tubesncubes

Looking to do a significant drop on my GTA and wanted to get some feedback on what is needed as well as what side effects and remedies I need to look out for. Current setup is LS1/T56, big brake spindles, Koni Yellows, Pa racing front end with power rack and aams have spring perches, adj phb, lcarbs and adj lca. TNT 8.8 being built with stock suspension mounts. Due to the location of the t56 from the bmr swap cross member I'm sitting at 28/29 static height with less than 3" of clearance.
My goal is to land somewhere between 24-25" of static height with a square 275/40/18 setup on 9.5s.
Anyway, Ive done my homework and so far I know I'm in for weight jacks with shorter springs, cc plates, shock mounted bump stops, cutting bump stops and rolling fenders, possibly spindles and ball joints (although If possible id like to keep what I have) and maybe moving shock mounts on the rear. I'm concerned about pulling the trigger on this stuff and the car rubs, hits, runs out of travel etc.
If I could get a rundown of what to expect to avoid common pitfalls and have a sound setup that would be awesome!
Thanks TGO.

tubesncubes

This isn't how it sits now.

plum92_camaro

Sounds like you're on the right track. With the money you have invested in suspension already, it really only makes sense to go with weight jacks. They'll work well with your konis too. The CC plates are a great idea. I didn't use the shock mounted bump stops. I trimmed the stock bump stops in the front (25 5/8" ride height), Haven't needed to trim the rears yet, I haven't got the rear suspension completely worked out yet either. I haven't needed to to roll my fenders yet with the 275/40R17's on 17x9.5" ZR1's. Extended ball joints are a good idea too. They will help raise the front roll center back up. I can tell you, if you stiffen up the rear suspension too much like I did the rear end will get really loose. You'll either need to remove the rear sway bar as a band aid or get a UMI or Unbalanced Engineering Panhard lowering kit, or watts link to correct the rear roll center. I'm getting a watts link before racing season starts again.

I've never looked into the drop spindles, look into DBL_TKE, or itsMikey. They have the lowest cars I know of with all the mods you mention including raised shock mounts. Here's a link, https://www.thirdgen.org/forums/auto...gens-post.html

plum92_camaro

double post

tubesncubes

Thanks plum92. I've read through dbl_tkes thread of the 91 camaro and the slammed thread to get an idea of what I'm in for but can't collect enough facts for a difinitive answer. it seemed that dbl_tke fixed an issue of suspension travel and created another to tackle as he lowered the car so it's hard to tell what would work and what's ideal for driving. Absolutely an awesome ride and one of my favorites for stance.
I looked at the new umi phb drop piece and figured that's also on the list of parts to buy.
I guess my overall question is what are the supporting mods to safely (understanding that's a relative term) drive with a 24" height?

RT66ProTouring

iTrader: (2)

3" of clearance at the transmission is surprisingly low.

What is it about the BMR cross member that causes the ground clearance issue? Can you post a picture?

Any other components hanging low?

tubesncubes

Heres the thing: bmr creates these pieces to be bolt in so any shop can do it but the issue is really with the third gen frame. In order for it'll the trans to just bolt in the t56 has to be dropped to a ridiculous angle when what should happen is the tunnel should be cut to raise the trans tail shaft so the trans tucks in. Look at 1meanz's tko600.
The t56's tailis dropped because It doesn't fit in the tunnel the same as the t5/700r so the crossmember is lowered to hold the trans and then exhaust has to be run. Just isn't possible with the bmr piece.

I've got a significant amount of frame work that I'll probably make another thread about it. In short I'm going to cut the tunnel, lift the trans, cut the back of the frame boxes off and run them into a fabricated crossmember similar to the trak pak but with a long torque arm. All tucked under the subframe connectors.

RT66ProTouring

iTrader: (2)

That makes sense. Thanks.

The other question I have about your post is your PA Racing K-Member

I wasn't aware anyone offered a power rack and pinion. Am I not understanding your post correctly?

tubesncubes

Its a 1off make I bough from a member here. It's a thunderbird rack mounted on the k member with 1 off tie rods, bump steer kit, flaming river steering knuckle, and 4th gen column.

tubesncubes

After doing more research it looks like I'll also need to lower the phb (already have the adj bar) and get extended ball joints however I can't seem to find extensions for the arms I have. I've got 10277 Napa ball joints installed on my pa arms and can't seem to find anything longer. Is this pretty much iterative to find what's longer or do most run Howe/qa1 extensions on stock arms? Thanks.

83 Crossfire TA

iTrader: (2)

I don't think you'll ever get below 25" without major changes. You'll need drop spindles or extended ball joints to get into the mid 25's and still have travel (you can cut the front bump stops, but then the rear of control arm contacts a stock K-member, with aftermarket stuff it's all a crapshoot). When you get into that range you'll either have to modify the fenders/inner fenders/run more camber or shorter tires to give the tires somewhere to go.

And that is assuming that you deal with the stuff hanging down first.

My '83 was somewhere in the mid 25" range in the front (I want to say right around 26 rear, honestly it's been a while, I would have to look it up), and had nothing hanging down and I had ground clearance issues (DC Metro roads, not the best but nowhere near the worst). I got very good at replacing the exhaust crossover (most of the time I would just chop off the bottom half of the pipe that got flattened and weld a new one on), I tore off the trans pan (700r4) 2x, flattened the oil pan once, and the one time my wife drove the car she got it stuck on one of the in ground tank filler caps at a gas station. I also had people comment on how obviously low the car was, I remember some old guy at a gas station talking about it when he noticed how my tank filler was almost down to my knee (I'm pretty tall, 6'4")

tubesncubes

Yeah, the entire underside is being addressed next so I can tuck bigger exhaust in the tunnel when the car is lowered.

I understand that there's a significant amount of work involved in attaining the drop I want, just looking for advice on what is possible and how to get there. I'd like to keep the stock spindles if I can get away with it but I understand the need for suspension travel becomes critical as the car is lowered. I'm hoping that taller strut mounts and ball joints can get me there.

TEDSgrad

iTrader: (4)

Back-off the significant amount of work, and add a significant amount of planning. No need to hack the frame, especially with a T-56. You will need a better trans x-member.
If I can fit 3" exhaust around a 4L65e, you can do it around the T-56.








Strong drop spindles are hard to find, and will limit your tire width. I believe they are worth it (have them), but most believe more tire width to be the monolithic answer to grip (search here for "The Grip" Parts I, II, III).

Plan your suspension to be adjustable. Keep some clearance for the street, and go low for track or known roads for fun. If you build limits into your car, you will use it less, loose interest, and the car will be worth less.
Your car should scream, "Drive Me", on the road or at the track:

tubesncubes

Thanks for the reply TEDSgrad. I'm cutting so I can fit exhaust inside the frame specifically at the bottleneck at the rear of the boxes. That's the only way I've found to get significant clearance to lower the car. Looking at your exhaust the setup sits well below the frame and the trak pak hangs lower than that. This what I'm looking to remedy so I can keep the car lower for street driving.

I plan to use weight jacks and konis to keep the adjustability and be able to lower the car further from just street driving.

What are my options for spindles that are strong? Aje? Racecraft? And what tire width could I go for on a 18x9.5?
What all do you have in addition to the spindles?
Thanks.

TEDSgrad

iTrader: (4)

No current options on spindles, unless you buy used, and won't fit a 18x9.5. Big, heavy wheel combo! - no sidewall: Good Luck keeping flat and even wear pattern w/softs. Plan on going 120+ mph? Merely lowering the car and putting the fr. RC 5" below ground will not be effective, but, spend your labor and money and report back. Paul has an excellent price point and weight in 17's.
What is your budget? You still have way more to plan/spend. Application, application, application! If you deviate, you won't be happy, be broke, and will sell to one of us for pennies on the dollar - happens all the time.
If you're just looking to slam it and put big heavies on it, I have no advice for you.

If you won't search under my user , then why should I spoon you?

The collector flanges are the lowest point, followed by the trak pak (mm's from the floor plan), and k-member--> I see no recourse (within reason) to alter these. I did re-do the pass side trans x-member to attach to the frame horizontally rather than vertical for more tuck-up (that's the difficult side for 3"). You can go too low for street, but you don't want to hear that.

tubesncubes

I understand the importance (and lack) of roll center for a thirdgen. Lowering by spring only puts the arms too high limiting travel as well, thus the need for extended joints, spindles, and higher caster camber plates to put both of these back to a usable range.
My question is: as far as stance vs performance, what am i looking to put the car at with ball joints, cc plates, konis, and weight jacks? or should I just go back to the drawing board and look elsewhere?
I don't plan to compete with f1 cars and this is not a max effort track only car, It may see a road course in its lifetime but that is not the goal. However, this does not discount the need to build a good car and do diligence in planning and execution.

Wheel weight is important as you've pointed out in the grip threads but in this specific area in my scenario form is important for wheel choice as I am building this car as a whole. I know the excellent product Paul makes and If this was a max effort track car I would have them, but again, Its not a track focused car and the style of the wheels is not what I'm after with my build. Am I completely shooting my foot to run 18s because they are that much of a weight on the end of the arm? the 9.5s are 30lbs and 8s are 28lbs

I'm trying to be transparent and teachable but I don't want to spend a career worth of time to know more than ill ever need/want to.

TEDSgrad

iTrader: (4)

OK, application helps.
Howe makes an extended BJ - look at Coleman Racing (and others). That's the only partial solution for 9.5" wheels. It will give you some benefit. Spindles are just too hard to come by (production ones), and do limit wheels to 8-8.5". Custom?
You will not regret getting weight jacks - do get them: OR, WJ's up front and coilovers on rear. Just make sure you get a coilover matched to your intended ride height - not what people will try to sell you!
Just for reference, Paul's 17 x 8's were like 18 lbs! + tire weight. When you get 18's, you want to fill up the wheel - means larger rotors (not necessary and more rotational weight). A 13" two piece rotor with FSL calipers are plenty - will fit most 17's nicely. Check to see how that looks with whatever 18" you're looking to buy. Check on availability and price of tire selection. The small sidewall on a McStrut car will have a more jarring effect, but you've made that choice. There's no right choice, just choices that cut you off from making other choices on down the line. That's why application is so important.
You can go with aluminum hubs and quality bearings (going to need those with the weight). A-arms can be adj tubular or stock with upgraded bushings. But going after all these other savings when the wheel is heavy kind of defeats the bang for the buck - still has savings, though. You'll need a front spring of about 1,000 lb.
As far as street stance, everyone has their own opinion. I started at 26.5 fr/ 27.25 rear and felt it was too low for road trips on unknown roads. I've not had a problem, yet, and I'm at 26.75/27.5 and thinking of going up another .25. I do bring it back down for track.
If you're going to autoX, you can make this work; but your camber curves better be spot on. High speed road course, I would want more sidewall at speed. My car does spend a lot of time above 100 mph.
In my opinion, your wheel choice is not optimal. But you can make it work for you, and have a lot of fun. Perceived optimal does not prohibit fun and enjoyment - that's the goal. You're just going to have to work harder at unsprung weight control, rotational weight changes, and become good at camber control adjustments to save your tires.

tubesncubes

So the wheel weight is that drastic.. hmm. I understand it has more leverage being on the end of the aarm. Is this essentially a bandaid (albeit a good one) of the poor roll center?
My 18s are mesh so they'll hide small brakes. I got my kit from flynbye so I've got the hubs they provide and ls1 brakes (may go to ctsv or c5). I'll need kore3 hubs?

I've got a set of zr1s, would that be a better option if I wanted a set of track wheels? Taller side wall, lighter, and more section width.

This is also why I want to cut the frame up to achieve lower static height when I want without being concerned for ground clearance. I don't really see 26/27 as much of an improvement in stance for me but I'll take what I can get.

TEDSgrad

iTrader: (4)

This is what happens. You make the heavier choice upstream, and you loose all incentive to go after every pound downstream. You choose the heavier wheel combo, then why get two piece rotors w/ FSL's, then why get lighter hubs with stronger bearings?, then why?... At every turn you are foregoing the lighter option. It snowballs on you. You can get away with one heavier choice(if you work hard to mitigate it), but you are making all of them.
Flynbye's LS1 kit is an improvement and cost effective. But it is heavy, but a two piece 13" w/FSL is much much better.
I'm sure your car will be fun to drive, and you will enjoy your efforts. Good Luck. Post pics as you go along.

tubesncubes

Ok I understand now.
So I get all the facts, if I were to go with a lightweight wheel then hubs, rotors etc will have that much more impact on handling due to unsprung weight moving easier on the aarm's travel?