-rings in the rear once I have my new outdrives. I was enjoying how the car was going before it broke.

O Rings when under heavy compression such as landing a big jump compress/deform to almost nothing. If it's essential you stop the travel then solid limites sound wise like the XX4 WE rear shock setup.

How about 4-5mm fuel tubing as a stopper?

I run my Cat outdoors today with 2 O-Rings on each shock, i had a very slight rubbing on one of the driveshafts. I think i will put a small solid spacer in there to be safe :)

Solid it is then I think :)

has the impact bent the wishbone hanger mounting bolt as this can happen thus causing possible contact with the outdrive?

The inner wishbone pin and the hub carrier pins are still perfectly straight on my CAT so I would say that in my case that is not what has caused the problem.

Is there any cuplets that would fit like the Losi savers of that veriety?

I broke my first one at the weekend, i just landed off a jump - didnt crash, just a landing from a big jump. Its odd that Matt and Simon didnt have problems with pre-release cars, im thinking maybe its an iffy batch, i know schumacher have had broken ones back from team drivers to analyse and come up with a solution so it wont be a permanent problem.

Which are failing on the car? Is it the front or rear drives?

I think most have had rears fail but it was a front one on mine :eh?:

Humm, Chris and Ben broke them at York a good few weeks ago i beleive i heard. Is it the high grip? In there case carpet that 'Could' have killed them?