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Discussion Starter #1 (Edited)
4ACCAF15-D206-4174-B11E-BD70175C3A54.jpeg 523F07F3-E777-4C07-9C23-DB96937383B5.jpeg 43C10BCF-EB4B-4733-BFD9-2C2A06A3BC25.jpeg

I do understand that the best thing to do is get it fixed ASAP.

Both the nuts securing the driver’s side Rear Upper Trailing Arm were found to be missing. The washers were likewise gone. The front bolt was just sitting there, while the rear bolt was only going through one hole.

One of the rear holes may have been slightly “ovaled out,” but there isn’t any play with an inserted bolt. The ears don’t seem to have been bent.

The vehicle appears to have tolerated my driving sans one Rear Upper Trailing Arm for what probably has been a few months.

The question is - with the driving habits of a granny - just how unsafe will driving with a missing Rear Upper Trailing Arm be?
 

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Discussion Starter #2 (Edited)

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Discussion Starter #3

Found a video; nothing acutely catastrophic, it seems?
 

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Discussion Starter #4

Another guy just happened to come across the failure.
 

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Discussion Starter #5 (Edited)

This one was more noticeable.


Others mention that it's more frequently an incidental finding.
 

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Discussion Starter #7
My rear end started to clunk and handle poorly. A check revealed rear right arm, rear bolt had loosened off. I now check them regularly.
Could you comment on safety?
 

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Just how long do you intend to have one removed.
IMO gentle throttle and braking could make do on secondary roads for a short while.
The issue may be where eg emergency maneuvers or braking is necessary, you are adding stresses that were never intended for for one arm (way offset) to handle.

You could go up one size of bolt and drill out bracket and rod end slightly to take clearance out of everything. This could be a permanent fix.
A slightly larger dia would be a non metric.

If the rod end was always loose ( and sized for a standard bolt size) use that dia ( that gives a zero clearance fit in rod end. )

I would not run with one arm if at all possible


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It is not safe. Period. A little bit of welding, grinding, drilling and some new grade 8 bolts will do the trick. My concern that if the rest of your rig is in the same condition. A safety check is in order.
 

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Note that if using your own metric bolts, they should be grade 12.9, which is a commonly available grade. (Toyota uses a special grade 11.9 (sometimes only the number "11" is shown on the head) for cost savings because it is exactly what is required). So, either buy new bolts from your dealer, or if you choose to buy aftermarket, use the readily available 12.9 (they'll just have a higher proof load than required).

The original 11.9 bolt = 970MPa proof load, or 140.7ksi (in SAE units).
For a 12mm dia bolt, that works out to 90kN Tensile strength.

Grade 8 (SAE) bolts have only 120ksi proof load, or in 1/2" dia, that works out to 17klbs, or 75.7kN Tensile strength, not strong enough. So in order to fit an equivalent, if someone did want to use a non-metric bolt in place, as Datajockey suggested, would require an SAE grade 10. Good luck finding that, I just searched for SAE equivalent bolts, to match Metric 11.9 or 12.9 and could not find any. Maybe I just didn't look hard enough ("hard", did you see what I did there? all of this is dealing with harness of the fastener, you see... ). :)

Or, if drilling out the hole to a larger diameter to crudely eliminate an out of roundness, make sure the larger diameter fastener, if SAE grade 8, works out to an ultimate tensile strength greater than 90kN (or 20.2klbs).

Summary: replacing just the bolts, buy your new bolts from the dealer, or use metric grade 12.9. If going to a larger diameter to drill out an out of round hole, work out the strength of the new fastener and make sure it is at least as strong as what was there.

I'd prefer to follow the other posters here and weld on a plate to restore the hole to original diameter, round condition, and use OEM bolts, or longer bolts of the original diameter, metric grade 12.9.


Torquing them:
The 12mm dia upper control arm bolt torque requirement is 80Nm.
The larger, 14mm diameter lower control arms and panhard rod bolts require 130Nm torque.

Note that none of these are meant to be torqued to final torque until AFTER the vehicle is back on the ground and been bounced several times to centralize the bushings in place, then you do final torque. That step will prevent binding the bushing and leading to early wear.
 

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Are you asking if it is safe to drive to a shop to get it fix? Or if you can live with it like this forever? I'd say it's ok to drive carefully to a shop so you don't have to pay to get it towed, but you should definitely fix it. The function of the upper links is to prevent the axle housing from turning over. The tires apply torque to the road from either accelerating or braking. Your axle housing would like to spin in opposite direction. The upper and lower links are separated like this to react that torque and hold the axle housing up right. So technically if you don't accelerate or brake too hard, you minimize wheel torque hence minimize the load on upper links.
 

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Discussion Starter #12
Thanks for the information, guys.

I”m hoping things will stay acceptable for work and a few grocery runs (all short drives, a few traffic lights) until the shop has a slot.

The shop says their schedule has been a mess because of the recent airbag recall.

Regarding the slightly ovaled hole - there doesn’t seem to be any play with the bolt inserted, best I can force it. What’s the likelihood of welding being required?
 

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Could you comment on safety?
As said by others it is not safe to drive with it missing or loose as the rear axle can move. If you have replaced the bolts and tightened it up then I would drive on it. I would also paint mark all the bolts and check them daily until I was happy they are not loosening again at which point I would check them weekly or after any long or off-road trips.
 

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Discussion Starter #14
For reference, these are the parts, some of which went AWOL...

Any recommended dealers who could overnight a few?
 

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Thanks for the information, guys.

I”m hoping things will stay acceptable for work and a few grocery runs (all short drives, a few traffic lights) until the shop has a slot.

The shop says their schedule has been a mess because of the recent airbag recall.

Regarding the slightly ovaled hole - there doesn’t seem to be any play with the bolt inserted, best I can force it. What’s the likelihood of welding being required?
I wouldn't worry about the slightly oval hole. The diameter of the hole is not carrying the load. This type of connection rely on the bolt clamping down the bracket onto the joint.
 

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Discussion Starter #16
I wouldn't worry about the slightly oval hole. The diameter of the hole is not carrying the load. This type of connection rely on the bolt clamping down the bracket onto the joint.
Is it more of the bracket's "ears" being squeezed down onto the steel tube inside the "rubber" bushing that keeps things in place?
 
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Is it more of the bracket's "ears" being squeezed down onto the steel tube inside the "rubber" bushing that keeps things in place?
Yes, it's all held in position by the friction between the inner faces of the bracket, clamped against the ends of the steel sleeve in the bushing by bolt tension. Even if the bolt hole is slightly enlarged, the friction between the underside of the bolt head and the underside of the nut, against the outer faces of the bracket, should prevent any movement. As long as there is adequate tension in the bolt, the clamp load is sufficient to prevent any movement.

HOWEVER, if tension in the bolt is lost, any clearance between bolt and bolt hole will allow movement and 'hammering' of the bolt shank against the thin sheet metal of the bracket, which will quickly open up the hole even further. If you use your FJ for rugged off-roading, I'd suggest welding on washers or doubler plates, and using a longer high-strength bolt with a Nylok nut.
 

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Discussion Starter #18
Thanks.

I might be able to get it fixed this week, we’ll see...

These bolts / washers / nuts are apparently not regularly - stocked items with most dealers.
 

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Thanks.

I might be able to get it fixed this week, we’ll see...

These bolts / washers / nuts are apparently not regularly - stocked items with most dealers.
McMaster-Carr (mcmastercarr.com) has a huge selection of high-strength (grade 10.9) metric bolts ... does anyone know the thread pitch for the M12 and M14 control arm bolts?
 
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