Rob94hawk

Engine's going to be out soon so why not lighten the front up a bit and get some clearance. Now I know Spohn, BMR, and PA k members but is UMI the latest contender?

What I really want to know is, 1. which one is the lightest and 2. is it worth it to put in aftermarket upper and lower control arms?

Thanx

Injuneer

PLEASE post on the correct forum.

Rob94hawk

Sorry Fred. With all the different sections here I had no idea there was a seperate suspension forum.

slomarao

If you talk to sam strano you will find he had a lot to do with the designs of UMI suspension products. I know he had a decent amount of input on the K member + a arms.

I think BMR is the lightest but if i was dropping that kind of coin I would get the UMI stuff. I have a buddy who has the BMR stuff and wants to get rid of it, if that tells you anything.

Rob94hawk

I thought the Spohn chromemoly was the lightest by 30lbs?

And I've never heard of BMR K members having issues.

QWKzee93

X2 on the umi... I have umi k member and love it plenty of room and is damn light.

JakeRobb

AFAIK, UMI is the only one that makes one that isn't drag-only. If I ever get an aftermarket K-member, I'll be getting the UMI road race version. I like turning!

pgerst

I went with UMI "road race" due to the second tube and additional bracing, think it saves about 20 pounds over stock. Don't have any experience with the others but fit and finish on the UMI were excellent; I have other manufacturer suspension components that were, shall we say, a little less installer-friendly. I used an engine bar to support the engine from above, loosened up the trans mount and was able to get it in all by myself (jack under K-member, minimal use of pry bar to align engine). Not sure on your mileage and ultimate plans but I also put in poly engine and trans mounts while I was in there; if you are into six figures mileage wise, even just putting in new stock mounts while you are in there is probably a cheap investment.

As far as upper and lower arms, there are some weight savings there (I have Spohn with the del-sphere lower and delrin bearing upper, very stiff and a bit more difficult on the install due to fitment issues) but it is only a few pounds. I think you will shed far more unsprung weight getting rid of the front brakes and going to the 98+ brake mod (plus the brakes are like ten times better). I got a used set of spindle/arms, rotors, brake barckets, and calipers for $250 to my door, bought new rotors, street/race pads (Hawk brand) and used the old calipers for cores. All in I spent a bit less than $500 on the brakes and shaved about 10-12 lbs per wheel, plus it is a completely different car under braking.

JakeRobb

What about the 98+ brakes makes them lighter than the 93-97? I hadn't heard that before. I know the rotor is larger (12" instead of 11") and the calipers are better, but I wasn't aware of any changes that would decrease weight.

pgerst

I wrote the weights down when I did it and will try and find the note but the 98+ aluminum calipers are significantly lighter than the cast iron 93-97 calipers. Spindle is lighter as well as the caliper bracket is cast into the 93-97 arms versus a forged piece for 98+. I used a fishing scale and came up with a bit more than 10 lbs less (it was my brothers scale so it could have been a bit hot on weights). The other thing that the 98s have is probably double the pad surface as well as dual piston. I think of all the suspension/brake mods, the 98+ brakes is the best value mod you can do. (I also did a watts link on the rear which is a not-so-close second.)

JakeRobb

Ah, I didn't know the 93-97 calipers were iron. That would do it!

merim123

i have the BMR stuff that I bought before UMI was available. I street drive the car and I don't have any issues. Not sure what all the complaints are about the BMR one. i haven't seen a thread to say that there have been any issues with these kmembers.

bluz28

As far as K-members, I can't really help you there I'm still on the stock one. The only one I've given any serious thought is the UMI road-race model, since it's built stronger.
Up front don't bother with the upper arms just install new stiffer bushings(GlobalWest or Strano's) and new ball joints, no weight savings there. Now if you plan to autocross or road race your car at stock ride height then the upper arms will allow you to dial-in a lot more negative camber. If your lowered IMO don't run them, you run the possible risk of them hitting the upper shock towers, before the shocks ever bottom out.
The front lower arms are worth it though, clearly lighter then stock, and corner turn-in is noticeably sharper. IMO, UMI should be at the top of you list. Spohn and BMR make good products but in my experience with all 3 brands, UMI make a better product.

NJ-LE

pgerst:
"(I also did a watts link on the rear which is a not-so-close second.) "
I assume that was from Fays2. I was considering trying that but your comment seems to imply it may not be a significant improvement over what I already have ... can you review the Watts link. I have the UMI front brake package (very happy with it) and UMI's double adjustable panhard rod and trailing arms (happy with those too).

pgerst

NJ-LE -- the watts link (fays2) made a difference, just not as big a difference as the brake swap as the LT1 brakes pretty much, well, suck. My ranking is probably due to noticing the brakes in all driving conditions whereas the watts link really does not show up until hard cornering. (FYI, I have CA smog motor M6 with every suspension mod, larger sway bars, u/l fca, rca, stb, sfc, springs, konis, 98+ front brakes, watts link, k-member, TA, don't think I forgot anything but I may have. If I could only pick one mod - it's brakes. Next would be watts link, then probably shocks, the rest only add marginal improvements which I am probably not utilizing as a street driver.)

As to the Fays2 review, no "data" other than me in the seat but the rear is more stable under rapid cornering like a slalom (not sure what this would be called, yaw, maybe?) and also the rear of the car now tracks the same for both right and left turns. My understanding is this has to do with elimination of lateral axle movement and constant height of the roll center, versus PHB which roll center raises/lowers when turning left/right and axle also shifts left to right through the arc of travel of the axle/PHB. I also think I have less understeer and think the car launches better, again I think it has to do with the constant roll center.

I drive it hard on the street and it makes a difference, if you were doing autocross (slalom) or road racing (high speed turns) it would be really noticed. My summary is that, given how I drive the car (street), it is no longer the rear end that limits cornering. I suspect that the rear end will probably always be the limit with front engine, live rear axle but it is now much higher limit than the speeds/forces I am generating on the street.

My install on a 10 bolt: Pieces were well made. An aluminum "truss" bolts to the upper driver and passenger PHB location, driver axle attachment is not used. Two axle tubes hold the outboard end of the arms (10 bolt axle needs inserts which are included, think a 12 bolt or 9" does not), inboard ends of the arms are attached to a yoke in the truss at center of rear end.

Install was easy with all required fasteners plus some extra nuts for adjustment purposes which you swap out for nylock; there were spacers for stock sway bar which i did not use. Need 100 foot lbs torque wrench as well as larger sockets (think the largest was 1-1/4 inch.) Good detailed instructions but I think everyone will need to remove the axle tabs that hold the brake lines; used a cold chisel and grinder. I also had to cut flats on the washers on the factory bolts at the driver side upper mount and trim some of the muffler heat shield to get it to fit in but other than those "mods" it fit right in. (I took the muffler out to put it in, gives you a lot more room to work.)

POssible negatives -- You end up with a little less clearance for larger exhaust pipe and possibly might have issues with a diff girdle having enough clearance; I think an oval pipe section and low profile girdle would easily solve these two things I thought might be issues. Also uses rod-ends so will be a bit noisier than bushings.

Mods -- Sorry so long of an answer and double sorry abut the hijack.