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Your thoughts on my proposed lowering and wheels setup?
Okay, after a few threads and lots of feedback from TGO folks here is what I am proposing for my street driven, LB9 auto, IROC vert. All stock with 3:42 axle ratio... 120,000 miles
Re: Your thoughts on my proposed lowering and wheels setup?
The only thing I might look into would be an adjustable torque arm to account for the new driveshaft angle. I'm never found a hard answer as to whether or not it's absolutely necessary. Obviously, geometry says the angle will change, but whether or not it'll move it outside of acceptable parameters I suppose is debateable, and is probably also slightly different from car to car. For my experience, I can say that lowering DID change it enough to warrant the new torque arm.
Keep in mind that minor little vibrations that you CAN'T feel can have an effect over time causing problems.
Re: Your thoughts on my proposed lowering and wheels setup?
You may also need some lower control arm relocation brackets and a panard bar relocation kit. Or an a adjustable bar. Both angles change. The trailing arms affect traction so those may not be needed. When the panard angle changes the rear end will be pulled to the passenger side, and with 275's it maybe enough to cause the tire to rub at some point when cornering. I don't think I would use front lowering springs with a 1/2 drop ball joint. I would do one or the other. Just my opinion. The other thing is I would just buy new tubular trailing arms with the 3 piece bushing. I got mine from Founders performance and they were under $100 and you won't fight trying to get the old bushings out and press the new ones in.
Re: Your thoughts on my proposed lowering and wheels setup?
+1 more for the panhard bar. Thought of that as I was typing about the torque arm and forgot to mention! You may not need it for clearance, but it'll throw off your thrust angle regardless. This is another one of those things that may or may not have a direct negative impact on your particular car, but geometry doesn't lie, and it WILL be off.
Re: Your thoughts on my proposed lowering and wheels setup?
Originally Posted by Tootie Pang
Good stuff. Wouldn't the 1/2" extended ball joint only drop the car another 1/4", maybe a little less? but help retain OEM geometry?
Yes, but if you use a it with a 1" lowering spring I would think it would add up to I.5" of total drop? Our cars ride low as it is and I.5" may make it a little tough on transitions in driveways and such.
Re: Your thoughts on my proposed lowering and wheels setup?
What is this ball joint kit you guys are talking about? I can't see how a LONGER ball joint would help since we only have lower ball joints. I think the extended ball joints are typically for the UPPER a arm. -am I not right? Not an expert. Feel free to learn me new stuff!
Re: Your thoughts on my proposed lowering and wheels setup?
2" or more can be problematic, especially with soft springs; AND it messes up the steering geometry. 1.5" is just fine for the street. 2" is great for the track if you have adjust-ability.
The Ext BJ's correct this, to a degree. A drop by spring and ext BJ "drop" are not the same thing. Ext BJ alters the angle of the a-arm - not a drop per se. It raises the front roll center - which is in the weeds and when you hit the brakes with a soft front spring it goes below ground level - very bad. The ext BJ's will lower the ride height a little; BUT, most of us who go down this path have adjust-ability in our front suspensions (WJ's or constant fitment refinement with cut springs). The OP should be OK as stated.
Raising the front RC and lowering the rear RC are probably the two greatest things to do for improved handling. The Ext BJ's up front, and a panhard bar bracket on the axle side are relatively easy to do; don't cost a whole lot; and are not massive changes to the RC's. From the factory, 3rd Gen cars are heavily slanted towards the front (just throwing #s out: frRC = 5", rrRC= 14"). That would be a 9" slant back-to-front. When you lower the car by springs only, the frRC goes down almost a one-to-one ratio. Let's say you lower by 2", then the frRC is lowered down to 3". The rrRC does not go down anywhere near one-to-one. For ease of math, let's say the rrRC goes down at 50% (probably less than that) so that the rrRC is now at 13". By lowering with springs, you have just increased the slant to 10" . This would be a worse handling car for sure.
The ext BJ's will raise the frRC by .5" which will now equal 3.5". Then, the PH bracket will lower the rrRC by 2" which will now equal 11". The slant is now 7.5" AND the center of gravity is lower, too. These numbers are just for conceptualization!
Here's a rough pic to get the concept. Pink is stock height; yellow is lowered w/springs only; green is with ext BJ and PHB. It should be mentioned that when lowering the rrRC, the spring rate should be increased. A packaged spring kit will have the rear springs too soft when the rrRC is lowered.
Re: Your thoughts on my proposed lowering and wheels setup?
NOT LCA bushings.
They are all but impossible for the average Joe to replace without destroying the LCAs; and even if you succeed, you're still stuck with the weenie little tinfoil LCAs themselves, which you will discover, you can actually bend with your hands. (or at least I can with mine... and I'm just yerbasic classic 6'1" 145-lb weakling) Panhard bar is the same way.
Replace them both with good aftermarket. If you're buying all that other stuff from UMI, maybe they have a package you can get from them that includes those other things.
Don't be too surprised if you buy "lowering" springs, from WHOMEVER, and your car actually sits HIGHER after you put them on than what it does now. You wouldn't be the first to have that happen. "Lowering" isn't like you just open a bottle of "lower", pour it all over the car, and the car just jumps itself xx" closer to the center of the Earth. "Lower" is a COMPARATIVE word; it requires a REFERENCE of some sort; as in, "lower than [something]". And what your car will be LOWER THAN, is its ORIGINAL height, not its CURRENT height.
Last edited by sofakingdom; 02-24-2019 at 01:01 PM.
Re: Your thoughts on my proposed lowering and wheels setup?
Alright, alright. So I decided to keep it all stock. It is what it is and isn't anything more than a great running bone stock LB9 vert that I continue to restore. I'm having the OEM wheels refinished and ordered the Moog CC635 and 5662. I was really tempted to go for the "stage 1" stuff but that will be for another build. Awesome advice here on lowering. These cars really do handle great.
Sofa, I got the original bushings out and it wasn't too bad. And they were really corroded in there.
I drilled out the rubber all the way through axially, all the way around and pushed out the inner sleeve and pulled all the rubber out. To get the outer housing off, I cut it length wise using a lengthwise line of 1/4" holes and splitting the rest using a 1/8 punch and hammer. I used a small cutting grinder to split the bushing flange face. Once split, I used the punch and hammer to knock the outer sleeve in on itself (at the split) and it just dropped out at some point. Once I got into the rhythm, it was a less than ten minutes per bushing. Real easy. I did have the A-Arms all the way off though and in a vise. I sand blasted them and put some fresh black on them.
I did try a press on the bushings at first. No way would that work!
Last edited by Tootie Pang; 02-24-2019 at 09:10 PM.
Re: Your thoughts on my proposed lowering and wheels setup?
Originally Posted by TEDSgrad
2" or more can be problematic, especially with soft springs; AND it messes up the steering geometry. 1.5" is just fine for the street. 2" is great for the track if you have adjust-ability.
The Ext BJ's correct this, to a degree. A drop by spring and ext BJ "drop" are not the same thing. Ext BJ alters the angle of the a-arm - not a drop per se. It raises the front roll center - which is in the weeds and when you hit the brakes with a soft front spring it goes below ground level - very bad. The ext BJ's will lower the ride height a little; BUT, most of us who go down this path have adjust-ability in our front suspensions (WJ's or constant fitment refinement with cut springs). The OP should be OK as stated.
Raising the front RC and lowering the rear RC are probably the two greatest things to do for improved handling. The Ext BJ's up front, and a panhard bar bracket on the axle side are relatively easy to do; don't cost a whole lot; and are not massive changes to the RC's. From the factory, 3rd Gen cars are heavily slanted towards the front (just throwing #s out: frRC = 5", rrRC= 14"). That would be a 9" slant back-to-front. When you lower the car by springs only, the frRC goes down almost a one-to-one ratio. Let's say you lower by 2", then the frRC is lowered down to 3". The rrRC does not go down anywhere near one-to-one. For ease of math, let's say the rrRC goes down at 50% (probably less than that) so that the rrRC is now at 13". By lowering with springs, you have just increased the slant to 10" . This would be a worse handling car for sure.
The ext BJ's will raise the frRC by .5" which will now equal 3.5". Then, the PH bracket will lower the rrRC by 2" which will now equal 11". The slant is now 7.5" AND the center of gravity is lower, too. These numbers are just for conceptualization!
Here's a rough pic to get the concept. Pink is stock height; yellow is lowered w/springs only; green is with ext BJ and PHB. It should be mentioned that when lowering the rrRC, the spring rate should be increased. A packaged spring kit will have the rear springs too soft when the rrRC is lowered.
Great explanation! I am planning to keep my height “maybe stockish” but since my car is 28 years old I am sure it is lower than stock and I like about where it sits now. My plan is to use the Ground Control Weight Jack/ Koni package. If I use .5” extended ball joints and use a panhard bar relocation, what what would be suggested spring rates for front and rear? Want it to handle well but not be so stiff as my wife wont ride in it...
Re: Your thoughts on my proposed lowering and wheels setup?
Assuming a V8 car: #900 - 1,000 is sporty stiff not harsh (an LS can get away with #850 - 950); #750 - 900 would be comfortable soft but still tighter than stock.
Stiffness is not just springs - includes shocks and sway bars (wheel assembly weight). General consensus is to use the 36mm stock bar for V8's, then match a spring rate that you want.
For the rear (if lowered RC), start at #225 and go upwards. Then, use a smaller rear sway bar - should have several rear bars from JY to educate yourself and have options. You need to have some independent wheel action to counter the lower rrRC and stiffer spring.
DSE advertises #950 fr and #250 rear. I have an LS and other weight saving additions: FR - #850 w/36mm WJ's, & Konis; Rear - RideTech coilovers #250 w/19mm. I'll probably move up to #900 Fr in the future.
This is ballpark advice, and all refinements are your responsibility and enjoyment! Learning car control is FUN!
Re: Your thoughts on my proposed lowering and wheels setup?
Originally Posted by TEDSgrad
Assuming a V8 car: #900 - 1,000 is sporty stiff not harsh (an LS can get away with #850 - 950); #750 - 900 would be comfortable soft but still tighter than stock.
Stiffness is not just springs - includes shocks and sway bars (wheel assembly weight). General consensus is to use the 36mm stock bar for V8's, then match a spring rate that you want.
For the rear (if lowered RC), start at #225 and go upwards. Then, use a smaller rear sway bar - should have several rear bars from JY to educate yourself and have options. You need to have some independent wheel action to counter the lower rrRC and stiffer spring.
DSE advertises #950 fr and #250 rear. I have an LS and other weight saving additions: FR - #850 w/36mm WJ's, & Konis; Rear - RideTech coilovers #250 w/19mm. I'll probably move up to #900 Fr in the future.
This is ballpark advice, and all refinements are your responsibility and enjoyment! Learning car control is FUN!
Once again super helpful!! Thank you very much for advice!
My car currently has a stock 305, but I am planning an LS, aluminum block swap and t56 by next year. Sorting out the chassis first. I currently have the stock 34mm front, and 21 mm rear sway bars. RS with F41 package. I also have a 19mm rear bar that came with my 4th gen posi rear so I can begin to experiment with that.
It sounds like 225# rear springs should work well.
For front, I would prefer springs that can handle the iron block I currently have, but will still work decently (for a while at least) when I swap in the aluminum LS. From your description, it sounds like maybe #900 would be a good starting point.
(Update 3.11.19)
I spoke with Ground Control and described this conversation and my plans. The guy I spoke with owns a thirdgen so is very familiar with the platform. They recommended that I go with a #950 front spring and a #200 rear. They felt strongly that this wont ride too harsh since I am going with their custom valved konis as well. Said it should be very well balanced. I did read a couple threads though since my call that discussed different length springs. I called and confirmed that all their springs are the same length so those older threads are outdated in that regard.
Last edited by Sdmodified; 03-11-2019 at 03:09 PM.
02-15-2019, 04:00 PM
