DR

Hi Hacker,

Are you sure about the extra 13mm clearance difference on the fender between a 9" ET57 and a 9" ET65?

Good point about test fitting and trying them to see what works, I've done that also, more times than I can remember...but at least I got to play with New Stuff. :-)

Hi Jeff,

Amen to that!!


We were, then someone said a 255 is too much tire on the front of a 928 and I just had to respond and you may be new here, but threads always evolve...LOL

Doc is just trying to confuse us with Doctor Talk(way to go Doc), I hear it almost every other day at all of Doctor's appointments! J/K!! Regardless, he did temporarily trick me and at a glance it looked like he said offsets higher than ET60 on the front was "concerning".

ET45 larger offset than ET65? ET45 insertion Depth is 45mm and the ET65 Insertion Depth is 65mm, so now which one is technically "smaller"?

Backspacing ? Nah, we were all on the same page using the offset numbers that apply to a 928, if we stick to that, the info will flow more effectively without the confusion of negative positive offset...there is enough of that already..ha, ha!

BTW, when you said above "these are negative offsets", did you mean the stuff Doc was talking about or 928 in general?



Cheers,

Dave

hacker-pschorr

Great, thank you for the German language lesson.....
Point is, right or wrong, I hear it all the time when people say "larger" offset they are referring to wheels that stick further out....
Unless Doc says otherwise I'm figuring his experience was talking about front wheels with a number smaller than 60-65 for offset.

Oh FFS, nice typo...

Well, on an et57 9" wheel it could be too much tire, and that's the wheel being discussed here. Sure you made it work with an et68 9" wheel which gives you just a tad bit more clearance..... and as you are well aware it can greatly depend on the tire itself. I've seen up to a full inch width difference between different brand tires of the same "size".

The OP doesn't sound like he's trying to squeeze the absolute most rubber he can under the nose, he just wants some different wheels that will fit without hassle. Not everyone can afford a custom set of Fikse wheels.

I fully understand the difference, but to some people the wheels which stick out further are the larger offset. Don't ask me why, I didn't put that in their heads. Maybe the "larger" track width means "larger" offset....

We wouldn't be having this side discussion had Doc included the offset of the wheels he was talking about in the first place.

Doc specifically said: "rather large offset" and while et65 is stock, we've seen racers run et70 which isn't a significant different from stock, especially compared to say an et45 or even an et40 which I've seen people run on the front of 928's.

...and here yea go, Doc fitting a et47 wheel on the front of his 88:
https://rennlist.com/forums/928-foru...l#post12108369

SwayBar

The people who do not know nor understand the concept of offset should do a simple Google search, read and learn, and then report back, as opposed to the calls to dumb-down the concept to 'make it easy' for them, which only confuses the matter more.

Speedtoys

Add in scrub radius and its pros and cons...offset how-tos dont often go that far.

hacker-pschorr

Sure, I'll expect that to happen right after everyone agrees on politics.

Here's an easy example as to why this is so confusing for people.

Go find someone that put a huge ultra wide body kit on their 911 and say this:
"I see you decreased your offset to create a wider stance with those wheels".
Most people will look at you like you just asked what the color purple tastes like.

It may be a 100% factual statement, to the average lay person, it makes no sense.

So instead of climbing up on soap boxes and belittling people around here, how about we take a step back, realize 100% of the population will never fully understand (and most don't even care) and lighten up a bit?? Is that so hard?

Again, even if you could make everyone understand the engineering and science behind such topics, most people are not going to give a rats patoot or believe that 8mm of front wheel offset difference is going to suddenly make their car unsafe to drive.
I sure as hell don't agree with that thought process.
One of those things which is factually true on paper, may not translate to real word performance and / or experience. Sure there are extremes like running say an et35 on the front of a 928....I'm sure that will handle like crap. But et55 or et57? Meh....my cars handle fine to me.

worf928

DR

Hi Hacker,

Very good post, but don't be too hard on Swaybar, it can get very frustrating trying to have a technical discussion when people throw out info presenting it as fact that you know from lots of experience is dead wrong. One quick example, when Jeff posted this:

The reality is adding both F/R stiffer swaybars changes nothing in relation to oversteer, you are basically right where you started. Everyone in the industry knows that to reduce oversteer you use a stiffer front, softer rear, or a variation of the 2. That is how you change/control oversteer with swaybars, just stiffening both swaybars the same, not so much.

So when you are active in an technical discussion thread, do you just let something like that just lay there in the thread forever for others to read (and possibly assume as fact), or do you at least try to correct something like that,... or at least offer an alternate point of balance in the thread?

It's all a tough balance and I don't envy you trying to keep your own balance when you are not only an active vocal participant in the technical discussion, but also a Mod who's job it is to keep the "peace". I guess the trick is to try like heck to be an active participant without using the extra mod powers to influence the flow of the technical discussion when others share a differing point of view. I feel for ya man!

Have a wonderful day and keep up the good work you do for all of us!

Cheers to you,

Dave

Speedtoys

DR: my point was be cautious with just doing one...we dont have a lot of options. Doing both ends up 'same', but its not entirely the same..of there's no need to change anything at all.

DR

Hi Jeff,

Yes, it is frustrating not having more options! I am so sorry I abandoned the swaybar project after working for many years to get it right. My bars were designed to not only give stiffer options, but also softer options so everyone could tune to their style of driving. I just couldn't deal with the inconsistent manufacturing at Addco and every other manufacture I tried pushed the price point to where I felt it was out of reach for the average 928er.

Anyway, thanks for the clarification, but as you said there are not many options especially for doing both ends. I can't think of any "matched" sets readily available that can be predictable in their interaction with each other.. I fear people scrounging around finding this front bar here and that rear bar(or just force multipliers) there, made by different companies, adds more confusion to the mix...and more improperly setup 928s on the streets.

Have a great one,

Dave

Speedtoys

Is your bar, the red one? Sorry if that's not descriptive enough...I like it.

I need to buy an endlink kit for it as well, you have those...I think? As long as it clears a factory muffler. (the steroid links do not)

The devek bar had adjustable/collapsible ends to adjust it quite a bit...I find the Devel Blue with this red bar in back, kinda nice.

SwayBar

Erik, really?? The two are not even remotely related...

Offsets are set in stone with objective mathematics, whereas discussing politics can be subjective at best.

Geez, talk about being on a soapbox!

FAKE POST!

DR

Hi Jeff,

Yes mine were red, glad you like it. I plan to go back to my storage in NC this fall and I will bring all of the kits and individual hardware I have left there.
Some of the rear bars were recalled, modified, and later resold as "budget bars"(a decision I regret), IIRC the area where there was a problem was on the passenger side plastic cover over the fuel lines, SCARY!!
Anyway, if it has 3 adjustment holes it should be OK, just keep an eye on the passenger during and after installation(lifted and on the ground) . IF you get a 4 holed version the last hole for sure section needs to be cut off. These were just some of the many quality issues I ran into with Addco. I am hoping you got one of the first editions, those were the most consistent with my original design and are BADA$$!!

The Devek bar, yes I had one of those all the way back in 1997 even before 928 Specialists was born. If setup correctly and tight (and absolutely grease free on that sliding adjuster area, and double checked for inner wheel clearance, they are great bars. I was never comfortable with the sliding adjuster pinch clamp setup. It certainly allows for minute changes, but it also allows for many minute uneven changes on 2 axis (vertical, and axial) and must be measured/centered carefully. Plus I had, and others reported issues with that "clamp" slipping/rotating under hard use. The leverage from the linkage could "rotate" the clamp under extreme hard corning unless it was aligned/tightened perfectly. The other thing to watch for is inside wheel clearance, it has been documented at events like the Frenzy, most famously by Ed Ruiz, how the design caused bar to inner wheel lip contact on basically any wide wheels tires including the 8" Club Sports. The fix at the time was installing an extra stop on the steering rack to reduce the steering slightly. Just to clarify, all of this about the Devek bars was in the earlier days so I do not know if there were updates made etc. But as you probably know when it is set exactly the way you want/need it, it works very very well and has way more adjustabilty than my bar.

FWIW, On my bars I preferred to use a more modest factory style setup, but with some adjustability that reduced the chances of user error, and simplified the setup to get a perfectly balanced setup every time with no chance of an unbalanced side to side installation.

Please let me know if you run into anything you can't handle (doubtful :-) and I will do my best to help you. Oh, in the meantime you can run your stock drop links with my bar until I get the kits in my hands...just don't use the stiffest position, I don't think it will last long there. LOL

EDIT: Here are the links to my install guides for the front and rear bars in case you don't have them

Rear
https://www.928gt.com/rearswaybarinstall.htm

Front
https://www.928gt.com/frontswaybarinstall.htm


Have a great evening,

Dave

Speedtoys

Good stuff to re-document.

I havent had any devek bar issues on C3 wheels, and no notable issues in the rear.

The stock rear links are still there, but..they dont like it.

DR

Hi Jeff,


I went looking for the offset of your C3 wheels to verify you won't have inner contact before responding to your last post about C3 Wheels and Devek Bar. I wasn't sure if they were aftermarket or Factory Porsche wheels, well after a quick search for C3 Wheels under your username, I found these posts from 2 years ago in this thread you started...

https://rennlist.com/forums/928-foru...-question.html




You gotta admit it was ironic to read after everything in this thread, it was just too ironic/funny to pass up. I sincerely hope you can see the humor in this!

But, at least I found the offset there!

Oh, and yeah, the C3 ET57 you have should be fine with the Devek bar.

You and I know for darn sure, in the context of "life", none of this should be taken so seriously, especially on a FRIDAY!!!

Happy Friday and all my best,

Dave

docmirror

First let me apologize to Dave, and all the other racers who are going around a track, with track suspension, and track tires, and modified sway bars, and all the other gadgets that are running high offsets with no problem. Of course, whatever works on the track, translates perfectly to the bone stock car, on a bumpy road, with street tires, that sometimes run in wet, oily, loaded and lower speed conditions. They are - exactly the same use case, and I should have known better than to advise a street user on a public forum on offsets when it's been done perfectly by pro racers for years. My apology.

On a 9" wide rim, the zero offset is at 5" from the back flanged edge of the rim. If one were to put the wheel flat on the ground, stick a tape measure in the spoke and measure to the mounting surface it would read 5". Why is it not 4.5" which is half of 9" ? I don't know, but it just is.

When we take a 'positive' offset, we move the mounting face of the wheel outward toward the street side, or one could say we move the inner wheel flange inward toward the shock and ball-joints. Let's not bother about negative offset, I don't know anyone who would use a negative offset for the street. The chart shows the axis in inches and the offsets inside in mm. Starting on the left with a width of 9" and moving right to the 64mm box, then move up we see that the mounting surface is now 7.5" away from the inner wheel flange. And for greater offset, the inner flange of the rim will continue to move inward towards the articulation point of the ball joint. This pic is useful, because it shows the susp geometry, and the changes from OEM to higher offset.


Now on to cases for this car. I think the stock offset for the S4 was 65mm? So when I said that offsets over 60mm could be a problem, that was wrong. It was an error. It was a mistake. the "60mm" should have read "65mm". Some early 928s used a 60mm offset I think, and later cars used a 65mm. I don't know exactly. However, when I put a 68mm offset wheel on a S4, it did not handle well. Fortunately I sold the cars with the stock wheels on it, and advised the buyer that the newer wheels didn't work well.

So, I offer another apology for writing '60' in place of '65', and causing all this manufactured outrage. I did qualify it with 'YMMV' but of course, if one makes even the tiniest of errors on 928 rennlist the cast of experts will take relish in smiting anyone who puts in the wrong data point. Wish I could go back and reverse the planetary rotation, and put it right, but - it's been quoted, so it will live on, in electron history for billions and billions of years.

In closing, run any offset you want. I will offer a money back guarantee that it will work with no problems. Take it to the bank.