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Polyurethane bushing grease fitting install

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  • Polyurethane bushing grease fitting install

    I took a few pics when I was out working on the car today to try to throw together a basic install guide for grease fittings on poly bushings. Any criticism and comments are welcome before I throw this up on freshalloy/zilvia.


    In this picture you can see the center groove of the bushing. You're going to drill through the arm and into this groove.



    Mark the arms/spindle while they're installed on the car to find the easiest access to the grease fittings and to make sure the fittings won't interfere with anything when the suspension moves through its travel.



    Find the distance from the edge of the bushing to the center groove. You can use almost any small object to get the distance. I used a caliper.



    You don't need an actual number for the distance. Just take the distance you measured and hold it up to the area you marked on the outer shell of the arm.



    I scribed a small line in the paint with my punch.
    Jordan Y.
    1991 240SX Coupe

  • #2

    Punch an indent into the arm to start the drill bit and keep it from walking.



    Small indentation punched into the arm.



    Drill through the arm trying to keep the hole as straight as possible. When you hit the bushing drill through it until you drill into the center of the bushing where the metal sleeve goes. The size of the drill bit you use depends on the tap and grease fittings you're going to use. I used a 13/64" drill bit instead of the #3 bit my tap specified.



    Picture of the hole. I managed to walk the drill bit over a bit despite punching a starting point because I hit some weld splatter from the factory weld. If you suck less than I do you should have a nice round straight hole.

    Flossing a shop towel through the bushing did a nice job of clearing out grease and poly shavings.



    Clear any remaining poly around the drill hole.
    Jordan Y.
    1991 240SX Coupe

    Comment


    • #3

      You have to give the grease somewhere to go or it just squeezes out between the outer surface of the bushing and the arm's inner sleeve. I decided to cut spiral grooves leading from the bushing's center groove to the outer grooves. This idea was based on the design of a Delrin bushing set my friend just bought for his 99 Cobra which came with grease fittings and had similar grooves. Grooves shown in third picture

      I tried to make the grooves as narrow as possible and about as deep as the factory grooves, but it can be hard to be that precise using a Dremel with a small drill bit. Try to make the two grooves about the same size so that grease doesn't just flow out the path of least resistance. I started the grooves from different starting points on the center groove keeping them away from the hole I drilled- the idea being to make the grease fill the whole center groove before moving out through the spirals. I tried to make the spiral cover as much of the circumference of the bushing as possible without going all the way around- again, just trying to get more surface area covered without compromising the bushing structure (and the stiffness you upgraded for in the first place).



      Picture of the grooves. Mine were sloppier than I'd like- I've been sick and on meds and it seems one of the side effects of either the cold or the meds is a hand tremor which made the Dremel work even tougher.



      Two different lengths of grease fittings. I originally tried using the longer ones and just threading them in halfway, but it stripped out when I tried to pop the grease gun off the fitting. You need the shorter one that you can thread in all the way flush for strength without going in so far that it interferes with the metal sleeve. I used the longer ones in the front LCAs because the bushings were thicker and I could thread them in farther (need to take pic of fittings on installed LCAs). I also intend to use the longer fittings in the rear uprights which have much thicker walls than the arms. You want the fitting to protrude into the hole you've drilled through the bushing so the grease goes into the center of the bushing, but you don't want it in so far that it could contact the metal sleeve when the bushing compresses. I don't know how much poly can compress so I tried to keep a good 1/8" clearance or more.

      I got my fittings from Amazon Hose in Tampa. The long ones were 1/4" -28 Thrd Straight (Long) part# 1652B, the short ones were 1/4" -28 Thrd Straight Short part# 1641B. They were $.15-20 each.



      I got a 1/4"-28NF tap to get some threads started before trying to thread the fitting in. I got the front LCAs and the first attempt on the rear to thread in without a tap just drilling a 13/64" hole and threading the fittings in while pressing down steadily on the wrench. You might get away without the tap here but I figured that when it came time to do the upright bushings the tap would become necessary.

      Tapping this hole was a PITA. I think it was because I walked the drill bit a bit and didn't have a perfectly straight hole, but the tap did not want to go in straight. I finally got it to bite and got my two threads in the thin metal of the arm.



      Once you tap the arm thread a grease fitting all the way in. Pick a grease fitting length based on the thickness of the metal and the bushing. I used the short fitting here. It's better to have the fitting threaded in all the way for strength. It takes a good bit of sideways force to disconnect the grease gun, and when I initially tried using the longer fittings threaded in halfway the fitting stripped out before it popped out of the gun . On the other hand, I used the longer fittings threaded in about 3/4 on the FLCAs and they worked fine.

      My recently acquired 20-ton press makes the sleeve install easy . You can probably remove and reinstall the sleeves by standing on the arm or even by hand depending on how tight yours are in there and how dry they've gotten (bind city and the reason for installing these fittings in the first place). Grease the sleeves a bit to help them slide in easily.
      Jordan Y.
      1991 240SX Coupe

      Comment


      • #4

        Picture of the grease fitting installed on the arm.



        I found that if you dab some grease on the fitting before popping the grease gun onto the fitting it makes it a lot easier to disconnect the gun when you're finished. This is important because the arm metal is thin and if you put too much force on the fitting you can rip it right out of the arm. I did this twice when I was trying to use the longer fittings threaded in halfway. Very annoying.



        Now that it's all together pump grease into it until it comes out both sides. The grease should be coming out between the metal sleeve and the inner circumference of the bushing. If it's coming out between the outer circumference of the bushing and the arm, or from the threads on the grease fitting you probably need to cut your spiral grooves deeper. Push the metal sleeve back out and see where the grease was going and where it was getting blocked.



        A bit more pumping and grease started coming out the other side. Obviously I didn't cut the grooves exactly the same and it was easier for grease to go out the other side. It started coming out one side first but a few more pumps got a bit to come out the other side. Ideally the same amount would be coming out at the same time but that's probably too much to ask from rough freehand cuts. If I have to waste a bit of grease to make sure both sides get a fresh coating, so be it. If no grease comes out on one side even after repeated pumps you need to go in and cut the groove deeper on the dry side. You can see where the grease is being blocked and go a bit deeper from that point on.
        Jordan Y.
        1991 240SX Coupe

        Comment


        • #5
          The grease I used is Lubrimatic Water-Resistant Marine Bearing and Bushing grease from pretty much any hardware store. It was the only recommendation I could find for automotive applications- I did a search on forumdig.com and the Jeep guys were the only ones discussing grease to use on suspension components. Well, there were a few posts on honda-tech and NASIOC on the subject of installing grease fittings, but nothing conclusive as far as which grease to use. I guess I'll take a pic of the tube of grease.

          That pretty much covers it. I suppose some pictures of the FLCAs and other arms installed would be nice, so I'll try to take some when I finish this PITA job. Probably need to take pics when I do the upright bushings depending on how different it is going through the thick iron. Again, any comments or criticism are welcome, both on the guide and the actual install itself.
          Jordan Y.
          1991 240SX Coupe

          Comment


          • #6
            Nice writeup! I really wish I bought some poly bushings for my LCAs (cheap and effective), but I've been putting it off since they'll just be replaced by heims this winter.

            Comment


            • #7
              WOW, you took a lot more time then I did! Good work! I just eyeballed it and didn't bother to tap the holes. And yes the uprights suck balls! Mainly because there is no nice flat area on the bushings for the toe arms to install the fittings, so you have to grind a flat.
              function > form
              1990 240sx fastback: IN PROGRESS

              Comment


              • #8
                Just a bit of an update; I'll consolidate everything before I cross-post this, after the job is done.


                I had a hard time getting good cuts with the drill bit at an angle on the regular bushings, but on the narrower and longer RLCA bushings it was even worse. I ended up with cuts deeper, wider, and more inconsistent than I liked. Probably not bad enough to affect functionality but annoying. I sat there looking at them and thought "Gee, I wish they made some sort of small 90 degree cutting wheel for softer materials." Then I realized that they probably did, and they do.

                I still haven't tried this sucker out yet, but it looks like it should make cutting the grooves much easier and faster with a much better result. If it works as well as I think it will I'll consider it a must-have tool for the job.



                Side view.



                I thought the upright would be harder to deal with but it was just as easy or easier than the arms. Took longer to drill through, but it had more meat to work with which actually made it easier to tap and thread the fitting into.



                Finished product. I used the longer grease fittings for the upright which should protrude into the bushing slightly if I've eyeballed it right, which should help get the grease where it needs to be.



                All the arms on one side are done. Just have to get out and finish up the upright, which hopefully should be cake with the new Dremel cutter, and it'll be ready to bolt back into the car.


                I figure I'll take maybe one or two more pictures using the new bit, and I'm going to try doing the bushings for the other side before I press them in. Only concern there is reducing their strength before forcing them through the holes with the press, but I'll give it a try on one or two and see how it goes and if it makes the whole process any easier. After that I'll get everything installed and get the car aligned and hopefully all the work I've been doing over the last two months will be worth it.
                Jordan Y.
                1991 240SX Coupe

                Comment


                • #9
                  If you're going to do this job you NEED that Dremel bit. It made it 10x easier and gave 10x better results. Then on top of that, doing the cuts before installing the bushings made it another 10x easier and another 10x better. Do both and the cuts look almost factory. With these new cuts being so nice I highly doubt it will cause problems during the pressing process.





                  And that should pretty much be it other than a quick snap of the FLCA at some point. I really really wish I'd known about that cutter before I carved up the bushings in all of those arms, but I was going to replace those with heim joints eventually anyway, right?

                  Thanks again for bringing the binding issue to my attention and giving me the grease fitting idea in the first place. I'd be driving around cluelessly with more stiction than suspension if not for you guys. Now with a mere two weeks' worth of spare time I've given myself the ability (and obligation) to crawl under the car every few weeks to keep my suspension from seizing up and my rlcas from snapping, or whatever nastiness prompted the original discussion.
                  Jordan Y.
                  1991 240SX Coupe

                  Comment


                  • #10
                    Is it worth it to do the grease fittings? Does it prevent against suspension binding? I've been have quite a bit of trouble with my inside rear wheel lifting more lately.

                    Comment


                    • #11
                      Not a lot of info from people who've done it because there are not a lot of people who've done it. On this forum where the idea was proposed there's me and racepar and... that's it? Wish I could give you my take on it but I've been working on my friend's Cobra and not on my car.

                      The bushing companies have always said that you're supposed to grease the bushings regularly, but nobody wants to pull apart their suspension to do that. These things simply allow you to keep up with a regular maintenance item that has previously been neglected.

                      On the Cobra (which has a double-wishbone rear suspension, so not quite the same) too much resistance on the LCA bushings can cause "pogo-sticking" and can lift a wheel. Too much bind in the suspension and you no longer have a suspension, you have a girder.
                      Jordan Y.
                      1991 240SX Coupe

                      Comment


                      • #12
                        Several cars ago I had poly sway bar bushings. When the grease wore out and you went over a speed bump, the poly would actually squeak. That was pretty annoying. Grease fittings would have definitely worked there. I ended up wrapping the bar in teflon tape, which wouldn't really work in the uprights/arms.
                        She's built like a Steakhouse, but she handles like a Bistro.

                        Comment


                        • #13
                          Hmm, I was wondering because Ive heard mixed reviews about running poly bushins in the uprights. I dont exactly have $500+ to spend on 3 metal bushings. And I can do the grease fittings pretty easily. I think I might just do this and see how it works out. Im just trying to get rid of my rear tire lifting off the ground.

                          Awesome write up btw.

                          Comment


                          • #14
                            My poly bushings squeak right now and it has been less than a year since install. Definitely gonna do this mod over winter. Brilliant.
                            "To an engineer, the glass is neither half empty nor half full. It is twice as big as it needs to be."
                            '96 Nissan 240SX KA-T
                            '05 Grand Cherokee

                            Comment


                            • #15
                              That's the thing, on a budget this is as good as it gets. Some people like to leave the stock rubber bushings in there, but IMO there is too much flex in the rubber bushings. Everyone wants bearings, but not everyone can afford them. My next suspension project is making delrin sway bar to frame bushings and spherical endlinks for the stock sways. I'll also give another shot at drilling the front sway for just a bit of adjustability.
                              function > form
                              1990 240sx fastback: IN PROGRESS

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