Getting the "right" stance

[JLM]

I've been doing tons of research on this and I'm getting close to ordering front and rear suspension componants.

What I'm looking for is to get the stance to about where the front and rear wheels are tucking into the fenders and 1/4 panels (69 Firebird). Not smallmed to the ground by any means but enough that the tops of the wheels are covered by sheet metal.

I'll be running 26" tall tires (245/45/17 front, 275/40/17 rear).

What I'm looking at doing is AFCO 9.5" x 5.5" springs with hidden adjusters in the front and custom leafs in the rear that will show about 3" drop. I'm also looking at going to half height solid body mounts. With this get me the stance I'm after?

Opinions?

[Travis B]

Sounds like it should be pretty low(which is good)! The 1/2 body mounts will help a bunch to, that will hide more of the ugly subframe. I like the idea of the adjustable coils on the front!

[Ralph LoGrasso]

Becareful with the half height body mounts. You may find yourself raising your transmission tunnel depending on which tranny you run. With a T56 it will almost definitely need to be raised up.

[JLM]

The transmission will remain the stock TH400. At least for the forseable future anyway.

[JLM]

Ya know Ralph you really got me thinking. I think with the half height mouns I may not run into trannsmision tunnel problems but I'm almost positive I'd run out of clearance under the hood. Poncho's sit pretty high in the engine compartment and with the performer RPM intake it's already a very tight squeeze to get in there.

I'll have to take measurements on that to be sure. This is exactly why this site is so great. Stuff you don't even think about and you guys are there to solve a problem before it starts.

[vanzuuk1]

Also steering alignment, you may have to losen a few bolts to line it up.

[Ralph LoGrasso]

Ya know Ralph you really got me thinking. I think with the half height mouns I may not run into trannsmision tunnel problems but I'm almost positive I'd run out of clearance under the hood. Poncho's sit pretty high in the engine compartment and with the performer RPM intake it's already a very tight squeeze to get in there.

I'll have to take measurements on that to be sure. This is exactly why this site is so great. Stuff you don't even think about and you guys are there to solve a problem before it starts.

Glad to be of some help. I hadn't even thought of engine problems myself, good point. I've heard of a few people raising their trans. tunnels 1/2" or 1" because of the half height mounts, though. I would say skip the half height mounts, and save yourself the headaches. Find that extra 1/2" or so elsewhere.

[Stu Seitz]

I'm running a t-56 with GW 1/2 in. bushings it's mated to ls1, but i don't think that would matter. I'm using a ATS crossmeber with a turbo 400 mount, neg 3 deg. pinion angle and I still have the STOCK tranny tunnel it's really close but it don't hit.

[parsonsj]

Are you doing any suspension mods to compensate for the low stance? Otherwise you've used up all the factory's designed bump travel and are out of the suspension's sweet spot. I don't know how the suspension (especially the front) reacts there, but I doubt it will be good. At minimum, you will need to cut or remove the travel bumpers and put a bump steer kit on it. You may have a lot of static camber as well, so be ready to modify the mounting holes on the upper control arm.

jp

[JLM]

Are you doing any suspension mods to compensate for the low stance? Otherwise you've used up all the factory's designed bump travel and are out of the suspension's sweet spot. I don't know how the suspension (especially the front) reacts there, but I doubt it will be good. At minimum, you will need to cut or remove the travel bumpers and put a bump steer kit on it. You may have a lot of static camber as well, so be ready to modify the mounting holes on the upper control arm.

jp

JP I'll be doing The G-Mod using reinforced stock UCA's and LCA's up front with AFCO 9.5" springs with a rate around 800 lb/in with hidden adjusters and bilstien shocks in the front. When the time comes I'll look at having a matching set of leafs built for the rear of the car also using bilstien shocks.

Will this eliminate the bumpsteer and camber issues? what would you suggest if not? Thanks.

[JLM]

Another thing that I was thinking about is the fact that these mounts, even half height might actually raise my car a little bit. The factory rubber mounts are still on the car and they are rather deteriorated from the years the car has spent on the road. They aren't providing much height to the body from the frame currently.

Does anyone know the exact measurements of the half height mounts?

[MuscleRodz]

I just measured my stock DSE mounts and they are 3/4". They say it is a 1/2" drop which would make them 1/4" between the body and frame. The pic in the catalog shows 1/2" drop mounts and they look like 1/2" tall. If I remember right the stock rubber is about 1" before compressed. If you figure a 1/4" compression of the stock rubber, 1/2" tall would make sense.

Don't know what your budget is, but you might look at ATS's new spindle coming out. They have about a 3/4" drop, improved geometry, and easy retrofit of C5 brakes. They will have a couple versions available so I would talk to them directly about which one would work best for your needs.

Mike

[JLM]

I'll have to call ATS on that spindle. I could probably swing the spindle but if they won't accept the current discs I hae I'll have to hold off. It would give me reason to change over to a nice break setup. The MP brakes I have now work great, but I'm sure a nice set of wilwoods would work even better!

I'm going to get under the car this weekend and measure how much height the factory rubber bushings are currently giving me. I'll make a decision on the body mounts then.

[CarlC]

I agree with John. If the front end is lowered too much the steering does funny things.

To mimimize steering issues, try to get the center of the sphere in the lower ball joint 1/2" lower than the center of the front A-arm bolt when the car is at full weight and on the ground.

With your tire size, with the car on the ground and at the height listed above, the center of the A-arm bolt should be around 9-1/2 - 9-3/4" from the ground.

Unfortunately, I've seen several cars that looked bad-ass low, but they were both ill-handling and had little, if any, suspension travel.

[parsonsj]

JLM,
The parts you've mentioned don't change the geometry and won't fix the fact that your ball joints are probably too high relative to the frame/car body. One thing that can help is to increase the spring rates (which you've done) to minimize bump travel from the static ride height. Other than that, not much is possible unless you are willing to relocate the control arm mounting points. And then, you'll need to move or fuss with the tie rods to minimize bump steer. If I were you, I'd get a bump steer kit, and make sure you don't hit the travel limiters during normal or high-spirited driving. Making turns on the travel limiters can really cause odd and non-linear behavior.

jp

[JLM]

I could see that doing very bad things.

Tell me something. I have heard that it's a good idea to position ride hieght of the car so that the lower control arms are parallel to ground level? Any truth in this?

I'm assuming a bump steer kit would be advisable even if I go with full height body mounts correct?

[parsonsj]

I've heard that too, but Carl's advice is sound (and similar). The real thing to look at is the ball joint relative to the control arm mount point. He says LBJ 1/2" lower than the frame.

And yes, you need a bump steer kit for both cases.

jp

[JLM]

I've heard that too, but Carl's advice is sound (and similar). The real thing to look at is the ball joint relative to the control arm mount point. He says LBJ 1/2" lower than the frame.

And yes, you need a bump steer kit for both cases.

jp

Exactly the information I'm looking for. I'll keeb the lower ball joint location in mind when setting the rideheight.

Question. Would the G-Mod be needed if I went with one of the new ATS spindles? Isn't that the point of the G-Mod in the first place is to correct the effects of the "too short" stock spindles?

[parsonsj]

The new ATS spindles are indeed taller, and will change the camber curve to help correct the poor factory design. The G-mod improves the camber curve, but also adds caster. The ATS spindles won't have any effect on caster. So yes and no ...

Perhaps Shane, Tyler, or Tom will comment.

jp

[JLM]

I would (at least if utilizing stock UCA's) need to do some adaptation of the G-Mod. Perhapse just a lateral move of the mount as opposed to a lateral and verticl move that you would see by just doing the G-mod.

Perhaps the ultimate setup would be a set of aftermarket control arms like Global Wests that improve caster along with the taller ATS spindle to improve the camber curve.

This site makes me spend way to much money!