The rear brakes on my S1.5 I have the c-shaped “rear caliper mounting adapter plate” (p/n C22859) that has three holes for bolting it to the differential, and two threaded bolt holes for attaching the brake caliper to the adapter plate. The three bolts that hold the plate to the differential have holes for safety wire, as do the two brake caliper bolts. I believe the three adapter plate bolts should be safety-wired together, and the two brake caliper bolts should be safety wired together. Will someone confirm that my understanding is correct? I ask because these bolts were not safety wired that way when I removed them, the manuals I have are unclear, and I’m wondering what’s correct. After some of the reading I’ve done, I suspect the safety wire may be belt-and-suspenders anyway, and all the bolts were tight during tear down, but I figured the holes were there for a reason and I was looking for some experience.
I have never safety wired before - I’ve read a bit on this forum and watched some videos on the internet. After several hours (3?) and several feet (4-5?) of safety wire, I have a newfound respect for it!! Below is where I ended up after my third(?) attempt at wiring the three adapter plate bolts together. I knew this particular wiring job was going to be difficult (three bolts, difficult access) but I wanted to give it a shot. I’m a bit humbled now!
I’m asking for feedback from knowledgeable members on how my wiring job looks. Is anything wrong/questionable, or is there a different approach that would offer a better result? I worked from the bottom bolt towards the top one and the pictures are in that order.
Looks good! You were an attentive student. 7-10 twists per inch and you even curled the pigtail, though technically you have the bottom wire on the top photo looped around the wrong side of the bolt head.
Carroll Smith, ex F1 mechanic and author of many books on car prep, famously said that safety wire was simply to catch loose parts on aircraft to keep the parts from falling out of the sky. As Carroll (and Wiggles) states, proper torque is the key to holding a bolt tight. That said, I add it in places like the OP is discussing simply because it is authentic.
@Aristides - thanks for that link! That video is one I’d stumbled upon and watched. I also found this one to be very helpful, and had a few tips that helped me get the wires tighter than I had on my first couple of tries - https://www.youtube.com/watch?v=grO_q4sDcjU
@mminnich, will you expand on this for me as I’m not sure I’m following. I did struggle with how to route the wire on the middle bolt of the three - is that the one you’re talking about? I also struggled with the very top bolt, which was the last one in the string of three - I barely left myself enough wire to work with and access with the pliers was difficult.
For all - so I’m assuming that the three bolts I’ve wired together is correct, and then the two brake caliper bolts should be wired to each other, once installed?
When I disassembled things I think a shortcut(?) had been taken in the past. The top and bottom caliper bolts were wired to the respective top and bottom adapter plate bolts, and the middle adapter plate bolt was left without wire. Some pics -
As I said, I’ll add safety wire to be period correct. That’s about all it’s good for. In Jaguar’s case, I suspect it’s a holdover from their aircraft background but even then, they certainly understood that torque is what held things together.
BTW I don’t want to come off as argumentative here. Generally speaking, the bolts we have discussed are primarily loaded in shear. As such, they will continue to do their job even if they loosen up a bit. But there will be some slop introduced and in the long run, damage will probably occur. A really experienced guy with safety wire can probably get enough resistance introduced into the wires to contain the rotation of the bolt head to a survivable amount. Most of us are not that good. Fortunately, if one applies proper torque and when appropriate, adhesives such as Loctite, then even this secondary function of the safety wire will never be called into play. So in effect, I approve of safety wire to make your car period correct but I would not sweat the details on your installation because at the end of the day, it really won’t come into play from a functional standpoint.
From a historical perspective, I know my Porsches from the 80’s have zero safety wire. I suspect sometime between the 60’s and the 80’s it fell out of favor. Also, from a mass production standpoint, it is very time consuming versus torque and adhesives.
For a really critical application, like rod end bolts/studs (and in my work life, reactor vessel head flange studs) you go a step further and measure the elongation of the stud as the primary load nut is rotated. This takes the “fuzziness” of the torque to tension relationship out of the equation.
You aren’t, so no worries there. And thanks for the perspective, it makes sense.
I’ve always wondered what drove Jaguar’s choice of what to safety wire vs. what not to. The big end trailing arm bushings always seemed to be an odd choice to me.
I have always held that Jaguar’s fascination with safety wire was a fealty to older aviation engineering practices: I think Harvey makes a good point.
If one needs be “period correct,” and safety wire on all that was from the factory, that’s fine, but its lack will not necessarily lead to crap falling off the car.
Lock wire or not Hmmmmm
As mentioned earlier jags came from the aviation designers and they used lock wire labour was cheap and they didn’t have lock tight
Now at 150 mph you don’t want things coming undone , remember jags came from the race world and they didn’t up date the manuals
I use lock wire in the aviation world so my rear end gets it cams too, per manual because I don’t want to revisit it
Jack car ,Remove exhaust, lower rear end and what damage is done
As mentioned it’s period correct and looks good when done correctly it takes practice
I don’t like to use lock tight I have enough trouble getting bolts out
There’s a lot of discussion about new cars not using it
I don’t know any cars that have lock wired oil filters …but I don’t know any airplanes that don’t have lock wire filters because they don’t want to be that one in 10 million
On the front end it’s easy to see easy to get at but I do it for cosmetics shows attention to detail
Couple of tips to help
The lock wire should be tight like a guitar string tap it like a tuning fork ,8 turns / inch ,twisting one way then opposite on the other side of the bolt
To get it tight make a circle motion as you pull it from the bolt head . 032 is the standard lighter wire is used on accessories and heavier on something like a prop you bend the finished ends over so you don’t cut your self the finished end is easier if longer and needle nose pliers help
Just my 2 cents
Cheers jagjim1
As a Helicopter Crew chief and Mechanic, we safety wired most everything… so on my Jag, I safety wire everything… Safety wire pliers help a lot, and practice helps… hated it when the tech inspector told me the wire was too loose, or had plier serrations, and I had to redo the safety… you learned to do it right the first time…
Don
Part of my IRS build YouTube Play list is how to lockwire. It’s pretty dry, and my least watched video… right up there with the importance of thread filing and bolt repair.
