Delrin Bushing Size?

Dumfast

Well-Known Member
What is the typical size of a Trophy Truck lower A arm Delrin bushing?...They are typically a Nylon/Delrin type of thing right?...What size bolt also?....Thanks!
 

L&LMotorsports

Well-Known Member
The lower arm inner mounts seem to be all over the place in material and design. Some designs use a uniball inner mount, others use a traditional bushing design. At a minimum it would need to be a 2.250" .250 outer sleeve, 1.750" .250 delrin, 1" .250 inner sleeve, 3/4" bolt. You do not want to skimp on the inner sleeve wall thickness, it can compress/crush with the load of a 3/4 inch bolt torqued to 340 ft.lbs. Of course it will hold up better if you do not properly torque the bolt. :eek:

There are guys out there running oil impregnated brass which is what I believe we will end up with on ours, we are also planning to put an o-ring at the bushing/outer sleeve surface to help keep the dirt and dust out. Given the application delrin is cheap and would work it just requires alot of maintenance especially after the sleeve and bushing turn dry or full of dirt for a few hundred miles during a race.
 

FullsizeFun

Well-Known Member
2" x .250 wall outer sleeve, 1.125" x .188 wall inner sleeve, 3/4 bolt. Delrin Bushings. Kartek has these bushing assemblies ready to go.
 

Captain Air Time

Well-Known Member
2" x .250 wall outer sleeve, 1.125" x .188 wall inner sleeve, 3/4 bolt. Delrin Bushings. Kartek has these bushing assemblies ready to go.
How long does a Delrin bushing last in a high load suspension application, say compared to PU or rubber? or a SRE/uni?

I can see the beneft of the precise location, but curious about the wear characteristics. Maybe OK for a race-maintenence schedule, but not so hot for a play/road going car? Cheap and easy replacement is awesome for a race car, but might be too labor intensive for a 'rode hard and put away wet' play-mobile... ?

Is it noticeable harsher in shock transmission than polyurethane/rubber? softer/quieter than a solid bearing type connection?
 

Dumfast

Well-Known Member
Thanks for the info...I currently have 3/4"x3/4" Hiems with 1/2" bolts(not my design)...Always knew I would have to upgrade to something stronger.
 

joe1369

Well-Known Member
The 3/4" x 3/4" heim does not seem to be a major issue for me. Try to find a 3/4" x 3/4" high misalignment heim ( it has misalignment spacers built in) and use a 3/4" bolt, or at least use a misalignment spacer that reduces to 5/8" bolt size minimum, but have fun changing bolts, because that misalignment spacer usually breaks at the smallest point and pinches down on the bolt like a chinese finger torture devise. You have to beat the bolts out. JMHO:)
 

Dumfast

Well-Known Member
You bring up an interesting point..I was thinking the 3/4" hiem was not strong enough but if the bolt is the problem, I could just remove the 3/4" to 1/2" spacers and run a 3/4" bolt with some big 3/4" spacers..Its bolting the A arm to the chassis and has no need for the mis-alignment spacers...3/4" hiem is strong enough?...This is a truggy with a weight of 4000 to 5000 pounds when finished
 

joe1369

Well-Known Member
You bring up an interesting point..I was thinking the 3/4" hiem was not strong enough but if the bolt is the problem, I could just remove the 3/4" to 1/2" spacers and run a 3/4" bolt with some big 3/4" spacers..Its bolting the A arm to the chassis and has no need for the mis-alignment spacers...3/4" hiem is strong enough?...This is a truggy with a weight of 4000 to 5000 pounds when finished
I think the 5000 lb experts need to chime in here. Thats a lot of weight, and probably a 60/40 split front to back on the weight??? 3/4" might be on the margional side, but you have 1/2" bolts now, have you had any bolt breaking issues???? If not I think your good. Worry about it once you break something. I know, not the safest answer, but I am looking forward to a truck/truggy expert to chime in.;)
 

Dumfast

Well-Known Member
I think the 5000 lb experts need to chime in here. Thats a lot of weight, and probably a 60/40 split front to back on the weight??? 3/4" might be on the margional side, but you have 1/2" bolts now, have you had any bolt breaking issues???? If not I think your good. Worry about it once you break something. I know, not the safest answer, but I am looking forward to a truck/truggy expert to chime in.;)
It is a ways from being finished...It has never seen dirt...When I got it, all that was done was a bare cab cage and front arms with single shear uprights...I am currently making some more traditional trophy Truck type spindle/uprights and was concerned about the A arm hiems...It will be alot closer to a 50/50 or 45/55 front to back weight split
 

Captain Air Time

Well-Known Member
Well, a 1/2" grade 8 bolt if memory serves has approximately a 12000 LB sheer strength. 3/4" should be around 30K (somebody correct me if thats wrong) I've never calculated loads on A-arms before, but I've done quite a bit on 4-link rears, and for that weight vehicle I would guess load values to be considerably less than 12000 B, but perhaps not enough to satisfy specific requirements for margin of safety. If you are redoing everything anyway, I'd definitely step it up to at least 5/8". FWIW the '08 Ranger I just pulled apart had 5/8" LCA bolts. I was surprised (thought they'd be in the 1/2" range), but its an indication that 3/4 on a more abused vehicle wouldn't be overkill. On the other hand, OEM's have crazy margins built in...
 

joe1369

Well-Known Member
Well, a 1/2" grade 8 bolt if memory serves has approximately a 12000 LB sheer strength. 3/4" should be around 30K (somebody correct me if thats wrong) I've never calculated loads on A-arms before, but I've done quite a bit on 4-link rears, and for that weight vehicle I would guess load values to be considerably less than 12000 B, but perhaps not enough to satisfy specific requirements for margin of safety. If you are redoing everything anyway, I'd definitely step it up to at least 5/8". FWIW the '08 Ranger I just pulled apart had 5/8" LCA bolts. I was surprised (thought they'd be in the 1/2" range), but its an indication that 3/4 on a more abused vehicle wouldn't be overkill. On the other hand, OEM's have crazy margins built in...
I think the issues start when things start to looses up, of they do, bigger is better, my 2800 lb car broke (2) f911 1/2" lower a- arm bolts, but they were, or came loose, switched to 5/8" big difference in clamping force etc, its all good now.:D
 

GregFoutz

Well-Known Member
How long does a Delrin bushing last in a high load suspension application, say compared to PU or rubber? or a SRE/uni?

I can see the beneft of the precise location, but curious about the wear characteristics. Maybe OK for a race-maintenence schedule, but not so hot for a play/road going car? Cheap and easy replacement is awesome for a race car, but might be too labor intensive for a 'rode hard and put away wet' play-mobile... ?

Is it noticeable harsher in shock transmission than polyurethane/rubber? softer/quieter than a solid bearing type connection?
A good delrin bushing will last you a long time. Typically longer then a spherical bearing will. We have seen the larger bushings like this last for almost a whole season of races (4 or 5 races) without wearing to the point of needing to be replaced. Also the surface area on the delrin bushing helps with keeping the bolts from bending. We always use them on the lower A-arm and then heims on the uppers so you can adjust a little for the camber, caster stuff. Everyone has good points on the bolt stuff too, but we end up with 3/4 bolts due to the fact that we have seen bending and shearing in 5/8 and less. Its the heavy hit accidental slam into a rock or big hole on the one wheel that spikes up and damages this type of thing. Even when the bolts are tight sometimes we would see the heads shear, just pop off the shaft of the high quality bolts. With the 3/4 overkill bolt you dont see it. So I guess we dont really know how much load ends up on one of those in a 100 MPH hit like that. Not sure if anyone has been able to really measure that well??? Anyone??? We are using a 2.25" Delrin bushing in our new TT stuff. The Swift 7200 Ranger has a delrin bushing too.... Anyway....
 

Captain Air Time

Well-Known Member
So I guess we dont really know how much load ends up on one of those in a 100 MPH hit like that. Not sure if anyone has been able to really measure that well??? Anyone??? We are using a 2.25" Delrin bushing in our new TT stuff. The Swift 7200 Ranger has a delrin bushing too.... Anyway....
Yeah, hitting ANYTHING at 100+ MPH has to leave a dent; it is preferred to leave it in the obstacle I guess :p
 
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