67 GTO Rear Suspension Q's [Archive]

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67gtonut

10-10-2010, 04:13 PM

Hello, new here....

I am looking to take my GTO suspension to the next level..... not go crazy, just notch it up a bit.

What I have...

Hotchkis Springs Front and Rear
Poly bushing in front control arms
1.25" Front bar out of a TransAm
Bilstein Shocks Front and Rear
Aftermarket Upper and Lower Rear control arms ( too many years ago.... forgot brand)
7/8 GM rear sway bar

First thing I am considering is the ADJUSTABLE TRAILING ARM MOUNT BRACES..... such as these from PMT
http://www.pmtfabrication.com/Products/94-64-67-chevelle-ss-adjustable-trailing-arm-mount-braces.aspx
https://static1.pt-content.com/images/noimg.gif

As much as I love Hotchkis stuff.... these are 1/2 the price of Hotchkis.... is there a difference?

Next thing is a rear sway bar upgrade....

Couple of choices from what I see....

1. 1" Solid bar that connects like OEM to the LCA's

2. Hotchkis Extreme Bar - Does mount to rear axle assembly, but still only mounts to forward hole of LCA's
https://static1.pt-content.com/images/noimg.gif

3. A bar that mounts to the rear axle but also mounts to the frame such as the Spohn/SC&C Touring bar
https://static1.pt-content.com/images/noimg.gif

I am only running 15" wheels with 60 series tires....

At what point is overkill as far as the rear bar is concerned?

Will the extreme bars hurt ride quality?

Has anyone used the Hotchkis Extreme bar?

Would love some opinions....

Thanks in advance

Troy

Oh.... gotta just show her off a little
https://static1.pt-content.com/images/noimg.gif

Mingus

10-10-2010, 05:50 PM

Hi Troy,
Welcome to the site. Nice GTO.
I only have springs and Varishocks in the back so far and I have been reading up on suspension pieces. From what I've been able to gather the rear sway bars that mount to the frame are a good way to go. I haven't read about the Hotchkis ones that only use the forward hole, but I've heard the stock ones bind the suspension the way they mount to the lower arms.
I don't think for the braces that there would be much difference between the brands. As far as the arms, everyone seems to really like the Currie ones with the Johnny Joints. I believe DSE has some new arms with a swivel type end too. My current setup to prevent rear suspesnion bind is 44 year old stock bushings. :)
I don't have a rear bar right now and mine seems to do okay without it.

kochevy67

10-10-2010, 07:50 PM

I have a complete Hotchkis setup front and rear on my 67 Chevelle and I love it. Granted I don't road race it but it handles like it is on rails.

69cutlassrkt

10-10-2010, 09:05 PM

I have the hellwig adj rear bar. I had it on its tightest setting for drag racing. Then I got tired of the way the car rode with it like that so I put it on its loosest setting, It took me about 30 mins to change it, but would have taken a bit less if my exhaust wasn't in the way Now the rear suspension doesn't feel so stiff and it will oversteer a little instead of understeering like when it was on the tightest setting.

Its not a bolt on deal though you would probably have to take the rear springs out to drill the holes for the mounts for the sway bar links.

CHILI442

10-10-2010, 09:21 PM

Why in the world would trailing arm braces need to be adjustable? You just bolt them in.

69cutlassrkt

10-10-2010, 09:38 PM

Why in the world would trailing arm braces need to be adjustable? You just bolt them in.

yeah I don't get it either

67gtonut

10-11-2010, 01:16 AM

I have a complete Hotchkis setup front and rear on my 67 Chevelle and I love it. Granted I don't road race it but it handles like it is on rails.

Which rear bar? Normal Sport Bar or the Extreme?

silver69camaro

10-11-2010, 04:03 AM

67gtonut

10-11-2010, 04:43 AM

Larger anti roll bars will hurt the ride quality compared to smaller ones in a one-wheel bump (which most are). If I were you, I'd purchase items all from one company to make sure you have a balanced combination of parts. Many people mix and match and end up with a car that under or oversteers too much, or rides harsher than it should.

Thats one of the reasons I was leaning toward the Hotchkis bar..... but I was told on another forum.... because it still hooks to the LCA's it doesnt do much.... Hard to believe.... so it leaves me questions....

silver69camaro

10-11-2010, 05:31 AM

Thats one of the reasons I was leaning toward the Hotchkis bar..... but I was told on another forum.... because it still hooks to the LCA's it doesnt do much.... Hard to believe.... so it leaves me questions....

I don't see why it wouldn't work. If the bar is sized properly (which it looks like it is) to work with the motion ratio, I don't see any problem with that. I'd say the MR is pretty low, but it looks like they took that into account when they selected whatever bar size that is. It looks pretty darn large (I'm guessing 1-1/8" x 0.156").

wmhjr

10-11-2010, 08:36 AM

Why in the world would trailing arm braces need to be adjustable? You just bolt them in.

Maybe just so that a single part fits multiple applications? Dunno. :idea:

67gtonut

10-11-2010, 08:43 AM

Why in the world would trailing arm braces need to be adjustable? You just bolt them in.

I would think there is some variation between car to car for the distance between the upper and lower control arm mounts...

69cutlassrkt

10-11-2010, 10:10 AM

Larger anti roll bars will hurt the ride quality compared to smaller ones in a one-wheel bump (which most are). If I were you, I'd purchase items all from one company to make sure you have a balanced combination of parts. Many people mix and match and end up with a car that under or oversteers too much, or rides harsher than it should.

Though with the adjustable rear sway bars you can tune out ride harshness. And it can help fix understeer and oversteer.

gearbanger

10-11-2010, 11:17 AM

I would think there is some variation between car to car for the distance between the upper and lower control arm mounts...

Exactly.

CHILI442

10-11-2010, 11:24 AM

T-CHRGD

10-11-2010, 12:34 PM

Frame mounted swaybars are the most efficient, having a direct connection from the axle to the body.

If you really want to move your car to the next level, look at the front geometry issues, and look into the SC&C stage 2 plus kit. SPC adjustable upper A-arms, and Howe tall ball joints. :)

wmhjr

10-12-2010, 06:26 AM

Whatever. Never had a problem with the Hotchkis ones I bought for me '68 442. Maybe I just got lucky. Everyone and there mom has been building these braces for years, and I've never heard of anyone having a problem making them fit. Nevertheless, this guy built a better mouse trap :rolleyes:

What I meant was that they could be used on different car models - not just variation on the same model line. Not sure if it applies. I also agree that it's hard for me to imagine needing even close to that much adjustment on the same type vehicle. Typically, they just fit.

deadeyedck

10-12-2010, 08:50 PM

If you want the biggest improvements the parts your looking at won't get you there.

1. the front geometry is where you will see your biggest improvement.
(unless your shocks and springs are totally sacked, looks like thats not the case for you.)

There are a number of ways to accomplish this. After doing much research I chose the kit put together by savitske classic.

unlike a sway bar or stiff springs there really is no downside to installing these parts. your car will handle better and ride better.

The reason is you can eliminate most of the bump steer, gain positive caster and a flatter plant of the tire in corners.

There is a computer model where you can mess with these setting and see for yourself.

2. if you are going to get a rear sway bar hellwig seems to be the most reasonably priced and works the best, it's hollow and made of chromoly. This type of adjustable sway bar will work worlds better than the old stuff that connects to the control arms and at the same price or less.

Skip Fix

10-13-2010, 06:52 AM

"What I meant was that they could be used on different car models - not just variation on the same model line. Not sure if it applies. I also agree that it's hard for me to imagine needing even close to that much adjustment on the same type vehicle."

I think the main question was why not use these at half the price of the Hotchkis.

wmhjr

10-13-2010, 07:02 AM

I think the main question was why not use these at half the price of the Hotchkis.

I'm not disagreeing. I was just responding back to why they would be adjustable to begin with. These braces in particular aren't rocket science. All they do is connect a lower control arm mounting point to the crossmember/upper control arm mounting point. It's not like they change the geometry or anything. I'd guess you could make an argument that because they're adjustable, the design would allow them to flex just a little more, but even that sounds a little crazy to me.

67gtonut

10-13-2010, 11:18 AM

Well, I just got off the phone with Marc @ SC&C.....

Wow.... great guy. But I think my brain is now mush, and confused.

Needless to say..... I am now thinking of upgrading my front upper control arms instead.....and putting off the rear bar upgrade for now...

Mach Par

10-13-2010, 11:56 AM

wmhjr

10-13-2010, 02:32 PM

You're on the right track. The stuff I got from Mark (along with his advice) has made my '66 more fun to drive than should be legal.

Skip Fix

10-13-2010, 05:52 PM

I'm not disagreeing. I was just responding back to why they would be adjustable to begin with. These braces in particular aren't rocket science. All they do is connect a lower control arm mounting point to the crossmember/upper control arm mounting point. It's not like they change the geometry or anything. I'd guess you could make an argument that because they're adjustable, the design would allow them to flex just a little more, but even that sounds a little crazy to me.

Yep, if they are half the price might be a piece to consider.

FWIW the guy that ran the speed shop when I was in high school(early 70s) had a 64 Chevelle BBC Mod Prod car(big slicks legal) that "spun" the rear end housing mounts because the very early Chevelles did not have even the stamped steel ones like the stick GTOs got later on. So I think they are probably a worth wile addition for any kind of traction and alot of power.

wmhjr

10-14-2010, 06:27 AM

The GTO story is interesting. They weren't even available at first, then they were options with manual trannies. The first year they were installed on the manual trans cars they were a dealer installed item. They finally later got installed on manual tranny cars at the factory.

There's no reason for anyone having a traditional rear suspension to not install them. They provide some additional support that is very helpful. I used the Edelbrock ones. IMHO they all function the same.