rack and pinion bushings - I made some

[supernova_6969]

*admins, please put this where you think it goes. this was the best section I found for it....

 

Hi guys. 

 

So.  last year, I changed my front suspension.  and as I foolishly turned the wheel hub by hand (with a lot of strenght to overcome resistance), making the rack and pinion move as I did that and and one of the rack and pinion seals blew.  

Fast forward to this year (cause I'm lazy and didn't do it during the winter), I took the rack out and am rebuilding it.  As I did that, I realized my passenger side rack bushing, which has been copiously bathed in engine oil for years, was shot.  All mushy and broken.  

 

And just my luck, they don't really sell them anywhere, or if they do they charge an arm and a leg for it.  or it's just the driver side.  or... whatever.

 

So I made one!

 

Here is the crummy one next to the brand new one. 

 

 

 

I used the measurements from the rack, the old bushing and the bracket that holds the rack in place to 3d design mold, 3d printed it, greased it up with petroleum jelly, and some (not all tha tmuch, actually) 3M windshield urethane (high viscosity, which cures a little harder)... 

 

Here are some more shots of it, including fitted on the rack, and with the bracket that holds the rack on..  I'd say the hardness is right on par with the other side's bushing which is old but still looks healthy.  Yes the surface finish is a little rough, but it's sound..  I'm happy with it. 

 

 

 

 

 

 

 

I'll be putting it back on the car as soon as I motivate my sorry ass to put the rack and pinion back together (btw, used a 55 CAD$ kit, that came with almost all the seals (all the important ones, really), and that worked really well. it's not hard at all following the FSM manual).  I'll make certain to wrap it really well in some plastic or another to try to keep the oil off of it (yeah I know I should fix the leak).

 

If I'd have to do it again, I'd try the lower viscosity urethane as this one was a b*tch to get out the tube...  if I'd live in the states, I'd buy some pourable 2-part urethane and simply pour it in, but there is none around me, at least not in reasonable quantities at a reasonable price.  THAT would be a dream to use...

 

This technique can be done for the other side as well, or any other similar bushing.  if anyone is interested I can post pictures of my mold (4 parts), and even share the 3d files.  Keep in mind that this bushing is bigger than the driver side (I have the files for 3d printing the other one too) and won't fit older models.    Making a new model for a mold for any sort of similar part is a pretty quick affair and printing one in this size was about 6$s worth of plastic.   I can also make and sell some, if anyone is in need of one.

 

Questions welcomed. 

 

have a good night!

 

s.

[supernova_6969]

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[calZ]

I have a 1972, but I'd still love to see pictures of the molds. What material did you print them in? 

[supernova_6969]

hi!

 

I printed it out of PLA, with 5 walls and 30% infill.  the 5 walls were probably overkill.  there wasn`t much pressure even pushing the center in, and the mold is SOLID.

 

Here is an image of the cross section  of the mold..  there is also a center plug and a tiny plug that sticks in the side, to create hole in the part that sticks out.  

 

here is all the parts, including the bolt that I used to squish the center in...

 

 

essentially, since I wasn't pouring in material, I was injecting very slowly and painfully from a caulking gun, I slightly filled the bottom ridge (to avoid voids), then a ring around the bottom 1/3 in both halves (leaving the center part mostly empty, to be filled with the center plug) , like this: 

 

 

Then I put matted the two halves, put them in a vice (the holes on the side, with the square projections, are for nuts and bolts to hold the mold together, but ended up being too small) and pressed in the center bit in from the top, by hand at first, then finished it with the big bolt, through the center (with a nut under).  that squished all the material up, filling almost all the mold without any voids.   

 

It would look like this (but filled and with a bolt running in the center, vertically):

 

 

(the screws on top were for pulling the center out after it cured... it didn`t help actually, I wiggled it loose)

 

After that, I pushed in the side plug (push then screw in the center plug) and filled the top from above.  it worked out really well, with minimal waste.. 

 

I hope that's somewhat clear.  if not, let me know what part isn't, and I`ll edit it to make sense.

 

Edited August 28, 2021 by supernova_6969