Does anyone have any thoughts/experience with rear coil-over conversions? Specifically, I'm looking at UMI's setup:
https://www.umiperformance.com/home/...g-rating=150lb

My initial take on them is that they would give me ride height adjustability but would make spring swaps significantly more difficult. Do they drop any significant weight over going with the same shocks and stock style springs??

I have no idea what spring rate to go with, it's I guess technically a streetcar which with respect to track time will see much more dragstrip than anything else but does see some autox and even RR use. For 85-90% of its use, I'd probably go with the 175# springs and trim them slightly to get into the 200# range (since they only list up to a 1" drop and I'd like more like 1.5-2"), but for dragstrip use, I'd really like something in the 110-135# range. In theory, sticking with stock springs I can swap them out quickly for a different use, in practice I haven't found any really soft stock style rear springs for drag use.

 

subscribed, I am curious too.
truly a real deal street-car but I hit the dragstrip about 9 times this year, 2 autocross events, and 3,000+ miles
currently running koni yellows in the rear, but with replacement Moog style springs.
a coil over might help me cut better 60 foots than my 1.64

hoping to hear some good tech discussion on this topic!

 

Spring swaps with coilovers are easy.

UMI has decent brackets with their package, but the Viking shocks are similar to QA1. QA1 is a MN company, hence the Viking name, which is a spin-off! Blahh in my opinion.
I prefer RideTech with Fox as their shock producer. If you know motorcycles, you know Fox!

Coilovers are all about range, collapsed, and extended. Call DSE and ask what the JRi's are, then look around for similar - that's what I did. You really only get about 1-1.5" adjustability with coilovers. You have to buy right!



Dampahhs and Rubaahhs - spend the money.

 

To properly lower a coilover, you need to lower the bottom mounting point, the adjusters are for fine adjustments and preloading.

My experience, they don't work well on a 3rd or 4th gen. The fitment isn't great and there is little benifit over a seperate shock and spring.

 

Phil is a great and knowledgeable guy, but I have a differing opinion - just an opinion.
I think when you weld a plate up in the rear, you actually improve the angle - debatable but certainly do not hurt.
The current shock options are not that current, and coilover tech is really improving vs. stale old shock options.
Just my opinion, and I don't want to argue with a 12k poster!
The key is to purchase knowledgeably.
I welded plates both fore and aft - not necessary but strength insurance.

 

Coilovers are basically shocks with a body that accepts the coils on the outside. I don't know how tech would improve besides better shock valving, action... which would also improve with standard setups.

What angle are you improving?

As far as 86TA's comment, shocks are designed to work in a specific range, when you move outside of that range you end up with them not acting as designed. So yes, if you change the ride height of a coilover you should change the shock mount, but it's the same if you change the ride height with a spring swap or a weight jack.

 

Well, can anyone tell me when the Koni yellows were designed? What tech was available when they were designed. Old Yeller!
Fluid dynamics is...well, fluid! Magnetic?..well, let's not get caught in that orbit. Having fun with words.

Angle is minimal, I probably should not have mentioned it, but there is slight improvement because of change in attachment points (specific to torque arm suspension). Definitely not a hurt and debatable if an improvement.

Yes, absolutely designed to work within a specific range - more people need to understand this. That's why I kept that small spreadsheet with what I learned. Like I said, you get maybe 1-1.5" adjustment with a coilover - that's it. So If you bought right, you don't
need to change mounts.

The prob in finding new parts, is to get new tech for range and attachment points. And, if you can tune the valve curve to your application - you're golden.

I'll repost some shock tech from Ron Sutton. As you know, he knew his suspension stuff, but was lousy at business. We are all flawed!
Anyway, he explains new shock tech.

 

The Quick Answers:
JRI is the best racing shock. In my experience JRI racing shocks provide more tire grip than any other shock made. The only two cons are price & that they need to be rebuilt with seals sooner. That’s a minor thing when winning performance is the goal. The Ridetech shocks provide the best grip of what I consider to be street shocks. The level of grip, while greater than any other street shock I have experienced, is not in the same league as JRI race shock grip. One is a race shock & the other is a street shock. Unless something damages the shock, the Ridetechs will not need to be rebuilt with new seals for a long, long time.

Both are very tunable & responsive to tuning changes. Both can be valved with “linear/digressive”, “digressive/linear” & “high-zero-number” valving curves. Those traits are key to achieving the secret sauce valving I do to achieve the most grip possible from the shocks. The JRI shocks will accept significantly stiffer “high-zero-number” valving while still being responsive & maintaining grip. With the JRI shocks, we can tie the front end down longer … for longer corners. This is not an issue for autocross, but does come into play for road courses. For this reason, I supply Ridetech Triple Adjustable shocks (with my special valving) standard on my AutoX-Star front suspensions. For my Track-Star front suspensions, JRI double adjustable shocks (with my special valving) are standard.

When I first started exploring the PT scene, I saw that Ridetech was very popular and didn't really know why, as I had not heard of them in the racing world I came from. Over the last year, I've gotten to look at a lot of shock valving curves from almost all of the PT Shock manufacturers. After some dyno testing & revalving Ridetech shocks of our own, the picture got clear. There are many factors that define the actual real world handling & ride characteristics of a shock. The dyno curve is one of them. It’s an important one, but just one of several factors.

The factors that matter most to the ride & handling are:
1. Piston design - defines the valving curves possible, responsiveness,
2. Piston seal & friction - self explanatory
3. Bleed valving - controls the initial shock responsiveness control
4. Valving control – in most cases a stack of special shims that deflect & define the oil flow through the piston
5. Adjustability range - To tune or adjust for very different situations like track & street
6. Rebound & compression bleed over - how much does one adjustment affect the other valving
7. Body & overall shock design – affects how it manages the pressure, control & responsiveness
8. Stiction (from piston seal & shock bore surface) = pressure required to get the shock to initially respond
9. Internal rod/shaft pressure - affects initial shock responsiveness

 

I’m sure I left some things out, but you get the idea. Items 1, 2, 3, 4 play the biggest role in the valving curve. Items 5 & 6 define the range & accuracy of tuning. Items 7-9 define how well the shock can keep the tire gripping the asphalt over irregular surfaces.

Other things matter too, like ...
• Is it rebuildable?
• Is it revalvable?
• Parts availability?
• Tech support?
• Customer service?
• Warranty?
• Return/repair policy?
• And lastly initial purchase price & TCO ... total cost of operation.

What I learned about the Ridetech shock … and I hope I’m not sharing any of their trade secrets … are:
a. By running larger bleed valve orifices
b. Combined with stiffer main valving from the piston & shim stack
c. Inside an extremely well designed shock
d. Provides the best balance of ride comfort over irregular surfaces & bumps … and handling control with heavy cars in cornering situations.

Other perks or benefits of their design are:
e. Wide range of effective adjustability
f. Very low pressure bleed over
g. Fully rebuildable
h. Easy to revalve for different curves

I have experienced good parts availability, tech support & customer service. Since I don’t own a set of Ridetech shocks on a street car, I can not personally vouch for the million mile warranty or their return/repair policy … but I hear great things from their customers. Where the rubber meets the road for most guys is initial purchase price. I am super impressed with how much shock you get for your money. In my opinion, the Ridetech shocks are the best shock in their price range by far. Nothing that costs the same as the Ridetech shocks can compare to the quality & performance of this shock. It is a heck of a value.

Most people … not all … but most, do not look at TCO (Total Cost of Operation). They should, but don’t always think past getting their baby running. When we factor in the million mile warranty and you realize you won’t ever need to replace these shocks. After years of use, if the shocks fail, just have Ridetech rebuild them. So the initial cost is the total cost … well … wow.

I have revalved many Ridetech shocks with my “secret sauce” valving to achieve what I call “Autox Valving” & "Mean AutoX Valving". On Lance Hamilton’s 85 Monte Carlo SS Shocks with “Autox Valving”, we can tune the valving to be a good AutoX performer … kicking butt on an amazing list of C6 Vettes, WRX’s & other cars … and the wide adjustability range allows the shocks to be adjusted back to great street ride. In other cars we have shocks with “Mean Autox Valving” we make the “zero-number” rebound valving higher for competition purposes and the ride can be adjusted back to “pretty good” for the street, but not as well as Ridetech is famous for. This second version is for cars that see less street time & are more concerned with winning events. I was blown away at how well these shocks perform on the autocross track with my “secret sauce” mean race valving.

Do I feel Ridetech are the best shocks available at any price? No. I hope I don’t hurt anyone’s feelings, but there are a true racing shocks out there that are going to perform better on track, autocross or road course. High end racing shocks cost more ... often a lot more ... and in higher levels of competition where winning competitive events is king, these racing shocks will be a better choice for racing or all out track & competitive event performance. I feel Ridetech shocks are best at providing a balance of street ride, handling & durability … and occasional AutoX or track day. They offer the closest handling to a race shock without having a race shock.

 

I know that they weren't new when I got my first set in.... '92 I think it was...

What front struts are you running?

 

Koni Yellows - all I can afford at present. I talked with Ron Sutton a few years ago to get RideTech to build them - or give Ron the basics so he could finish. They (RideTech) agreed to attempt, then ran into a problem with the brackets, ran up against some SEMA deadlines, then it fell away. Two or three years later there was some more talk, but nothing finalized.
JRi just is not in my budget. DSE did a fantastic job with their offering, though. We do need a middle ground option.