ConcoursMustang Forums

Restoring - General discussions that span across many different groups of years and models => Suspension => Topic started by: Stangly on March 25, 2017, 02:49:19 PM

Title: cutback style control arm fatigue cracks
Post by: Stangly on March 25, 2017, 02:49:19 PM
I have a pair of rust free UCA that are of the cutback style, Mid June build Date 68 San Jose car. Both arms have half inch long fatigue cracks as discussed in some older threads at the area cut out near the ball joint. The cracks are on each side of the ball joint towards the closest bolt hole and thru the section of metal. This is consistent with both arms. Both arms had four waffled rivets so I believe them to be original to the car. I found the letter K on one and the number 4 on the other stamped on the top of the ball joint end. Can these cracks be welded/repaired by a qualified welder. The car is being restored as an occasional driver and I am concerned about the integrity of the repaired part. Any input would be greatly appreciated.

Thanks,
Title: Re: cutback style control arm fatigue cracks
Post by: Bob Gaines on March 25, 2017, 02:59:20 PM
I have a pair of rust free UCA that are of the cutback style, Mid June build Date 68 San Jose car. Both arms have half inch long fatigue cracks as discussed in some older threads at the area cut out near the ball joint. The cracks are on each side of the ball joint towards the closest bolt hole and thru the section of metal. This is consistent with both arms. Both arms had four waffled rivets so I believe them to be original to the car. I found the letter K on one and the number 4 on the other stamped on the top of the ball joint end. Can these cracks be welded/repaired by a qualified welder. The car is being restored as an occasional driver and I am concerned about the integrity of the repaired part. Any input would be greatly appreciated.

Thanks,
It is most logical to replace them with other like cut back arms . I suppose they could be welded but how are they going to look and what effort to weld them and dress them out presentable is a question to ask yourself compared to what other nice cores may cost. If you feel that you have to have them on occasional driver car replace them with like arms and wait for those to crack too. Maybe they will and maybe not. Of course you could always go with  the stronger UCA used in production before or after the cutback design. There are far more of those around compared to the weaker cut back design. 
Title: Re: cutback style control arm fatigue cracks
Post by: Anghelrestorations on March 25, 2017, 08:36:04 PM
I see this issue all the time on the cutback control arms.  They can be repaired (welded and ground down again) but its a bit of a process.  I would say that more than 50% of the control arms like this I see have those exact same cracks. 
Title: Re: cutback style control arm fatigue cracks
Post by: Stangly on March 26, 2017, 07:44:29 PM
Thanks for input guys, I have two more sets to check for condition and style hopefully I can scrounge a descent pair.