Mark944na86

hi Jon,

Since I thought there might be some general interest in your question, I thought I'd post my answer here -- hope that's OK with you.

Yes, I installed the KW V3s a few months ago now, without having to reindex the rear torsion bars.

I have the car height front and back at the top of the recommended range of adjustment for the KWs (i.e., recommended "street" height) , which incidentally is very close to where the car was before I installed the KW V3s. I think this is about 1" lower than stock set-up, but as you know, the stock set-up varies from one country to the next, so I'm not sure how this would relate to the stock US height, for example.

Without having to reindex the torsion bars, there remains a bit of downward adjustment at the rear, but I wouldn't be able to get it all the way down to the minimum recommended height without reindexing. For me, this is not a big deal, because the recommended "street" height is working very well for me so far, both in street and the (very limited) time I've had it on the track. I can't see any need to change any time soon.

For the compression and rebound settings, I also went with the default recommended intial settings, and I'm also very pleased with these, both for street and the limited track time I've had so far.

One reason I am happy not to have to reindex is that it gives me a very flexible set-up if I ever want to swap the rear Bilsteins back in for any reason (e.g., the rear KWs need to be sent away for service or warranty replacement.) Anyway, that was part of my initial thinking, but I hope I wont have to swap them back in anytime soon -- the KW setup is just so far and away superior.

I did the installation in two stages -- front struts first, and then the rears a few days later. I was actually quite surprised at how much difference the rears made -- at least as much difference again as replacing the fronts struts alone, which shows how important it is that everything in the suspension system balances properly, I guess.

In any case, I'm running with the kit pretty much standard as recommended by the KW installation manual, stock (S2) sways front and back, and the handling is head and shoulders above the Bilstein set-up I had in there previously. Seriously, easily the best money I've spent on the car since I've owned it -- I just wish this had been available years ago.

The only minor tweak I did do was to reuse the Porsche all-metal locking nut for the front strut camber adjustment eccentric -- simply because there was some discussion in some earlier threads that the nylon lock-nut supplied with the kit might not be up to the job. In any case, I've not had any issues with it coming loose so far.

Even if you do decide to go the reindexing route for the rear height adjustment, I'd certainly suggest installing the rear KWs before any reindexing, just to check out how far from your target height you are to begin with. Like me, you may find that you don't need to to reindex; or, if you decide you do, at least you'll have a fairly accurate idea of how much you will need to adjust.

Good luck! And hope you enjoy them as much as I do.

rluciano

I had almost exactly the same experience installing my KW V3s a little over a year ago. They are great. Now it is time to get the drive train up to the standards of the suspension and brakes.

jlturpin

I agree with the OP. KW V3's are one of the best upgrades I have ever done to a 951/44/68.

docwyte

I hated the KW V3's. Had a real issue with durability and warranty coverage. Never going to run their product on my cars again.

Techno Duck

Mark, thanks for your input. I am going to do the same with the front eccentric bolt as i read the thread also about the nylock nut working loose. My biggest concern was running both the torsion bar and coil over in the back and getting that 'preload' set right. I am really looking forward to a new suspension on this car. I have been running Koni's with stock springs / torsions and the car is ridiculous soft.

Eric_Oz_S2

No experience with V3s, but just installed rear coilovers with similar rate. Mark's car may have been previously lowered, mine certainly wasn't. When I installed mine (without reindexing), the car sat way too high, noting that my coilovers don't have helpers like the KWs come with. So I set mine so with the shocks extended there was no slack between the spring and plates. This resulted in the ride height going up maybe 20mm - not good. So I then reindexed by 1 inner spline, dropping the rear by 65mm (based on tbars alone) and just below stock with coilovers taken into account.

What you also need to be careful with, is getting the balance right with the tbar preload. My first set of rear springs (250#) were a little long, and I had to set them with maybe 15mm of preload. What I found happened with this is the rear became unsettled as the initial movement was resisted mainly by the springs not the tbars. I then installed shorter (225#) rate springs (lower rate to get the ride height a little lower without further reindexing) with no preload (springs just fit between perches). This resulted in more preload being applied to the tbar, and the result is the rear is much more settled. Of course this result would be linked with my koni series 30 shocks, which admittedly are not as sophisticated as the KWs.

I guess in conclusion though, if I were installing KWs I would still reindex, as otherwise your spring rates will possibly be quite non-linear, yet not progressive either. This could lead to perhaps excessive rear body roll or unusual handling.

Chris White

Lets toss in a little suspension ‘theory’ on the indexing issues –
If you do not reindex (or remove) your torsion bars you are going to get some interesting nonlinear behavior. If the ride height was where you wanted before you added the coilovers than the coil over spring will have no load on it when you are at static ride weight. Whenever you are in compression you will have torsion bar + coil spring rate and when you are in extension you will be torsion bar only. This will cause in interesting response when you go over larger bumps – you can’t tune the shock to dampen a particular spring rate because you have two rates.

We can also look at the sway bar interaction – the sway bar works by biasing the spring rate on one side of the vehicle against the other side. When the car rolls one side compresses and the other side extends – the sway bar resists this movement by transferring load form one side to the other…but if the spring rates are different in compression and extension then the movement allowed will be different on either side. Not a huge issue when at steady state (mid corner) but the transitions can be a bit weird (slalom or tight esses).

Is this going to be a huge issue? No, but why spend a bunch of $ on a mod and then not get the most out of it? It you really like the ride height and don’t want to reindex or remove the torsion bars then mount the rear shocks without the coil over spring (I can hear the whining about not getting the stiffer spring rates!) If you really want the stiffer spring rates then reindex the Tbars – do it right!!

BTW – if you are going to reindex the Tbars…..just take them out!

Techno Duck

My initial plan was to remove the torsion bar, however the KW does not use a spherical mount at the rear. It uses a regular rubber bushing with metal sleeve (like the stock setup, Bilsteins..etc). So i am not to keen on running without a torsion bar in the back. I asked Karl at RacersEdge about this and he said i would probably be fine running the stock bolt in this manner but i still feel safer with the torsion bar in. Plus these KW's were designed to be run with torsion bars and plenty of people seem to have them setup to there liking with.

I am going to install only the rears first to see what happens to the ride height. If its way off i may end up just taking it to a local p-car place to have them reindex and set it up for me. I talked to the owner about doing it and they mentioned it was no problem. If i decide to take them out, i just need to order a pair of springs through KW.

I have considered having the KW's modified to accept a spherical lower shock mount, but i need to find a place i trust to have that type of work done..plus i have a feeling that will void any warranty on the rear assembly.

StyleLab

out of curiosity how many miles are you guys getting out of these between rebuilds?

-Nick

rluciano

Chris,
In my case the height eccentric on the spring plate was moved from having the height almost all the way up to all the way down, and the ride height went down a little to put it almost in the middle of KW recommended range. So, I think I kinda of did it close to right. The springs should be loaded at all but extreme droop.
YMMV,
Richard

Techno Duck

Just called KW USA Tech, they do not have a recommendation of a rear spring rate without torsion bars. Not surprised.. i can just figure that out on my own. I think DVC said he used a 500lb'er i think. Anyhow i did ask about modifying the lower pickup point with a spherical bearing, it can be done and will not void warranty. He said i can send it out to whomever i wanted, but KW can do it for me. Something else to think about now..

jasonlp

I'm on year 3 still strong

Techno Duck

Some more food for thought, i just stopped by my friends place and picked his brain a little. He said he has setup a number of cars using the Bilstien Escort Cups with no torsion bar and stock lower mount (same style as KW), one of which is his wifes 951 track car. He said he has never had problems. That along with Karl saying the same thing makes me feel a little better.

Researching the spring rates i would need with no torsion bar, it looks like i would need something like a 700lb rear spring to match the effective wheel rate. With stock torsion bars and the KW provided springs i end up at aprox. 300lb wheel rate. So depending what you believe what the correct multiplier for effective rate is (.42 or .63??) i would need something like a 700lb rear spring to get aprox. a 300lb wheel rate. Does this sound right?

Ill have to call KW again and see if they think the valving on the rear shocks can handle that.. somehow i doubt it!

333pg333

I was advised that the KWs will take a pretty big range of spring rates. If you have an effective rate of 300lb/in at the rear, what are your fronts? You may need to go up there too.

Techno Duck

Well the fronts come with 340lb springs (i think that is it). I am just trying to get the rear spring rate at aprox. the same effective wheel rate as the torsion bar + spring wheel rate, which appears to work out to be about 295lbs if im doing the math right. So a 700lb spring on the rear works out to be 294lbs effective wheel rate (700*.42=294). Im just wondering if i am using that conversion factor correct.