Advisable GC springrates for a canyon carver...

[golde30]

eh, i DD on 450/750 and solid mounts front and rear. im running top adj konis in the rear and short bodys in front.

[K-Swiss]

Well I obviously need to do some investigation. I didn't build this car and just bought it the way it was....

[JRKOUPE]

eh, i DD on 450/750 and solid mounts front and rear. im running top adj konis in the rear and short bodys in front.

you will need some new lumbar discs in a few yrs......give me a call...I take ins!

[Fair!]

Currently my car (89 325I) has 375 lb's fronts and 475lb backs. It rides like a hung of plywood with wheels attached so it needs to be softened up substationally. Any ideas what I should drop it down to?

Stick some zip ties around the strut and shock shafts, pull them snug, now slide them to the bottom of the shafts. Drive the car and check them in a few weeks... if these "tattle tales" are then buried up inside the bump stops, that means your suspension is bottoming out - which would explain the poor ride.

This is the NUMBER ONE reason people with extremely lowered cars complain of poor ride. Some people remove their bump stops "for more travel" and wonder why their shocks explode, too. ;) Don't overlower your car, and keep an eye on your shock travel.



I wouldn't run much softer rates than you have, for sure. Our autocrossed E30 (shown above, at road course speeds) has 570F, 570 R #/in springs, and we had 750 rear at one point (testing showed it was faster with less rear spring rate, for our set-up that doesn't have and can't use an LSD). The car still leans more than I like, and needs more swaybar even with these rates. Its daily driven, and while it is "firm", it is not "harsh". A lot of that has to do with the shocks, of course. We can get away with a lot more spring rate using adjustable monotube shocks and the valving at full soft (for street use). Bigger pistons, and all that.

Cheers,

[pogiboy9]

you will need some new lumbar discs in a few yrs......give me a call...I take ins!

right, so i take it all the riders in california should see you too ? are suggested walk ins your bread and butter?

[AlarmedBread]

Thought about tender springs? Coupled with the regular springs you could make a progressive setup which would be soft for daily driving but stiffen up when you need it to. It would obviously increase body roll I'm no expert on using such setups, but possibly something to look into.

[DSP74]

If you end up going softer, which I think you CAN go softer with coilovers let me know. I want the front springs. And I may even be interested in the rear springs....Are the rear springs the same dimension as the front with the GC stuff?

[JeffRR]

I agree with Terry,

With out knowing exactly what type of ride trouble your having, I'm going to assume that its not the spring rate. Most ride complaints on lowered cars are not from springs, you'd be surprised with how much spring you can run with proper damping. Look at your bump travel. Your most likely bottoming on the jounce bumpers, its very common on lowered cars.

I've had experience with the Koni's/GC's, even on a marginal drop the Koni's don't provide enough compression damping to keep you out of the bump stops. Adding some mid~high speed compression (that's shaft speed) will help.

I've developed a number of lowered production cars and every time I run into bottoming in normal driving and end up cranking in the compression damping. The other solution is to find more travel but that's not always so easy.

The reduced height Koni's that GC sells is another option but I don't have any experience with that set-up, they still may need to be revalved.

Koni will revalve your shocks for a fee.

[SpeedTheory]

Terry: What are you using for sways?

[Fair!]

Terry: What are you using for sways?

Uhh..... stock. :grin:

We try not to rely on the "crutch" of swaybars to fix the handling in a car, instead relaying on spring rate and shock valving for a majority of the control. Still we normally put adjustable and big antisway bars on both ends of the car for track-side tuning, for changing conditions. We just haven't gotten to that yet on this particular E30. This car is also hamstrung by the lack fo a rear diff (due to goofy class rules) so we need minimal rear bar to help put down the massive power of the 250,000 mile bone stock M42!

[Mike B.]

Koni will revalve your shocks for a fee.

See the sticky at the top of this forum - http://www.r3vlimited.com/board/showthread.php?t=100681

I have had very good experiences with Koni.

[DSP74]

I agree with Terry,

With out knowing exactly what type of ride trouble your having, I'm going to assume that its not the spring rate. Most ride complaints on lowered cars are not from springs, you'd be surprised with how much spring you can run with proper damping. Look at your bump travel. Your most likely bottoming on the jounce bumpers, its very common on lowered cars.

I've had experience with the Koni's/GC's, even on a marginal drop the Koni's don't provide enough compression damping to keep you out of the bump stops. Adding some mid~high speed compression (that's shaft speed) will help.

I've developed a number of lowered production cars and every time I run into bottoming in normal driving and end up cranking in the compression damping. The other solution is to find more travel but that's not always so easy.

The reduced height Koni's that GC sells is another option but I don't have any experience with that set-up, they still may need to be revalved.

Koni will revalve your shocks for a fee.

This discussion went round' and round' with the F-body guys in ESP....

There are more ways to skin a cat. If you are bottoming out, that isn't a compression issue most likely. That's a simply matter of a combination of to low, not enough travel for the height, and to soft a spring.
Compression valving is to control unsprung weight. Short of using compression as a crutch such as what stock class autox guys do there isn't much to compression valving...

Like I said, IMO, YMMV

[DSP74]

Uhh..... stock. :grin:

We try not to rely on the "crutch" of swaybars to fix the handling in a car, instead relaying on spring rate and shock valving for a majority of the control. Still we normally put adjustable and big antisway bars on both ends of the car for track-side tuning, for changing conditions. We just haven't gotten to that yet on this particular E30. This car is also hamstrung by the lack fo a rear diff (due to goofy class rules) so we need minimal rear bar to help put down the massive power of the 250,000 mile bone stock M42!

Again more ways to skin a cat. There is inherently nothing wrong with using swaybars to control roll and therefore camber. And w/most cars swaybars actually do more work in the way of roll resistance anyhow. A softer car will almost always have more mechanical grip over any type of un-even surface. Even if that softer car has a BIG swaybar (the shocks have to be valved to match)
With that said, given the lack of an LSD in your STS car, I'm VERY surprised you didn't go with a larger front bar.......


With all that said, I also think that NO bar or very little in the back is the way to go on an E30. They are to close to lifting that rear wheel than I care for. Not only hurting power down, but if you have a car that normally carries front wheels and the back comes up your on TWO WHEELS which REALLY makes me nervous.

[JeffRR]

[QUOTE=DSP74;1018278]This discussion went round' and round' with the F-body guys in ESP....



I used to lurk over at z28.com and posted a few times a number of years ago. I've got a 94 Z28 6MT sharing garage space with my e30.

Anyway, I've had very good luck with balancing compression and rebound. Its pretty common to get wrapped up into the compression for unsprung, rebound for sprung debate which is the mind set I was basically at when I started doing ride development.

I agree with high compression damping to control bottoming is a crutch, but sometimes its all you've got, ideally you'd have designed enough compliance to accommodate the energy input from your road load data. On production cars at design ride height or purpose built race cars this is done very early in the design process. Once the main architecture is set and we start tinkering with ride height, we've thrown off a major factor in that design for compliance. We've still got the same energy inputs but less spring/damper/bushing/bumper travel to dissipate that energy. How we deal with that as ride height changes and the energy management is our discussion.

In my experience doing ride development I’ve been able to back off on high rebound damping which was causing other undesirable traits by increasing the compression. Just for clarification I’m talking about Mid~high speed damping. This is working on ride quality, slowing the wheel down as its compressing and slamming the bumper. From a ride stand point this is looking at primary ride (low frequency body motions) such as going from the road surface to the slight elevation change of an overpass. But its also useful with secondary ride (high frequency body motions) such as wheel shake (undamped motion of the unsprung mass).

I was supposed to drive a SR swapped/lowered 240 that belongs to the brother of a co-worker, he’s complaining of ride harshness and looking at swap springs. The drive was called off since its pretty slick with the fresh snow. But really I don’t need to drive it, its the same issue as the original poster was having. How to handle bottoming

Wow I’m rambling sorry, just an interesting topic.

[FredK]

Wow I’m rambling sorry, just an interesting topic.

Ramble on! :D It's interesting to read expert opinions on this kinda stuff!