Worst case scenario would be that the link is perpendicular to the path of travel. In this case none of the motion of the suspension would be applied to the bar because the link would just rotate.

Best case scenario would be that the link is parallel to the path of travel. In this case all motion of the suspension would be transmitted to the bar with no rotation of the link.

Anything in between is a compromise. This may be splitting hairs. I couldn't tell you where the drop off in effectiveness is. It could be perfectly fine until you get to 80 degrees out of sync with the direction of travel. In which case this is all pointless. But I'd bet it's a direct correlation and the closer you are to parallel, the better because less of your action is spent rotating the link.

If you're using a bar, none of this matters, you just use what you got and make it work. If you're designing a bar you have to think about these sorts of things if you want to make The Best ™.

I did not intend to create a storm on our calm sea.

All I can say is that Britain has set his bar in a position that is softer compared to mine.

He has demonstrated a way to adjust the "unadjustable" rear bar...Brilliant!

Unlike the SRP front bar with infinate adjustment.

KT

Interesting theories presented here. The design goal will be to have the swaybar arm and trailing arm close to being parallel to each other, and the drop links perpendicular to them. It doesn’t need to be perfect, but will help provide the most efficient design and minimize additional component loading.

Thanks for all the pictures, comments, and offers to help!! I’d like to work out some kind of initial release at a discounted rate on the first run. Brad would get his discount on the discount. It will kind of be a big test group. I wont promote the bars to my other customers until afterwards.

Brad, I’m looking forward to hearing about your e-commerce site. I’m currently working on my own as well, in between Boxter/996 droplinks, 914 swaybars, boxter swaybars, and keeping up with all the daily stuff.

Here’s a picture of what the 914 bar is starting to look like. There’s still LOT of work to do.

im down for a test vehicle. got a t bar up front, why not one in the rear

Hey Ira...

I just bought your front bar system ...(Don Kravig called you re: my car). My car is pretty well slammed down and the drop links from the stock rear bar are about 30 degrees from vertical at rest. I'm operating on the theory that I can get a lot more compliance and a lot less roll with 165 pound rear springs and a rear bar than going back to 250 pound rear springs with no bar. Andy Ritter likes that feeling of loose fillings I guess but I drive a lot of less than perfect non-track surfaces, and my old fat butt likes a little "give". If I can edge in front of the rest of these miscreants, I'd love to get your rear bar set up (sorry AAron...) when its ready...

It's been a while...Why are we still waiting?

KT

I wouldn't expect anything until next year.

“Next Year” ??

It’s coming along slowly, but not that slowly. It’s actually almost ready for testing and was on display yesterday at the Euro/Dunkel swap event. Just received the last of the NC machine parts on Friday. I still need to finish the softer bar (this week) that we’ll be testing, but it will be going onto the test car (thanks Mark G.) in two weeks. We’ll be testing at the next PCA event at the end of next month, but hopefully we can find an SCCA slalom or at least an empty parking lot for some pretesting. I’ll post some pictures later on tonight.

Ira

Hi Ira,

Did Brad Roberts talk with you about using my new race car as a test bed for the rear bar? Late last year he said he spoke to you about it.


914-6 3.6 liter 993 motor
Semi-Tube Frame
Raised suspension points
Slicks all around
etc....

I've been curious as the frame is close to painting....I want all of the welding done soon.

Let me know. Thanks.

Bill P.

Hi Bill,
Thanks for your offer to help out with testing. I haven’t talked to Brad about it much lately, except that he did mention that he would have a car to do some testing with. I built two sets of prototypes and will be testing the first one on a local San Diego car. After some initial testing here, the other set will probably go on one of Brad’s customer cars so that he could be involved with the testing. Please tell me a little more about your car, springs, shocks, wheel size, ect. There’re a few guys that have offered to help with testing so far. If Brad still wants to be involved, I’m probably going to leave it up to him to decide who would be the best candidate.

BTW where is Brad these days? I haven’t heard much from him lately. Is he still stuck in the snow somewhere?

Here’s a picture of what it looks like so far. I still need to finish a softer bar and build some backing plates for mounting to the bottom of the trunk.

Ira

This view is a mock up that kind of shows where it will be mounted.

how do you keep it from bottoming on the trunk floor?

I have a few different sized drop links to try out. I’ll use the longest one that is a safe distance from the trunk floor. The one in the mock up view looks very close to the floor, but it’s actually a bit shorter than the Weltmeister version, so it may be ok. If not, I have a shorter one.

QUOTE (Ira Ramin @ Feb 7 2005, 10:03 PM)

I have a few different sized drop links to try out. I’ll use the longest one that is a safe distance from the trunk floor. The one in the mock up view looks very close to the floor, but it’s actually a bit shorter than the Weltmeister version, so it may be ok. If not, I have a shorter one.

good idea.

Ira,

Bills car has the entire rear trunk floor cut out of it. This will make for GREAT viewing of a new rear sway bar setup. The tub is being powder coated soon, so if you have the billet rear pivot blocks done.. send them to me so we can weld some brackets to the rear frame section to hold them. Give the distance they need to be apart.

Send them here:

Yeaman Autobody
2025 East Bayshore road
Palo Alto, Ca. 94303

I have to have custom rear shock bolts made to hold the race shocks we are running.. I'll need to know what size heim joint you plan to run on the drop links.

B

This is gonna be cool

More parts...

KT

Brad,
I’m using 10mm rod ends for my drop links. They will be positioned .8” from the edge of a Koni shock lower mounting bushing. See my shock bolt below.

I’d like to send you the entire assembly so that you can set it up in the correct position more easily. I’ll have it ready to send to you within the next couple of days. It will include a mocked up bar with shaft collars installed to locate the bearing blocks. All you’ll need to do is position it relative to the rest of the suspension.

Ira

I don't think I like that arrangement at all.
With the weltmeister and the stock bars at least the arms are long enough so the rear wheels will droop a bit when the car is lifted up.
Because the bar comes from the opposite direction as the trailing arm the torsion bar will cause binding of the rear suspension whenever the droop straightens out the drop link, which will happen easily since the arm and drop link are so short. You will have AX guys coming in from their runs with the car cocked to one side.
Another thing, if someone is using stock type springs on Bilsteins with the car heavily lowered the drop links will interfere with the spring perches unless the drop links come up from below. Doing this was discussed earlier in the thread.

Hi Ira and Brad,

Thanks for arranging my car to be a test vehicle....what we learn we can apply to all the members on the board...

Brad and Scott are building one of the nicest race cars in the 914 community for Doris and I. It's hard sitting in the pits while the season starts, but the wait will be well worth it once the car is up and running and dialed in.

Thanks guys!

Bill P.

Chris,
Thanks for your comments. These are very good points and are also my biggest concerns with the design. I moved the bar forward because it significantly simplified the arm design. It was difficult to design a machined arm to clear the sheet metal rib on the bottom of the trunk. The arms are shorter but the drop links should be slightly longer than the Welt design. They connect to the upper edge of the arms which makes them the highest point and allows their length to be maximized. My hope was that this would help make up for the shorter arms.

I designed the bars around a car with Koni shocks and aftermarket springs. The drop links are spaced far enough away from the shock to clear that setup and I thought it would clear the stock spring setup, but I’ll double check. I may have access to some KYB shocks to check this out with. Do you think that it would be similar as far as clearing is concerned? If needed, I can make the bar shorter and space the links farther away.

Brad,
Since I haven’t even mounted the prototype yet, it’s a little premature to put it on a car like Bill’s. I would hate to see you need to make changes to Bill’s beautifully powder coated frame to fix binding or spring interference problems. If you have the complete rear suspension on it, you can fully check it out before welding in mounting brackets. That was part of the reason for me sending the complete swaybar assembly. If needed, we can probably build longer drop links for his car to address any binding problems. Clearance between the drop links and spring hats will need to be checked.

Thanks,
Ira

I'll be on the a/x track in 3 weeks. I wanna help!

Does the new rear bar mount in the stock bushings or do you need to do an all new install?

KT

QUOTE (trekkor @ Feb 15 2005, 08:35 AM)

Does the new rear bar mount in the stock bushings or do you need to do a all new install?

It looks like it would need new mount points. This is because a hollow bar would have to be straight and it can't snake around the tranny mounts like the solid bars do.

QUOTE (Ira Ramin @ Feb 15 2005, 08:20 AM)

These are very good points and are also my biggest concerns with the design.

i've said this before, i for one wouldn't hesitate to install a version that mounts like on the factory GT's.
bar inside the trunk, droplinks down through the trunk floor. not bottom out, droplinks hitting anything ...

Andy

i hope glenn doesn't mind posting this ...

Send it to me. I'll mock it up and see what we have.

Notice in the GT pic that sway bar doesnt pick-up at the rear shock mount. It has to be mounted to some place on the control arm forward of the axle. I promise travel is limited on this setup.

I have Randal Barricks really clean 914 that we can test with also (stock tub on slicks)


B

QUOTE (Brad Roberts @ Feb 15 2005, 11:16 AM)

Notice in the GT pic that sway bar doesnt pick-up at the rear shock mount. It has to be mounted to some place on the control arm forward of the axle. I promise travel is limited on this setup.

i would have to disagree with that assesment. look at the GT pic closely, then look at trekkor's under body shot.

you can see that the GT droplinks come down right where the stock droplinks mount.
i think all they did was making longer droplinks ...

Andy

QUOTE (SirAndy @ Feb 15 2005, 12:27 PM)

QUOTE (Brad Roberts @ Feb 15 2005, 11:16 AM) Notice in the GT pic that sway bar doesnt pick-up at the rear shock mount. It has to be mounted to some place on the control arm forward of the axle. I promise travel is limited on this setup. i would have to disagree with that assesment. look at the GT pic closely, then look at trekkor's under body shot. you can see that the GT droplinks come down right where the stock droplinks mount. i think all they did was making longer droplinks ... Andy

i agree....mounted in the exact same place....just on top of the sheet metal...

Looks like a stock bar mounted on top.

QUOTE (McMark @ Feb 15 2005, 11:38 AM)

Looks like a stock bar mounted on top.

yepp, stock bar in the stock mounting location, just on the other side of the floor sheetmetal.

Andy

QUOTE (SirAndy @ Feb 15 2005, 05:20 PM)

QUOTE (McMark @ Feb 15 2005, 11:38 AM) Looks like a stock bar mounted on top.  :confused: yepp, stock bar in the stock mounting location, just on the other side of the floor sheetmetal. Andy

why did they do it?

my guess is to keep the bar from bottoming on the trunk floor... conventional wisdom would say that thet used the same length droplinks..... bar wont bind into the floor..

Ira,
Here is a picture of my car with the Weltmeister bar installed and my custom drop link arrangement. This worked out very well by the way.
When I had stock type 180lb springs the lower perch was located at the lowest adjustment groove on the shock. If the drop link was above the shock attachment point it would interfere with the spring perch.
When I had the bar set a bit stiffer it interfered less but I sometimes ran into problems on the race track with the unloaded side binding up in a corner, which totally ruined the handling for the rest of the session. The reason it bound up is that the drop link would extend horizontally in line with the sway bar arm as the inside trailing arm drooped and would not return to the correct position after exiting the corner.
I guess a chain to prevent the trailing arm from dropping too far would eliminate the possibility of this happening but there is another issue. If the trailing arms are restricted from extending downward when the car is raised it becomes difficult to remove/install the wheels. There is a delicate balance somewhere in all this, and I would rather see you build the best possible system without investing in a lot of parts that become unsuitable for sale first.

Trekkor,
The bar mounts in a different position, about 3” forward. I figured that was no big deal since most cars don’t have factory brackets anyways. Thanks for offering to help with testing. I wish that I had built three sets, but I only built two and they’re already spoken for. I’ll definitely keep you in mind if things don’t work out with them, or for the next batch.

Andy,
I will probably be doing a version that could be mounted in the trunk. It may only consist of changing to a longer drop link, possibly the one that I use on the front swaybar. Keep in mind that it will need more than just a hole in the floor for the drop link. It will need a long slot to allow for the adjustment. Hopefully I will end up with a design that will work good without needing to be mounted in the trunk.

Brad,
The bar is on its way to the shop for Bill’s car.

Chris,
What do you think about mounting the bar below the transmission and connecting the drop link the way you did? It would probably solve the possible binding and clearance issues, and the geometry might be a little better than your current setup. It would be similar to my rear 911 design. Figuring out what to mount the bearing blocks to would be a little bit of a challenge.

Ira

Since the dogbone/tranny mount seems to be a bit of an obstacle, what if you reverse positioned the bar, not upside down - but turn it around.

Something like this: obviously the pillow blocks would need to be further inward due to the rear shock mount cutouts, hell it is an idea...

Also, since the bars up an down movement is in unisyn (sort of) with the shock and control arm, I don't know how there would be an interference with the rear shocks. As long as there is X amount of room away from them, that X should always stay the same, no?

Travis,
Your sketch has the best geometry of any of the designs but I think that the engine or the starter may be in the way. I think we considered mounting that way, but it’s definitely worth taking another look. We’ll be installing the prototype on Saturday morning and will try to take a fresh look at the other possibilities.

I see what you’re saying about clearing the shocks, it makes sense.

Ira

If you made long mounting blocks to position the bar beneath the tranny (at the back) you still have exhaust interference issues to deal with (except with the Tangerine header), as well as worker access issues.

Should be no problems with engine interference, but I didn't think about the starter. that'll be a tight fit.

Or you could do a through body one (like the front) but have it in the trunk going through the walls of the rear strut mounts, obviously you would need longer and doglegged arms for clearance.