[lackskill]

Thanks for the update!

[stretch]

TiC, if I'm looking at the problem correctly it could be alleviated by moving the lower spring perch lower and giving the spring more room to crush into. You'll then have to run a longer spring to keep the same ride height, and that's where your added spring travel comes from. Duncan's explanation does seem more likely; I don't think a modern damper will hit any kind of hydrolic lock the way 1930's progressive dampers would. What length springs are you using? FWIW, it seems to take a while for coil bind evidence to show up in the paint of springs. My own setup is binding in the rear (I can prove it) but the springs look fine.

I'm going to edit my earlier post regarding the Koni housings, that's way off topic and distracting.

[Turninconcepts.com]

Originally Posted by stretch

TiC, if I'm looking at the problem correctly it could be alleviated by moving the lower spring perch lower and giving the spring more room to crush into. You'll then have to run a longer spring to keep the same ride height, and that's where your added spring travel comes from. Duncan's explanation does seem more likely; I don't think a modern damper will hit any kind of hydrolic lock the way 1930's progressive dampers would. What length springs are you using? FWIW, it seems to take a while for coil bind evidence to show up in the paint of springs. My own setup is binding in the rear (I can prove it) but the springs look fine.

I'm going to edit my earlier post regarding the Koni housings, that's way off topic and distracting.

The first round of springs we have to try here are 8" free length. We're coupling them with helper springs that when compressed by the car's weight will yield a length of about 1.25" IIRC.

[Turninconcepts.com]

Originally Posted by DuncanG

I've used ASTs and I now use Ohlins - there's no comparison.



I too found that on hard bumps they went solid at the front and pogo'd at the back but my conclusions were very different to yours.

IMO the sportline-1 I had were way underdamped on the hi-speed and that combined with either (depending on ride height) coil bind or the strut body hitting the upper spring perch (with the bumpstop squashed inside the conical perch). Either way the front was going metal-metal with the witness marks to prove it, so I'm doubtful of your hydraulic lockup theory. I see from your pics that they've continued with the same conical upper perch design that loses 20mm of travel and swallows the bumpstop. Check your front springs for coil-bind witness marks and also check the upper perch for contact marks.

In less severe but fast bumps they were obviously underdamped regardless of the adjuster setting.

Just a heads up - I haven't measured the AST ones yet (as they are on the car), but I measured the ones from a set of Ohlins we have here. The Ohlins come out to a height of 9.18mm. I'll add the measurements of the AST ones when the new set arrives.

[DuncanG]

Here's a sketch to illustrate what I was getting at regarding the conical upper perch -



As you can see the effective stroke has been reduced by around 20mm and there is a void that a substantial part (maybe all?) of the foam bumpstop will squeeze into and so reducing its effectiveness. The current bumpstops look at little larger however.

[stretch]

I was looking through Swift's spring catalog and am finding Swift springs have slightly more stroke than Eibach springs for the same length. Nice. Swift also claims their springs are linear from 20-80% of their travel, compared to 30%-70% for Eibach. Again, nice.

If TiC is using 8" long springs front and rear at 392/280 spring rates, that means they'll have 5 inches of stroke front and 5.2 inches of stroke rear (though Swift recommends you limit stroke to 4.5 and 5 inches, respectively). I'm going to assume 8" springs because that's what everyone else seems to use, including the Whiteline forerunners to these.

This means that for a 3400lb STI with a 58/42% weight distribution, the front springs will have 2.8 inches of travel remaining before coil bind and the rear will have 3.1 inches of travel before coil bind. Subtract the bump stop length from those figures to see how much linear travel they're capable of supporting. The bump stop will prevent the springs from going beyond what Swift recommends using as the max compression of the spring (the 4.5 and 5.0 figures).

Most other companies seem to use 8" springs too, only their 8" springs have a shorter stroke. For comparison, Eibach springs- which are already better springs than most- seem to offer about a quarter inch less travel, which in this application would reduce bump travel by 10%. A quarter inch is important.

Personally, I'd like to see even more travel in the spring if possible because a coilover at stock ride height may be able to use more than 3 inches of travel. Unfortunately, Swift's 9" springs don't seem to offer that. They do go further before coil bind but Swift strangely doesn't recommend you compress them that far. Still, I like to see them used instead if it makes sense to do so. I'm guessing 10" springs won't fit.

Anyway, I'd be willing to bet that many competing coilovers cannot support a stock ride height without coil bind; these at least come close (if not actually succeed). I'd name what look like some offenders but this isn't the thread to do so. Hopefully the spring tophat will not cause issues as outlined in the previous post, because if so, these things are likely going to be the linear suspension travel kings. For that, I'm stroked. I mean, stoked.

I think the choice of Swift springs is another reason to get excited about these coilovers.

[DuncanG]

I used 10" (well 250mm) springs without helpers in my ASTs to gain more bump travel, in addition to longer stops. That alleviated the coil-bind but didn't resolve the poor hi-speed damping. Hopefully Tic will get that fixed.

BTW the Group-4s had quite a bit more travel than the (shortened) ASTs.

[stretch]

If 10" springs fit, that's awesome. TiC, use them!

Was all the Whiteline's added travel droop? I know Whiteline claimed to have about 3" of bump travel at their spec'd ride height, pretty good. I'm hoping TiC's have at least that, too. However, Whiteline ran 8" long 280lb/in springs that would only permit them to use ~2" of that travel, shame shame.

[DuncanG]

Note that was 10" without helpers - with the soft rates I was using (50/40 N/mm) these gave me enough droop without needing the helpers. I'm into bumpy backroad driving and droop is just as important as bump. With the stiffer springs you are looking at they might be getting short on droop without the helpers/tenders.

I completely agree with you re the Grp-4s. If you search on Nasioc you'll find I (duncangrant) was trying to educate Arnie on that very point. From memory I reckoned they had about 60mm usable bump and not the humungous amount that was claimed.

Btw, the G4s although made from AST parts had longer struts hence more travel than the AST branded dampers - at least for the units I had.

Its good to see that this stuff is getting some attention, keep up the good work

[lackskill]

Originally Posted by DuncanG

Its good to see that this stuff is getting some attention, keep up the good work

That goes for both of you, and anyone else that is smart enough to contribute.

[Turninconcepts.com]

We'll be using helpers in the this next setup which should add about 1.25" of length to the 8" springs we picked up for this round.

The second set of dampers are on the way, and should arrive by the 23rd. Before we throw them on the car I'll take a bunch of pics and overlay measurements to show some numbers.

Additionally, I asked the AST guys to hook me up with some different perches. Word is they threw something like 7 different types in the boxes for me (I love these guys).

If it comes down to a matter of usable stroke due to damper body length they we'll look into using the G4 parts. AST has already told me they will more than happy supply me with those parts, and we can have them valved just about any way we want.

[lackskill]

[fanboi]god I love you guys[/fanboi]

[mgsm666]

Originally Posted by Turninconcepts.com

We'll be using helpers in the this next setup which should add about 1.25" of length to the 8" springs we picked up for this round.

The second set of dampers are on the way, and should arrive by the 23rd. Before we throw them on the car I'll take a bunch of pics and overlay measurements to show some numbers.

Additionally, I asked the AST guys to hook me up with some different perches. Word is they threw something like 7 different types in the boxes for me (I love these guys).

If it comes down to a matter of usable stroke due to damper body length they we'll look into using the G4 parts. AST has already told me they will more than happy supply me with those parts, and we can have them valved just about any way we want.

wow...that's all i have to say. Awesome work guys - can't wait to see the finished product! This is EXACTLY what i've been holding out for....


Jesse

[stretch]

Originally Posted by Turninconcepts.com

We'll be using helpers in the this next setup which should add about 1.25" of length to the 8" springs we picked up for this round.

Helper springs don't increase the bump travel of a spring, though. They only increase droop. You may be making the combined spring longer but that just means it compresses further before it reaches its ride height. Basically, no matter what you do, the main 7kg/mm spring is still going to compress 2.17 inches any time you put 850lbs (roughly the sprung weight at each front corner) on it.

I'm not saying your 8" springs won't have enough bump travel, I'm just saying that helper springs do nothing to help bump travel.

If your coilovers have as much bump stroke as Whiteline's coilovers did, however, then I'd recommend you switch to longer springs. Doing so will keep them in their linear range longer and allow full bump travel over a greater range of adjustment. 8" springs would have 2.8" of stroke left at ride height but the Whiteline-spec struts supported 3.25 inches of bump stroke even when lowered 3/4 of an inch. Perhaps yours do too. If you're counting, that's 4" of bump stroke if run at a stock ride height!!!!!! (Might as well use it!)

The second set of dampers are on the way, and should arrive by the 23rd. Before we throw them on the car I'll take a bunch of pics and overlay measurements to show some numbers.

Additionally, I asked the AST guys to hook me up with some different perches. Word is they threw something like 7 different types in the boxes for me (I love these guys).

If it comes down to a matter of usable stroke due to damper body length they we'll look into using the G4 parts. AST has already told me they will more than happy supply me with those parts, and we can have them valved just about any way we want.

That's great news about the spring perch!

I'm really hoping you can make a product with as much stroke as the Whiteline kit. They had an amazing amount of suspension travel. It was even excessive in my opinion, but I'm not complaining! If the price of parts is the same to you, why not reuse what Whiteline spec'd for the housing and shaft lengths to recapture the "suspension travel king" title? Maybe you're doing this already, I don't know. But if you don't have quite as much travel as the Whitelines, no sweat- as I said, it was excessive. In particular, there's no way your stiffer springs would need as much droop travel as the Whiteline's had. Specs per Whiteline follow:

Originally Posted by Previous Whiteline post

Group’4 kit @ ride height of 360mm front, 350mm rear
front bump = 83mm (including 43mm long bump stop)
front droop = 106mm
rear bump = 134mm (including dual 43mm long (2 x 43) bump stops)
rear droop = 76mm

[Turninconcepts.com]

Originally Posted by stretch

Helper springs don't increase the bump travel of a spring, though. They only increase droop. You may be making the combined spring longer but that just means it compresses further before it reaches its ride height. Basically, no matter what you do, the main 7kg/mm spring is still going to compress 2.17 inches any time you put 850lbs (roughly the sprung weight at each front corner) on it.

I'm not saying your 8" springs won't have enough bump travel, I'm just saying that helper springs do nothing to help bump travel.

If your coilovers have as much bump stroke as Whiteline's coilovers did, however, then I'd recommend you switch to longer springs. Doing so will keep them in their linear range longer and allow full bump travel over a greater range of adjustment. 8" springs would have 2.8" of stroke left at ride height but the Whiteline-spec struts supported 3.25 inches of bump stroke even when lowered 3/4 of an inch. Perhaps yours do too. If you're counting, that's 4" of bump stroke if run at a stock ride height!!!!!! (Might as well use it!)


That's great news about the spring perch!

I'm really hoping you can make a product with as much stroke as the Whiteline kit. They had an amazing amount of suspension travel. It was even excessive in my opinion, but I'm not complaining! If the price of parts is the same to you, why not reuse what Whiteline spec'd for the housing and shaft lengths to recapture the "suspension travel king" title? Maybe you're doing this already, I don't know. But if you don't have quite as much travel as the Whitelines, no sweat- as I said, it was excessive. In particular, there's no way your stiffer springs would need as much droop travel as the Whiteline's had. Specs per Whiteline follow:

Hey Stretch - just for you I have some 9" springs on the way so we can look at putting those on instead.

-Clint