The Miata Bushing MEGAthread: Heirarchy, DIY delrin dimensions, info and discussion
#44
Well damn. For a little bit more than FM rubber how could I not get a delrin kit. I'll have an order in soon as I figure out exactly what I need.
Are the four bushings that aren't delrin included in the kit? I'm guessing they're rubber if they are, and the higher price up is for poly/bronze.
Are the four bushings that aren't delrin included in the kit? I'm guessing they're rubber if they are, and the higher price up is for poly/bronze.
#46
SadFab CEO
Thread Starter
iTrader: (3)
Join Date: Sep 2012
Location: your mom's house phoenix, AZ
Posts: 4,560
Total Cats: 1,142
Any races in the next 3 to 4 weeks? We can get just the offsets in there sooner, like this weekend, if needed.
#48
I'm doing the Pro East event on Feb. 20/21, then on the 22nd I'll check on the status of the coilovers and if they are on schedule I will just take all the control arms off the car and bring them over. The next "deadline" would be the NASA east event on March 5/6. Probably want to be ready to corner balance and align by Thursday March 3rd, so three weeks from now.
#54
SadFab CEO
Thread Starter
iTrader: (3)
Join Date: Sep 2012
Location: your mom's house phoenix, AZ
Posts: 4,560
Total Cats: 1,142
The Miata Bushing MEGAthread: Heirarchy, DIY delrin dimensions, info and discussion
No. I use 7/8" sleeves which is 22.22mm. 20mm is a decrease and would be to small for the camber locations. Also the OD should ideally be a bit bigger than 40mm to aid in the interference fit, and you would still need to drill out the bushings after pressing them in still anyway. Never mind the fact that they all have shoulders. I also doubt the ID of plastic tubing is held to any of sort decent tolerance.
Last edited by hi_im_sean; 02-14-2016 at 07:26 PM.
#55
Maybe this was mentioned in another thread, but why 863 bronze over 841? I realize 863 is stronger and has a higher load capacity, but doesn't the iron content make it prone to rusting? Is the extra bearing capacity necessary? I can't imagine any single bearing seeing even close to 1500 lbs. of load under hard cornering...a 1G (~2500lb) cornering load, even if all of it was directed through just the lower arm of one wheel would still be divided among roughly 4 bearings so the per-bearing load would be only 625 lb.
#57
SadFab CEO
Thread Starter
iTrader: (3)
Join Date: Sep 2012
Location: your mom's house phoenix, AZ
Posts: 4,560
Total Cats: 1,142
Maybe this was mentioned in another thread, but why 863 bronze over 841? I realize 863 is stronger and has a higher load capacity, but doesn't the iron content make it prone to rusting? Is the extra bearing capacity necessary? I can't imagine any single bearing seeing even close to 1500 lbs. of load under hard cornering...a 1G (~2500lb) cornering load, even if all of it was directed through just the lower arm of one wheel would still be divided among roughly 4 bearings so the per-bearing load would be only 625 lb.
It wont rust seeing how its oil impregnated and alloyed with copper. Periodic greasing with the zerks will also mitigate or eliminate any rusting that would occur.
Although static loads in cornering may not exceed bearing load, shock loads will. Rumble strips, pot holes, etc. Although im sure 841 would work without cracking in two, as leafy said, 863 will wear longer. Its only about $35 for the entire car to use 863 over 841.
#59
SADFab Destructive Testing Engineer
iTrader: (5)
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 18,642
Total Cats: 1,866
Delrin is very stiff, and also requires a lot of labor to machine (instead of just being cast like poly)
See the details about the bronze bushing conversion kit if you want to get rid of some of the binding issues with poly.
That being said 90% of track miatas run poly, and it performs perfectly fine, it just isn't the best solution
#60
So what about delrin bushings inside of the poly? If solid delrin bushings work with the bearing loads that these part see, then why wouldn't a delrin sleeve inside a poly bushing? You can buy tight tolerance 3/4" ID x 7/8" OD tubing (+/-.010") for $5 per foot, which is CHEAP!!:
McMaster-Carr
Or you could go with oversize tube and finish it to the necessary size if the above tubing proves to be too sloppy:
McMaster-Carr
Or you could go with igus bearings for $2.74 each in quantities of 50:
igusĀ® Plastic Plain Bearings: iglideĀ® J
I am considering these options along with stainless sleeves - possibly precision ground 440C or even 17-4 PH if I can successfully drill it.
McMaster-Carr
Or you could go with oversize tube and finish it to the necessary size if the above tubing proves to be too sloppy:
McMaster-Carr
Or you could go with igus bearings for $2.74 each in quantities of 50:
igusĀ® Plastic Plain Bearings: iglideĀ® J
I am considering these options along with stainless sleeves - possibly precision ground 440C or even 17-4 PH if I can successfully drill it.