PST or Bergman LCA bushings and pivots?
- Thread starter Mojoe9955
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Pshas192
Active Member
Peter Bergman of BAC is hands down the best source for information, advice and parts.
Peter worked with me on my 1972 Duster 340 four speed. He designed, built and sourced my Viper braking system, suspension design, steering system, engine components and many other components. He understood I was building a “Day 2” look with excellent drivability and performance and he nailed it!
He returns calls and emails immediately! Peter’s knowledge gave me confidence as he navigated me through my build. He would not let me fall into the trap of buying unnecessary parts and components. He is my go to guy!
Don’t waste time on any other vendor, speak to Peter Bergman. He is the best Mopar vendor period!
Paul Shastany
Peter worked with me on my 1972 Duster 340 four speed. He designed, built and sourced my Viper braking system, suspension design, steering system, engine components and many other components. He understood I was building a “Day 2” look with excellent drivability and performance and he nailed it!
He returns calls and emails immediately! Peter’s knowledge gave me confidence as he navigated me through my build. He would not let me fall into the trap of buying unnecessary parts and components. He is my go to guy!
Don’t waste time on any other vendor, speak to Peter Bergman. He is the best Mopar vendor period!
Paul Shastany
What is the plan with the car? Tall tires in back? I would use old stuff that is in good shape, although I have had good experiences with both of those venders. I have PST 20:1 steering box and Bergman pins/delrin.....but i have yet to run the car down the street.
@72bluNblu
@72bluNblu
I recently rebuilt the front suspension on my Duster and one of the new rubber Moog LCA bushings is somewhat squished/distorted for some reason. I'm going to replace it and get some bigger torsion bars while I'm at it. I added late model disc brakes and a Hellwig sway bar, but that bushing seems to affect the suspension, especially when hitting a bump as it seems to "slide" so I want to clear it up. Right now I have 15" wheels and a 318, but when it comes to cars you never know what's in store... maybe a 360 Magnum and some 18" wheels. I think the pst torsion bars are priced right and they have a pretty deal on the lca stiffening kits that include the poly bushings and pivots. I have 6 decent piviots so technically I just need the bushings and am just wishy-washy about the poly versus delrin.
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In your original post, you talk about "uca" and "pivots". The only place that has pivot pins in the LOWER control arms, so lets make SURE of what you're talking about here.
Ok, that's the LOWER control arm pivot pin and bushing, not the "UCA" as you originally mentioned. I also cannot recommend Peter Bergman enough. I've spoken with him a couple of times regarding the pivot pins and his delrin bushings and that's the direction I'm going.
Happens to the best of us. I wasn't trying to nitpick. I was trying to make DAMN SURE you got the right advice.
So you’re looking at a couple of differences between the polyurethane and Delrin LCA bushings.
The poly bushing material is a little softer. But it must be lubricated, otherwise it will squeak and degrade. Keep it lubed and it will last forever. The poly bushings will also install into the old LCA bushing shells. That can be good, it saves you from removing the old outer shells. But, the bushings must be a tight slip fit into the outer shells. If they aren’t, well, you need new outer shells and the advantage is lost. For poly I also recommend using greaseable pivot pins, so you can add grease without pulling the suspension apart.
The Delrin bushings from Bergman Autocraft are harder than poly, so even less deflection for more accurate suspension inputs. But less cushion than even the poly bushings. They’re self lubricating, so, other than the initial lube to install them they shouldn’t need service again, unlike the poly. They also take the place of the original outer bushing shell. So, you have to remove the old shell but don’t have to worry about it’s tolerance with the new bushing. They don’t need to be lubricated, so in theory you could reuse your original LCA pivot pins. But because Delrin is so hard, the fit of the pivot pin into the bushing is CRITICAL. It has to be a tight slip/loose press fit. Any end play will be play in the LCA, and despite the hardness of the Delrin it will cause premature wear.
I have run both poly and Delrin on my cars on the street. I honestly like both, but the poly has to be lubricated periodically. The Delrin is a little more work on install and the fit is a bit more critical. I honestly couldn’t say there’s any more road noise with the Delrin vs the poly. In theory there should be, but with good shocks I can’t say it’s something that I really noticed when I switched from poly to Delrin.
The poly bushing material is a little softer. But it must be lubricated, otherwise it will squeak and degrade. Keep it lubed and it will last forever. The poly bushings will also install into the old LCA bushing shells. That can be good, it saves you from removing the old outer shells. But, the bushings must be a tight slip fit into the outer shells. If they aren’t, well, you need new outer shells and the advantage is lost. For poly I also recommend using greaseable pivot pins, so you can add grease without pulling the suspension apart.
The Delrin bushings from Bergman Autocraft are harder than poly, so even less deflection for more accurate suspension inputs. But less cushion than even the poly bushings. They’re self lubricating, so, other than the initial lube to install them they shouldn’t need service again, unlike the poly. They also take the place of the original outer bushing shell. So, you have to remove the old shell but don’t have to worry about it’s tolerance with the new bushing. They don’t need to be lubricated, so in theory you could reuse your original LCA pivot pins. But because Delrin is so hard, the fit of the pivot pin into the bushing is CRITICAL. It has to be a tight slip/loose press fit. Any end play will be play in the LCA, and despite the hardness of the Delrin it will cause premature wear.
I have run both poly and Delrin on my cars on the street. I honestly like both, but the poly has to be lubricated periodically. The Delrin is a little more work on install and the fit is a bit more critical. I honestly couldn’t say there’s any more road noise with the Delrin vs the poly. In theory there should be, but with good shocks I can’t say it’s something that I really noticed when I switched from poly to Delrin.
jos51700
Green Bearing thread connoisseur
I used polyurethane on mine. I've done extensive design work with delrin and a few other plastics and I wanted to have SOME give in the suspension. I don't want every little bump and jolt transferred to the rest of the car.
Besides, I've seen delrin fracture, especially when cold, and I didn't like the idea of that in an application that sees....impacts.
Besides, I've seen delrin fracture, especially when cold, and I didn't like the idea of that in an application that sees....impacts.
I mean, my experience is that as far as ride quality and vibration the poly and Delrin are very similar. It’s not like I installed the Delrin and suddenly noticed more road vibrations. I get the theory on it and the Delrin should transmit more. But from the real world? I didn’t notice any increase.
I’ve been running the Delrin LCA bushings for about 5 years now, and that definitely includes driving in sun freezing temperatures. Haven’t had any issues so far. I know Peter has been running his a lot longer!
Thanks you. I already removed the outer bushing shell from the control arm so the poly might not be my choice. That said, I think I'll get the BAC kit with bushings and matching pivots to insure a good fit, provided there are no issues with the control arms.
I use the plates too, I just add an additional strap across the back so it keeps the halves of the LCA from spreading right at the pivot lever. The plates help with the torsional rigidity and flex on the body of the LCA.
You can’t see the plates on the bottom, but they’re there. I made my own plates but they look the same as the ones you can buy.
@Jim Lusk has a great video of how to repair and improve the LCA’s
ESP47
Well-Known Member
Did you tighten the nut on the pivot before lowering the car to the ground? I tightened everything on my first suspension rebuild before I lowered the car on the ground and I wound up having to redo my UCA and LCA bushings because they only lasted a month or two. Left everything loose the next time and torqued while the car was sitting on it's own weight and everything has been fine since.
The plates I see are both different. Yet the ad's mention a pair. Are they side specific or is there one for the top and one for the bottom?
I have the skills and tools, so I'll probably make my own as well.
I have the skills and tools, so I'll probably make my own as well.
Yup, that will tear the bushings. The rubber only has so much flex, and since nothing spins all the suspension travel is flex in the rubber bushings. So ride height has to be the neutral position, so half the flex is compression travel and half the flex is extension travel. Tightened with everything hanging all the flex is in one direction, and that's more than the rubber can flex.
With poly or Delrin bushings the bushing rotates on the LCA pivot pin, so, you can torque them with the car in the air, it doesn't matter at all.
The plates just go on the bottom, and they are identical side to side. You can see the install process in Jim Lusk's video, and in this article from Motor Trend
Tips and Tricks for Rebuilding Lower Control Arms
The holes in the plates don't all have to be ovals either. The one for the torsion bar bolt should be an oval because of how the adjusting plate and bolt can rotate a little bit in that half moon mounting hole. So it's easier to not run into interference issues if that first hole is an oval. The middle hold can just be round, it's only there so you can get to the nut for the lower bump stop. As I recall the outer hole is just there so they can be flipped/reversed, the only thing behind it is the rivet and forged piece for the strut rod and ball joint end. You may want a hole there just so it doesn't collect road debris, but it doesn't need to be an oval. So the outer two can just be a step drill or hole saw operation.
Oh, the upper plates in that picture are for the ‘73+ B bodies.
The lower plate in the picture is the A body plate, you should have 2 of the same.
So as a result of a call to Peter at BAC I ended up getting the delrin LCA bushing and pivot kit. I called to ask about using my old pivots, which is possible, but as he explained that you need to leave the bushings inner metal shell on the pivot which is interesting, as you have to remove the bushings outer shell from the arm to use his bushing. As I mentioned earlier it was as he said a tolerance issue and was better safe then sorry to order the complete kit.
I also ordered his LCA stiffening plates which I thought of making my own but at $30 bucks a pair, you can't go wrong, as buying the material and even though I'm retired if you factor in my old union labor rate it would probably would cost almost 10 times that much to fab my own and will look much cooler with his CNC cut logo on them. Once I looked at it like that, I decided to get some adjustable strut rods, which he recommended using the money, I technically saved on fabbing
the plates. So it was a win/win for both of us as all you guys said "he's a good guy and asset to our hobby" ...Thanks Peter
I also ordered his LCA stiffening plates which I thought of making my own but at $30 bucks a pair, you can't go wrong, as buying the material and even though I'm retired if you factor in my old union labor rate it would probably would cost almost 10 times that much to fab my own and will look much cooler with his CNC cut logo on them. Once I looked at it like that, I decided to get some adjustable strut rods, which he recommended using the money, I technically saved on fabbing
the plates. So it was a win/win for both of us as all you guys said "he's a good guy and asset to our hobby" ...Thanks Peter
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Poly and delrin a two totally different materials. Delrin is superior due to increased stiffness, longevity and they are quiet.
I have an update on my front end upgrade. The parts I ordered late Monday morning arrived sometime Wednesday afternoon, so first I want to give BAC and PST kudos on there amazing customer service. Knowing I wanted to do this upgrade I picked up a pair of lower control arms at a swap meet for $20 and had them stripped and ready to go. On Wed evening I welded the plates on and hit them with a couple coats of paint and in the morning cleaned up the over-spray and pressed in the BAC bushings...so much easier than rubber bushings with metal sleeves. I got both sides apart, cleaned up and had one side put back together yesterday and this morning I spent a few hours finishing up.
First thing I noticed was that the the car sat visibly higher, measuring from the floor to top of the wheel well it 2.5 inches on the left and almost 3 on the the right. I took it for a ride and noticed a big difference in how it handled...much better but a little squirrley. When I got back it had settled down quite a bit, but the right was still higher so I let it down some and measuring from the top of the wheel well to the centerline of the wheel I had 15.5 inches on both sides, before I started the job I was 14.25.
l drove it again for about 15 minutes, giving it a bit of a workout...WOW what a difference. I'm impressed.
Using the adjustable strut rods I didn't think to measure them while putting them in and adjusted them until all the slack in them and the LCA's was gone. When adjusting the ride height I noticed the left side was about an inch longer than the right.
The ride is great and visually the wheels are centered in the wheel wells front to back within .25" +/- . The gap up top is huge though! I had a little toe-in and some caster which appears to be still there although there is a a noticeable difference from side to side. I have the UCA's with stock bushings, set all in on the back and all out on the front as before. Can the different length strut rods be affecting that?
The ride is pretty firm but not harsh on the bumps, the car tracks straight, doesn't pull, and corners great. I'm just trying to figure out what to do next to fine tune it, especially when it comes to the strut rods. Thanks
First thing I noticed was that the the car sat visibly higher, measuring from the floor to top of the wheel well it 2.5 inches on the left and almost 3 on the the right. I took it for a ride and noticed a big difference in how it handled...much better but a little squirrley. When I got back it had settled down quite a bit, but the right was still higher so I let it down some and measuring from the top of the wheel well to the centerline of the wheel I had 15.5 inches on both sides, before I started the job I was 14.25.
l drove it again for about 15 minutes, giving it a bit of a workout...WOW what a difference. I'm impressed.
Using the adjustable strut rods I didn't think to measure them while putting them in and adjusted them until all the slack in them and the LCA's was gone. When adjusting the ride height I noticed the left side was about an inch longer than the right.
The ride is great and visually the wheels are centered in the wheel wells front to back within .25" +/- . The gap up top is huge though! I had a little toe-in and some caster which appears to be still there although there is a a noticeable difference from side to side. I have the UCA's with stock bushings, set all in on the back and all out on the front as before. Can the different length strut rods be affecting that?
The ride is pretty firm but not harsh on the bumps, the car tracks straight, doesn't pull, and corners great. I'm just trying to figure out what to do next to fine tune it, especially when it comes to the strut rods. Thanks
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