Solid Pucks

[MoparKidD-4]

I know this thread is pretty old but I read through it and I'm surprised nobody mentioned using Delrin to make the "pucks" out of... super light compared to iron or aluminum and harder than polyurethane. Pretty sure it's cheap and easy to machine as well.

 

[89.Fifth]

I know this thread is pretty old but I read through it and I'm surprised nobody mentioned using Delrin to make the "pucks" out of... super light compared to iron or aluminum and harder than polyurethane. Pretty sure it's cheap and easy to machine as well.

The question is whether or not it's strong enough to take the impacts. Plus it's just not as known as more common materials.

 

[kkritsilas]

There are dimensional drawings of the pucks somewhere on the site, so anybody could make them up out of whatever material they chose.

I don't know how well suited Delrin is for this type of application. Polyurethane (some call it polygraphite for some reason, usually marketing) has been used for suspension pieces for a long time, and for probably thousands of different part types. I don't knkow that I have ever seen delrin used, at least for off the shelf suspension parts. might be something to look into, if just for the pucks. I don't have any access to any machine shops, so I can't do anything in that direction.

Please also note that Polyurethane comes in a variety of hardness. so a blanket "Delrin is harder than polyurethane..." is not always true. Hardness is desirable for the pucks if that is what you want, but it may not be if you are trying to strike a balance between stiffness and a smoother ride.

 

[Dr Lebaron]

I used 20ct gold because it's hard and soft.

Has anyone made a set yet with the posted dimensions?

 

[MoparKidD-4]

I would weld my K-frame straight to the "frame" rails if I could. I have a '70 Duster (currently out of commission due to blown engine) and the completely non-isolated front suspension (along with the upper A-arms tied directly into the frame rails) drives so much better and really doesn't have any noticeable difference in vibration. It's still way better than a modern car where you feel every single piece of gravel on the road.

Found this on Delrin:
http://www.sdplastics.com/delrin/delrin[1].pdf

According to that it would be more than strong enough to handle this type of application. I myself didn't really start hearing about it till a few years ago but it's really starting to catch on in the aftermarket for the hard-core road-racers who want the hardest bushings possible without going to a metal bushing.

 

[kkritsilas]

...and that is where the possible problem is. These are not "...hard core road racer..." type cars. There may be some that want that stiffness, there will be some that don'tm just like some want to build drag oriented cars, there are others that just want cruisers. Other posters have stated that they don't like the ride with the polyurethane bushings and pucks, finding that they don't like the ride or the excessive amount of feedback from the smallest road irregularity. A little give goes a long way, for those of us who are non-road racer types.

Also note, that street cars don't work in the same environment as road racers. Street cars need to work on streets with speed bumps, ruts, potholes, washboard/rippled roads, and the rest of the under-maintained streets that are part of everyday life. Road racers, on tracks, don't. That is why you will see heim joints in race cars, and don't in street cars. ||I don't know anything about Delrin, but it will be subject to a lot of shock loads a lot more often from road imperfections that race cars don't see.

 

[MoparKidD-4]

My point is Chrysler Corp. built cars for 30-some years with non-isolated front ends and you didn't hear people crying about the ride being like a dump truck... I don't understand how taking the car back to how they were originally designed can make it ride worse than a car that originally never even had rubber isolators under the front subframe. Especially if you're leaving the rest of the front suspension stock with rubber bushings.

 

[kkritsilas]

Our cars WERE built with rubber bushings. The reason that people are replacing the bushings is due to their being over 30 years old, and in doing so, are looking at some alternatives, like metal or polyurethane mounts. One of the reasons that our cars ride as well as they do is due to the transverse torsion bar front end. Ma Mopar managed to get a ride almost as good as the big C bodies in a smaller car. However, part of that is the use of a lot of rubber (including the K member mounts) and a sub optimal geometry for high G force turns. However, some people want the cushy ride, some would prefer a tighter, more precise front end feel. People who look for the tightest front end go with solid metal (steel or aluminum). People that want a soft ride get original rubber replacement mounts. Some try to retain most of the soft ride while getting a firmer front end use polyurethane. All have proven track records as being able to stand up to regular street use. Delrin may be able to do that, or it may not. I don't know, but where it fits in the firmness/rigidity spectrum between metal and rubber mounts is an open question as well. The weight point is not an issue in the vast majority of cases for our cars. Even if the Delrin mounts weighed nothing, the total weight reduction is probably no more than 30 lbs,, probably less than 20 lbs. vs. polyurethane or rubber. In essence, it doesn't matter, considering that weight of our cars. In a road race car, where effort is made to get to the absolutely lowest weight (within the regulations), it is far more important.

 

[MoparKidD-4]

I don't disagree with you and I understand most of the time people are replacing not just the isolators but other suspension parts as well. I'm just curious what it's like to replace ONLY the isolators with metal/delrin/whatever hard stuff while leaving the rest of the suspension bushings stock rubber.

I guess it makes sense Ma Mopar tried to emulate the C-body ride considering those made up almost 50% of car sales for the entire corporation throughout the '60s and early '70s. Still doesn't really compare though IMO I've driven a couple C-bodies (1969 Polara 383 2-dr and 1972 Polara 440 4-dr) and the ride on those is like nothing I've ever experienced in a car.

 

[Shorty Thompson]

I don't disagree with you and I understand most of the time people are replacing not just the isolators but other suspension parts as well. I'm just curious what it's like to replace ONLY the isolators with metal/delrin/whatever hard stuff while leaving the rest of the suspension bushings stock rubber.

When I used to do the demolition thing , I derby-ed ' M ' body cars . They are tough . If ! you build them right . We always took the pucks out and welded straight to the frame . If you took a hit to frontend from a side shot , it pushed the frontend way out wack and you couldn't steer it very well . What we learned that it actually helped to steer the cars better . Made turning more crisp . But it didn't come without modifications . Steering shafts had to have the steering geometry re-angled , the steering shaft was constantly in a bind . The radiator lower hose was now hitting the k-member . You had to torch out a pocket to accommodate it . The stock fan blade now hit the hood , as did the carb cleaner . There's a lot of things that need to be taken into consideration before you simply jump into something like this .

 

[kkritsilas]

I don't disagree with you and I understand most of the time people are replacing not just the isolators but other suspension parts as well. I'm just curious what it's like to replace ONLY the isolators with metal/delrin/whatever hard stuff while leaving the rest of the suspension bushings stock rubber.

I guess it makes sense Ma Mopar tried to emulate the C-body ride considering those made up almost 50% of car sales for the entire corporation throughout the '60s and early '70s. Still doesn't really compare though IMO I've driven a couple C-bodies (1969 Polara 383 2-dr and 1972 Polara 440 4-dr) and the ride on those is like nothing I've ever experienced in a car.

Ma Mopar didn't match the ride of the C bodies exactly, which is almost impossible on a car that is 2-4 feet shorter and over 1000 lbs. lighter. What they did do with the transverse torsion bar front end is make a smaller car with a close to "big car" ride. It was a vast improvement over the ride of the small cars from GM and Ford, which is why initial sales were so good.

I don't know of anybody who has replaced the mounts without replacing the other suspension bushings. They are usually replaced together, or the suspension bushings are replaced first, and then the mounts. To be a valid impression, somebody would need to replace the bushings first, then the mounts with rubber (essentially bringing the car back to factory original condition). Then they would need to drive it around to get used to the suspension feel and ride. After that, they would replace the mounts (only) and then form an opinion on the effectiveness of the mount change. Changing the mounts only would not be a good test, because the old bushings would affect the feel and ride of the car so much that the mount effects would probably be invisible.

 

[BudW]

I have plans on visiting a drag strip at least once in my cars lives (once I get big blocks installed), and participate in at least one road race course, as well.
Depending on how car does, I may participate in the road race course more than once.
Otherwise will be street driven about 20-30k miles a gear in either car.

Note: the big blocks will be aluminum everything, except for iron block and metal moving parts), and will have working A/C and P/S. I expect overall weight to be about the same pre vs. post engine change (finger twisting . . .).

Now with that all said, I don’t think I care what the pucks are made of, and plastic appears may work well in this case.
I’m leaning not towards polyurethane for my 2nd set - but it’s not ruled out. I have current set of aluminum set from FFI (a bit more weight than rubber). I’ve worked with the factory cast iron versions (a good substitute for a boat anchor) and those will give you a workout to move from point A to B.

My plans for both of my cars are solid pucks (Poly, plastic or aluminum – rubber and iron are off of the table. I might use iron if given to me, maybe), poly sway bar bushings and rubber UCA/LCA to K-frame bushings for the front.
For the rear, rubber bushings on both ends of leaf spring, older shock plates (for ISO-clamp removal) and poly bushings for sway bar.

Note: poly is a good substitute for the rubber biscuits in the ISO-clamp – but the clamp itself is the weak link and worthy to get rid of, for that reason. The rubber biscuit removal is big plus, when you do.

Also I don’t have access to a machine shop to get a set made. The FFI ones look great but are also too expensive for second set. I’d be game for a set of plastic ones – if someone was to machine a set – and price is less than the FFI ones.
BudW