Guldstrand 5 Link, Anyone Anywhere Installed?

Twin_Turbo

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I scrapped my 5 link because I went to double a arms. Built an upright and arms. Pics are on here somewhere

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Ralphy

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I started thinking about bind and why, if you added another member to the Guldstrand. I hadn't thought about toe-in settings. Which would make the front camber toe rod shorter than the rear a bit. Then there's the exact angle of the inner mount. Gets complicated exacting all the motions going on.

Hey Stroker, are your toe rods pretty close in length to your HS's? Are they a bit longer than your HS's? Also have you played with the roll steer any more? It sorta sounded like TT tried to build a GS copy.

Here's a guy who did a double wishbone on a frame just like mine. I don't know if I have the inspiration and perspiration to tackle this large of a project. I would lean toward the C5/C6 design with my C3 diff.
Rear chassis Medium

Thanks Guys!
Ralphy
 
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Twin_Turbo

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I did not build a GS copy, I built something like the Greenwood system and at the time when I built it was not aware of it's construction.

This is my old setup, the rear toe rod bracket and the toe rods are not in the pic. I lost the pics where I had it finished, I only have the design drawings and a pic of the batwing modified to bolt down the bracket. I lost the other pics in a hard drive crash and could not restore them. This is over 10 years old, back when on CF Lohkay built something similar. I built it in secret in fear of people copying my stuff. I had that happen with the simple coil over system i built and also my cam operated suspension system. Not literally copied but ideas were "borrowed" One current manufacturer of coil over rear susensions literally asked me about the ins and outs via PM back on CF. They put it in production.

24a719b94c6405

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I scrapped it all for this:

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It's fully adjustable.
 

Stroker-427

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Ralphy,
the HS is not anymore part of the suspension.
Of course the pump (and roll) steer was the main concern of my design... if you check the pics you will see 3 different holes where to connect the outer toe link in order to have the toe control you like.
In my design the camber gain is not an issue due to the very short stroke of the wheel (some 3.5") and because I'm very convinced that the toe characteristic is the more important factor for a well predictable car.
You know that if a car start to surprise you when driving fast between corners, yuo will loose confidence and your speed will decrease for shure!

With this configuration in a track day I was not in trouble following C6's, Vipers and a well done GTM Factory Five.

TT,
I think I know the history of the pullrod rear coilover...... but they are wrong in the design of the cam...
 

Twin_Turbo

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Yes, they have the cam ratio the wrong way around. I posted about that when they 1st showed their spy photos of it, that was the reason they ran duals hocks, the shocks (and springs are grossly inefficient with that setup
 

Ralphy

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Twin Turbo,
I forgot that pic missing the toe link was yours. I must have came across it more than a handful of times. When I looked at it closely I said to myself, where are the missing links, where did he put them? LOL!

Stroker427,
Why I ask about the length is, if you did have an OEM style HS's and your toe links were level and parallel to the HS would you be at zero RS? Or with your setup can you dial in zero or near zero RS by leveling your toe rod with your splined HS's?
 
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Stroker-427

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Ralphy,
due to the fact that the HS don't have anymore a role in the suspension (by the way I have splined HS) the roll steer is defined by the whole 3 links:
Upper, lower and toe link.
The front two links are only controlling the longitudinal forces (acceleration and brakes)... to be onest they can even change the longitudinal swing arm in order to control the antisquat (very poor, but you don't really need it when the suspension is very stiff) and the wheel hoop when braking (this is very important).
By design the suspension is designed around some -0.5° to -1° of camber gain per inch of wheel travel (looks a lot, but remember that I have nearly 1.5" of static sag and 2" of max bump with rubber bump-stops fully compressed) so I can assume that the rear camber is varying between -0.5° to -2° (with some 1.5° of body roll).
The toe link must teoretically rotate in the same arc of the two others links in order to have zero bump steer.

Changing the outer pivot point of the toe link I can put some negative bump steer..... I like this configuration in autoX for the following reasons:
1) when braking hard before the corner, the risk is to reach the limit of the front wheels grip, causing heavy understeer...... some rear toe out in this condition (the rear suspension will rebound generating this rear toe out) will improve the corner attack.
2) coming out from the corner the big acceleration in lower gears will generate rear suspension bump with the consequent toe in..... avoiding part of the power oversteer.

Of course this is my feeling.....
 
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Ralphy

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Stroker-427,
What spring rate are you using, I'm guessing around 600 to 700 lbs? I enjoyed reading your last post. Sounds logical to me, what little I know, but seems mechanically sound.

Ralphy
 

Stroker-427

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I have quite stiff springs.... in the ballpark of 1000 lbs front and rear, but the ratio in the front is some 70% instead of the back, where the ratio is very close to 90%.
Basically I use near zero preload on the springs.

This is the reason I sed that QA1 have not enough fluid control to dump such spring during fast wheel travel (bumps or curbs).
If you have seen the inside of a QA1 coilover, you can imagine the reason of that:
the piston diameter is very little and the oil recirculation is demanded to a small tube of less than 1/8" ID.
Of course during quick compressions the bump/valve is fully opening, overwhelming the knob adjusting which is mainly working on the oil recirculation.
For this reason, QA1 will be allways over-dumped in slow movement ( roll control or general control of weght transfer ) and under-dumped in fast movement (road/track bumps or curbs).

Penske are very exepsives (in the range of 1000$ each) but is an other history!!!!!

My next move will be to reduce sway bar stiffness, thanks to the rollcage frame stiffening.
 

Stroker-427

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I forgot to add a note to my previous post...

The rear toe control setup I mentioned before is only for very tight autoX..... at the track a setup with zero rear bump steer is allways a good move..... at linst as a start point for your tests!
 

Twin_Turbo

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I have quite stiff springs.... in the ballpark of 1000 lbs front and rear, but the ratio in the front is some 70% instead of the back, where the ratio is very close to 90%.
Basically I use near zero preload on the springs.

This is the reason I sed that QA1 have not enough fluid control to dump such spring during fast wheel travel (bumps or curbs).
If you have seen the inside of a QA1 coilover, you can imagine the reason of that:
the piston diameter is very little and the oil recirculation is demanded to a small tube of less than 1/8" ID.
Of course during quick compressions the bump/valve is fully opening, overwhelming the knob adjusting which is mainly working on the oil recirculation.
For this reason, QA1 will be allways over-dumped in slow movement ( roll control or general control of weght transfer ) and under-dumped in fast movement (road/track bumps or curbs).

Penske are very exepsives (in the range of 1000$ each) but is an other history!!!!!

My next move will be to reduce sway bar stiffness, thanks to the rollcage frame stiffening.

QA1 is juk, the only quality coil over they sell is what used to be the carrera coil overs and even better the advanced carrera coil overs. I'm not even sure if they still carry it in their bling bling line but they did buy out carrera shock co.
 

Ralphy

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I have quite stiff springs.... in the ballpark of 1000 lbs front and rear, but the ratio in the front is some 70% instead of the back, where the ratio is very close to 90%.
Basically I use near zero preload on the springs.

This is the reason I sed that QA1 have not enough fluid control to dump such spring during fast wheel travel (bumps or curbs).
If you have seen the inside of a QA1 coilover, you can imagine the reason of that:
the piston diameter is very little and the oil recirculation is demanded to a small tube of less than 1/8" ID.
Of course during quick compressions the bump/valve is fully opening, overwhelming the knob adjusting which is mainly working on the oil recirculation.
For this reason, QA1 will be allways over-dumped in slow movement ( roll control or general control of weght transfer ) and under-dumped in fast movement (road/track bumps or curbs).

Penske are very exepsives (in the range of 1000$ each) but is an other history!!!!!

My next move will be to reduce sway bar stiffness, thanks to the rollcage frame stiffening.

QA1 is juk, the only quality coil over they sell is what used to be the carrera coil overs and even better the advanced carrera coil overs. I'm not even sure if they still carry it in their bling bling line but they did buy out carrera shock co.

Funny I hear guys swear by QA1's. On the other hand I also hear others swear those 10 position adjusters are worthless. I think Pro Shocks designed the QA1 shock. I once called Pro Shocks and talked to one of their field guys. Turns out they're more of an engineering company. I was told they design more than a handful of aftermarket dampers.
 

Twin_Turbo

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I have pro shocks, they are a lot better than the sloppy QA1 ones. The QA1s come with the junk stuff from speed direct, they are worthless!
 

Ralphy

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Another story I was told. The moto X industry had some of the best shock technology engineers money could buy. Penske stole these guys away to work for him.
 

Ralphy

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OK, Let me try this a different way. LOL!

If I wanted to somewhat copy the C4 design using the HS as a member. With parallel equal length trailing links and coilovers. However modify the toe rod similar to what Stroker has. I'm thinking I should make the toe rod the same length as the HS. Then instead of moving the outer mounting point down to gain toe. I could move the inner toe rod point up to gain toeing. Hmmm? Having my toe rod dead parallel and equal length to the HS should give me pretty much zero toe change?

Another change I'm contemplating is moving the coilover behind the HS. My reasons are clearance issues. My frame width pretty much requires having the coilovers exactly straight up. Behind the HS removes any interference with the trailing links, etc... I'm looking to put the trailing links beside the uprights not in front. I can get a few more inches in length. What effects does moving the coilovers behind have?

Talking with Pro Shocks I was made aware there are springs with a smaller ID, maybe 2 1/8" vs.
2 1/2" ID. For more clearance, same dampers.


Ralphy
 
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Twin_Turbo

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That's what I have the 2-1/8 but I don't think they fit all shock models, only the narrow body shocks. You need those for clearance.
 

Ralphy

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With parallel equal length trailing links and coilovers.

Ralphy, What is the reasoning for parallel equal length trailing links?

Well......... Hmmm.....

As best I have seen many performance suspensions use parallel trailing links. To me first off, it stops any rotation of the uprights. If I were to try and remove any toe change, just the rotation would create some effect. The toe rod and camber rod being two different lengths and in two different areas would not necessarily have the same effect when the uprights do rotate. Again from what I have read trailing links also should rise somewhere between 1" to 2" per foot to the front. I'm shooting for app. 1" plus. Second, with regard to jounce my thought is more wheel base is better. Even if it's not much it removes or limits any forward motion of the upright. I do believe I have seen conversion brackets for the C4 that set these links parallel also.

As best I get from reading, today's performance trends seem to keep things simple. Making changes easier to sort out. Works for me?

TT, it's been awhile but I remember the Pro Shock guy saying it was the same shock. Have you ever talked with someone and later it sinks in what they said? Well that's what happened and I wish I had questioned him more on that exact issue what your talking. I also remember discussing spring OD's and mention all OD's are not the same due to wire size. Plus the OD growing when compressed.

A side note, do I see this right? If you were to take the Guldstrand design. Then move the front camber/toe links inner point forward of it's outer point. You can induce roll steer? They would look more like this \ l than this l l . The more forward the more RS? By moving the front inner and not the rear inner, the RS should be closer to a linear motion. Since the closer the trailing links near level the slower the rearward motion. The front camber/toe link arcs further and increases inward motion.

Please shoot holes in my ideas if you see any issues. Also this is not a Vette chassis I have.
Ralphy
 
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