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Transmission mount attachment bolts snapped - help!
There are 4 bolts that vertically attach the top of Transmission mount directly to
the bottom rear end of the Transmission housing.
I bought a new mount and gave it to my independent mechanic.
I instructed him to remove the worn old mount, and install the new mount.
Prior to his work, when the car was on the lift, I noticed that 2 of the 4 bolt heads were rusted -
all the bolts are difficult to see, because they are obscured by the mount's metal frame.
Sure enough, when I picked up the car, he told me that 2 of the existing bolts sheared.
At that time, the car was off the rack, so I could not see anything.
I did not really comprehend what he said. BUT, 12 hours later, I am concerned.
From what I can tell by looking at the old mount, it seems he used something,
to assist in freeing the bolts, but he was successful in unscrewing only 2 of them.
I did not witness his shop's work.
I installed the worn mount's bolts about five years ago without any anti-seize compound,
possibly over torqueing them, etc.
My questions are:
1. Do any forum members have any proven ideas/methods on how to remove the broken bolt stubs from inside the housing?
I want prefer to have a good removal method in my mind, to rebut any of his potential "nothing can be done" comments.
2. Does having only 2 bolts attaching the mount to the transmission(rather than 4), have any significant or long term
adverse affects on adequately securing the mount to the trans?
3. Will the mount's dampening be reduced, etc.?
I appreciate all the forum's help. Many thanks.
Last edited by Paulanth; 09-26-20 at 09:42 PM.
Reason: added comment
All the fasteners involved, the mount and the cross member underneath, have a torque spec UNDER 20 ft-lbs.
If bolts are shearing something is definitely wrong. A torque spec that low is basically a sign screaming DO NOT OVERTIGHTEN.
Oh boy. Yeah something can be done but it's requires someone really skilled with extractors/and or a welder to get them out. It's like when exhaust manifold bolts/studs snap off in the head at this point. As stated above the TQ value is not high for mounts when you are screwing into an aluminum casing/threads of any type.
hey good luck, and be careful, and don't make it worse, maybe take it somewhere. Personally, a plumbing scenario comes to mind where I decided I am going to get the bolts out no matter what, and it was a bad decision. It's just an inanimate object so someone with the right patience and state of mind can fix it....
There are 4 bolts that vertically attach the top of Transmission mount directly to
the bottom rear end of the Transmission housing.
I bought a new mount and gave it to my independent mechanic.
I instructed him to remove the worn old mount, and install the new mount.
Prior to his work, when the car was on the lift, I noticed that 2 of the 4 bolt heads were rusted -
all the bolts are difficult to see, because they are obscured by the mount's metal frame.
Sure enough, when I picked up the car, he told me that 2 of the existing bolts sheared.
At that time, the car was off the rack, so I could not see anything.
I did not really comprehend what he said. BUT, 12 hours later, I am concerned.
From what I can tell by looking at the old mount, it seems he used something,
to assist in freeing the bolts, but he was successful in unscrewing only 2 of them.
I did not witness his shop's work.
I installed the worn mount's bolts about five years ago without any anti-seize compound,
possibly over torqueing them, etc.
My questions are:
1. Do any forum members have any proven ideas/methods on how to remove the broken bolt stubs from inside the housing?
I want prefer to have a good removal method in my mind, to rebut any of his potential "nothing can be done" comments.
2. Does having only 2 bolts attaching the mount to the transmission(rather than 4), have any significant or long term
adverse affects on adequately securing the mount to the trans?
3. Will the mount's dampening be reduced, etc.?
2001-2003 LS430 A650-E transmission employs an extension housing containing transmission mount holes . 2004-2006 is probably similarly configured.
6 horizontal bolts hold it in place and are accessible while transmission in vehicle.
To access it, you must remove center exhaust section (y-pipe) , heatshields, driveshaft and transmission yoke to perform replacement.
An avid do it yourselfer could tackle this with a shop manual, but perhaps replacement or repair is better executed on a lift at a transmission shop.
The extension housing internally indexes an a shaft mounted component ( someone know what it is called?)
Top view of A650-E transmission extension housing. Bottom view of transmission extension housing depicting transmission mount tapped holes.
A link to parts diagram of extension housing and related fastener project.
09-26-20, 09:35 PM
Transmission mount attachment bolts snapped - help!
