Trailing Arms & Toby TABs Revisited after 8 years.

[Drive Stainless]

Like the title says, after driving around on my Toby TABs for 8 years, I broke it all down over the past week. The primary purpose was to install DPI's new S/S trailing arms, S/S hard brake lines, S/S trailing arm brackets, and adjustable rear upper links.

Naturally, I was eager to see whether the Toby TABs had lived up to their indestructible reputation. They had. I found no deformation nor corrosion of any kind.

Upon reassembly, I realized that if I installed the TABs with the bolt-heads facing outwards, it would enable me to torque the nut rather than the bolt. Doing so would obviously promote a more accurate torque measurement for the joint since the friction created by rotating the bolt within the bushing and trailing arm would not factor in. I would recommend everyone install the TABs with the bolt-heads facing outwards for the same reason. I added two grade 8 nyloc nuts on each side (double-nutted).

I elected to torque the TABs to 60 ft*lbs, though I could not do so at the proper ride height because I do not own a four-post lift. Even with the rear wheels on ramps, some of the weight is unavoidably shifted to the front wheels, which raises the rear ride height from its resting position. Accordingly, I will advise the technician to de-torque and re-torque the upper rear link bolts and trailing arm bolts while the car is sitting flat on a four-post lift during my four-wheel alignment this week.

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FWIW: At the factory trailing arms were installed with the rear suspension hanging in the air (Celebrating the Impossible Page 274 clearly shows a trailing arm in place). You can also see a trailing arm being attached to a bare frame in the air at 31:56 in the BBC Car Crash documentary.

Bill Robertson
#5939

[kenny]

Good to hear the Toby tabs are holding up well. Mine are on 9 years, been a while since I checked them.

Im fairly sure that the guys with automatic transmissions dont have a choice due to clearance and have to mount the bolts with the head facing out.

[jmettee]

I elected to torque the TABs to 60 ft*lbs, though I could not do so at the proper ride height because I do not own a four-post lift. Even with the rear wheels on ramps, some of the weight is unavoidably shifted to the front wheels, which raises the rear ride height from its resting position.

With the rears on rams, I've jacked the front (jack centered under the front cross-member) up so the car is level to torque the TABs. Just a thought if you're rather do it yourself rather than asking the shop.

[Nicholas R]

I agree that often torquing the nut is often better than torquing the nut; however, I think it's a little less critical on the TABs than on some other bolts. Because of the potential of crushing the sleeve, you dont actually get the proof loading on the boat that you would normally look for when torquing a critical fastener. As such, I believe the most important thing is that you always use locknuts. Plus, in the case of Toby TABS, I'm not sure what the spring rate is of the inconel, but I'm sure you're not stretching it the way you could a 10.9 or 12.9 bolt, haha. Still, it is good practice to try to torque the nut.

I actually haven't changed my TABs with the transmission in the car. Do you have the ability to put the bolts in from either orientation with the transmission in place? I'm sure you cant with the automatic because of it's size, but what about with the manual?

[EdR5150]

Automatic Transmission cars can have their TABs face either direction. You need to disconnect the trailing arm at the hub, which allows you to maneuver everything around. Just don't twist up the hard brake line.

I made a video on this about 8 years ago: youtube.com/watch?v=Q1fdmmdd-hA Except every time I watch that video, I hate it a little more...

[Drive Stainless]

I actually haven't changed my TABs with the transmission in the car. Do you have the ability to put the bolts in from either orientation with the transmission in place? I'm sure you cant with the automatic because of it's size, but what about with the manual?

I have a manual trans. I was able to install the bolts in either direction and with the trailing arm still attached at the rear hub carrier.

[David T]

I would not recommend using 2 nylock nuts per side to double-nut. Either use 1 nylock nut or use 2 standard nuts, one locking the other. Other things you can do, use a paint mark to make it obvious if anything moves, use a castellated nut and cotter pin. Since the TAB is such a critical fastener the cotter pin is probably the best way to go. Because the bolt is subjected to rotation and you cannot torque it to within it's yield point, if it was in an aircraft, it would probably be wired, cotter pined at least. IMHO the TABS don't loosen up because the nut was not tight enough or not double-nutted. They loosen because they were too tight and collapsed the sleeve or they bent and stretched and become loose. Cars where the TABS have never been touched don't seem to have as many problems as the cars were the TABS were touched, either to be replaced or to add or remove shims during an alignment. Plenty of Deloreans are still using the original TABS with no problems.

[Nicholas R]

I would not recommend using 2 nylock nuts per side to double-nut. Either use 1 nylock nut or use 2 standard nuts, one locking the other. Other things you can do, use a paint mark to make it obvious if anything moves, use a castellated nut and cotter pin. Since the TAB is such a critical fastener the cotter pin is probably the best way to go. Because the bolt is subjected to rotation and you cannot torque it to within it's yield point, if it was in an aircraft, it would probably be wired, cotter pined at least. IMHO the TABS don't loosen up because the nut was not tight enough or not double-nutted. They loosen because they were too tight and collapsed the sleeve or they bent and stretched and become loose. Cars where the TABS have never been touched don't seem to have as many problems as the cars were the TABS were touched, either to be replaced or to add or remove shims during an alignment. Plenty of Deloreans are still using the original TABS with no problems.

I have never once seen or heard of someone with drilled trailing arm bolts using castellated nuts and a cotter pin. Do you have this on your car?

I believe there is a time and place for castellated fasteners, but I do not believe that TABs are one of them. If you are worried about nylock nuts being effective, there are better options than drilling holes in your trailing arm bolts for a cotter pin. You could use a tabbed washer, or even better use an all metal locknut, such as a Stover Lock nut. I spec these out periodically when a bolted connection is subjected to high vibration.

Also I agree, 2 locknuts back to back are less effective than a single locknut and jam nut, because the captured nylon ring is soft and should not be torqued against.

[Drive Stainless]

I have never once seen or heard of someone with drilled trailing arm bolts using castellated nuts and a cotter pin. Do you have this on your car?

I'll stick to one nyloc nut then, thanks.

I surely won't be drilling through my Inconel 718 TAB. . .unless David T. is buying the drill bits.