There is a considerable dearth of performance bushings for my car of choice for this year's challenge, notably NO polyurethane bushings for anything except sway bar end links (because those are largely universal). But, since in I can get the stock rubber ones- I'm hoping to make my own poly bushings (and hopefully save some money along the way). I remember there was an article- or at least part of one- a little ways back about this, could someone point me to which issue it was in? Not that I don't enjoy flipping through my pile of old issues, but I also have a lot going on these days so saving me a bit of time would be good. Thanks!
As an alternative, I have filled the voids in stock rubber bushings with 3M Window Weld with good results.
Ive not had great success with window weld. It eventually worked itself out of the motor mounts that I had it in. Not sure if the failed OEM rubber I pushed the weld into was the culprit - just too weak to hold onto the urethane, or if the urethane itself was suspect. Either way, it didnt last too long in my last DD.
I have however had a lot of success with cutting up hockey pucks and using them for motor mounts. Some creativity and time with hand tools could probably yield other typed of bushings from puck material as well. Its vulcanized, fuel/oil resistant, dimensionally stable across a wide range of temperatures, cheap, and cuts easily.
IIRC, Swank Force 1 had just taped up the bottom of some mounts and poured 70A hardness liquid urethane into them to fill the voids. He said they held up well over time, and actually wished hed gone with 90A (Harder).
I'm going to be looking at using hockey pucks for some of the subframe mounting bushings that probably need to be replaced (I know at least one needs it). If I can use the pucks for one side and cast a poly bushing for the other it will save me a LOT over the $30/mount that getting them new would be (and there are 6 bushings on the front alone...).
I'll probably be looking at stiffening up the stock engine mounts by filling the voids with polyurethane as well, haven't gotten to that point yet.
A friend has used the Energy Suspension kit with good results. I think he had the factory part, so he used a bit of wet sand to make a mold of it, then put in a layer of cellophane before pouring in the poly.
I have done this as well. I have not had great success filling voids but making a completely new bushing with liquid urethane has worked. When you make one without voids it works better if you don't go to the stiffest compound. Without the voids the bushing will be "stiffer" even it the material used is as soft as OEM material. Remember air is not very stiff!
Pour your own materials
I have used several of these casting compunds (both urethane and silicone) with good results. If there is anything like a shell to pour the material into they work very well. They are very thin when mixed/poured so make sure whatever you seal the back/bottom of the mold with is water-tight. I usually pour the leftovers into a disposable plastic cup in case I need to make something on the lathe or mill later.
I have used this stuff primarily to fill round bushings with metal inner sleeves and they have held up to some pretty excessive abuse and heat. I even made a male/female die set for making carbon intake trumpets.
I have tried to make open blocks with metal internal linking for your typical Chevy/Ford engine mounts but had problems with the material peeling away from the metal too easily. Containing the material inside a shell is the easy solution.
In reply to stafford1500:
The stuff from McMaster is what I'm most likely to get (the ES kit looks interesting too, but I wish it said how much of it you got to compare the prices...).
These are the bushings I'm most interested in making in poly- they only come in rubber that I can find, and while the bar they go with (an uprated one from a performance Caddy package) is an improvement inherently, having stiffer bushings should help even more. Haven't decided if I want to try and make poly front bar bushings or not- there's an argument to be made that keeping the front softer on the Riviera would is advantageous.
In reply to Ashyukun:
It gives you the volume of finished material in cubic inches. The 25 in^3 size is basically a quart of material or enough to do a few of the bushings you listed. If it were me, I would make an outside mold of that shape at least 12 inches long and then place a sacrificial tube/rod in the center that is slightly undersized to your sway bar. Pour in the goo, let it set, and then hack saw the parts into the lengths you need. That should give you an extra set or two...
Making the outside shape will be the challenging part. Try using metal roof flashing (thin and formable). That way it can be peeled of the part after it cures. You could make a channel to get most of the shape and cap it wit a flat piece and tape the crap out of it to keep it from leaking.
Try not to de-mold it until at least as long as the time listed. You can clean up any leak/flash edges with a sharp knife.
Keep in mind it does shrink some (~1.5%) so make the mold just a bit oversized.
Preparation is very important for getting the window-weld to stick.
I had a local shop completely replace the rubber in my engine mounts with custom-cut pieces of solid urethane stock that are then pressed and glued into the mount. It's a bit harder than window-weld mounts but they're bulletproof.
Have you looked at the universal bushing catalog at the PolyBushings Website?
You might be able to use T bushings with some home made adapter pieces and the like.
In reply to stafford1500:
I saw that the McM-C ones list the volume- it was the Energy Suspension kit that I didn't see it for. I had been thinking of making the bushings along the lines of how they were done here, or trying to do it quick & dirty with wet sand and cellophane- but the flashing idea isn't a bad one. If I wanted to make more than just a few (say I were going to try and sell them) I'd go the fancy route and 3D print mold at the Makerspace I'm a member of.
There may be some things that the 'T' bushings from PolyBushings would work for, but I don't think they'd work quite right in this particular application.
Looks like the energy suspension setup is 400 ml (or 1 2/3rd cups, if that's your unit of choice).
sounds like one 25cuin kit will make 2 sets... and some left over to play with
