Intrax RSA vs 1K2

[belcom]

I am looking for a new suspension setup. I've gone from completely shot stock shocks when I got the Coupe to Bisltein B6 and H&R springs (springs were already on the car). Got about 4-5k on it with some track time. Obviously it was an improvement and rides decent. But there is a number of cons. I'd say my car is a weekend warrior and used 50/50 street/track.

I am looking at Intrax in detail. And received some responses to my questions from Donald. Looks like I can go for full RSA setup, RSA front and 1K2 rear or full 1K2 set (Є2100/Є2300/Є2800 respectively without options like ARC or Black Titan). Definitely a divorced spring/shock combo for rear. Ideally I'd go for 1k2 with ARC and black titan coating however that setup will push me way over any reasonable limits with my budget. I am also kind of sort of considering Bilstein PSS10 as an option but it appears that a custom built set of Intrax RSA or RSA/1K2 might be actually a better option at about similar price point considering the Intrax suspension is built/valved for you at the factory for your car setup/driving style/needs.

Actually, I must also mention that I am in contact with a local enthusiast who plans to sell his car in spring and might have a good set of KW Club Sports available soon. But I am not extremely excited about this option due to it being quite harsh on street from what I hear. Although great on track.

So... my question is if anybody ever experienced RSA vs 1K2? I understand RSA shocks have thinner shock bodies than 1K2 (40mm vs 45mm) and made of anodized steel rather than aluminum. But still feature internal thermostat and I am assuming same/similar technology within the shock itself. Only 1K2 are compatible with ARC and are also upgradable down the road. 1K2 are also lighter.

Although I do understand all technological selling points I would love to know how that translates to ride quality, body control, longevity, squatting, leaning, low speed vs high speed performance, the way the suspension absorbs curbs etc.

I am thinking RSA, considering budget and all that without going overboard. Maybe with the piston/tube coating which should prolong service life. Or RSA front and 1K2 rear no options. Help me decide. Any and all feedback will be appreciated especially if you've got experience and seat time with Intrax suspensions mentioned above.

[Ed Doe]

viewtopic.php?t=139664

KWs/Billies/Intrax all recently discussed in the thread linked above

A user on here Mikey_Boy I think has ARC on his 1K2s, so would be a good man to hit up for impressions on how that works on the road and track.

I cannot comment on comparisons as I have not had RSA, Bilstein or KW coilovers on mine, but I do have Intrax 1K2 (without Black Titan and without ARC). They are firm for sure but not outrageous for the road. I'm yet to try my new set on track (there was a very old 1k2 setup on the car when I bought it - hadn't been looked after and was pretty seized so no basis for comparison, and subsequently removed and replaced). I am running a true rear coilover for info.

I have Donington booked on 17th April, and a 'ring trip in May - will report back on the performance if you've not made a decision and purchased by then!

[Beedub]

viewtopic.php?t=139664

KWs/Billies/Intrax all recently discussed in the thread linked above

A user on here Mikey_Boy I think has ARC on his 1K2s, so would be a good man to hit up for impressions on how that works on the road and track.

I cannot comment on comparisons as I have not had RSA, Bilstein or KW coilovers on mine, but I do have Intrax 1K2 (without Black Titan and without ARC). They are firm for sure but not outrageous for the road. I'm yet to try my new set on track (there was a very old 1k2 setup on the car when I bought it - hadn't been looked after and was pretty seized so no basis for comparison, and subsequently removed and replaced). I am running a true rear coilover for info.

I have Donington booked on 17th April, and a 'ring trip in May - will report back on the performance if you've not made a decision and purchased by then!

ed, offsubject but did you fit the momo yet?? i cant wait to see your choice on a race wheel

[TomK]

Ideally I'd go for 1k2 with ARC and black titan coating

I think black titan coating is an absolute must unless you fancy cleaning your shockers every week

I understand RSA shocks have thinner shock bodies than 1K2 (40mm vs 45mm) and made of anodized steel rather than aluminum. But still feature internal thermostat and I am assuming same/similar technology within the shock itself. Only 1K2 are compatible with ARC and are also upgradable down the road. 1K2 are also lighter.

I didn't and don't know of anyone who's been brave enough to order 1k2 in aluminium. If you're street driving them it's unwise for the weight saving unless you're loaded and are happy to replace them all the time.

Afraid I haven't come across anyone using the RSA, I was and know of lot's of happy 1k2 customers.

[Ed Doe]

ed, offsubject but did you fit the momo yet?? i cant wait to see your choice on a race wheel

I haven't taken the plunge yet - had some other things come up that have taken priority elsewhere, but will get to it! I'll keep you posted with what I end up doing

I think black titan coating is an absolute must unless you fancy cleaning your shockers every week
I didn't and don't know of anyone who's been brave enough to order 1k2 in aluminium. If you're street driving them it's unwise for the weight saving unless you're loaded and are happy to replace them all the time.

Hi Tom,

Not sure if you were aware of this but the Black Titan Coating is only applied to the guide & piston rods of the dampers, not the bodies themselves. I didn't bother with it, but that being said I store the car during winter months.

Even the steel bodies on the 1k2's are prone to corrosion though - my old ones were hanging when I took them off...!

[TomK]

Not sure if you were aware of this but the Black Titan Coating is only applied to the guide & piston rods of the dampers, not the bodies themselves. I didn't bother with it, but that being said I store the car during winter months.

Even the steel bodies on the 1k2's are prone to corrosion though - my old ones were hanging when I took them off...!

You're quite right Ed, it's been a while. Definitely go for stainless bodies rather than just steel for corrosion protection, and over aluminium as well which can react with the steel clamp. I seem to remember that the black titan stops pitting on the rod but maybe that's not really an issue.

[Ed Doe]

You're quite right Ed, it's been a while. Definitely go for stainless bodies rather than just steel for corrosion protection, and over aluminium as well which can react with the steel clamp. I seem to remember that the black titan stops pitting on the rod but maybe that's not really an issue.

Marti at MS Motorsport advised me Black Titan coating probably wasn't worth bothering with unless I was planning on racing, as the primary benefit was friction reduction... could be mis-remembering that now though, it's been more than a year since I last discussed the topic!

I thought the Intrax bodies were anodised steel, I didn't think they did stainless bodies. Could be wrong but it's part of the reason I'm a little precious and avoid driving mine during winter months - I really cba with the cost of new bodies through corrosion again!

[TomK]

Anodised steel? I always thought the options were aluminium, steel or stainless bodies. Either way I remember there being a fair few moanings about corrosion, understandable given the price. Your old ones were from a while back right? They did look bad I had a set on my m3 that seemed to last ok, stainless & black titan iirc

[belcom]

For Z4M I was given options of RSA or 1K2 (plus 2k2 etc but that's not affordable so I am not even going there). RSA has what looks like anodized steel (or maybe zinc plated, not sure. I am not a metallurgy expert) shock bodies and 1K2 are aluminum. In my email exchange with Intrax I was not offered to have 1K2 with steel or stainless shocks. But I suppose I'll ask. Maybe a full set of 1K2 in plated steel could be had for a lower price if built from different materials... not sure.

Anybody here also mucked around with MCS suspension? Not a cheap option, but supposedly really good and has great range of damper adjustment? 1-ways seem to be somewhat decent price wise. However, I asked Bimmerworld guys and they said the MCS 1-way would adjust rebound with only a slight change in compression unlike Intrax where the adjustment takes care of both in a correct ratio. Which again makes Intrax look good in comparison. Plus with MCS you buy the dampers and then your own springs, camber plates etc to complete the set.

Ed Doe, I did read the thread you linked above before my post. No one is talking about RSA in there though. So I needed my own thread for people to comment with their experiences.

I wish I could ride in a Z4M with all these different options which would make it easy to decide and choose. But that is simply not possible. At the end of the day I have to rely on what other people have to say.

I am still not quite sure on the KW Clubsport by the way. Some people complain about teeth rattling ride on the street and some say its absolutely fine and firm but compliant. I am not looking for rolls-royce comfort but do not wish to break my back either. Reasonably balanced would do it.

[Ed Doe]

Whereabouts are you based? You're welcome to have a go in mine - personally from what you're saying 1k2 sounds like the right solution, maybe if you looked at it that way then a drive in a so-equipped car might alleviate any concerns?

[sjh00u82]

Marti at MS Motorsport advised me Black Titan coating probably wasn't worth bothering with unless I was planning on racing, as the primary benefit was friction reduction... could be mis-remembering that now though, it's been more than a year since I last discussed the topic!

I ordered some last week and pretty much got the same advice. Black titan is more about heat reduction from reduced friction than it is about corrosion resistance.

From my research the simple answer is, there is no perfect coilover for the Z4. Some are cheap, some are easier to set up, some are better at corrosion resistance and some are better at being suspension. You just have to pick where you want the balance to be.

There doesn't seem to be an easy to setup, corrosion resistant (to OEM levels), top quality coilovers available at any price. You just have to choose what is going to annoy you least for your set of circumstances.

[Ed Doe]

perfectly summarised I'd say!

[Mikey_Boy]

Marti at MS Motorsport advised me Black Titan coating probably wasn't worth bothering with unless I was planning on racing, as the primary benefit was friction reduction... could be mis-remembering that now though, it's been more than a year since I last discussed the topic!

I ordered some last week and pretty much got the same advice. Black titan is more about heat reduction from reduced friction than it is about corrosion resistance.

From my research the simple answer is, there is no perfect coilover for the Z4. Some are cheap, some are easier to set up, some are better at corrosion resistance and some are better at being suspension. You just have to pick where you want the balance to be.

There doesn't seem to be an easy to setup, corrosion resistant (to OEM levels), top quality coilovers available at any price. You just have to choose what is going to annoy you least for your set of circumstances.

Yep - perfect summary! I liked the Bilstein set I had (PS10) but it’s nothing compared to Intrax. A whole new world. ARC is definitely worth it - you can put the suspension pretty soft, even on track and it firms up on cornering like some kind of black magic. Like others, I store my car in winter so can’t comment on corrosion resistance.

Speak to Martin at MS Motorsport - he will advise you well on options, but 1K2 with ARC and no black titan is pretty optimal for fast road and trackdays, plus you can tailor the units to your car’s weight and your driving style.