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?

At Newbury the broken out drive count was two rear and one front, The two rears broke on the adjustment screw side which is classed as the female output drive.

I saw a broken part yesterday, is this a design flaw or is it a bad batch to come out of the factory? Any idea if the bad parts would be replaced if so? Very tempted by the car but would like to know first if this is fixable?:thumbsup:

Tris is on the case of some outdrive savers :thumbsup:

I will keep you all updated!

I have broken 2 all year, so can safely say this is not a design fault. Both of the 2 i did were off the back of large impacts to that particular side of the car, so dont worry Griff

A question for Simon and all the Team:

Did you ever try on shock shaft, to replace the short ball sockets by long ones ?

I mean, this way, it prevents dogbones to hurt diff outdrives at full compression and it allows more droop setup :thumbsup:

Just my 2 cents

RPM do these. 70311 Up Travel Limiter Clips For All 1/8" Diameter Shock Shafts

http://i12.photobucket.com/albums/a2...lcars/7031.jpg

Will they fit and has anybody tried them for other cars etc. May be better than the o rings compressing and snapping the out drive.

I did this, it was awful :(

Hey guys

I saw the new cat @ york a few weeks ago Ben Jemison was driving it and for the couple of lap he managed between breaking diff outdrives it looked awsome!

I don't think he managed to finish a run due to the poor quality of the diff componants, he seemed a little P**sed off to be honest

I'm sure that schumacher will sort out the problem and reissue everyone with new updated parts

Buggymaster

I think ben had made a mistake with the build though, i think his caster blocks were on the wrong way.

I think its best to let schumacher make an announcement on if there is an issue or not, instead of assuming what will happen. I personally dont think that is fair as people will be calling schumacher after reading your post and asking when their replacement parts are coming in.

yeah true alot of people havent had a issue with there outdrives anyway theres plenty of things to take into account before making assumtions on the build quality.

I'll try and be thorough with this. The SX is an absolutely awesome machine so please do not let such a minor hicup tarnish your opinions of it. ;)

The outdrives are strong for the purpose, when they are weak is if something catch's - such as the bone into the slot, or a stone caught in there. So they don't have that added strength to cope with this additional strain.

So do take care with setups. What can cause the additional strain is:

- Too much camber change, raise internal ballstud/use a longer turnbuckle position

- Too much up travel, use external shock limiting of around 2-3mm

- Too much driveshaft plunge, go to diff high position.

If you do break an outdrive, feel free to post on here but I do strongly recommend that you contact Schumacher, take photos, write out a setup sheet. This will help Schumacher in their findings, it is being looked at.

Personally, I have broken 1 on the rear using the manual setup. So to prevent any further I have done the following things: (which also results in a far better setup)

Trimmed the top off the front castor blocks, lowering the outer ballstud.
Remove all spacing from front inside ballstud, raising the inner ballstud.
(Together gives far less camber change, and more progressive steering)

Gone to shortest inboard rear CF bracket, with 4mm ballstud.
Outer hole on hub, with 60mm turnbuckle (longest posible link)
(This gives linear camber change throughout suspension travel).

Limited all four shocks externally by 3mm

Gone to rear diff to high position, set the belt 1 setting looser than manual.
(This will reduce driveshaft plunge, increases traction)


If anybody wants to PM me or any other Schumacher team driver, please do, I'll always put 100% into helping anybody. :thumbsup:

Chris

http://i12.photobucket.com/albums/a2...lcars/7031.jpg

Those RPM limiters are very convenient parts because of they could be clipped on the shock shaft without disassembly. But unfortunately most of the time, even the thiner one are too thick :cry:

I would suggest a far cheaper idea: home made "C-washer":
http://img123.imageshack.us/img123/7195/dscn8649ad1.jpg

Based on 1mm thick Nylon washer, transformed the "O" into "C" with just a cutting pliers. Easy to clip and it allows very fine tuning ;)

:thumbsup::thumbsup:

I never started with the manual steup and started very far from it and have run the car 15+ times around Southport with only scratches to show for it, and on one set of the new yellows which will do another week.

higher inboard ballstuds and lowered castor block on the front, and longer camber link at the rear, less anti squat, low diffs, loose belts drilled rear pistons with 30wt, 35wt front kit pistons, no limiters at all, middle at the top and inside at the bottom on shock positions.
plus it`s had lots of air over both the doubles and table top at speed.
5.5L on a 18t to kit spur/ratios,

I agree with Chris the quality of the car is excellent and strong.

Plus stop knocking the wing mounts they are far better the most other manufactors.
Si.;)

I agree with you Chris :thumbsup:

I was thinking about shiming out the pivot blocks (let's say 1mm on each side) to push a little the limit of driveshaft hitting the outdrive... Of course it depends on adding 2mm on the track width makes the car still complies the rules :confused:

Great advice Chris.

Still doesn't change the fact the outdrives are too hard IMO.

The fractures are all brittle fractures. I would rather have a more ductile failure on a component like this. A little more ductility and flex would allow just enough play to prevent flexes.

I am not talking about a low yield high UTS material, I don't want to bend a handful. I would just prefer a slightly lower modulus.

Agreed. But for now they don't have the flex/ability to take any strain, they just *ping* broken, so until it is resolved we have to just think about avoiding the cause to keep this awesome machine on the track.

Ah yes, good point. This also helps by reducing the depth of the driveshaft plunge :thumbsup:

I know Matt White & I think Barnyard too, both run a wider car. Currently mine is as per manual, but there is room for additional width. I am going to compare mine to the B4 for width and then add shims to suit. This puts a little extra strain on the 2.5mm screws, so do check them for bends.

I run as std 2mm between the front blocks and have gone out as far as 3. For rear i am currently running 4.5/2. This does obviously pull the drive shaft away from the out drive. This was not the reason for me making it wider - it was a handling preference.

Thank you Matt :thumbsup: