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Full Version: Pros and cons of UMI's road race cross member...
F-Body Road Racing and Autocross Forums > Community > General Discussion
Steve91T
Ok go
SS Performance
Couple of questions, why are you considering a aftermarket k-member and how will you be using the vehicle?

Aftermarket tubular k-members aren't as strong as the stock units. They weigh less than stock but you pay for that in strength. Also many are made from chromoly. I have seen some, not UMI, that MIG welded chromoly!

Aftermarket k-members are very popular in drag racing. However they don't see the stresses that we see.

If you are looking to lose weight you can lighten the stock unit and maintain the strength.
Steve91T
QUOTE (SS Performance @ Jun 21 2016, 02:04 PM) *
Couple of questions, why are you considering a aftermarket k-member and how will you be using the vehicle?

Aftermarket tubular k-members aren't as strong as the stock units. They weigh less than stock but you pay for that in strength. Also many are made from chromoly. I have seen some, not UMI, that MIG welded chromoly!

Aftermarket k-members are very popular in drag racing. However they don't see the stresses that we see.

If you are looking to lose weight you can lighten the stock unit and maintain the strength.



I've heard about them being weak, but UMI now has one built specifically for road racing. How have they been holding up?

The car is a 97 with an LT1. I will be swapping a ls1 later this year. I have a 99 ls1 cross member off a parts car in my garage and it's taking up a ton of space. So I was considering selling it and putting that money towards the UMI cross member. The weight savings is a huge plus, but I'm wondering what other advantages there are. More alignment adjustability?

Since I'll be swapping engines, this will be the time to get the UMI crossmember. That's why I'm asking.

The car is my weekend warrior and also track toy. I'll be competing in TT3, which means I'll be limited to about 340 rwhp. Right now my car weighs 3400 with me in it, obviously it'll be around 3300 after the LS swap and light flywheel and battery. I run 275/40/17 NT01's on the track. Someday, maybe, I'll jump to a 315 square set up.
dailydriver
I'm guessing your roads are in MUCH BETTER shape than what us Yankees' are forced to drive on??

If so, and it will see very little street time anyways, then go for it! (Yes there IS much more adjustability, and more header clearance as well, IF you go that route for the swap.)

As much as I want to, I just CANNOT use one of these (yes, EVEN the UMI RR version one), given the road conditions around here, all of the SHARP/TALL speed humps the local towns and developments INSIST on installing in the false hope of slowing, or "calming" traffic, and the fact that this is my ONLY ride. sad.gif
Ramey36
Hey guys.

Ramey here from UMI.

From a non-engineering standpoint I can say that we beat these senseless and never have a problem.

I can reply with more detail here in a bit.

In the meantime, bolt these in with confidence, even on a daily.

ramey
Steve91T
Ha. Yeah roads are pretty decent around here. Except for bridges. I guess they figure that if the bridge is within about 2 feet of the height of the road, that's close enough. At 80 MPH, you hardly notice it in an SUV, but I swear if I didn't have my seat belt on in my Camaro, I would have been ejected out the t-top.


So I just had a 30 minute conversation with a guy at UMI (I'm bored). He was honest and told me the only problem they had with the crossmember was the lower a arms could slip. So they added locking tabs to fix that. He also said it would be smart to grind the powder coating off so the bolt can grab metal instead of the paint. Other than guys pulling 3' wheelies and slamming them back to earth, they haven't had any structural failures. It does save something like 25 lbs, and adds a ton of room for headers. At the same time, he told me that while it's always great to get weight off the nose, there are probably better ways to make the car faster, and I know he's right.

The cool thing is he said they are putting a ton of effort into Fbodys.

Not long ago a corvette racer (forgot his name) jumped in UMI's 4th gen. It's making stupid power and has all of UMI's goodies on it, but is still full weight. His first time out, this guy was faster than in his SCCA winning corvette. He was so impressed he is building a 4th gen to try to win LS fest.


So maybe I should just run the stock cross member and put that money towards their shock package. I'm on strano's koni front, bilstein rear shocks that are not only about 6 years old (not many miles though), they were designed for 550/150? springs. I'm running 750/250, so I'm sure proper shocks would make a difference.

I need more moneys.....
rocky
We all need more money lol. I am about to get some UMI goodies too
79T/A
I took a shot on a UMI RR piece, been pounding on it 2 years with zero issues now. Track, autocross, shitty CT roads, you name it. It's been awesome so far.

It opens up miles of clearance for headers, oil cooler lines, etc. Makes the car a million times easier to work on, plug changes are a snap. Put the car on a lift, unbolt the header and there better be someone to grab it because it will fall straight out and hit the ground.

No issues with alignment slip, and I don't use the locking tabs although mine was built with them. Using stock LCA with global west spherical bearings tweaked by Blaine. Slots are longer in the UMI piece so you have a greater alignment range to work with.

Like with any part on a track car, it gets a visual inspection before and after every time the car is driven in anger. So far zero issues. I wouldn't build another 4th gen without one, simply because it makes working on the car so much easier. The weight savings off the heaviest part of the car just makes the deal even sweeter.
trackbird
QUOTE (Steve91T @ Jun 21 2016, 03:53 PM) *
Not long ago a corvette racer (forgot his name) jumped in UMI's 4th gen. It's making stupid power and has all of UMI's goodies on it, but is still full weight. His first time out, this guy was faster than in his SCCA winning corvette. He was so impressed he is building a 4th gen to try to win LS fest.


So maybe I should just run the stock cross member and put that money towards their shock package. I'm on strano's koni front, bilstein rear shocks that are not only about 6 years old (not many miles though), they were designed for 550/150? springs. I'm running 750/250, so I'm sure proper shocks would make a difference.

I need more moneys.....


I think that was Danny Popp. I bought my Koni DA's for my original 2002 from him. He used to autocross with the local SCCA on occasion. Danny is FAST.

I ordered the UMI coilovers today. I'll have some experience with them fairly soon.
Steve91T
QUOTE (trackbird @ Jun 21 2016, 06:37 PM) *
QUOTE (Steve91T @ Jun 21 2016, 03:53 PM) *
Not long ago a corvette racer (forgot his name) jumped in UMI's 4th gen. It's making stupid power and has all of UMI's goodies on it, but is still full weight. His first time out, this guy was faster than in his SCCA winning corvette. He was so impressed he is building a 4th gen to try to win LS fest.


So maybe I should just run the stock cross member and put that money towards their shock package. I'm on strano's koni front, bilstein rear shocks that are not only about 6 years old (not many miles though), they were designed for 550/150? springs. I'm running 750/250, so I'm sure proper shocks would make a difference.

I need more moneys.....


I think that was Danny Popp. I bought my Koni DA's for my original 2002 from him. He used to autoross with use on occasion. Danny is FAST.

I ordered the UMI coilovers today. I'll have some experience with them fairly soon.



Yep, they was him. I'm anxious to see what you think of the coil overs.
Ramey36
Danny drove our 4th Gen within 4 tenths of his AS Vette at Norwalk the first time he was in it. As one of the designers of many of the products on it, I was proud.

He's the Optima champ, GG champ, NASA champ and who knows what else.

Our k-member has those cool anti-slide mounts which we designed when we started getting into the FRRAX type stuff. We also have a cool laser cut reinforcement plate which stiffens it even further and reduces a few feet of tubing and about half a pound over the older model.

We are also fortunate to have Sam Strano on our team, master of all things fast. I still don't know how he does it. He's like a freakin' missile.
pharmd
I've had the UMI RR kmember on my car for 4 years and over 20K miles. MANY AutoX events and some HPDEs and so far NO issues (cracks, stress fractures, or A Arm slippage). These guys at UMI are legit, they are interested in our 3rd and 4th gens, and they are putting money into AutoX/HPDE development...AND their stuff is quality. They have my full support because they race the parts they build. Buy the RR K member with confidence, it has performed really well for me.
trackbird
But I don't think they have a "convertible version" of the road race K member. tongue.gif
Rampant
UMI RR K here too. Fair bit of beatings on curbing. I will say only consider the RR A arms, if you want those. I have them as well and we are currently at 2.5 degrees of camber and played with the idea of trying 3 degrees. There is enough to go there, but we left it at 2.5.

Ramey36
QUOTE (Rampant @ Jun 22 2016, 02:00 AM) *
UMI RR K here too. Fair bit of beatings on curbing. I will say only consider the RR A arms, if you want those. I have them as well and we are currently at 2.5 degrees of camber and played with the idea of trying 3 degrees. There is enough to go there, but we left it at 2.5.



Whoa. That is a cool photo!

Thanks for mentioning UMI!

ramey
WarShrike
Can't run the UMI k on mine unless I do an engine swap from my silly V6, but I run another brand that is a road race reinforced one. The tube crosses in a full hoop frame rail to frame rail so no failure points introduced 1/4 way through like I've seen on some k-members where it's made of sections of piping/brackets.

I've daily driven mine on rough friggin roads with some auto-x on street tires without any issues and I'm the second owner of the k-member. There's tons of room to do work on the engine now and can pull the oil pan without having to drop the k-member. The rest of the stuff is predominantly UMI or Strano centered on the car, barring that BMR cross member (was the easier/cheaper one to buy and modify for the T-56 conversion).

dailydriver
QUOTE (79T/A @ Jun 21 2016, 05:10 PM) *
I took a shot on a UMI RR piece, been pounding on it 2 years with zero issues now. Track, autocross, shitty CT roads, you name it. It's been awesome so far.

It opens up miles of clearance for headers, oil cooler lines, etc. Makes the car a million times easier to work on, plug changes are a snap. Put the car on a lift, unbolt the header and there better be someone to grab it because it will fall straight out and hit the ground.

No issues with alignment slip, and I don't use the locking tabs although mine was built with them. Using stock LCA with global west spherical bearings tweaked by Blaine. Slots are longer in the UMI piece so you have a greater alignment range to work with.

Like with any part on a track car, it gets a visual inspection before and after every time the car is driven in anger. So far zero issues. I wouldn't build another 4th gen without one, simply because it makes working on the car so much easier. The weight savings off the heaviest part of the car just makes the deal even sweeter.


THANKS for that review, especially the bolded part, as I thought that most were still saying that these things were NOT strong enough to stand up to our P.O.S. northeastern roads, with a stiff suspension. 2thumbs.gif
dailydriver
QUOTE (Steve91T @ Jun 21 2016, 03:53 PM) *
So maybe I should just run the stock cross member and put that money towards their shock package.


IF it were a (budget directed) choice between those two items, I would DEFINITELY go with their coil overs FIRST, and then save up your (many) pennies for the RR K member. wink.gif
Steve91T
Im sold. I want one. Since I already have Afco coilovers and the suspension is working, I'm going to save the new coilovers for next year. I'll be doing the engine swap this year, so it makes sense to swap cross members at that time.

Do any of you guys use their solid motor mounts?
UMI Performance
Thanks for the all the positive replies. It is great to see.

A few years ago we decided the best way to continue to prove our items was to race them more and that is what we have been doing. Our event calendar has been growing each year and hopefully over time we can bump into each one of you at a track.

On the K-member, to be honest it is hard to justify the benefits of a $800 k-member, the pro's don't always equal the cost and we understand that. There is some benefits to be found though, 20+ pounds of weight savings, extra room like mentioned and more alignment ability. All of that can seem small compared to price, but if you saw what it takes to build these things more people would understand. Not that anyone is complaining on price, but I know it's high, we strive for quality. Our newer coming soon boxed lower a-arms include more caster and we are still working on some upper a-arm options.

We have a lot of heavy hitters on our team as we continue to develop the 4th gen product line. So be watching for more cool stuff 2thumbs.gif
WarShrike
I saw pics of those prototype A-arms! Those look really slick.

I'm glad there's both a company that is interested in continued development and a racing series that is keeping things lively in the f-body community.
79T/A
Steve, I also use their billet motor mounts in conjunction with the k-member. They are great pieces, and well worth it if you are doing the swap. They fit perfectly, and don't move the location of the motor like other brands. I think solid mounts are a must for a track car like yours.
landstuhltaylor
QUOTE (trackbird @ Jun 21 2016, 06:37 PM) *
I think that was Danny Popp. I bought my Koni DA's for my original 2002 from him. He used to autocross with the local SCCA on occasion. Danny is FAST.

I ordered the UMI coilovers today. I'll have some experience with them fairly soon.


He still does. He is actually making a reappearance at the national events this year, or at least the ones here in Ohio.

Would run the K-member if I could, but not able to in ESP and I don't think it's worth the weight penalty in CP.
Steve91T
Well crap, looks like a NASA TT rules require a penalty for aftermarket cross members.
Badtzmauri
I have the standard K-Member with the boxed lower control arms on my 4th gen using 200 TW tires. The roads I drive on have large bumps and the k-member has scraped the ground at speed multiple times without any problems. My only complaint is the back lower control arm nut hits the body and required me to file down the nut slightly to fit properly.
v7guy
Are these boxes A arms already released? Do they mount the coilover on those small tubes like they currently have on the website?

Maybe it shouldn't, but that coilover mount that goes on those lil tubes makes me hesitant.
Ramey36
QUOTE (v7guy @ Jul 6 2016, 08:00 AM) *
Are these boxes A arms already released? Do they mount the coilover on those small tubes like they currently have on the website?

Maybe it shouldn't, but that coilover mount that goes on those lil tubes makes me hesitant.


The pedestal coilover mount works great and is pretty much bulletproof. We have a version of the boxed arm that uses a true double shear mount that allows use of a competition coilover. It's clean and simple. I'll find some pics.
trackbird
Ramey,

Can you tell me if the delrin bushing equipped upper front control arms add castor and negative camber or are they effectively "stock" geometry?
Ramey36
QUOTE (trackbird @ Jul 7 2016, 01:09 AM) *
Ramey,

Can you tell me if the delrin bushing equipped upper front control arms add castor and negative camber or are they effectively "stock" geometry?


They are stock a few thousandths away from stock geometry, with a tiny bit add'l caster (rearward relo) and slightly shorter pivot to ball joint. Prob about half degree each. I wasn't on board at UMI during initial design so I'd have to look up the numbers.
landstuhltaylor
QUOTE (Badtzmauri @ Jul 4 2016, 12:16 AM) *
I have the standard K-Member with the boxed lower control arms on my 4th gen using 200 TW tires. The roads I drive on have large bumps and the k-member has scraped the ground at speed multiple times without any problems. My only complaint is the back lower control arm nut hits the body and required me to file down the nut slightly to fit properly.


Easy solution there is to drop the K-member a bit. Can be done very quickly and without disconnecting anything as long as you only loosen the bolts and don't completely remove them.
Badtzmauri
QUOTE (landstuhltaylor @ Jul 14 2016, 01:26 AM) *
QUOTE (Badtzmauri @ Jul 4 2016, 12:16 AM) *
I have the standard K-Member with the boxed lower control arms on my 4th gen using 200 TW tires. The roads I drive on have large bumps and the k-member has scraped the ground at speed multiple times without any problems. My only complaint is the back lower control arm nut hits the body and required me to file down the nut slightly to fit properly.


Easy solution there is to drop the K-member a bit. Can be done very quickly and without disconnecting anything as long as you only loosen the bolts and don't completely remove them.


What is this a solution to?
Steve91T
The lower control arm that needs to be filed.
Badtzmauri
QUOTE (Steve91T @ Jul 14 2016, 03:31 PM) *
The lower control arm that needs to be filed.

The head of the nut hits the body. If I spaced the k member, I'd have to use 3-5 thick washers moving the k member down roughly 1/4-1/2 an inch. I bought my k-member with the control arms used from UMI a couple months back. I'm not sure if this problem has been solved through newer versions of the unit or perhaps I was supposed to use special umi hardware.
landstuhltaylor
Shouldn't the nut be on the bottom?
Ramey36
I'm a little confused also. Not sure what needs resolving and there are is no special hardware required.

Post pics if that would help us.

thx

ramey
Badtzmauri
QUOTE (Ramey36 @ Jul 14 2016, 07:48 PM) *
I'm a little confused also. Not sure what needs resolving and there are is no special hardware required.

Post pics if that would help us.

thx

ramey


Sounds good. I'll try and get some pics this weekend. If you have the nut on the bottom, you would have to drop the k member to get the control arm out....
79T/A
No you don't. Slots are long enough if you push the caster bushing all the way in you can drop the bolt straight down. You should always have the nut on the bottom. That way, if it manages to loosen up, the bolt won't fall out.
Badtzmauri
QUOTE (79T/A @ Jul 14 2016, 09:15 PM) *
No you don't. Slots are long enough if you push the caster bushing all the way in you can drop the bolt straight down. You should always have the nut on the bottom. That way, if it manages to loosen up, the bolt won't fall out.

You're right I forgot my k member came welded so the bolts wouldn't slide in the slot. Mine hits the body because it is welded maxed. Thanks for the help!
rgauder
Any guys running them in a 3rd gen?
trackbird
QUOTE (rgauder @ Jul 16 2016, 08:00 PM) *
Any guys running them in a 3rd gen?


3rd and 4th gen K members do not interchange. Or did I misunderstand the question?
Badtzmauri
Has anyone had to replace lower ball joints on the umi boxed control arms yet? Just want to confirm that the Moogs would fit before I ordered them from summit.
CrashTestDummy
I think rgauder is asking if anyone is running a UMI 3rd Gen k-member on their 3rd Gens.
rgauder
QUOTE (CrashTestDummy @ Jul 16 2016, 09:40 PM) *
I think rgauder is asking if anyone is running a UMI 3rd Gen k-member on their 3rd Gens.


Yes, 3rd gens seem to be forgotten.
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