How Low is Too Low?

[Damon in STL]

My car is finally back on the ground after about two years of mods. It is not done....but, it is capable of moving under it's own power.


One of the primary goals was to get the car as low as possible while maintaining proper suspension geometry. One of my surprises was how low the oil pan actually was once the car was on the ground.




Looks like I got a bit lower than I anticipated. I've got about 1.5" of clearance to the oil pan. I have a track day coming up in a couple of weeks and will be focusing on mechanical grip. If I stay away from the curbs....I should be fine. I'd need about 3" of compression on one side to rub the pan.

The pressure piping is temporary as I have the intercooler out right now for better access.





Damon in STL

[gobuffs]

Nothing a dry sump can't fix.

[TOOLEAN]

Have you adjusted the suspension pickup points or stock?

[Damon in STL]

Nothing a dry sump can't fix.

Dry sump is in the works....



I just now cleaned out a spare oil pan and am looking into how to modify it. I have a Weaver Bros. pump which I need to have modified to allow me to rotate the pump 180 degrees. I just don't have room to mount it side by side with the engine...so, it will have to be rotated and mounted in front of the engine. Not the best arrangement.

Damon in STL

Have you adjusted the suspension pickup points or stock?

The pickup points have been raised into the chassis. I pulled the fender and it looks like I have about 2" of compression travel to work with. I may be able to gain about 1/2" by folding over the sheet metal at the top of the tire travel.



Damon in STL

[Massive Lee]

Cut the frame's lip until you meet the inner fender.

[PCarroll]

One interesting lesson I learned was about lowering the car versus lowering the engine. By fiddling with engine mounts, I found I could lower the center of gravity without lowering the actual suspension. Dropping the engine 1/2" made a surprising difference in the handling.

Also beware dropping the rear too far. Running the half shafts at too great an angle can have disastrous effects. Even on my wife's E46 M3. We lowered the rear ride height too far. There was still lots of play in the shafts - i.e. not binding. But still they kept exploding. The inner boot would blow up like a balloon and would eventually fail. You don't have to go that low to have the problem. Even with the stock bodywork you can get into trouble. We had it with maybe 1" between the top of the rim (18") and the bottom pf the lip.

[yokoseiki]

That pan looks really low. You should be fine as long as you stay off the curbs and don't go off. Not joking around, be careful around the paddock getting up and off paved areas onto the grass too and vice versa.

[robjohnson]

Amazing how similar your car and mine are. Great minds think alike! I like the turbo, it will be fast. I'm broke so I'm sticking with a naturally aspirated engine and mostly stock parts. The radiator will be smaller that way and stay in the front of the car. How did you size the water pump to move the fluid that far and back to the engine? Do you have a secondary pump to assist?

I have E46 Knuckles on my car, I'm going to run something similar to the BW roll center solution for the control arms with 15 inch rims. Once my car hits the ground in two weeks, I am going to do some measurements and make new brackets for the steering rack. Since I'm using tiny wheels I will not be able to use an off the shelf bump steer kit. I think I will have to move it up and forward to get the steering to be somewhat normal. I have not lowered my engine yet because of the oil pan deal you have here. When I did the mock up out of the car I saw this and only lowered it 12mm.

Are you planning on using an E36 swaybar or making something trick?

[flink]

1-1/2" is too low, methinks. My undertray is 3-1/2" and it scrapes along the car's centerline doing regular berm jumping at Buttonwillow, and straddling that stupid hump in the middle of T4 at Sears Point's NASCAR config.

I fear you might dump a full load of oil onto the track?

[Bud Scott]

IT.................................IS............. .......................ALIVE!!!!!!!!

Could be a momentous weekend in November! You breaking in Frankenbeast and me in the newly caged (AND a BIG HP UNIT!) POS-325e. Bound to get a possum story or two out of this.

Have you done some look see/calculating/cipherin at theoretical roll center with this ride height and anticipated suspension compression? Too low could, indeed, be too low.

[JS154]

Nothing a dry sump can't fix.

Agreed.

Also like Pcarroll said, plan on replacing half shafts much more frequently.

You really should make a skidplate for it until you run dry sump.

[ZimDoc]

I'll save you some time.

http://www.drysump.com/BMW.htm

Can't wait to hear how this car drives on track!

[Evice]

I am still trying to figure out what kind of a zombie I am looking at!

[Damon in STL]

Amazing how similar your car and mine are. Great minds think alike! I like the turbo, it will be fast. I'm broke so I'm sticking with a naturally aspirated engine and mostly stock parts. The radiator will be smaller that way and stay in the front of the car. How did you size the water pump to move the fluid that far and back to the engine? Do you have a secondary pump to assist?

I have E46 Knuckles on my car, I'm going to run something similar to the BW roll center solution for the control arms with 15 inch rims. Once my car hits the ground in two weeks, I am going to do some measurements and make new brackets for the steering rack. Since I'm using tiny wheels I will not be able to use an off the shelf bump steer kit. I think I will have to move it up and forward to get the steering to be somewhat normal. I have not lowered my engine yet because of the oil pan deal you have here. When I did the mock up out of the car I saw this and only lowered it 12mm.

Are you planning on using an E36 swaybar or making something trick?

Hey Rob,

I'd like to see some pics of your car....it does sound like we are going down the same path!

The jury is still out on if I need the extra water pump. I've setup a location to install a Davies Craig unit if it becomes necessary. As for the anti-roll bar, the ST bar I had will fit. But, my project management skilz failed me while fast tracking the engine install....I'll need to re-allocate resources to finalize the bar install (um...I forgot to put it in....it does fit though!).

IT.................................IS............. .......................ALIVE!!!!!!!!

Could be a momentous weekend in November! You breaking in Frankenbeast and me in the newly caged (AND a BIG HP UNIT!) POS-325e. Bound to get a possum story or two out of this.

Have you done some look see/calculating/cipherin at theoretical roll center with this ride height and anticipated suspension compression? Too low could, indeed, be too low.

Rarely will I ever say this.....but, yours is bigger than mine.

But!!!! I believe I just may make better use of it!

On that cipherin' of the theoretical roll center....looks like I forgot to carry the naught and may need to take another look!

Damon in STL

[yokoseiki]

The photo is a little dark but based the angle of the control arms, you car looks a little low from a geometry standpoint. I want to say on my car the control arms hang down 2-3 degrees with the tie rods hanging down about 1/2 that? You must have lowered your motor too to get the pan that close to the ground.

[TC Kline Racing]

When the car is on the ground your LCA's should be just above level. If the LCA's are level or start to point downward (from the spindle to the chassis) then you are compromising the capability of your suspension. It IS possible to be too low.

[jimmypet]

Holy cow Damon.

Is it possible this is the same car?
Garage door looks the same haha.

Before:


After:


To say you have put alot of work into this project is a huge understatement.
jimmy

[Damon in STL]

Holy cow Damon.

Is it possible this is the same car?
Garage door looks the same haha.

To say you have put alot of work into this project is a huge understatement.
jimmy

Hey Jimmy,

That's the 1987 Euro model I had a while back. It was the 46th non-cat unit produced. I really hacked it up good!

I got back into tracking in that car....and realized I was pretty fast. I then bought another e30 M3 that had been raced with Midwest Council and for a time was using the euro as a daily driver and the other for track.

I think I am valuing my time at right about 14.32 cents per hour at this point.

Phase 47 of the project will be to put the s14 back in this car and turbo it!

Damon in STL

When the car is on the ground your LCA's should be just above level. If the LCA's are level or start to point downward (from the spindle to the chassis) then you are compromising the capability of your suspension. It IS possible to be too low.

Thanks for the tip! Now that I've moved the car a bit I'll take a look ant the LCA angles.

I moved the entire subframe up on this version. I have another version which is fully adjustable with heim joints. I also made the inner joint vertically adjustable....but, I not really happy with it at this point. It needs more development. So, I am currently running the stock arms with the modified subframe. That reminds me....I never milled/installed the bump steer spacers...things should be coming off the list....not back on!!

Damon in STL

[HDawg 440]

Another thing to consider is: Does your powertrain or body touch the ground when the suspension is fully compressed? This is a desirable attribute for some classes of low-rider competition or maybe the bottom of an F1 car. Probably less so for an S14 oil pan. You may never truly bottom-out in quasi-static conditions, but inertia forces in dynamic situations can be very high. Meaning: you can compress your suspension very much if you hit big bumps, like in an off or an accidental curb-hopping event. No need to turn something the car should handle easily into a pants-shitting event.

I would say remove your suspension springs and lower the car to rest on its springless suspension, and see where you stand. It might prompt you to raise the car, install special bumpstops, or maybe install some skidplates (please use nylon - it slides on asphalt very well), or maybe something else.

Chris