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I wanted to record 2 failures I've had with UMI's weight jacks as a warning to other racers who might want to use them.
this isn't a Mudslinging thread but rather a PSA on issues I had with my UMI front weight jacks.
I've used these weight-jacks for 2 autocross seasons, usually 3 events a month
2019 I used 1050/200 springs
2020 I used 1200/400 springs.
Issues:
1. wobbly thrust bearing (see video)
the washers used have a smaller I.D and won't allow the thrust bearings to be tightened further, eventually like mine, they started clunking and wobbling.
the rear jacks wobble in the same way and make a TON of noise, but I don't have a tool to reach the nut on the rear jacks.
since i'm converting to PENSKE coil-overs, i'll leave the rear jacks as is
2. A bent bottom plate with a cracking weld---
somewhere along the line UMI changed the weight jack metal thicknesses from 1/4in to a thinner 3/16in
and stopped welding 100% of the circumference. The weight-jacks are now thinner with just 2 stitch welds.
Over time the area between the welds were bending and peeling away at the 2 stitch welds.
This was primarily on the front driver side weight-jack
The passenger weight-jack was bent a little but not enough to start cracking welds.
I forgot to take pic of the damaged driver side weight-Jack and I had already welded up the cracking/gap
pic is the non damaged passenger side for reference
the fix was welding 2 more stitch welds to the jacks where UMI excluded them
a few minutes and a TIG welder made short work of it
my brother media blasted them and a few coats of POR-15 chassis paint brought them back to life.
so if you are an avid racer, make sure to keep this in consideration as a possible inspection point for failure
i'm gonna try to make some Billet weight-jacks of my own design to avoid any further potential issues 2 stitch welds instead of the 4 it needs This is the undamaged passenger side, but this is where the split was happening. Extra 2 stitch welds added for a total of 4 Blasted after welding POR-15 Chassis paint and they are good as new before blasting a quick TIG fillet weld with mild steel filler wire
Billet 6061 Aluminum Prototype 3d printed, still need changes
I got a lot of flack when I posted this on some of the Facebook pages.
mostly from UMI sponsors like TOM (guy with the nice red TransAm)
they claimed I was just "too had" on parts and how it was my fault.
They said they had done 1,000's of race miles without issue, But, I think the UMI parts they got were before the cost cutting was started.
for $400 for the front kit, I kinda expected better
I got a lot of flack when I posted this on some of the Facebook pages.
mostly from UMI sponsors like TOM (guy with the nice red TransAm)
they claimed I was just "too had" on parts and how it was my fault.
They said they had done 1,000's of race miles without issue, But, I think the UMI parts they got were before the cost cutting was started.
for $400 for the front kit, I kinda expected better
Are you surprised by the UMI shills? Sure they had done 1000s of miles racing no issues. Bet their def of racing is alot dif than yours.
Are you surprised by the UMI shills? Sure they had done 1000s of miles racing no issues. Bet their def of racing is alot dif than yours.
Yea they test their stuff harder I have seen it first hand. I been and toured their shop seen the cars they built and seen them run laps on their race track my wife even got to go out for a ride along in there amazing second gen. I cant say enough for the amazing people at UMI.
This is certainly disappointing... I have DSE weight jacks on one of my IROCs and they have been great, but i did need to do a modification to the UMI K - member spring perch to add an anti-rotation feature.
I have the UMI front spring jacks on two of my other camaros. I went this route once they introduced their set as it eliminated the need to modify the spring perch... I haven't had any issues to date, but I haven't been racing those IROCs either.
I generally really like UMI components and I have had very good luck with discussing things with them.
Obviously none of us are perfect, hopefully UMI is aware of this issue and will be correcting it... McLovin1181 have you directly contacted UMI about this and your experience?
Yea they test their stuff harder I have seen it first hand. I been and toured their shop seen the cars they built and seen them run laps on their race track my wife even got to go out for a ride along in there amazing second gen. I cant say enough for the amazing people at UMI.
Seems to me they didn't shake these down hard enough.
For the price of these things they should be perfect and last... There really isn't much $ involved in the material to build the perch or the jack bolt.
I'll be building my own set if I'm not happy with what I'm trying this year.
We actually take note of any feedback we get. Sometimes that feedback is discrete and sometimes it causes a stir. No matter what, we always strive to improve.
Huh, I'm trying to figure out why that thrust bearing is necessary in there...
As far as UMI goes I still consider them one of the better builders for our cars. Yes, you had failures, but that's the thing with "racecar parts" used in racing, sometimes even the best-designed ones only show problems when they're pushed hard. I've found flaws with their manufacturing process, literally YEARS after originally purchasing the product and Ramey from UMI (he's a member here) took care of it and replaced the part. I don't know if you've tried contacting them about your issue, but they are very responsive to problems with their products and as far as I can tell their customer support is second to none.
Huh, I'm trying to figure out why that thrust bearing is necessary in there...
As far as UMI goes I still consider them one of the better builders for our cars. Yes, you had failures, but that's the thing with "racecar parts" used in racing, sometimes even the best-designed ones only show problems when they're pushed hard. I've found flaws with their manufacturing process, literally YEARS after originally purchasing the product and Ramey from UMI (he's a member here) took care of it and replaced the part. I don't know if you've tried contacting them about your issue, but they are very responsive to problems with their products and as far as I can tell their customer support is second to none.
Hi Mark.
It's me. I'm still here.
The thrust bearing is for less friction when raising or lowering the car. It may not be as necessary as when using an aluminum shock but still makes for a nicer adjustment.
Ground Control Made these weight jacks before UMI. On the outside they are identical to the ground control kits. Been runing mine for about 4ish years now. No issues, and I drive the car hard. Honestly sad to see a decline of quility from UMI. But Im sure they will fix this, and it looks like they owe you something if they plan to copy your Billet Design. Still would take anything from them over others Like Spohn (Dont get me started on them). When it comes to all these companies, they all piggy back off each other. UMI Copies this company, Founders copies them, and so on.
Since these threads live forever, it's important to note there was no "decline in quality" and our design was clean sheet. Just because a company introduces weight jacks doesn't mean they're a copy. As a matter of fact our engineer is adamant about not researching other companies designs. A weight jack has to have a plate and a screw.
We have no interest in the OP's billet design.
If first design parts were always perfect there would be no improvement and we would all be driving Model A's.
Since these threads live forever, it's important to note there was no "decline in quality" and our design was clean sheet. Just because a company introduces weight jacks doesn't mean they're a copy. As a matter of fact our engineer is adamant about not researching other companies designs. A weight jack has to have a plate and a screw.
We have no interest in the OP's billet design.
If first design parts were always perfect there would be no improvement and we would all be driving Model A's.
ramey
thanks for being responsive and participating in the discussion of this topic. while people may still have different views and can choose their preferred preference for their project, it is helpful to have UMI comment on products and take the end users feedback good/bad. this is helpful for everyone
Ground Control Made these weight jacks before UMI. On the outside they are identical to the ground control kits. Been runing mine for about 4ish years now. No issues, and I drive the car hard. Honestly sad to see a decline of quility from UMI. But Im sure they will fix this, and it looks like they owe you something if they plan to copy your Billet Design. Still would take anything from them over others Like Spohn (Dont get me started on them). When it comes to all these companies, they all piggy back off each other. UMI Copies this company, Founders copies them, and so on.
Your a funny guy sounds like you seem to think ground control weight jacks have never failed. If im on the right path UMI came out with their w/j cause of a weak setup from ground control in the first place.
The thrust bearing is for less friction when raising or lowering the car. It may not be as necessary as when using an aluminum shock but still makes for a nicer adjustment.
The OP has contacted us.
LOL, I guess you and I were both replying at the same time and you beat me too it...
Your a funny guy sounds like you seem to think ground control weight jacks have never failed. If im on the right path UMI came out with their w/j cause of a weak setup from ground control in the first place.
Yup. I drove on the GC kit for one summer and had issues with plate bending, and one of the screws that held the threaded rod to the top plate came pretty loose at one point. It never truly failed, but it made me uncomfortable and I bought the UMI kit in November 2017 because the description explicitly mentions that they're designed to resist bending. I've put at least 11,000 miles on them with 2 road course days, a couple long road trips, and some hard runs at the tail of the dragon and haven't noticed any noises or other issues. I'm on 1050# springs. I'll pull them the next time I do a brake job though and report back. OP, when were yours purchased and how many total miles were on them at the point that you noticed issues?
Just installed the UMI 2065-1-B. They actually fit on the Spohn Performance front A-Arms #732 (discontinued - newer style is #782, would probably fit as the UMI spring is same diameter as stock). I still have OEM crossmember. Kept the spring isolators to sit the UMI weight jacks. They are a breeze to install. No need for spring compressor to install, just set them a lowest setting.
The weld issue mentioned in this thread is fixed. They are welded all around. Not much wobble, by design they have to be a bit loose to allow turning of adjusting screw. Will monitor and report back if any issue.
I would highly recommend those over Eibach Pro kit if one wants to lower their ride. The adjustment is awesome.
Just installed the UMI 2065-1-B. They actually fit on the Spohn Performance front A-Arms #732 (discontinued - newer style is #782, would probably fit as the UMI spring is same diameter as stock). I still have OEM crossmember. Kept the spring isolators to sit the UMI weight jacks. They are a breeze to install. No need for spring compressor to install, just set them a lowest setting.
The weld issue mentioned in this thread is fixed. They are welded all around. Not much wobble, by design they have to be a bit loose to allow turning of adjusting screw. Will monitor and report back if any issue.
I would highly recommend those over Eibach Pro kit if one wants to lower their ride. The adjustment is awesome.
The only problem I have is ride quality. They are firm and beat the heck out of you. In addition, if you jack the front of the car high enough they can pop out of the perch and get bound up.
The only problem I have is ride quality. They are firm and beat the heck out of you. In addition, if you jack the front of the car high enough they can pop out of the perch and get bound up.
What spring rate are you talking about? 850 or 1050 lb/in?
I can't see how "they can pop out of the perch and get bound up". I could visualize a catastrophic failure of the jack screw if fully extended that would lead to the spring flying out or getting jammed sideways or something like that. If you could describe it better, maybe I could visualize it. Thanks.
What spring rate are you talking about? 850 or 1050 lb/in?
I can't see how "they can pop out of the perch and get bound up". I could visualize a catastrophic failure of the jack screw if fully extended that would lead to the spring flying out or getting jammed sideways or something like that. If you could describe it better, maybe I could visualize it. Thanks.
I had to jack the front of the car up and the front wheel sagged so low the weight jack assembly unseated itself so that when I lowered the car off the jack it didn't sit back down in the A -arm. Not really a big deal, but was annoying to take the wheel off, jack the car and lower the strut to get it back in the perch. I just avoid letting the front end sag that low without something under the front tire. I have the 850 lb'ers.
I had to jack the front of the car up and the front wheel sagged so low the weight jack assembly unseated itself so that when I lowered the car off the jack it didn't sit back down in the A -arm. Not really a big deal, but was annoying to take the wheel off, jack the car and lower the strut to get it back in the perch. I just avoid letting the front end sag that low without something under the front tire. I have the 850 lb'ers.
Ahhh I see. Thought you were talking about "while driving". Yep, if you lower them to a certain point, when you jack the car up and suspension hangs, they might become unstable and move. Will post back on ride quality with my set-up once I get on the road. I have Koni yellow, Spohn A-Arm, stock sway bar, full poly bushings and just a bit lower than ride height (lowering created too many issues). Koni yellow really helped ride quality. UMI 850s should be stiffer than Eibach Prokit.
Last edited by SbFormula; Feb 15, 2023 at 09:29 AM.
My front suspension doesn't have enough droop that the weight jacks will unseat. The rear does though. I ended up ordering custom springs for the rear that were longer to fix that.
The shorter rear springs that came with the weight jack kit would literally drop out of the car if the axle dropped. Now I have to compress the rear springs very slightly to get in/out of the car. I can do it by hand and I think most average people could but maybe half the people out there would need a compressor tool.
My front suspension doesn't have enough droop that the weight jacks will unseat. The rear does though. I ended up ordering custom springs for the rear that were longer to fix that.
The shorter rear springs that came with the weight jack kit would literally drop out of the car if the axle dropped. Now I have to compress the rear springs very slightly to get in/out of the car. I can do it by hand and I think most average people could but maybe half the people out there would need a compressor tool.
Bro just copy what Mecham racing did in the 1980s with the Droop limiters I have a set on my 86 TA with the Original Ground control weight jacks. Keeps the rear from traveling
Bro just copy what Mecham racing did in the 1980s with the Droop limiters I have a set on my 86 TA with the Original Ground control weight jacks. Keeps the rear from traveling
Nylon limiting straps are often used in the offroad world, it would work well for this application too.
Will post back on ride quality with my set-up once I get on the road. I have Koni yellow, Spohn A-Arm, stock sway bar, full poly bushings and just a bit lower than ride height (lowering created too many issues). Koni yellow really helped ride quality. UMI 850s should be stiffer than Eibach Prokit.
Ride quality has not changed! No rattle or anything. Same as it was with Eibach. I lifted the ride height 1/2in on driver's side and 3/4in on Passenger side. This really helped with clearance and it got the u-joint under 3* working angle. Very happy with this for street use. Gotta think twice before lowering a street car.
Last edited by SbFormula; Mar 27, 2023 at 06:05 PM.
Went to do my yearly Suspension maintenance check.
and found this.
These weight jacks are like a gift that keeps on giving.
-Mod washers and -re torque bearings.
-Then have to Re-Weld the inside of the jack.
-And now coat the 1in-8 threaded rod in red locktight and hope the lock nut doesn't loosen again.
I really need to finalize my Billet weight jack design.
Maybe I can find some aerospace 6AL-4V titanium scrap to use
i don't know what k member you have, but i noticed this new weight jack integrated spring perch that they now have for use with their weight jack... it eliminates one of the components... i had the same UMI weight jack kit on my camaro that blew its ramjet so while swapping that out this winter i changed to this weight jack arrangement as i have their k-member... i haven't had the same issues to date that you have had with the original design, but i liked the way this new design better so i switched... haven't driven it yet
'
Went to do my yearly Suspension maintenance check.
and found this.
These weight jacks are like a gift that keeps on giving.
-Mod washers and -re torque bearings.
-Then have to Re-Weld the inside of the jack.
-And now coat the 1in-8 threaded rod in red locktight and hope the lock nut doesn't loosen again.
I really need to finalize my Billet weight jack design.
Maybe I can find some aerospace 6AL-4V titanium scrap to use
Still not sure what you're doing to these that no one else is to bust them up this bad. We've had ours on the car since the part was introduced after breaking the Ground Control units. We've put close to 4000 autocross laps, 2000 road course miles, and another 8000 street miles on the car since then and nothing has broken or shown any damage on the weight jacks. This is in a 3800 lb car with 1100 lb front springs and a 315/30/18 tire.
Seems to me they didn't shake these down hard enough. 
