Time to replace rubber suspension bushings on my TR. When installing the large bolts through the bushings which connect the control arms to the frame and hubs, is best practice grease, anti-seize, a combination of the two, or dry?
The bolts had to be cut out of my TR with a hacksaw in 2008 when I bought it and needed to replace the bushings. So maybe anti-seize is a good idea? They came loose pretty easily this time. If there is a reason to leave it dry, what is it? I thought the factory didn’t grease it because grease is expensive and the workers hated people who could afford these cars.
The bolt needs to provide enough clamping force to prevent rotation of the bushing under any circumstance. Any lubricant prevents that from happening. Do not deny a component the ability to perform its primary job for your convenience. The factory despite wives tales you have read on the internet uses lubrication where there is supposed to be lubrication, they use sealants where there are supposed to be sealants. We would all be well advised to follow their lead because there are reasons in every case.
So, the control arms don’t pivot on the bolts, the inner sleeve of the bushing remains static and the outers sleeve rotates, stretching the rubber torsionally as it turns? I never knew that. Interesting.
I put LPS2 on the nuts and bolts to prevent rusting. It also adds some lubrication, but not as much as grease or oil.
You can put a small amount of antiseize on the flat portion of the bolt that goes through a bushing, that will prevent the bushing insert and bolt from corroding together, which would not help with a future removal. The factory dry approach is what has been designed in, but they do not care about how hard it is to work on the car in the future. In fact the factory would recommend not reusing heavy bolts like used in suspension items, as the high torque stresses threads optimally as part of why they hold under such high forces conditions. In the real world many bolts are reused all the time and on our Ferrari's the ever present nyloc nuts are probably reused far beyond where they still provide their full function. So hopefully the factory envisioned real world conditions and has a margin of safety in its design specifications on safety critical parts. The real goal is clamping load, and torque is simply a proxy for that goal. My understanding is clamping load will vary for bolts torqued the same based on the nature of the surface materials, cleanliness or otherwise of the threads,etc. Torque specs are set with the expectation of a +-10% effect on clamping load to handle real world variability. In my earlier day, I have had immense challenges in the rust belt working on old suspensions, and was tempted to slather anti sieze everywhere on reassembly. But then you need to reduce the torque value by about 25% to avoid over tightening, yet end up with a bolt that will be more prone to vibration loosening it. I considered using the Loctite Blue threadlocker as a way to address the corrosion prospect without causing as much of a functional/safety tradeoff. But in theory one would also still reduce torque due to the lubricity property of wet threadlocker. Threadlockers have some anti corrision properties, in that they harden to a plastic that will prevent moisture creeping into the threads. But in the end, I choose to leave the bolt threads clean, dry and torque to spec. Then spray some anticorrosion compound on the outside of the properly torqued nut and bolt, and touch that up every few years, and you will prevent external corrosion and moisture access which should be better than nothing without compromising safety/function. I like to use this stuff, the private aircraft people seem to use alot of it, does not make a big mess and attract grime. https://www.amazon.ca/dp/B07DG3NN18?ref=ppx_yo2ov_dt_b_fed_asin_title
Anti-seize is going to increase the final clamping load. If the factory arrived at the original torque figure assuming a dry thread installation - and you go adding a bunch of lubricants - you are effectively increasing the clamping load on the components and bolt itself. This can increase the likelihood of exceeding the yield strength of the bolt and/or causing too much stretch or even causing plastigation in the bolt itself. These are all bad things when it comes to holding your suspension together. Listen to the wizard... "still a bad idea" Ray
Sometimes you can even see this effect taking place in real time - if you are using an analog style torque wrench (i.e. with a needle). This can be especially vivid when dealing with something like aluminum threads. If you put too much lubricant or anti-seize on the threads and/or under the bolt head, then start torquing away, you sometimes will see the load increase (via the needle on the dial), then see it settle back as you are still attempting to reach the prescribed final torque (as things stretch and/or start to pull apart internally). If you apply more torque, the situation starts to spiral down hill. More torque, more deformation - needle goes up, then rolls back before hitting the final torque reading you want. With no lubrication, generally the needle will peak very sharply and come back as you ease off on the wrench, not during the torque moment. If you have a torque wrench with a tell-tale needle, you can sometimes really see this taking place. On a digital or click style torque wrench, it's much harder to see happen in real time. Ray
That's why on the loaded portion of the control arms you are actually supposed to put the vehicle on the ground before you do the final tightening- so you don't tear the bushings. In the real world we would just put the car on a lift and use the tool chest to lower the corner of the car on it so you can still get in there and tighten. Don't do that without working with someone who knows what they're doing. The car could fall.
It works for me since I don’t use a torque wrench; I do it by feel. No suspension problems in 45 years of ownership.
Thanks to all for the education. I am used to motorcycle rear suspension linkages, where things articulate on needle bearings or heim joints (like my Countach). The idea of just letting the rubber do the work seems crude but effective. No wonder urethane bushings might make the car feel different. I run oem bushings on my cars as I like the stock ‘feel’.
FYI. The 330 GTC factory shop manual does not specify any torque values for the control arm bolts. The procedure is to tighten the bolts so when the control arm is released from a horizontal position, it drops slowly. No torque wrench required, This procedure would compensate for lubrication, if any.
My suspension was partially refurbished in 2008, i just have to go though this once again, and I wish we had used anti-seize back then! Our vintage cars are seldom runing at their full potential, so should we maintain them "by the factory book" or with a view to make future maintenance easier? Maybe top performance will suffer, but I must admit my needle has not moved past the 180kmh mark for years.
