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.
So my front springs ended up making the car look like a 4x4, which is exactly what I was worried about. Id attach a photo but I'm too embarrassed lol. The front end is coming apart again for some different a arms, and I'm looking into weight jacks for the front, although I'm still not completely sold on them yet. My first choice was UMI, since I've had excellent experience with them so far, but I haven't seen many people talk about front weight jacks as much as rears. Id like to know other people's experience with UMI weight jacks as well as some kind of input? The spring rate options on the UMIs seem quite high for what I'd like to be a street car, but I'm not very picky and the roads on the central coast around here don't seem awful. I love the adjustability aspect, but am not so sure about drivability as well as reliability. Any input is appreciated.
Weight jacks have a shorter spring length so it requires a stiffer spring to keep the coils from binding. I think the lowest you can go is 750 lb/in and that would be custom order, not off the shelf. If you stiffen up the front that much without matching rears, the car is going to turn horrible.
Stiff springs are stiff. I don't care what anybody else tells you, the car rides rougher. It absolutely requires really good shocks to take the jitters and some of the harshness out of the ride. The ride won't smooth out until you put really grippy tires on the car and throw it hard into a corner. At that moment the high spring rates will make total sense. Out of that moment and it will just be a harsh ride.
I think at this point your best option is to cut the front springs. You already have them and it's a free experiment. You might cut out 1/2 coil the first time and then 1/4 coil for each further adjustment. The car will drop approximately twice as far as the coil cut.
Weight jacks have a shorter spring length so it requires a stiffer spring to keep the coils from binding. I think the lowest you can go is 750 lb/in and that would be custom order, not off the shelf. If you stiffen up the front that much without matching rears, the car is going to turn horrible.
Stiff springs are stiff. I don't care what anybody else tells you, the car rides rougher. It absolutely requires really good shocks to take the jitters and some of the harshness out of the ride. The ride won't smooth out until you put really grippy tires on the car and throw it hard into a corner. At that moment the high spring rates will make total sense. Out of that moment and it will just be a harsh ride.
I think at this point your best option is to cut the front springs. You already have them and it's a free experiment. You might cut out 1/2 coil the first time and then 1/4 coil for each further adjustment. The car will drop approximately twice as far as the coil cut.
I appreciate the response. My first choice was to cut the springs but I am skeptical about doing it because I'm not trying to have to take the front apart again Incase I'm still not happy with cutting. I assumed weight jacks as my best option since they give me adjustability almost on the fly without having to modify anything. The car isn't a daily of course, so I figure that having a rough ride really won't bother me that much assuming it's not undrivable which I doubt. I don't exactly use the car for cornering ever, but on the occasion I toss it around. I'm not sure if UMI does custom order spring rates but I'd probably opt for something lower than 850 that they advertise for "street" purposes.
Unless the car spends 95% of it's time on a race track, a harsh ride will definitely bother you.
I have another car that I drive 2 to 3 times per year. It has stiff springs and is lowered (so reduced suspension travel) and the harsh ride is a real downer for me...
Unless the car spends 95% of it's time on a race track, a harsh ride will definitely bother you.
I have another car that I drive 2 to 3 times per year. It has stiff springs and is lowered (so reduced suspension travel) and the harsh ride is a real downer for me...
What spring rate are you running? I unfortunately don't have any experience with super stiff suspension, since all my cars are pretty driver level, so gauging my preference is not possible. Central coast roads around here aren't bad though, so I'm not sure. I'm not exactly trying to lower my car a ton, but about 27.5-27.75 in the front is where I'm shooting for, which I don't believe is too low, especially compared to the 29 inches I'm at now...
I looked at UMIs and theirs is subtly different. Looks like the Ground control has more adjustment maybe. The overall concept looks the same. I welded mine to the sling perches that came with my UMI k-member.
Last edited by tomsaddy; Sep 12, 2022 at 04:38 PM.
Reason: Added pics
Call up ground controll and tell them what you want to with the car.
They'll recommend spring rates that arn't crazy.
GC jacks arn't really race ready for those who will push their 3rd gen to the absolute limit.
But the UMI stuff is also in a weird spotMore expensive than GC, but also not 100% race ready.
If you want to to full race:
Detroit Speed front jacks.
With high end coilovers in the rear.
JRI, Penske, ohlins, MCS exe.
Also, if your car is sitting 29in ground to fender; you either installed the wrong springs or didn't seat them in the K-member correctly.
(Ask me how I know ha ha)
28in is about stock ride height wise.
Most are 27in from spring sag over time.
Call up ground controll and tell them what you want to with the car.
They'll recommend spring rates that arn't crazy.
GC jacks arn't really race ready for those who will push their 3rd gen to the absolute limit.
But the UMI stuff is also in a weird spotMore expensive than GC, but also not 100% race ready.
If you want to to full race:
Detroit Speed front jacks.
With high end coilovers in the rear.
JRI, Penske, ohlins, MCS exe.
Well, I'm not actually looking for a "race ready" setup here, Just an adjustable spring for a street setup. I like UMI from previous experience and it sounds like their weight jacks are pretty sturdy(?) But I don't like their lack of spring options. And yes my springs are not clocked correctly and I'm aware of it, however I still like adjustability, so as long as I'm taking this thing apart again I might as well look into different spring options. The front of the car is all over the place right now.
But these rates I'd recommend for street cars. assuming nothing is out of the ordinary weight or geometry wise.
pure street, nice ride quality, ok to use with cheaper KYB shocks/struts700lb front/125lb rear
More aggressive street, ride quality ok with Koni yellows:850lb front 150lb rear anything beyond that range is gonna start getting real rough real fast.
But these rates I'd recommend for street cars. assuming nothing is out of the ordinary weight or geometry wise.
pure street, nice ride quality, ok to use with cheaper KYB shocks/struts700lb front/125lb rear
More aggressive street, ride quality ok with Koni yellows:850lb front 150lb rear anything beyond that range is gonna start getting real rough real fast.
UMI offers the 850 in the front, I'm still considering KONIs but not sure yet, currently running KYBs in the front and not all that amazing in my opinion. I have no issue with an aggressive build however I'm not sure about having a super stiff front and the rear end "stock" level. I run Bilstein in the rear with moog 5665s. Again I have no plans to be racing the car, just would like quality parts with that adjustability.
Weight jacks used to have better spring selection and then the owner of Blue Coil died. Then circle track racing changed rules and they could move away from that style of spring. Circle track was fueling all the variety. I'm not sure what spring rates are available now, only Ground Control can answer that.
Used to be the lowest you could go on the back was 150 lb/in. There are limits to how soft the spring can be due to the shorter spring length.
Stock V8 spring rates were about 700lb front 106lbs rear.
but size axles have a near 1:1 motion ratio, so rear spring changes make a MUCH larger difference in wheel rates.
A 125lb rear spring is way stiffer than a stock 106lb spring.
While say a 800lb front spring isn't much different than the stock 700lb ish spring.
UMI uses a 5.5in I.D, 8.5in tall front spring.
One end is flat, the other has a tail for the A-arm pocket.
The rear UMI kit uses a 5in I.D, 10.5in spring.
Both ends are ground flat.
GC uses use a similar front spring, the rears are a pig tail spring setup.
The choice is up to you. But either will work fine for a street car.
Stock V8 spring rates were about 700lb front 106lbs rear.
but size axles have a near 1:1 motion ratio, so rear spring changes make a MUCH larger difference in wheel rates.
A 125lb rear spring is way stiffer than a stock 106lb spring.
While say a 800lb front spring isn't much different than the stock 700lb ish spring.
UMI uses a 5.5in I.D, 8.5in tall front spring.
One end is flat, the other has a tail for the A-arm pocket.
The rear UMI kit uses a 5in I.D, 10.5in spring.
Both ends are ground flat.
GC uses use a similar front spring, the rears are a pig tail spring setup.
The choice is up to you. But either will work fine for a street car.
I'm only considering weight jacks for the front of the car, just chose UMI as my first choice but if GC is better for my application then I'd go that route.
The off-the-shelf springs that come with the weight jacks are intended for lowered cars. The springs are very short and can drop the car very low. You would end up turning the jack screw way out in order to get up to stock ride height (not good). You'll need to make it clear what you want to do and ask for longer springs for stock ride height. Ground Control Racing likely has a lot larger variety of springs than UMI.
I have Ground Control Racing front jacks with 800 lb/in springs at 9" free length. This is what GC provided and it is way too short, 11" would have been more appropriate. I also bought custom springs for the back that were longer than what GC provided the first round.
Honestly, what you want to do is kind of goofy. The whole advantage of a stock ride height is to have a lush ride with lots of travel. You're going to end up with stiff ride with small travel, and the rear is going to be mismatched. You're much better off cutting your existing springs.
The off-the-shelf springs that come with the weight jacks are intended for lowered cars. The springs are very short and can drop the car very low. You would end up turning the jack screw way out in order to get up to stock ride height (not good). You'll need to make it clear what you want to do and ask for longer springs for stock ride height. Ground Control Racing likely has a lot larger variety of springs than UMI.
I have Ground Control Racing front jacks with 800 lb/in springs at 9" free length. This is what GC provided and it is way too short, 11" would have been more appropriate. I also bought custom springs for the back that were longer than what GC provided the first round.
Honestly, what you want to do is kind of goofy. You're much better off cutting your springs.
It was my impression that the height with the weight jacks unadjusted was supposed to mimic "stock" ride height, but I can't verify that. Not sure what you mean when you say they are "intended for lowered cars" technically speaking the car can't be lowered without a different spring? Which is what these are... I have called both weight jacks companies in question and both specified to me that the weight jacks are meant to be adjusted alot or a little, it's a design not a feature.
I'm really trying to stay away from cut springs because in that case I have a one and done situation, can't go back once that's done without taking it all apart again. Could you post a picture of your car with the jack unadjusted? Id like to see what you mean if you are willing.
The springs are only about 2/3 of the stacked height of the weight jack assembly. The other 1/3 is the jack screw. Springs are on the bottom in the a-arm pocket, and the jack screw is above the spring. The taller the ride height, the longer the jack screw must rise above the spring (lifting the car higher above the spring). Spring height never changes, you're extending / shortening the jack screw above the spring to adjust ride height. The jack screw is basically a pole, and the weight of your car is sitting on top of that pole, and the longer the pole the harder it is on the parts that stabilize it. And your springs aren't actually aligned perfectly straight in the car, they bend in an arc that changes with a-arm movement. Screws don't like to bend, so you want more spring in the stacked height and less jack screw if you can help it.
The off-the-shelf springs supplied with the weight jacks are of a length that is ideal for aggressively lowered cars. You can adjust the total stacked height all the way up to stock ride height if you want, but it's going to require the jack screw to be extended pretty far, maybe up to 1/2 the total stack height of the system. The remedy is to use longer springs so you can shorten the jack screw. But you'll have to request longer springs or they won't do it.
The real purpose of weight jacks is to make subtle changes to corner weight the car. People tend to use them as an adjustable lowering kit instead, but the true purpose is for suspension tuning.
McLovin makes really good videos and puts them on youtube. You can find a video about weight jack install on his youtube channel, https://www.youtube.com/c/3rdGenGuy
What Moog front spring part number did you buy? And how many inches do you want the front to drop?
I can probably just tell you what Moog part number to buy to fix the issue. I've got a spreadsheet with all the Moog spring specs and can do the calculations.
Edit: I found your part number in a different thread. Those are 750 lb/in springs with intended installed height of 10.8" with 1690 lbs sprung weight. Buying different Moog springs won't help, you'll end up with the same ride height, maybe even higher. Your spring rate is so high already that weight jacks aren't going to ruin your ride quality any further.
Knowing that, and throwing in the extra variable that you have aftermarket a-arms.... yeah, just do the weight jacks. I suggest 11" long springs if you can get them, but I'm guessing a bit. That would work on my car with BMR A-arms but I'm not sure about your car.
Originally Posted by Benny04
Another thing I may add that would be great to have clarification on:. I'm using the moog 5662 on my TTA which has a very high spring rate, I'm worried these are going to make the car look like a 4x4. Should I be cutting coils or going a different route completely? At the time I bought them it seemed like nobody had a concrete answer for non lowering front springs on this car.
What Moog front spring part number did you buy? And how many inches do you want the front to drop?
I can probably just tell you what Moog part number to buy to fix the issue. I've got a spreadsheet with all the Moog spring specs and can do the calculations.
Edit: I found your part number in a different thread. Those are 750 lb/in springs with intended installed height of 10.8" with 1690 lbs sprung weight. Buying different Moog springs won't help, you'll end up with the same ride height, maybe even higher. Your spring rate is so high already that weight jacks aren't going to ruin your ride quality any further.
Knowing that, and throwing in the extra variable that you have aftermarket a-arms.... yeah, just do the weight jacks. I suggest 11" long springs if you can get them, but I'm guessing a bit. That would work on my car with BMR A-arms but I'm not sure about your car.
Ok just saw all your messages at once. I actually returned the aftermarket a arms, because they were impossible to get the spring into without a special spring compressor so we ended up rebuilding the stock arms with delrin bushings, energy end links, moog ball joints, and powdercoated. Id like the car to sit where it was before modification which was about 27 1/2 all around. What you said about ride quality is basically exactly what I expected to be perfectly honest.
