C3 POLYURETHANE questions

[LEEJANDZ]

Has anyone upgraded their stock rubber components to POLYURETHANE? I have picked up some ENERGY SUSPENSION pieces for my 79 L-82 and realized that it is a lot of work to get most of this stuff on.

If there is anyone with these mods, would you recommend them over a functional stock system. Or is it definately an upgrade worth putting in the time.

I am interested in having a better handling VETTE with the peace of mind that POLYURETHANE warrants.

Thanks

--------------------------------------------

JASON

good old rubber, probably as "new" as my VETTE

 

[Vette/Berlina-coupe]

-if'en you were going racing certainly the urethane-bushing would really stiffen things up for a more precision handling chassis, -however, if the originals indeed look sloppy, certainly fresh Rubber-bushing for a roadcar will be much less harsh; --although one exception is in the case of the antiroll-bar, using urethane only for the transverse-axis bushings (believe just four: two front, two rear) holding the antiroll-bar would net a slightly flatter handling chassis, without imposing any excess chuckhole compliance harshness. Also, see no advantage in changing to Urethane Eng./trans-mounts; --as it would only transmit more adverse vibration into the chassis (they wisely used rubber to isolate the drivetrain vibrations)! Let's see what others think, --especially with firsthand experience with a C3 chassis change to urethane....
~Bob vH
:nono

 

[LEEJANDZ]

A lot of my friends who drive the newer "imports" have POLYURETHANE everything, and I have noticed a big positive difference. However, I have not heard from any CORVETTE owners about the use of POLYURETHANE.

I am anxious to try the motor mounts and the sway bars. But the ball joints, steering, body mounts, etc seem like a lot of work.

 

[Scott81]

I have them on my 81, no problems, no squeaking, no harsh ride. If it's within your mechanical abilities to put them in, I would say go for it. I used poly for the entire rear suspension, transmission, motor mounts and then Brutus and I drove from Florida to Kentucky and it was not uncomfortable at all. Use marine grease when installing the poly bushings, makes them easier to get in. When I get around to it the entire front suspension will get new poly bushings too, then on to the body mounts.

Here's some help for you; http://www.c3sharktank.com/tech2/rear1.html

 

[Jack]

Jason:
I have a background in molded auto rubber parts mfg & I have changed my 71’s entire front suspension and motor & trans mounts to ES polyurethane. I got the front end kit from Van Steel ... very pleased with product & personal service ... I highly recommend Van Steel. ALL my old rubber was mushy from years of heat soak & oil/degreaser degradation. The poly stuff does stiffen things up ... but NEW rubber would have also. Rubber & poly parts’ “stiffness” is measured in durometer ... the stiffer it is the higher the durometer reading. While the new poly has somewhat higher durometer than new rubber, I believe new poly will also maintain its durometer longer than new rubber. I believe new poly stuff will stiffen things up a bit more than new rubber, but not tremendously more ... but I haven’t done such a direct on-car comparison & don’t know of anyone who has.

It’s a big dirty job to get all the front end pieces off the car. Be sure you have the car safely supported and beware of the coil springs ... even when slightly compressed they store enough energy to be potentially dangerous. If you’re using poly bushings there is a simple technique I used to replace them. I did not press out the old rubber bushings’ outer shells. The old rubber was pretty mushy & I used a small hole saw (about $10) mounted in drill motor to hog out the old rubber. Use a thin chisel or screwdriver to help spread the split in the old inner shell ... it may be rusted onto the control arm shaft ... clean up & lube the ends of the CA shaft. The new poly bushing assemblies are a slip fit. With fingers, just pop out the new bushing & inner shell from the new outer shell. Lay the new outer shell aside, it won’t be used. Lube the old outer shell (it’s still in the control arm) and new inner shell & new poly bushing ... then slide the latter two into the old outer shell and onto the control arm shaft. Make certain the threads in end of CA shaft are very clean & dry ... install the clean & dry bolt, lockwasher & bevelwasher with a dab of loctite on bolt. Presto ... bushing installed without beating & banging ... without pressing out or in. Bubba or not ... it works ... and I didn't risk bending CA.

There’s a lot said about benefits of graphite-impregnated poly ... for the most part I believe the graphite’s benefit is hype. On the other hand I believe the graphite interferes with the poly-to-metal bond found on bonded parts like the motor/trans mounts. Poly front end bushings (unlike rubber) do not have such a bond ... so bonding is not an issue with the poly bushings. I spoke with ES quite some time back and was assured all their black-colored poly parts are graphite-impregnated but their other colors do not have graphite. Although I am not particularly fond of colored motor mounts, I chose ones made from red poly.

Proper lubing of moveable poly parts is essential ... I don’t think graphite is up to the task (for very long). Bushings usually come with a too-small tube of silicone grease ... and as Scott suggests you can succesfully use readily-available silicone marine grease. I’ve used silicone dielectric grease with no problem. Had I thought of it at the time, I’d have used Scott’s suggestion because the marine stuff is often heavier than the dielectric. My rear suspension is next ... I'll use poly there & won't hesitate to call Van Steel first.

BTW ... I believe Heidi ( 78SilvAnniv ) may’ve recently gone the poly route on her 78 silver anniversary edition C3 ... hopefully she’ll chime in with her observations too.
JACK:gap

 

[LEEJANDZ]

Jack --- My rear suspension is next ...

Is VAN STEEL a vendor???
Ive never heard of them.

Its too bad you are so far away from me, maybe we could have done the teardown together.

I would like to do the front and the rear with POLYURETHANE, but since youve been down that road... How much down time did you have while doing the work???

Was there a big difference with the motor & tranny mounts???

Very informative post... Thank you!!!

------------------------------------

JASON

(A little overwhelmed, but OK)

 

[Jack]

Is VAN STEEL a vendor??? Ive never heard of them. JASON

Jason:
Van Steel is a vendor and rebuilder and installer ... with a very good reputation among alotta folks. They also offer a how-to video ($20) for C3 supension ... haven’t seen it but have heard it’s very good. Might be a good idea to contact VS & get a video & catalog as a primer. Contact Art Dorsett www.vansteel.com Clearwater FL 1-800-418-5397. Their Deluxe Poly front end kit ($200) is hard to beat. Dunno if they sell mounts or not ... got mine elsewhere. Lotsa info on VS site. My mounts were mush too (one was separated!) ...so the difference was huge ... but any NEW mounts’ difference would’ve been huge ... rubber or poly. As before, poly is stiffer ... but the difference between NEW poly & NEW rubber is not huge. I suggest you’ll be surprised at the difference but will also be pleased. Hard to figure my front end time because I did it along with other stuff. Average DIY’er should be able to do complete front end over a full weekend ... even less if real good/have help. Suggest it’ll pay in spades to pressure wash undercarriage real well before you start ... helps a lot to have air ratchet & impact, small side grinder ... and GOOD jackstands. It’s a tough & tiring job ... but LOTS of us have done it ... just get all your ducks in a row and you’ll be fine.

BTW, as you may know ... you don't have to buy a full front end kit just to get poly bushings ... several of my FE parts were still good ... but the full kit was inexpensive and time is not ... so changed out everything while I was in there. Also, I believe Scott has gotten to know the folks at VS pretty well ... I think he lives in vicinity of VS. Haven't looked lately ... seem to recall Scott had some good suspension photos/info at his site.
JACK:gap