[opelgt722002]

Zugstrebe

Has anybody seen or used this item on a GT?

http://www.cyi-priewe.com/VA Zugstrebe_e.htm

 

[RallyBob]

In simple terms, it's a 'strut rod'. If you look under the front of many Japanese small pickups, or early strut-type front suspensions on Datsuns and Toyotas, etc, the lower a-arm is supported or triangulated by the use of a strut rod.

The GT has a very narrow lower-arm mounting bolt pattern, so it tends to flex fore and aft quite a bit. So in the early '70's many GT and Kadett tuners such as Irmscher, Conrero, and Steinmetz added a strut rod to the lower a-arm to stabilize the front suspension.

It acts three-fold....it helps to prevent the a-arm from bending in an impact (which GT's are very prone to do), it stabilizes the car under braking (as mentioned on the website above), and it keeps the caster angle more consistent under duress.

Bob

 

[opelgt722002]

Will your Conrero replica be using this strut rod approach and /or this method to lower the GT?

 

[RallyBob]

I'm not sure if the early Conrero GT's used the strut rod reinforcement or not. I still have to do more investigating.

Regarding lowering the car, Conrero used welded strips of metal added to the bottom sides of the lower a-arm, and drilled extra holes to allow for relocating the spring ends, which lowered the front of the car.

I will probably use a similar method to the raised ball joint in your photo...I have done this for years via another method...a Chrysler ball joint which is taller, and basically accomplishes the same thing. It also changes the roll center, which was more in line with my original intent. I can improve the camber gain substantially this way.

Before I make my GT into a Conrero replica and modify the body with flares, I have one other thing I've always wanted to try. I want to break the Land Speed Record for the class. It requires a stock body, no aerodynamic improvements, and a naturally aspirated 2.0 litre engine. The old class record was set in '85 by a FWD Dodge Charger with a 190 hp destroked 2.2 (NA, not turbo). I believe it still holds the record at Muroc, El Mirage, and Bonneville. I think I can top the record with a GT and some serious tweaking. Got my gearing and engine all figured out already.....

 

[opelgt722002]

chrysler ball joint

will probably use a similar method to the raised ball joint in your photo...I have done this for years via another method...a Chrysler ball joint which is taller, and basically accomplishes the same thing. It also changes the roll center, which was more in line with my original intent. I can improve the camber gain substantially this way.

Is this ball joint taper the same as the Opels or do you also need to use a reamer? Which Chrysler products does this ball joint fit? I guess this is a screw in ball joint and you weld a sleeve in on top of the lower control arm.

 

[RallyBob]

Re: chrysler ball joint

Is this ball joint taper the same as the Opels or do you also need to use a reamer? Which Chrysler products does this ball joint fit? I guess this is a screw in ball joint and you weld a sleeve in on top of the lower control arm.

It's the same taper, but it's a larger diameter, so it still needs to be reamed out. I don't know the exact fitment application, but it's a common item in the racing world, most aftermarket a-arms use some variation of hte Chrysler ball joint. Yes, it's a screw in ball joint, and the a-arm must have the OEM ball joint area machined out, and the sleeve fitted in place and welded. It does not sit on top of the a-arm. You will also need to modify a ball-joint socket to fit it into the GT a-arm without hitting when you torque the ball joint into place.

 

[opelgt722002]

I think it is the MOOG pn K727, with a stud length of 3.346"($25 each). The base is 2.08" and the taper is 1.5206" per foot. Looks like I need to buy a 1.5" reamer ($80) and a lower ball joint socket ( $50) and 2 screw sleeves with flange ( $6.50).

As I understand it, this will lower the front 1 7/8" without the harsh ride that usually results with lowering the GT. Does it also eliminate the bump steer issue?

 

[Travis]

As I understand it, this will lower the front 1 7/8" without the harsh ride that usually results with lowering the GT. Does it also eliminate the bump steer issue?

Yes it will lower the font of the GT. How much depends on where you install the sleeve in the arm and how deep you ream the spindle. You are correct in that it won't stiffen the front end as a stiffer spring would but it will be stiffer than if you had added shackles.

As for the bump steer it will depend greatly on the ream depth and ball joint placement but it will most likely make the bump steer worse.

One word of caution. I know that Bobs used the ball joints in a GT with his fiberglass spring but I don't know if he's
used a stock spring or any other aftermarket spring. I am currently using an OGTS spring and the eye at the end is HUGE. In fact, I had to modify the spring to prevent it from binding against the stock ball joint which is MUCH smaller than the Chrysler ball joint especially when you consider the size of the Chrysler sleeve.

-Travis

 

[RallyBob]

The ball joint lowers the front 7/8" only, based on placing the bottom of the aftermarket sleeve in the locations of the stock GT sleeve. You can lessen or increase this a small amount by changing the location you weld the sleeve into the a-arm.

I have used these ball joints with stock GT springs, and my own aftermarket GT springs I used to sell (they were made by Benz Spring in WA, not the same as OGTS'). The eyelets did not hit the ball joint. With the fiberglass spring, and its' larger billet aluminum eyelets, they hit a LOT, and I had to relieve the aluminum to fit the Chrysler ball joint.

Bump steer will be worse (same as with any GT lowering method except notching the frame), but shock travel is not lessened, nor do the bump stops need to be cut when lowering via the ball-joint method, as the lower a-arm does not move from its stock location, only the spindle and upper a-arm move upward relative to the chassis.

When using an aftermarket 'sport' front spring, the bump stops are usually within 1/8" of striking the a-arm, which cause the 'bouncy' ride associated with a lowered GT as the bump stops bottom out over every bump in the road. Cutting the bump stops in half and using a high quality shock (with firmer valving to dampen a stiff spring's higher frequency), will make the car ride and handle a whole lot better.

Bob

 

[oldopelguy]

back to topic

Back to this "strut rod" thing, it looks a lot like it does the same thing the anti-sway bar on the Manta does.

Is there enough of an advantage to be gained from this thing to make it worth while to try and fab-up a Manta-type anti sway bar on the Kadett or GT instead of the convential one with links? On a suspension with shackles it wouldn't take a lot to use a rod end in place of the bolt in the lower control arm. Then the sway bar coud be connected directly to the rod end, without a link, and you would get both the beneifts of the sway bar and the strut rod.

Just one idea.

 

[baz]

all the strut rod does is stop for and aft movement it will not work like a sway bar as it is not putting any force into the action it just stops twist in the system
to do both you would need a "u" shaped bar right across the car with a fixing at each swinging arm and 2 onto the chassis to get the torque effect to work and thay would be some shape to work on a gt with the way the suspension is set up

 

[opelgt722002]

Thanks for the info Bob and Travis. I have the OGTS intermediate spring and had to grind the eye to eliminate the binding of the Opel stock ball joint. The Chrysler ball joint seems like a deal braker. However, I also have my stock leaf spring which should clear.

 

[OpelThom]

In simple terms, it's a 'strut rod'. If you look under the front of many Japanese small pickups, or early strut-type front suspensions on Datsuns and Toyotas, etc, the lower a-arm is supported or triangulated by the use of a strut rod.

The GT has a very narrow lower-arm mounting bolt pattern, so it tends to flex fore and aft quite a bit. So in the early '70's many GT and Kadett tuners such as Irmscher, Conrero, and Steinmetz added a strut rod to the lower a-arm to stabilize the front suspension.

It acts three-fold....it helps to prevent the a-arm from bending in an impact (which GT's are very prone to do), it stabilizes the car under braking (as mentioned on the website above), and it keeps the caster angle more consistent under duress.

Bob

It is just like Bob says, no more no less. And I know because i've it under my car for several years. Especially good working by hard braking and high speed corners.
On the photo's you can see how they look like.

Tom.