MG MGB GT

I think I've decided on coilovers for the rear (or at least I think I'm close):

Viking C205 w/ 300lb springs.

These have 4.2" of stroke which should be enough (somebody please gut check me).

Not much thought on that amount of shock travel, other than it is what I can package between the frame rails.

I'm hoping to keep the car around 2300lb w/ around 50/50 weight distribution. I'd love it to end up lighter than that, of course.

I followed Vikings guidelines on choosing spring rate but added my own fancy math to deal with all the uncertainty (actual total weight, front to rear distribution, etc all modeleded as random variables). Fancy math basically says my ideal spring rate is going to somewhere between 250 and 400lb, and most likely around 325lb. I'm leaning towards a 300lb spring because Viking doesn't have them in 325lb and it gives me some incentive to drop some weight from that 2300lb estimate.

Whats your motion ratio? Wheel to shock.

In reply to Shavarsh :

Planning on 1:1 with adjustability from there by messing with the rockers.

​​​​​​

Nice looking!

In reply to TurboFource :

Barnes 4WD gets all the credit for the truss. I was going to design my own and have it cut and bent, but theirs was too cheap to pass up.

I need to get to work finishing up the CAD for the link mounts and coilovers / rocker mounting setup, and maybe order coilovers soon.

I've got some work to do to actually get the rocker suspension working. I followed this little article to run the numbers of what I currently have in CAD, and it wasn't good: https://www.waveydynamics.com/post/rising-rate-suspension

Effective motion ratio was reasonably close to the planned 1:1 around ride height, but fell off (and digressive) once it got near full bump / full droop.

Much better now, with surprisingly little tweaking to the pushrod / rocker geometry.

I'd love to hear from any of you that are running similar set-ups. How progressive is too progressive? Ho much change in effective spring rate over the suspension's travel is too much? I really have no no idea.

A question more than anything. I always kinda understood you wanted ride height to be 2/3 to full bump and 1/3 to full droop, or some such ratio, rather than centered. The thinkin' being that when you hits the bump you want more room to absorb and damp the bump, where droop events tend to be less dramatic.

Of course, I've been wrong before, and usually am.........

In reply to twentyover :

Yeah I've read similar. I'll probably still tweak this a little to get closer to ~60% of travel for bump.

Thanks for keeping me honest!

Still iterating a bit:

I found a EFI manifold with fuel rail, injectors locally for a good price. Just the normal HO manifold and nothing fancy. It's a bit too tall.

Options:

1. Add more hood bulge

2. Use the HO lower and fab a custom upper intake manifold

3. Lower the motor

I'm split between 1. and 2.

3. is hard, because if I drop the motor any further the crank pulley tries to occupy the same space as the steering rack, and the oil filter boss gets real close to the frame rails.

Nukem said:

After cutting out parts off the differential for clearances what is this new part going to do? 

#2

With boost you won't need those long runners anyway

In reply to gumby :

Yes, yes...

In reply to MyMiatas :

That truss attached to the axle is just to give me a nice place to weld on tabs for the upper link mount, if that is what you mean.

Obviously, it's way beefier than it needs to be, and takes up a ton of space.

Some mindless porting work:

Oh OK. It is a variation of the CAD drawings you posted.

I tend to agree, #2 is a good idea. I used to run this Hartman intake on my fox:

In reply to Shavarsh :

That's a cool thing I didn't even know existed.

I'm guessing it's long gone?

In reply to Nukem :

My fox? Yes, unfortunately long gone. 

Anyone think I can get away with 3D printing an upper intake? That Hartman is plastic (likely ABS)...

In reply to Nukem :

There's a company called rapid3d making 3d printed CF nylon LS upper and lowers. Long term durability is still up in the air... im not a big fan of his "testing" methods for durability and the like, that ive seen... so we will see what the real world results actually are, now that they are starting to ship out.