Are you madabout kit cars      
 "We've Got Kit Cars Covered" Information about Madabout-Kitcars.com Contact Madabout-Kitcars.com         Home of UK kit cars - madabout-kitcars.com Various kit car write ups All the latest kit car news Kit car related and general discussion

Search
Manufacturers
Kit Cars
Kit Car Data sheets
Picture Gallery
SVA Knowledgebase
Clubs & Communities
Build cost estimator
Kit cars for sale
Knowledge Base 
KitcarUSA.com
Classic-Kitcars.com
 

Go Back   Madabout Kitcars Forum > Mad Build Area > Marlin 5exi builds

Marlin 5exi builds Calling all you sexi builders....sorry 5exi builders, show us your progress.

Reply
 
Thread Tools Display Modes
  #1  
Old 12th September 2009, 17:57
craig's Avatar
craig craig is offline
Senior Member
Enthusiast
 
Join Date: Nov 2005
Location: Tyne and wear
Posts: 784
craig is on a distinguished road
Default Broken rear wishbone!

Hi,

I was driving tonight about 65mph on a staright road approaching a slight left hander so backed off the throttle as I started to enter the corner and the rear of the car very nearly went!!

Very very scary stuff at that speed! I pulled over and inspected the rear to find a broken rear wishbone in exactly the same place as Rich h's car.....





This is far too much of a coincidence and really makes me think about what could have happened if it had totally gone?? As you can see the crack is about 2/3 of the way through.

As it's a weekend I have not contacted marlin yet so will wait and see what they say as two going in the same place is very serious and I certainly would not entertain driving my car again on the same replacement wishbones

My car has only covered 1300 (road) miles and never seen a track!! wishbones should last the life of a car.

Thanking my lucky stars tonight!!!!

Craig
Reply With Quote
Available from eBay
  #2  
Old 12th September 2009, 18:59
bigrich's Avatar
bigrich bigrich is offline
Senior Member
Enthusiast
 
Join Date: Nov 2005
Location: Cheshire
Posts: 404
bigrich is on a distinguished road
Exclamation

Looks like Marlin need to be having a recall.

Out of interest, do you know when your wishbones and Rich's that have failed were manufactured.

...I've done 6500 miles on mine now....and OK still....but only 1600 power!

Bad batch maybe? ...or I'm running the gauntlet!!

Rich
Reply With Quote
  #3  
Old 12th September 2009, 19:07
MikeR MikeR is offline
Senior Member
Enthusiast
 
Join Date: Dec 2006
Location: Wootton Bassett
Posts: 108
MikeR is on a distinguished road
Default

Hi craig,

Looks like you were very lucky it could have been very nasty indeed.

Keep us informed as to Marlins response - i'm glad now that my car is
on its way to Track Developments for their new rear suspension upgrade.

Mike
Reply With Quote
  #4  
Old 12th September 2009, 20:35
bigrich's Avatar
bigrich bigrich is offline
Senior Member
Enthusiast
 
Join Date: Nov 2005
Location: Cheshire
Posts: 404
bigrich is on a distinguished road
Lightbulb Important - Broken Wishbone - design changed??

Hi Craig,

Just looking again at your picture of the broken wishbone and comparing it to mine.

To me, it looks like the design has subtely changed.

If you look on the gallery pictures at my rear end mod pic #2, you see that the wishbone tube and weld is right at the end of the wishbone...i.e. the weld that holds the wishbone tubes together is right at the tip of the threaded insert in the wishbone.....therefore, very little leverage / flex point during power / brake application. This is an early wishbone....circa 2005.

If you look at your pics the wishbone leg tube is welded to the other wishbone leg at what looks like approx 10mm inboard of the end of the threaded insert...maybe this is the problem??, gives a lever point for the threaded insert / ball joint arm to flex about....

Any thoughts.

Bigrich
Reply With Quote
  #5  
Old 13th September 2009, 19:46
DavidH DavidH is offline
Senior Member
Enthusiast
 
Join Date: Aug 2007
Location: Saxmundham,Suffolk
Posts: 167
DavidH is on a distinguished road
Default

Umm looking at my MK2 rear suspension it also has about 8-10mm guess its how far the insert is welded though that will be a factor in how much of a lever there is.
Reply With Quote
  #6  
Old 13th September 2009, 20:42
alackofspeed's Avatar
alackofspeed alackofspeed is offline
Senior Member
Enthusiast
 
Join Date: Jul 2005
Location: Dorset
Posts: 1,180
alackofspeed is on a distinguished road
Default

Craig, I'm pleased to hear you weren't hurt.

I hope that this failure further alerts people to the potential danger of cracks in their wishbones. The cut through image I posted in Ric H's thread I hoped would be enough for people to seriously consider strengthening their cars, but I'm not aware of anyone doing anything to avoid further instances.

Hopefully your failure will prompt people to act with preventative measures, rather than wait for theirs to fail and cause an unpleasant crash, by which time it could be game over......
Reply With Quote
  #7  
Old 14th September 2009, 00:52
JG's Avatar
JG JG is online now
Senior Member
Big Cheese
 
Join Date: Sep 2002
Posts: 1,079
JG has disabled reputation
Default

Glad that your caught it in time and that you are ok.

Marlin havn't got a great track record with wishbones recently have they?

Time to beef them up me'thinks as its not doing their reputation any good.

John
Reply With Quote
  #8  
Old 14th September 2009, 08:44
chrislandy chrislandy is offline
Senior Member
 
Join Date: Oct 2008
Posts: 383
chrislandy is on a distinguished road
Default

It looks more like a shear failure at the weld rather than in bending
Reply With Quote
  #9  
Old 14th September 2009, 10:52
SDMC001's Avatar
SDMC001 SDMC001 is offline
Senior Member
Enthusiast
 
Join Date: Feb 2006
Posts: 351
SDMC001 is on a distinguished road
Default

Craig

Like the others glad you are OK, this becomes a worry I feel for all of us.

I picked up on a comment from Bigrich that the point of welding where the tubes triangulate is further back on his, this was the issue I had on my front wishbones, the ones that were replaced by Marlin. Like others I too feel Marlin need to take ownership of this issue, it will be intersting to see their responce.

I understand from a suspension specialist with things like the wishbones when they are made they should be heat treated after welding, I wonder if Marlin do this.
Reply With Quote
  #10  
Old 14th September 2009, 18:18
craig's Avatar
craig craig is offline
Senior Member
Enthusiast
 
Join Date: Nov 2005
Location: Tyne and wear
Posts: 784
craig is on a distinguished road
Default

Yes as bigrich has said I defo think that having the welded tude nearer the end would help but also as John d has pointed out maybe thicker walled material.

It's also interesting that both cars have been honda cars?? maybe the lesser power cars will go but will take longer.

The crack is not the actual weld but just behind the weld!

It's very hard to see the other side with my car in the garage but in the same place the powder coat has cracked but not the actual metal yet!

It looks like a matter of time
Reply With Quote
  #11  
Old 14th September 2009, 18:19
Ric H Ric H is offline
Senior Member
Enthusiast
 
Join Date: Sep 2006
Location: Cheshire
Posts: 184
Ric H is on a distinguished road
Default

Have you stolen my picture Craig?! That could be a carbon copy failure couldn't it! Glad you got away with it same as I did; mine had managed about 2500 miles.

I realise I never fed back to the forum the conclusion of my wishbone tale. I got a new pair from Marlin, and I spotted that, as Rich points out they seem to have returned to an earlier design where the diagonal is welded right to the tip - here's a pic:



I was reassured by this as it clearly removes the high bending load area that is where our wishbones have failed - where the weld of the diagonal is coincident with the end of the threaded insert. The tube gauge hasn't increased though - I checked by weighing and old and new bone. You'll see that Marlin were nice enough not to weld toe control arm tabs onto the arms (for me to cut off again) since they know I'm controlling the toe separately.

With that I swapped them both and haven't had a problem since, touch wood. The car has never been better since after fitting the new 'bones I've finally been able to drive it with the suspension tweaks. Did 600 miles last weekend without incident - great fun.

I know John thinks I should reinforce them and that may be a wise idea but the design tweak alone I think should have made a big difference. I'm going to be keeping a good eye on them for any cracks too...
Richard
Reply With Quote
  #12  
Old 14th September 2009, 18:31
craig's Avatar
craig craig is offline
Senior Member
Enthusiast
 
Join Date: Nov 2005
Location: Tyne and wear
Posts: 784
craig is on a distinguished road
Default

Rich,

That looks much better! I still think the walls should be thicker though which would eliminate all my fears!

I was always brought up to over engineer if in any doubt!

It's obviously flexing that has caused both failures.

Will wait and see what marlin say

Craig

ps Can you feel the differance in driving from the old wishbones? Does it feel tighter?
Reply With Quote
  #13  
Old 14th September 2009, 18:38
alackofspeed's Avatar
alackofspeed alackofspeed is offline
Senior Member
Enthusiast
 
Join Date: Jul 2005
Location: Dorset
Posts: 1,180
alackofspeed is on a distinguished road
Default

Craig, as a slight aside, I'd be willing to bet the fitment of the 888s sped things up nicely. I have to be an absolute savage to make mine slip, so the loads through the suspension must be very high!
Reply With Quote
  #14  
Old 14th September 2009, 18:53
Ric H Ric H is offline
Senior Member
Enthusiast
 
Join Date: Sep 2006
Location: Cheshire
Posts: 184
Ric H is on a distinguished road
Default

Quote:
Originally Posted by craig View Post
ps Can you feel the differance in driving from the old wishbones? Does it feel tighter?
Well, it feels a lot tighter than a cracked wishbone....

I came to the conclusion that mine had had a small crack for a little while adding flexibility an causing the rear to pull to one side on overrun. With all the mods and adjustments I wouldn't like to comment on what has made most difference - but it certainly feels a damn sight better than it did.
Reply With Quote
  #15  
Old 29th September 2009, 22:38
alackofspeed's Avatar
alackofspeed alackofspeed is offline
Senior Member
Enthusiast
 
Join Date: Jul 2005
Location: Dorset
Posts: 1,180
alackofspeed is on a distinguished road
Default

Got a new top wishbone yet?
Reply With Quote
  #16  
Old 30th September 2009, 16:56
craig's Avatar
craig craig is offline
Senior Member
Enthusiast
 
Join Date: Nov 2005
Location: Tyne and wear
Posts: 784
craig is on a distinguished road
Default

Quote:
Originally Posted by alackofspeed View Post
Got a new top wishbone yet?

Hi John,

I have only just taken them off as been on holiday so will send them off to marlin soon!
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +0. The time now is 21:46.

copyright © madabout-kitcars.com 2000-2024
terms and conditions | privacy policy