torque arm destroyed
not great on geometry, but it looked like mine broke from going front to back, the bolt is still in there wrench tight. not sure it makes a difference in theory, but mine is a tunnel mount. slots cut in bracket would not have held in this case, ie picture.
it definately would have helped solve this in design by making bolts go all the way through the rear end though. a new rear end is probably (knock on wood) not a viable option for me.
it definately would have helped solve this in design by making bolts go all the way through the rear end though. a new rear end is probably (knock on wood) not a viable option for me.
not much to look at from the pic, but it seems to me that the top front bolt is missing(loose and vibrated out). that would put all the pull side stress on the rear bolt, therefore causing the problem(the top pulls, the bottom pushes as the pinion rotates up). that bracket ripped out from the back... not the side. the thickness of the bracket wasn't a issue until all the stress was put on it and being loose at the same time.
also, the op says that the bolt is still in the hole and "wrench tight". this means that the bolt was probably bottomed out in the hole and not clamping the bracket to the housing properly.
three things to look at here... 1) design of the 4 threaded holes allowing a improper fastener to be used. 2) fastener and bracket hole size do not match. sooner or later this will begin to move around, no matter what you do with the bolt. tack welded after tightened or not, the bolt will come lose/break or the bracket will eventually clearance itself on the housing and begin to move around and break the bolt. 3) powdercoating should be removed where the bracket contacts the housing. we all as manufacturers powdercoat these parts for looks and durability, but in all reality this coating can and will cause problems with bolt clamping tolerances. the pressure of the bolt stretch will essentially squeeze out the powdercoating and make the bolt loose overtime. removing the coating where the bracket contacts the housing would help this from happening.
ideas for repairs/prevention...
drill/tap the holes in the housing to 14mm or 9/16 to repair threads and make the fastener and hole size match.
install spacer shim machined to fit the hole of the bracket to use the existing 1/2" hole in the rearend housing. once the t/a is installed weld the washers to the bracket(most important) and tack weld the bolt heads to the washers.
remove any coating that would isolate the metal to metal contact of the housing and bracket. if you are gonna do the washer/bolt weld operation, the coating will need to be removed anyway for a good weld.
be sure to use a fastener setup that will not bottom out in the hole. this will for sure lead to problems even if any other repairs or mods are done. use only grade 8 or higher hardware... washers and all.
theres nothing wrong with UMI's design.... its the rearend and the install that makes the difference. you simply have to be smarter that the metal you are working with....
also, the op says that the bolt is still in the hole and "wrench tight". this means that the bolt was probably bottomed out in the hole and not clamping the bracket to the housing properly.
three things to look at here... 1) design of the 4 threaded holes allowing a improper fastener to be used. 2) fastener and bracket hole size do not match. sooner or later this will begin to move around, no matter what you do with the bolt. tack welded after tightened or not, the bolt will come lose/break or the bracket will eventually clearance itself on the housing and begin to move around and break the bolt. 3) powdercoating should be removed where the bracket contacts the housing. we all as manufacturers powdercoat these parts for looks and durability, but in all reality this coating can and will cause problems with bolt clamping tolerances. the pressure of the bolt stretch will essentially squeeze out the powdercoating and make the bolt loose overtime. removing the coating where the bracket contacts the housing would help this from happening.
ideas for repairs/prevention...
drill/tap the holes in the housing to 14mm or 9/16 to repair threads and make the fastener and hole size match.
install spacer shim machined to fit the hole of the bracket to use the existing 1/2" hole in the rearend housing. once the t/a is installed weld the washers to the bracket(most important) and tack weld the bolt heads to the washers.
remove any coating that would isolate the metal to metal contact of the housing and bracket. if you are gonna do the washer/bolt weld operation, the coating will need to be removed anyway for a good weld.
be sure to use a fastener setup that will not bottom out in the hole. this will for sure lead to problems even if any other repairs or mods are done. use only grade 8 or higher hardware... washers and all.
theres nothing wrong with UMI's design.... its the rearend and the install that makes the difference. you simply have to be smarter that the metal you are working with....
Last edited by ssvert99; Feb 3, 2009 at 11:55 AM.
no bolts were broke....i don't know if the other bolt is bottomed out or not. i'll double check it before i put new bracket on though. i THINK the bolts used were bolts supplied by umi as an upgrade, but i won't swear to that.
umi is sending me a new bracket to fix the torque arm.....easy enough fix. i'll definately try using 1 or 2 of the ideas mentioned to help prevent this from happening again.
thanks again umi and everyone else that replied.
umi is sending me a new bracket to fix the torque arm.....easy enough fix. i'll definately try using 1 or 2 of the ideas mentioned to help prevent this from happening again.
thanks again umi and everyone else that replied.
