TX63CONV

I have a 63 convertible driver that I have slowly been refurbishing. My next task is to tackle the trailing arms. My plan is to remove, replace the hard and soft brake lines, clean, sand, repaint the actual arms and replace the bushings and inspect/clean/repack the bearings or replace.

Previous owner has welded a rear sway bar onto the top of both trailing arms. I also have a single fiberglass(?) rear spring.

My questions are these:

(1) Should I abandon the rear sway bar (its not a race car)?
(2) Should I abandon the rear spring and go back to original?

The car rides very rough--which is part of the reason why I am tackling the suspension. Front suspension will be next.

Thoughts?

jrm5657

Can you post a picture of the sway bar being welded to the trailing arms?

If it is truly welded and there is no flexible link, then previous owner has effectively eliminated the suspension system and it is no wonder it rides a bit harsh.

ILBMF

I'd like to see a pic too. You will need around $300 in special tools to get to the wheel bearings.

65hihp

See above.
Get that junk off of there.
63s tend to have a harsher ride even if stock due to lack of body mount "cushions". (they improved that in 64s)
Good luck restoring a comfortable ride back on your wonderful 63 conv.

Sky65

Check the front sway bar as well. If someone added a rear bar they may have installed a larger front bar as well. I don't know what a stock bar measures but l'm sure someone here does.

Tom

Mikado463

I believe the front bar should be 3/4" in dia.

as for the rear bar, if it's in proportion to the front bar (1/2") and done correctly I'd leave it on. Bottom line, properly executed sway bars make a marked improvement in handling, if you feel the need to soften the ride a bit be sure to use rubber bushings instead of poly.

SWCDuke

The C2 base suspension roll stiffness distribution is such that the car has very little understeer, but they are twitchy at the limit including trailing throttle oversteer.

Anything you do increase rear roll stiffness such as a higher rate spring or adding a rear bar without a commensurate increase in front roll stiffness will exacerbate the above problem.

The base suspension has decent roll control and reasonable ride rates. Compliance in the front bar link bushings tends to decrease front roll stiffness with increasing roll , which is what makes the car twitchy at the limit, and this can be mitigated by replacing the OE bar rubber link bushings with hard urethane bushings.

If you want to increase grip set front and rear camber at -1 deg., but with the typical rock hard S-rated "van tires" that most of these cars have, you'll be doing good if it can pull 0.75g lateral.

A set of Avon CR6ZZ tires will provide lateral grip up to at least 0.9g and maybe 1.0g with really good alignment tuning, and that's with the OE 0.75" front bar OE springs.

The high roll centers (relative to modern cars) means the springs alone provide a lot of inherent roll stiffness, so C2s don't need huge bars, but the high roll centers mean a lot of camber change through the range of suspension travel, which wide tires don't like, and that's why modern Corvettes have lower roll centers.

Duke

TX63CONV

I wasnt clear on "welded". The rear sway bar is attached with rubber mounts the same as the front. The PO welded a metal bracket to the top of the trailing arm.

I believe they also welded a bracket to the frame rail with a rubber bushing. I will snap a pic and post tonight. Ill measure diameters of both as well.

Again, the car is a sunday driver and I'm not interested in 'spirited' driving but I would like to improve the ride quality.

Any comments on the single what I assume fiberglass rear leaf spring?

rene-paul

Regarding the rear spring; You would have to find the advertised "spring rate" and if the shocks will "work" with that spring. IMO, for a driver, a light rate with matched shocks worked for me on my 63.. along with ALL suspension and alignment within specs. We will forever be reminded that these low food chain 63's have a much harsher ride/feel due to the body being hard mounted to the frame. Corrected of course in the following year/s.
Mine is the lowest of the low; Ermine white,base engine,Power Glide, I do have a radio and saddle leather seats and power steering and I also have the factory heater delete. Brgds,
Rene

63 340HP

If the goal is a nice driver you do not need the rear bar. Grind off the welded brackets before refurbishing.

You do need a balanced suspension. You want matched or balanced front and rear spring rates. Buy them as a set. The stock 63 rear 9 leaf is soft, and the front coils as well (one year only iirc). Balanced F41 equivalent springs are not harsh for modern standards with rubber arm and spring bushings.

ID the front bar. If it is the stock 3/4" diameter it is good with poly bar bushings and your choice of rubber or poly end link bushings. If it is a larger bar you need more consideration between spring and bar choice, or the more neutral 3/4 bar.

I suspect originality is not a priority so a C3 height rear camber crossmember will help lower the rear roll center height and assist with a more compliant ride with a firm rear spring. The VBP camber bracket and adjustable rods make this easy.

Take care to replace the rubber a-arm bumpstop and snubber, and rear bumpstop. They are not designer pieces but make a huge difference in practice.

​​​​​​​I added a Borgenson power steering box last winter and with a smaller steering wheel and a suspension like your goal, my 63 drives better than most modern sport sedans and sport utilities (tight, flat, quick response, and minimal noise).

I have a soft spot for black 63 convertables. They have their quirks, but worth the upgrades. Keep it running good.

ILBMF

Ran into the same thing last month. The left trailing arm had the bracket welded so I just cut it off, sent the trailing arms to Bair's for rebuild and drilled/bolted a new bracket on. I also found the left link installed backwards on that side. I assume the car had some sort of left side damage at some point because of this and a few other left side issues I ran into.

From what I've read about the fiberglass springs, you need to match shocks to that spring and stock replacements won't perform well.

TX63CONV

It has edlebrock shocks. Probably no way of telling what the leaf spring rate is. Also, the front of the car sits slightly higher and I wonder if someone put in stiffer springs up front. The front suspension is for a later date--just focused on the rear right now.

Here is a pic. The interior mounts are welded to the frame rail which would be impossible to replace the bushings. The outer bushings appear to be poly.

I didnt measure the thickness but the Front Sway is definitely thicker than the rear. I couldnt find my caliper in my toolbox when I snapped a pic but I will measure.

Mikado463

couple of things jump out at me .......

1) looks like the poly bushings are not correctly installed at the trailing arm point, is there not one below the 'welded plate' ?

2) bar appears too thick (for a rear bar)

3) the weld mount, thus eliminating bushing replacement, is pure 'hack'

63 340HP

The Edelbrock IAS shocks are really good shocks with the RICOR valve. They are on par or better than the similar mono-tube Bilstein's, with the better RICOR valve (better than a digressive valve stack when you want the resistance to release in a sharp jolt).

Count the rear spring leafs (9, 7, 5, or ?). It may not help, but it might be a clue to the rate.

Again, purchase the rear leaf and the front coils as a balanced set. The C2/C3 chassis has been around long enough that a call to one of the suspension suppliers should guide you to a balanced result when you get around to replacing the front coils.

TX63CONV

Good info on the Edelbrock shocks. It's hard to see in the pic but there is a poly bushing under the bracket on the TA. It's set up correctly.

The front sway bar is 1.25" and the rear is 7/8.

I did a 3 & 9 tug on both wheels and no movement so I think I am going to leave the bearings. I may just remove the TA, half shafts and clean/paint.

Below is a pic of the rear spring. I can call VBandP to see if they can give me any info. Just called them and it is a 280lb spring (k-280). What was stock? Again my rear seems low and my front seems high. I wonder if it is because this is a softer rear spring than stock?

Mikado463

way too big IMO .....

65hihp

suggest you don't call anyone,
just get that junk off your car, and put it back to stock specs.
you will be happy with it.

tuxnharley

I'm not sure I understand why those would necessarily be too big IF the springs and shocks are set up correctly? Seems like it would result in a very flat cornering ride with virtually no body roll, and with the front being proportionally larger than the rear the understeer/oversteer transition characteristics shouldn't be dramatically affected.

What am I missing here?

My ex had a '87 Firebird Trans Am GTA (no screaming chicken emblem) with bars about those same sizes IIRC, and it cornered very flat and rode and handled well.

Sky65

I had a 285# on my 65 convertible. It was a nice street spring with a good ride but too light for hard driving or packing the car with loads of baggage. Your shocks have pretty good reviews so I would keep them. If you just want to cruise I would suggest just scrapping the rear sway bar, go to stock on the front and leave everything else.

Tom

TX63CONV

I mis typed on the front sway bar--it is actually 1.75" and 7/8 on the back. Looks like stock was 3/4 inch.

I think for now I will leave as is and service/clean the TA, half shafts etc. When I get to the front suspension, I will revist. This will be a winter project.

Thanks everyone.