Front wishbone - another weak point? [Archive]

glypo

31-10-2008, 12:24 AM

Well I have broken 3 wishbones on my SX so far. One of them was full speed into a post, and wishbone completely snapped, can't blame anyone but me for that.

However 2 of the breakages have been really frustrating. It is the point where ball stud from the shock mounts into the wishbone. It's so frustrating to have to replace the whole wishbone and to have a race ended when the wishbone fails in this way. The image below shows my problems:

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

I apologise for the photo quality, I was using a flash. The second wishbone initially failed exactly the same as the first, it looks more damaged in the photo due to my testing.

Has anyone else had this happen to them? If so is it an issue Schumacher are aware of and correcting?

Thanks.

Garry Driffill

31-10-2008, 12:48 AM

Is there anyway were the Ball is on the arm on the snapped ones to re-drill and put a Titanium one inplace into the arm? - Just an idea...

glypo

31-10-2008, 01:23 AM

I'm not really sure I follow what you mean.

What I would like is 1/8th scale style wishbones, where the shock is braced both sides, distributes the load much better. Somehow I doubt Schumacher will do that though.

Just some wishbones that don't break would be nice :thumbsup:

Mike Hudson

31-10-2008, 01:25 AM

Just some wishbones that don't break would be nice :thumbsup:

I'm sure everyone would like that for their cars :woot::thumbsup:

sime46

31-10-2008, 06:55 AM

I've seen Cats take some REAL hammer and keep going without damage. If you hit stuff it'll break. I think its unfair to say it is in anyway weak. If the wishbones were stronger then you'd probably rip the mountings off the bulkheads or worse. Its easier to change wishbones than the mountings ect. Its a fantastic car unlike any other I've owned so you should consider the crashes before you condemn the design and manufacturer.

showtime

31-10-2008, 07:59 AM

which way up were they when they broke Jason?

if the holes were at the bottom it would be a case of the shock stopping due to being limited (to protect the porcelain outdrives :rolleyes:) but the force of the wishbone still being pushed up being enough to leave the bottom shock mounting behind?

were you landing on one front wheel when this happened or flat or on both?
most 8th cars have some reserve uptravel to take care of these landings but a car with limited shock travel landing on any of its corners would be severely stressing that part of the wishbone! :)

and like they say "somethings gotta give"!

Chrislong

31-10-2008, 08:25 AM

if the holes were at the bottom it would be a case of the shock stopping due to being limited (to protect the porcelain outdrives :rolleyes:) but the force of the wishbone still being pushed up being enough to leave the bottom shock mounting behind?

Exactly what I was thinking too. I am convinced the wishbones are strong, there has got to be a reason for this.

Sorry to hear about the breakages, I have broken none despite some major crashes - infact all I have done is 1 outdrive and nothing else!!

I have seen wishbones break, but never without good reason, and never in this way. :confused:

Perhaps, email Schumacher.

ryan

31-10-2008, 08:57 AM

I had a wishbone go exaclty like glypo's, also at newbury indoor. I will check the up travel of the front shocks, it sounds it could be that, it was a (very) big jump :thumbdown:

bigred5765

31-10-2008, 08:59 AM

looks to me as though the shock has taken an impact, which has tore the ball stud out of the wishbone, have a look make sure the top of the shocker is free moving at the shock tower side,just imho

peetbee

31-10-2008, 10:10 AM

They should have brought back the crashback system:woot:

sorry, couldn't resist:blush:

DCM

31-10-2008, 10:20 AM

by the look of it, it appears to me ripping the ball out on landing. This may either be a point where the wishbone needs a little beefing up, or the material not flowing correctly in the mould and cooling with a 'weak spot'. You expect a certain amount of breakages, but if they are coming from normal running, thats not a good thing.

Try some Tamiya front wishbones, might need a little adapting, but they may fit... if you are concerned.

glypo

31-10-2008, 10:40 AM

Sime46 - maybe take time to read my initial post before saying I am being unfair. I clearly say one of my breakages it my fault. The other two I feel are not.

Adam/Chris - Yes you are exactly right, I should have explained in my post. This happens after jumps, and it will be due to limited uptravel (although not because of spacers - I didn't have any in the front - it is limited enough under standard setup).

bigred - The shock is/was free moving on the shock tower, thanks for the idea though.

ryan - Glad I am not the only one :)

dcm - Good thinking about another wishbone. What makes you suggest Tamiya? Is it strength/impact resistance? Something I think I might look into.

I think the rest of the wishbone is indeed very strong. When this breaks, like in my photo, the rest of wishbone is fine, it is just the shock mounting that comes off. This hasn't been crash damage, I have crashed my cat sx plenty and can ensure everyone it is strong enough hitting stuff and I have only broken one wishbone in a crash.

jimmy

31-10-2008, 10:49 AM

501X carbon front wishbones - doesn't get stronger than those, so maybe worth a try.

DCM

31-10-2008, 10:51 AM

I think the Tamiya Wishbones are made from stuff planets are made from, I have been trying to break the ones on my DB-01 since I got the car, landing it on it's nose, hitting the track markers with them etc.... and not broke one.

Worth a look innit!!

Chrislong

31-10-2008, 11:19 AM

Innit!

(DCM, you developing a Manchester accent? :lol:)

SidewaysLS4

31-10-2008, 12:55 PM

josh_smaxx

31-10-2008, 01:08 PM

So is the shock bottom pushing through the bottom of the wishbone because its hitting its uptravel limit when landing?

I have to admit iv never seen a wishbone break in such a way (and i tended to clean out my LHS for B4 wishbones).

DCM

31-10-2008, 01:10 PM

Chris, aye lad.... LS4, lets just say, speed isn't an issue haha

rcracer

31-10-2008, 01:16 PM

501X carbon front wishbones - doesn't get stronger than those, so maybe worth a try.

as anybody tried matching them up ? garry has some here i might have a look.

glypo

31-10-2008, 01:45 PM

I totally forgot about the new more flexible option wishbones, Robin Schumacher suggested I try them. I will give these a go when they come out, I am sure they will sort my problems out.

Certainly a wise idea for a track with big air like Newbury :) (and a driver with skills like mine :lol:).

rcracer

31-10-2008, 01:53 PM

as anybody tried matching them up ? garry has some here i might have a look.

Just checked the 501x arms against the SX ones and they are a country mile out.

frogger

31-10-2008, 02:04 PM

Richard Lowe

31-10-2008, 02:26 PM

So is the shock bottom pushing through the bottom of the wishbone because its hitting its uptravel limit when landing?
When the shocks are limited enough to reduce the outdrives letting go the car runs out of suspension travel with the chassis about 5mm off the deck :lol:

mark christopher

31-10-2008, 02:32 PM

When the shocks are limited enough to reduce the outdrives letting go the car runs out of suspension travel with the chassis about 5mm off the deck :lol:

put like that then think on the £'s youll all save on undertrays:thumbsup:

josh_smaxx

31-10-2008, 03:41 PM

When the shocks are limited enough to reduce the outdrives letting go the car runs out of suspension travel with the chassis about 5mm off the deck :lol:

Ah....

5.5mm lexan undertray? :lol::thumbsup:

Northy

31-10-2008, 03:46 PM

When the shocks are limited enough to reduce the outdrives letting go the car runs out of suspension travel with the chassis about 5mm off the deck :lol:

Mine doesn't :confused:

G

Richard Lowe

31-10-2008, 04:20 PM

Mine doesn't :confused:

G

Little Bens does :eh?:

Northy

31-10-2008, 04:28 PM

Mine doesn't :confused:

G

Mossy

31-10-2008, 05:43 PM

Mine neither.

MattW

31-10-2008, 05:52 PM

Never had any issues with front up travel - never bothered to limit either!!

However, i think i have seen this style of breakage before - well, not technically true, as mine never got that bad, but I did crack one.

I think the "issue" is probably the small step that is in the ball joint - the top part that isn't threaded. When you screw this in, i think it stresses the plastic big time. I think i cut a small chamfer/countersink with a sharp scalpel, so that the step has somewhere to go. I haven't suffered this issue since.

I have just checked my car, looks like i probably have s shorter ball joint in there than is in the kit. Not sure if this makes any difference or not.

showtime

31-10-2008, 06:25 PM

Mine doesn't :confused:

G

are you running your diffs in the high or low positions?

Northy

31-10-2008, 06:38 PM

Std low......

G

sime46

31-10-2008, 07:00 PM

When my chassis is on the floor I still have 8-10mm of shock travel left. The blind part of the ball stud being forced into the wishbone and cracking/stressing the plastic sounds entirely plausable. Thankfully mine look ok. Good idea tho putting a chamfer on the edge of the hole giving it room to tighten up flush.

super__dan

31-10-2008, 07:07 PM

I think the "issue" is probably the small step that is in the ball joint - the top part that isn't threaded. When you screw this in, i think it stresses the plastic big time. I think i cut a small chamfer/countersink with a sharp scalpel, so that the step has somewhere to go. I haven't suffered this issue since.

I have just checked my car, looks like i probably have s shorter ball joint in there than is in the kit. Not sure if this makes any difference or not.

I do like to read the Schumacher threads despite me not having the car, anyway................................

When Losi brought out the new (shite) graphite with the small writing on the XX4 front towers, I broke off 2 front camber link mounts as I installed the ball end for the first time becasue I used a TI ball end that had a small shank and as that tightened it it opened up the hole and 'SNAP' off she broke.

Surely if you pop that bottom shock mount on and off a few times for setup/cleaning etc it's going to wear quickly? Wouldn't an eyelet like Losi/ AE etc be better?

MattW

31-10-2008, 07:37 PM

Dan, wear isn't generally a problem to be honest.

The Eyelet isn't a bad idea in principle - however, you would need to use an imperial screw - because metric would be too fine and would fail in no time - this is speaking from experience!! So, you rely on the 4-40 screw (2.45mm ish!) being ok in a hole that is intended for 3mm. It would probably be fine, but a bit on edge. The other thing with that type of fixing is that is actually has a fair amount more leverage on the hole IMHO, so is actually more likely to break out.