When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It's not a hard job, as you discovered, to simply swap the springs.
But even with you marking the strut plates... the way the weight is carried differently now, you likely should still have the car realigned and for sure now, corner balanced. And that's where the $$$ goes to properly complete this job.
If ride height is the same before and after springs - why would the static weight on each corner be different now? I thought unless I change the sprung weight or the chassis is sitting at a different angle, the static weight remains the same at each corner.
I'm for sure getting it re-aligned but I'm curious about this and would love to understand more.
Also worth noting - I don't know how much stiffer you went with these new springs, but the OE dampers are going to have a limit to how much spring they can control.
DSC used to modify the PASM-capable Bilsteins way back in the day so you could do spring changes... even they gave up on that and started selling their own shock/struts. At one point I'd sent a set into Bilstein that needed a rebuild (prior car was a PASM-equipped Cayman w/DSC box) and their advice was to NOT change out the springs, as the shock would not last.
I'm using a Tractive strut instead of the stock Bilsteins, and I've asked for a pvp chart to help understand where making changes in the DSC will have the most effect.
I can't speak about how adaptable the strut is to a higher or lower spring rate. I'll be spending some time driving and trying rebound and compression to see what sort of issues arise but its pretty subjective instead of data driven at the moment.
The springs are quite a lot firmer, with an increase of 73% front and 22.5% rear. I think the front is overly stiff from where I'll end up but like I said this was a deal on the kit so I don't mind swapping springs again later.
As to your other question, a few reasons:
- unless the ratio of F/R is dead-nuts exactly the same as the springs you took off, the car will definitely settle differently, front to rear.
- Eyeballing the ride height might get you close - but you can make a pretty big corner balance change with the perches before it becomes visible in the ride height. The last time I CB'd my car, 1/4 turn on the spring perch could shift the scales quite a bit.
We all know how the 45/80 OEMs are. Tarett has a well proven 80/100 setup. I and others are pleased with my simple front upgrade 60/80 package. I bet a 70/90 setup would be good as well right there in the middle. Just depends what you are looking for. I can tell you that the 60/80 works well on the firm setting of PASM. I suspect that the stiffer spring rates would benefit from a DSC Sport box though.
Lovetoturn - Could you post a link to the Swift front spring you are using? I like the idea of just replacing the front.
Put your parts on, play around with adjusting things, get the ride heights equal to the top of the fender well on level ground left to right, remembering that front and rear heights are completely different, drive it a few miles, let sit, make a final adjustment of the height, and take it in for an alignment. If you have the ride heights within a few mm left to right and the rake is good it will be very close to how it came from the factory. This can be done on fender wells if you are near the correct ride height or the best way to do it is to look up the measuring points and go for 109 front and 130 rear. This is not rake but variance in the measuring points. Of course having the cars ride height and corner balance set professionally is best before the alignment. I think a few hours to corner balance the car is plenty. I does not have to be perfect to the pound. Is it with you in the car or not, what happens when the gas level changes or you add someone to the car.
This was mine with me in the car and not. About 20 pounds of gas in the car.
No driver: (1577 x 1564). This a 13 pound difference in the cross.
Me in the car: (1656 x 1663). Again a 13 pound difference but going there other way.
This was achieved by being very precise with the initial ride height adjustments and maybe one turn of a coil one time. The minute you are on the track pitching the car around at full tilt sliding around having a great time, the 13 pounds out of 3319 just isn't going to make that much difference for our level of driving skill.
Last edited by lovetoturn; 03-16-2023 at 09:26 PM.
Interested in thoughts about the Designs by Jacob kit. From their website: "This Swift Springs upgrade Kit includes 2 front springs and 2 rear springs along with helper springs for the rear. We chose to use a longer front spring without helper springs so we can increase the amount of usable stroke in the front suspension by 1/2" when compared to other spring kits for the GT4."
How long was the front spring and how did it workout? My understanding was that he uses a 6 inch spring? I mentioned the longer front spring with my motorsport mechanic but he suggested we use the helper up front too. He said with the shorter but appropriate length spring that there would be slightly less travel and the car would stay flatter. This would improve handling and nose diving under braking. The longer one would have more compliance due to the slightly longer travel.
If you are going to hit a strut killing bump, the extra travel doesn't really matter, it is going to fail. Since both springs are under the same compression load and are of the same rate, that will still put both springs crashing into the bump stops with the same force. Either way can work. Just depends on what kind of ride characteristics you are looking for.
I have the DBJ spring kit on my GT4. I found that I needed to use the OEM rear helper springs on the front, despite what DBJ says on their website. (I'm not unique in this; I recall several other Rennlisters posting the same.) I'm very happy with the DBJ springs and found they helped settle-down the rear end under heavy braking at the track—they other key factor being good toe settings. There's a slight increase in stiffness on the street, but honestly not hugely noticeable.
03-15-2023, 04:55 PM
