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TEIN Flex Z Coilovers vs BC BR Coilovers

Picture of TEIN Flex Z coilovers

TEIN Flex Z coilovers. Image source https://www.importimageracing.com/products/vssb2-c1ss4-tein-flex-z-coilover-kit-subaru-wrx-sti-2015-2021

TEIN Flex Z coilovers and BC BR coilovers are the entry level height and damping adjustable coilovers from TEIN and BC. They both retail for around the same price, the question is, which is the best for a car used on the road?

In this article I’m going to go through the spec sheet of each damper to see which coilover offers the most for the money. I’ll score each feature to come out with a total at the end. Whichever kits scores the most points wins.

NOTE: This is a spec comparison and not a performance comparison. The scoring will also be subjective. What is important to me may not be important to you and vice versa.



Top Mounts

Both kits are supplied with top mounts. This makes installation easier because you do not have to disassemble your stock struts to recycle their top mounts.

TEIN say their Flex Z coilovers are supplied with either rubber top mounts or pillowball top mounts (pillowball equals bearing). This is what I would expect, some types of suspension gain little from having a ball bearing in the top mount eg double wishbone.

BC claim their BR coilovers are supplied with “pillowball” top mounts. However the pictures on the BR series webpage show rubber mounts.

Personally I would be surprised if every BR series coilover kit were supplied with pillowball top mounts and equally surprised if every kit featured pillowball top mounts front and rear.

The images BC use for the BR Series dampers. The photos in the image above do not seem to match the feature list they give for the BR Series dampers.

In short I think BC will use the same top mounts are TEIN and both will be camber adjustable where needed so I am going to call it a draw.

NOTE: BC UK do offer the customer the choice of having pillowball top mounts front and rear but it costs extra and spring customisation options are not available with the pillowball top mount option (see below).

Score: 1-1

Spring Seat Top Mounts

Tein Flex Z will either use the top mount as the upper spring seat or use an independent spring seat. This will come down to the type of top mount the strut has ie pillowball or rubber.

BC claim their spring seats use a bearing. Again, I would be surprised if BC are using a bearing mounted spring seat if they don’t need it and again, the pictures on the BR Series page shows the top spring seat being the top mount.

I believe the reality is both types of coilover will be using the same top spring seat type and this will be dictated according to the top mount.

I am going to call this a draw as well

Score: TEIN 2 – BC 2

Ride Height Adjustment

Both BC BR and Tein Flex Z adjust ride height (technically the compression and droop ratio for the desired ride height) by adjusting the bottom bracket.


Suspension Secrets have done an excellent article which details how to adjust the bottom bracket correctly. To summarise you choose the ride height you want and then adjust the bottom bracket to give you the correct compression to droop ratio (2:1) at this ride height. The spring seat is used to finely adjust the ride height. Full article is here. Well worth a read.

Another draw

Score: TEIN 3 – BC 3

Damping Adjustment

TEIN Flex Z has 16 stages of adjustment. BC BR claim to have 30 steps of adjustment.

TEIN claim the Flex Z uses needle valves whereas BC make no mention of their valve technology. Perhaps they use spool valves. KW also claim to use needle valves so I am going to assume it’s better than spool valves.

In my opinion 30 steps of adjustment is unnecessary for a road/track day car so no extra point for that.

Flex wins due to valve technology

Score: TEIN 4 – BC 3

Damper Design

Tein Flex Z coilovers use twin tube dampers. BC claim their BR series use mono tube design.

Mono tube dampers and twin tube dampers both have pluses and minuses.

According to TEIN, twin tube dampers are more suitable for cars used on the road. TEIN also claim Mono Tube dampers are better for extreme use ie track use but they also say their Type Flex twin tube dampers finished second in class in the Nurburgring 24 hours in 2005 with Prova Racing.

Penske also say Twin Tube dampers are more suitable for cars used on the road while Mono Tube are better for the track.


Kayaba corporate video showing the difference between twin tube and mono tube dampers. Kayaba say for road cars, twin tube design probably preferable.

I’m tempted to give the point to TEIN here because we are looking at the coilovers from a road perspective. Also twin tube dampers are cheaper to produce which could give TEIN more budget to spend in other areas, damper valves for example.

On the other hand if you have experienced your dampers losing their resistance because they have got hot you will probably have the opposite opinion!

Let’s call it a another draw

Score: TEIN 5 – BC 4

Spring Bottom Seat

TEIN use a low friction thrust washer on their bottom seat to make adjustment of preload & ride height easier.

BC state their bottom mount has “Tapered bottom mount locking collar to prevent collar working loose”. I’m not sure what this means but I don’t believe TEIN will have an issue with their spring seats working loose so no benefit here.

TEIN scores half a point more here for the low friction washer.

Score: TEIN 6.5 – BC 5

Spring Rates

TEIN & BC appear to supply the same spring rates on their kits. BC, at least in the UK give the customer the option of choosing a different spring rate. This is a nice touch, especially if you know that the supplied spring rates are too soft for what you want. I am sure TEIN can supply different spring rates if you ask but they don’t say it so they don’t score any points for it.

BC Wins by 1.5 points.

Score: TEIN 6.5 – BC 6.5

Spare Parts & Servicing

The TEIN Flex Z and BC BR Series coilovers use basically the same design which means all the components attached to the damper unit can be removed and transferred onto a new damper unit when the damper wears out. In effect, servicing is not necessary on either kit.

What is required is spare parts, if for any reason the parts attached to the damper unit fail. Prime suspects here are the top mounts, rubber or pillowball. Nothing catastrophic if you can’t get them immediately but it counts for something when you know you can get one quickly if you need it.

Having said all that, in Europe and North America both brands are well catered for. Elsewhere there could be a delay in getting them and they could be more expensive. But again, it’s even for both brands.

Score: TEIN 7.5 – BC 7.5

Dust & Rust Protection

I think both brands score equally here. Both are supplied with boots to protect the damper rods and both use protection to limit rust. A draw.

Score: TEIN 8.5 – BC 8.5

Warranty

Both brands have a one year warranty

Score: TEIN 9.5 – BC 9.5

In-Car Damping Adjustment

TEIN have their EDFC systems. EDFC Active & EDFC Active PRO. A stepper motor mounts to each damper unit and this stepper motor is connected to a control unit mounted in the car wirelessly. This allows you to adjust the damping force from inside the car. The EDFC Active line have up to 10 preset settings. The preset settings are programmed by the user.


TEIN EDFC damper control unit

If you had to adjust the dampers manually when you wanted to change the damping I’d say it was probably more trouble than it is worth but the fact that you can press one button and get the settings you want, that I think is a game changer.

But the EDFC Active line takes things a massive step further, the dampers can adjust, autonomously, according to speed and G-Force. You program what stiffness you want from the dampers at what speed and/or G-Force and the EDFC will automatically adjust the dampers to these settings as you drive. You do not need to touch the EDFC unit to adjust the dampers. The preset settings was a game changer, the Active line is a revolution for coilovers. The PRO model also accepts extra inputs so you can adjust damping force according to any sensors you wish.

The proviso to all of this is that the EDFC is extra and the cost is not insignificant. The EDFC Active unit is around 500USD while the all singing all dancing Active PRO is around 800USD (Prices at the time of writing)

While the EDFC brings simply massive benefits, the fact that it is an optional extra means it only scores one point.

BC Racing have no such in car adjustment option

Score: TEIN 10.5 – BC 9.5

TEIN Wins

Generally speaking the design philosophy for both the TEIN Flex Z and the BC BR Series are very similar. Namely both coilovers use a modular design where the damper unit is separate from all of the other parts in the strut.

The differences come with customisability. BC springs which can be chosen by the user (within reason) at the time of purchase. This can be a huge benefit if you are running a low ride height and know you will experience bottoming out issues with the standard spring rates. To give an example.

TEIN offset this advantage to an extent with their EDFC system. Yes it is an optional extra but the capabilities of the system and ability to use the same system on other coilover kits in the TEIN range means it counts for something.

The feature that tipped the comparison in TEIN’s favour is their use of needle valves which are claimed to give a broader range of adjustment while at the same time being able to precisely control small movements in the suspension. I am assuming that BC do not use needle valves, if they do then the win would turn to a draw.

TEIN Flex Z Coilovers vs BC BR – Which Would I Choose?

Because the prices of the two kits are so close and because TEIN is TEIN, I would lean towards the Flex Z coilovers. However the option to choose springs rates for the BC does not make this an easy decision.

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This page was last modified Jul 16, 2023 @ 11:21 pm

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