Now what should I do?

[Timothy B.]

I just found this site and this forum, and just joined the NCRS. This is unfortunate since I have been working on my car for years without really being able to ask others for advice except for sales people. So here is my dilemma: I have disassembled, reconditioned, and partly reassembled the front end of my 67 327 small block car over the last two years (yes, I'm slow). I have new polyurethane conversion kits from Vette Brakes for both front and rear, and the front kit is partially installed. I also have a new thicker front sway bar, rear bar kit (currently none), and new front springs they call 'Grand Touring' springs (rate in between stock and F-41 I understand). The upper and lower A-arms are completely finished and back on the car, so only the sway bar (also a newer thicker bar) is yet to go on. I have not started on the rear yet.

If I knew about this forum earlier I would probably have not used poly parts, as many of you have had bad experiences with them. Mine are supposed to be 'graphite injected'. I talked to as many folks as I knew, talked to folks at Vette shows, and read about them at the time. There appear to be two camps on this: One says they are "too stiff, poor ride, squeak, don't look right", etc. The other camp says "despite what you have heard, they IMPROVE the ride and the newer style poly bushings don't squeak, and never wear out".

I can't return the parts as it has been too long. Should I continue my assembly, or start over with all rubber, or maybe selectively use rubber in some places and poly in others?? Have any of you installed the Vette Brakes kits that include new "balanced" front and rear bars and GT coils springs and if so what was your experience?? My car is planned on being a driver car in mostly original condition. Thank you for your help.

[Tom H.]

Re: Now what should I do?

Tim, I'm using the same bushings in my 72 as you describe (graphite) With 7000 miles since the rebuild, no squeaks, handling is very good, and unless you really have to, you don't see them. After a while they look quite similar anyway. The ride is mildly harsh, but the addition of the rear sway bar seemed to be the big factor in that, more so than the bushings. I also but heavy springs (550 inch lbs.) on the front, and I'm sure that didn't help the ride.

[Tim Hill]

Re: Now what should I do?

I installed Energy Suspension bushings throughout on my '63 last winter when I rebuilt the steering and suspension. They've been silent so far and with stock springs front and rear and Tokico shocks all 'round and i'm very happy with the ride quality. Also, using the black bushings, you really don't notice that they aren't rubber.

[Terry M.]

Re: Now what should I do?

Tim,

Give some thought to what it is you want to do with your car.
If judging at NCRS or Bloomington Gold is in the cards, then there are a certain set of questions to ask.
If you want a car to drive for near maximum handling then another set of questions will come up.
There are a variety of uses for your Corvette between these extremes, and only you can decide what you want to do with the car, and what you are willing to tolerate as far as compromises to reach your goals. It is far easier to ask these questions and consider the compromises before the parts are purchased and installed.

[Timothy B.]

Re: Now what should I do?

Thanks for the reply. I did try to ask most of those questions before I selected poly, but I may not have asked the right people. My goal has been to have a car that looked original, is fun to drive with decent handling, while still having a nice ride that isn't too harsh. I'm not looking for hot rod handling, just a bit better than that of the base suspension it has had. I don't think judging the car is in the cards for me anytime soon.

[Terry M.]

Re: Now what should I do?

Glad you defined your goals - it will help you a lot.
Suspension changes should be considered as a system. Improving one component often will not yield the best results unless other components are also upgraded.
My experience in chassis modification involved higher compliance springs and larger stabilizer bars on a RWD body-on-frame vehicle, non-IRS. I retained the rubber suspension bushings, however. I have a substantially harsher ride than stock, and to my surprise more than I expected was due to the larger stabilizer bars. I changed them before the springs so I was able to separate the affect of each change.
Now change the shocks to higher compliance and see what happens. It is all a matter of how stiff you like the ride, and how much comfort you are willing to sacrifice in order to have greater control.
Don't forget the affect of tires as well. Modern tire technology will make a major change in how the car performs, and careful selection of brand and style can minimize the appearance changes of the tire from stock.
I believe some changes to the alignment specifications will also help, but a few others with experience with IRS are better authorities than I.

[Michael W.]

What you need to do is

find somebody who has put some real miles and sufficient years on the poly bushings to offer a valid opinion.

I innocently and ignorantly fell for the Bubba marketing hype and installed the 'permanently' lubricated poly bushings everywhere on the car during a frame off in 1996. That was eight years and about 25K miles ago. They started squeaking at about year three and have progressively gotten worse, particularly the A-arm bushings. I can achieve short term relief by squirting some light oil on and around the area, but as mentioned this is short term relief.

As to handling improvements, there are no valid comparisons that I know of. The only reason people change bushings is because the existing ones are worn out. Comparing the handling of a worn out bushing with a new one, and claiming the improvement is due to the use of a different material is pretty illogical. I'm sure I could have substituted a drilled out piece of firewood and in the short term the car would have handled better than the old bushings. Show me an example where new rubber bushings were compared to new poly bushings in a BLIND test on the same car. THAT would be meaningful.

Very few people drive their 30, 40 or 50 year old car hard enough to explore the limits of the stock components. The poly stuff will not improve handling over stock hardware if you're just out for a cruise in the country, or a blast on the freeway. These things are not a magic cure all.

Durability. The original bushings lasted 30 or 40 years. The vast majority of these cars did not get kid glove treatment from the first second or third owners yet the bog standard GM stuff toughed it out nonethless. If your car is now undergoing a frame off, I doubt it will then get thrashed and abused as it may once have been. If you were to put stock rubber bushings back in, the car would be 70-80 years old when these replacement bushings wear out. Even if the poly bushing do last longer (there's no track record of long term durability to prove this) will this be an advantage in 2044?

If I were you, I'd take the opportunity to ditch the poly stuff. There's plenty of people on eBay that would be willing to buy. Just advertise it as '67 L-88 NOS parts and you'll be rich.

[Roger Legge]

Re: What you need to do is

Preface: This is going to sound pretty dumb, but it's the truth. I bought a very original '68 that was sold to me as a 327/300 - my first Corvette. I later determined it is an L79, M21, A/C car. Had I known this, I would not have deviated one bit from original.

Having said that, here's what I did:

VB 550# front springs, VB 360# fiber rear spring
Energy Suspension poly bushings everywhere (their complete poly kit)
ES poly motor, transmission, diff mounts
KYB low pressure shocks with rears that are supposed to be valved for fiber
Stock front anti-sway bar (poly bushings), no rear bar (stock)
Kept stock aluminum body mounts - carefully checked torque/tightness

It has been this way for about three years, it is my primary daily driver and I've put about 25K miles on it in those three years. I live in Phoenix where the weather is typically warm (drove yesterday with T-tops off and back window out!) and the roads are smooth. My opinions:

It is a firm ride and I would not want it any stiffer than 550# in front.
The rear shocks do not properly dampen the fiber spring - 'bouncy'.
No squeaks, bought extra ES grease just to be sure I used enough.
This car is driven, and at times driven hard and it handles well.
It is fun for me to drive, but I have always liked a firm ride.

Hindsight: It was an extremely original (not super pampered, but not hacked) HP code car and had I known it back then, I would not have done the suspension changes. I still have the original coil and leaf springs, etc. Other than the obvious fiberglass rear spring, I am in the process of some careful ongoing restoration work with a definite eye towards NCRS standards. Personal opinion, I would not 'undo' the bushings unless you are marching towards getting the car judged. Hope this helps and good luck with your '67.

Roger
#36316

[Patrick H.]

Re: What you need to do is

I agree.

There are several on the Board who have gone to the poly bushings and then back to rubber ones. They, too, learned the hard way.

But, Mike's explanation is the best. Unless you are going to autocross the car or use it in a similar manner regularly, I don't think that the benefit of the polys is worth the potential cost of ride harshness and squeaking. Seeing as around here our local Club can't get anyone with a C1, C2 or C3 to EVER think about autocrossing, the odds that you'll suddenly take this car and do that are slim.

I replaced all the bushings and any replaceable component of my 1970 Cutlass' front suspension this past Spring. It rides and handles MUCH better now than it used to, and the bushings are all original style rubber. My 71 Corvette coupe will get rubber bushings, too, if I ever get around to it.

Either way, though, have fun with it.

Patrick

[Roger Legge]

Re: What you need to do is

As a follow up, Guldstrand used to sell what they called 'hard rubber' bushings as an alternative to stock rubber bushings. Not sure if they still do as I just looked at their web site and I did not see them listed in the C2/C3 section.

BTW, I have autocrossed my 1968! I don't see why not, it's just orange cones out there!

Roger
#36316

[Jim T.]

Re: Now what should I do?

Tim I installed the poly bushings in my original owner 68 about 15-16 years ago and like the performance of the poly control arm bushings and poly cushions for the sway bar end links. There are squeaks that occur that are silenced with spray lubricant. Do not plan on entering the car for any NCRS judging, so no plans to install the factory type rubber bushings. I do drive my 68. If you ever view a video tape that was sold at the Corvette Museum on the coverage of the grand opening this ole 68 is in it, its red and Stingray has been added to the side fenders. I also installed a Vette Brakes rear fiberglass spring several years ago and like this addition also. My 68 is a convertible and I dont't really notice the bounce that is mentioned. I do notice the Corvette squat is not as great as before when I get on it. When I get around to it, I have the Vette Brakes adjustable rear struts that I will install and they have poly bushings.
My original owner 70's first suspension modification was replacing the front springs with the F-40, F41, or FE-7 3832518 springs about 20 years ago. My 70 is 350, air cond, power brakes, and power steering and I liked the change in how it handled with these springs. Next change was installing a Vette Brakes 360 rear fiberglass spring about 15-16 years ago. I liked the change. About 9 years ago changed out the complete front suspension with the Vette Brakes control arms, front fiberglass spring, Carerra shocks front and rear, added larger sway bar in the front, ploy bushed Vette Brakes adjustable rear struts and installed a sway bar in rear. I drive this car a lot and it sure handles the curves. I really like the way it rides on the interstate highway and in daily traffic.
If you decide to go ahead and use the poly bushings in your 67's control arms, use lubricant on installation. If you don't like the suspension change, it is easy enough to change back to rubber. If you use the larger sway bar and don't like the performance you could reinstall the original sway bar and try it.
Although I have modified my 68 and 70 to my preference, it really would not take all that much work to go back to rubber bushings and original control arms as I have the removed parts to reinstall.
Enjoy your 67 when you get it on the road.