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UPR coil over with MM spring and bump stop

3K views 4 replies 4 participants last post by  macuser27 
#1 ·
Hi all,

Current aftermarket suspension setup is MM FLSFC, Koni STR.T dampers, Eibach Pro-Kit, X2 balljoints. Wanting to upgrade the fronts to coil over and found a UPR one without springs.

Since the rear will remain unchanged for a while (want MM adjustable LCA eventually), I’m thinking about going for 250, 275 or 300# springs. UPR springs come in 250 and 350# with 12-inch lengths.

However, I like that MM springs come in 275 and 300# with 10-inch lengths so I might go with them as well as their bump stops. Will also upgrade the front struts to Koni Yellows.

Question is, will the springs from MM fit the UPR sleeves? They both list 2.5-inch internal diameter.

Also, what spring rate (250/275/300) would you guys recommend for the front? It will be a street driven car with track days (Laguna Seca/Sears Point/Thunderhill) once or twice a year.

Thanks for your time and input.
 
#2 ·
MM springs should fit, but you can always call UPR and MM to confirm, both have pretty awesome customer service.

As far as spring rate, for my street/strip turbo V6 build I was recommended to run 12-250 spring rate.
 
#3 ·
MM uses Hyperco springs (very high quality) in their coilover kits. UPR uses Eibach (also quality) or QA1 (seemingly quality) springs in their kits. Any 2.5" ID coilover spring will work with the UPR kit. To save some money, you can find used springs on eBay for pretty cheap. I bought two Hypercoil springs for $30 (compared to $60 each new) for my MM coilovers.

As for the coilover kit itself, UPR kits are a universal design meant to fit a wide selection of struts (Koni sports might be an exception). Because of this, the threaded sleeves are designed with a certain tolerance to accept the varying outer diameters of the strut bodies. In other words, the sleeves fit loosely around the struts and can rattle around. This frequently results in complaints of noise.

MM and Griggs Racings make coilover kits specifically designed for Koni struts, meaning the sleeves fit very snug around the strut body. From my perspective, UPR coilovers are mostly used in drag racing setups with Strange or Lakewood dampers. This doesn't mean they are useless on the track, however, and--assuming they kit Koni sports--should work fine for you. You just have to weigh the option of saving money and possibly running into noise and fitment issues, or spending a little more for a purpose designed kit.

As for spring rates, I have 12" 200 lb. springs on the front of my car, combined with H&R Super Sports in the rear. MM recommended those rates to me based on my criteria of good street performance, while maintaining decent ride quality over rough road surfaces. 200 lb. springs are undoubtably too soft for real track use, though, and I bet MM would say the same thing if you asked them (which I highly suggest you do, their tech support is great). A 250 or 275 lb. spring should be a nice compromise for a street car seeing the track a few times a year.
 
#4 ·
You might want to check that the Koni STR.T dampers can handle the spring rate your going to put on. I don't know much about them, but MM doesn't even recommend coilover springs for some struts. Compare the wheel rates rather than springs rates of your current traditional spring to your intended coilover spring to find out how much of a jump you'll be making.
 
#5 ·
Thanks everyone. After all the (bad) comments I got about UPR, I'm going to stay with what I have until I can afford all MM parts.

Funny that even UPR owners do not have anything good to say about their products and are promoting MM.

I have contacted MM support many times, and am extremely satisfied with the stuff (CC plates, FLSFC, clutch quadrant+adjuster) I bought from them.

In the meantime, I might just replace the spring isolators in the front and add the spring spacers that came with the Steeda X2 ball joints. The Pro-Kit and X2 combo just makes the ride too low with the soft rate - I'm scraping everywhere.
 
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