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Urethane Vs. Polyurethane Vs. Polygraphite #2866084
12/29/20 03:19 PM
12/29/20 03:19 PM
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Gabmando Offline OP
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My 73 Charger Rallye 340 CID 4 SPD still has the factory installed K member and torsion bar cross member isolators.

Energy Suspension has them in Polyurethane.
Prothane has them in Urethane.
PST has them in Polygraphite.

I am not considering solid mounts.

I have Polyurethane leaf spring isolators so I am leaning towards Energy Suspension Polyurethane.

I really would appreciate feedback on the 3 options above. I'm looking for the best quality. Cost is of no importance.

Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: Gabmando] #2866145
12/29/20 06:26 PM
12/29/20 06:26 PM
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Suspension bushings are all versions of polyurethane compounds which are a fairly rigid compared with straight urethane which can have varying degrees of softness. I'm not away of anyone making soft urethane bushing. Polygraphite is a polyurethane that has graphite mixed into the compounds. The idea being that the graphite is self-lubricating and will avoid the squeaks that tend to come with using straight polyurethane.

The for frame and cross member isolators, I don't think the polygraphite version has any real advantage of regular polyurethane as they are not in a motion position that will constantly generate squeak potential. Once bolted down you should be fine.

Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: Gabmando] #2866207
12/29/20 08:46 PM
12/29/20 08:46 PM
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Central Florida
larrymopar360 Offline
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I think whether they squeak or not has a lot to do with the suspension design too. I have had polygraphite and urethane in Diplomat Police cars in the entire front end and had no squeaking. Never found them to be too stiff either. Really not any noticeable difference to me. So I would probably recommend polygraphite so that if there was going to be any squeaking it might help with that and not require routine greasing. I also had PST's and was happy with them.

I know you mentioned you did not want solid mounts. I have to say, one of the best upgrades I did on my Diplomat Police cars were aluminum k-frame biscuits from firmfeel. So much better high speed handling and just handling overall, and no bad side effects whatsoever. twocents



Facts are stubborn things.
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: larrymopar360] #2866210
12/29/20 08:54 PM
12/29/20 08:54 PM
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Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: larrymopar360] #2866214
12/29/20 09:04 PM
12/29/20 09:04 PM
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Norwich CT USA
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Originally Posted by larrymopar360
I think whether they squeak or not has a lot to do with the suspension design too. I have had polygraphite and urethane in Diplomat Police cars in the entire front end and had no squeaking. Never found them to be too stiff either. Really not any noticeable difference to me. So I would probably recommend polygraphite so that if there was going to be any squeaking it might help with that and not require routine greasing. I also had PST's and was happy with them.

I know you mentioned you did not want solid mounts. I have to say, one of the best upgrades I did on my Diplomat Police cars were aluminum k-frame biscuits from firmfeel. So much better high speed handling and just handling overall, and no bad side effects whatsoever. twocents



At one time Chrysler had a police kit to replace the bushings with Cast iron biscuits , I did that on my 79 300


Tom ,

2011 Ram 3500 C&C Diesel
2009 Challenger R/T
1971 Challenger Conv. 511/4 speed
1970 Challenger R/T 503/727


Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: moparts] #2866216
12/29/20 09:07 PM
12/29/20 09:07 PM
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Scranton, PA
Montclaire Offline
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One of the poly kits has an oval, steel insert; the other does not. I would buy the one with the insert. Check Rockauto for good prices.

EDIT - the Energy Suspension ones have the captured insert. If you look at the same set in red you can see it. Don't forget poly for the torsion crossmember, too.

Last edited by Montclaire; 12/29/20 09:12 PM.
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: moparts] #2866218
12/29/20 09:11 PM
12/29/20 09:11 PM
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Central Florida
larrymopar360 Offline
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Originally Posted by moparts
Originally Posted by larrymopar360
I think whether they squeak or not has a lot to do with the suspension design too. I have had polygraphite and urethane in Diplomat Police cars in the entire front end and had no squeaking. Never found them to be too stiff either. Really not any noticeable difference to me. So I would probably recommend polygraphite so that if there was going to be any squeaking it might help with that and not require routine greasing. I also had PST's and was happy with them.

I know you mentioned you did not want solid mounts. I have to say, one of the best upgrades I did on my Diplomat Police cars were aluminum k-frame biscuits from firmfeel. So much better high speed handling and just handling overall, and no bad side effects whatsoever. twocents



At one time Chrysler had a police kit to replace the bushings with Cast iron biscuits , I did that on my 79 300
I remember that kit. A NOS one popped up on ebay a year or so ago. Best upgrade ever!


Facts are stubborn things.
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: Gabmando] #2866222
12/29/20 09:24 PM
12/29/20 09:24 PM
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We have done a butt lload of PST kits over the last 20 years. using Liberal amount of the special lube on install we haven't had a squeaker yet twocents beer

Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: mopars4ever] #2866306
12/30/20 05:45 AM
12/30/20 05:45 AM
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Valencia, España
NachoRT74 Offline
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Originally Posted by mopars4ever


I was searching for them to post the option on thread, but on eBay. Tipically FMMOPAR had them in $299 as far I recall. AMD also shows them on a similar price than Moparmall but out of stock. There is an ebay seller offering just the K member pieces thought.

This would be my option but not at that price. Saying that and per what has been said here, would go with urethane.

Is really the rubber way more expensive material than poly or urethane to be sold on THAT price comparing with poly/urethane?

Last edited by NachoRT74; 12/30/20 05:54 AM.

With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: TJP] #2866488
12/30/20 02:22 PM
12/30/20 02:22 PM
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north of coder
moparx Offline
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Originally Posted by TJP
We have done a butt lload of PST kits over the last 20 years. using Liberal amount of the special lube on install we haven't had a squeaker yet twocents beer



how long, or how many miles has the longest install been used ?
just curious. i have CHS and probably couldn't hear a squeek unless it was 95 decibels or so..........
beer

Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: NachoRT74] #2866489
12/30/20 02:24 PM
12/30/20 02:24 PM
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Valencia, España
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Well As I told I knew FMMOPAR had those, but weird is not with the T bar crossmember isolator too. I know they had it on $299 or so

K member isolators FMMOPAR

There is a crazy guy selling the full set on $377


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: NachoRT74] #2866584
12/30/20 04:35 PM
12/30/20 04:35 PM
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Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: mopars4ever] #2866611
12/30/20 05:39 PM
12/30/20 05:39 PM
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Valencia, España
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Thaaaats the one. Dunno why I couldn't find it earlier!!!!


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: moparts] #2866666
12/30/20 07:11 PM
12/30/20 07:11 PM
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Between Houston & Galveston TX
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Originally Posted by moparts
Originally Posted by larrymopar360
I think whether they squeak or not has a lot to do with the suspension design too. I have had polygraphite and urethane in Diplomat Police cars in the entire front end and had no squeaking. Never found them to be too stiff either. Really not any noticeable difference to me. So I would probably recommend polygraphite so that if there was going to be any squeaking it might help with that and not require routine greasing. I also had PST's and was happy with them.

I know you mentioned you did not want solid mounts. I have to say, one of the best upgrades I did on my Diplomat Police cars were aluminum k-frame biscuits from firmfeel. So much better high speed handling and just handling overall, and no bad side effects whatsoever. twocents



At one time Chrysler had a police kit to replace the bushings with Cast iron biscuits , I did that on my 79 300


I've got an old DC kit on my wagon.

Never understood how people say a solid K rides SOOOOOO much harsher, when, essentially all you've done is make it like a '72 / older. confused If there is indeed any added harshness, the tradeoff for better handling is worth it.

But, I digress..... popcorn


John

The dream is dead, long live the dream.......😥
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: SattyNoCar] #2867013
12/31/20 03:02 PM
12/31/20 03:02 PM
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north of coder
moparx Offline
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is the torsion bar cross member isolated on the later B bodies like the K member ?
my old mind forgets. if so, are there kits to mount it solid ?
beer

Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: moparx] #2867036
12/31/20 03:29 PM
12/31/20 03:29 PM
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SattyNoCar Offline
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Originally Posted by moparx
is the torsion bar cross member isolated on the later B bodies like the K member ?
my old mind forgets. if so, are there kits to mount it solid ?
beer


Yes, the T-bar crossmember is isolated, so the car basically ends up with two crossmembers (the T-bars pass thru the first one).

Firm Feel makes solid mounts for the K and the crossmember.


John

The dream is dead, long live the dream.......😥
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: SattyNoCar] #2867052
12/31/20 03:49 PM
12/31/20 03:49 PM
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Thank You !
i thought so, but wasn't sure. i need to eat a few bottles of those pills advertised on tv that makes your memory better........ biggrin
beer

Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: moparx] #2867404
01/01/21 11:23 AM
01/01/21 11:23 AM
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Hence the reason why 73 and Lates T-Bars are longer than previous years and just aftermarket pieces are available, nothing from MP


With a Charger born in Chrysler assembly plant in Valencia, Venezuela
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: SattyNoCar] #2867726
01/01/21 07:35 PM
01/01/21 07:35 PM
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Central Florida
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Originally Posted by Satilite73
Originally Posted by moparts
Originally Posted by larrymopar360
I think whether they squeak or not has a lot to do with the suspension design too. I have had polygraphite and urethane in Diplomat Police cars in the entire front end and had no squeaking. Never found them to be too stiff either. Really not any noticeable difference to me. So I would probably recommend polygraphite so that if there was going to be any squeaking it might help with that and not require routine greasing. I also had PST's and was happy with them.

I know you mentioned you did not want solid mounts. I have to say, one of the best upgrades I did on my Diplomat Police cars were aluminum k-frame biscuits from firmfeel. So much better high speed handling and just handling overall, and no bad side effects whatsoever. twocents



At one time Chrysler had a police kit to replace the bushings with Cast iron biscuits , I did that on my 79 300


I've got an old DC kit on my wagon.

Never understood how people say a solid K rides SOOOOOO much harsher, when, essentially all you've done is make it like a '72 / older. confused If there is indeed any added harshness, the tradeoff for better handling is worth it.

But, I digress..... popcorn
Eggg zactly! People weren't bitching about a harsh ride back in the pre '73 cars.

To o/p: NOW is the time to get rid of the rubber K frame isolators! You won't regret it.

And that seller of the rubber ones is always super high priced. At least go polyurethane for better handling AND save money.


Facts are stubborn things.
Re: Urethane Vs. Polyurethane Vs. Polygraphite [Re: Gabmando] #2868642
01/03/21 09:09 PM
01/03/21 09:09 PM
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Gabmando Offline OP
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Thank you all for the responses. This has been quite the education.
In the old days one could have walked into a parts store and looked at the parts. Not any more!
Thanx again guys.

Last edited by Gabmando; 01/03/21 09:10 PM.






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