Rough Ride Anniversary

[ThickCobra]

Now, as I assume there are several 20th Anniversary cobras completed or in the works, I'm curious how you are finding the ride to be. These cars came supplied with double adjustable Koni shock and springs with weights of 500lb front and 400 lb rear. We have our share of rough roads here and when the pavement is not smooth, it's a harsh ride. A friend following even commented that mine seem to bounce around a bit. I have the shocks on full soft and tires on 18" wheels at 20 - 22 lbs.

I built the car for short trips and possibly touring and not the track. My wife and I were hoping to take the cobra on some road trips, but not with the current set up. Any feedback or suggestion would be much appreciated.

[Mike N]

The 18" wheels with low profile tires aren't helping. I am guessing that the brakes you have won't fit 15" wheels so a more compliant tire is out of the question. Springs are not too expensive and there are often sets for sale at a discount where people have increased spring rate for track use. You might want to try going with a spring rate 20% to 30% lower and see if it helps. The other thing that will help is a seat with webbing in the base. Foam just isn't that compliant.

[2bking]

Although not a 20th anniversary car, I have ridden in one with the 2015 IRS, 17" wheels (tires set at 22psi), Koni single adjustable shocks set on soft and same springs (500/400). It has roll bars on front and rear axels. It definitely rides much harsher than mine with the old style IRS and same shocks. Other than the roll bars and different IRS, the cars are the same except perhaps the springs and seats. I don't remember what springs were shipped with mine and I have the standard seats, his are for tall people and have less padding in the bottom.

[edwardb]

I don't know what to tell you. I don't find the ride in my 20th Anniversary Roadster with the exact setup as yours to be uncomfortably rough. We don't take long trips in it, but have done 100 - 200 mile cruises with no issues. It's partly a matter of expectations I guess. A short wheelbase car with a race suspension isn't going to ride like a Buick. This is my first IRS, and it rides noticeably better and smoother than the previous solid axle Roadsters, so probably that affects my opinion to some degree. I also don't find the 18 inch tires to be any different than the 17's on previous Roadsters. Our roads here in Michigan are probably about the same as yours unfortunately.

Having said that, it would be easy enough to take the sway bars off and see if that makes a difference. Changing springs also isn't hard. If you do look at Eibach. They have the same sizes as Factory Five in different weights, available at Summit (and probably elsewhere) and aren't that expensive. Had them on #7750 and they were very nice quality.

[Jeff Kleiner]

Sway bars DO NOT affect ride quality.

Make sure that everything is able to move freely, you don't have anything binding, a bushing pinched, tight/seized UCA pivot, etc.

I'm pretty hard core running mine on a 750/500 and honestly don't find it objectionable. Don't know how many others you've driven or ridden in but as Paul said it may be a matter of expectations; they don't ride like a Buick and if they did they'd corner like this



Cheers,
Jeff

[CraigS]

Try 300-325 springs in the rear. The rear affects the perceived ride a lot more than the front so start there. I will disagree w/ Jeff also. Swaybars don't affect ride nearly like springs do but, if you go over a bump w/ just the right side tires, it will be a stiffer ride w/ swaybars than w/o. If you pull into a sloped driveway entrance on a diagonal, bars will also make that stiffer.

[ThickCobra]

Thanks everyone. I think I'll try the easy items first to see whether I can make the ride more comfortable. And, though I may need to adjust my expectations, if no one else with the 20th anniversary set up feels the ride to be a bit harsh, maybe I did something wrong. So... first I'll remove both front and rear anti sway bars and see whether the suspension is bit more comfortable. If that doesn't help, I will reach out to Mark at Breeze and see about softer springs. Well see how that works.

[RRussellTx]

As another data point - I've got about 700 miles on my 20th Anniversary roadster and I would describe the ride as firm but definitely not harsh.

[Clover]

I would recommend stiffening the rebound up on your shocks. You stated your friend mentioned it looked like you were bouncing around and that makes sense if your rebound it turned all the way soft. When you hit a bump, the spring absorbs the impact along with the compression from the shock absorber. You have that compression set as soft at you can which should help ride comfort. However, after that spring absorbs the bump, it will unspring and move the car. The rebound on the shock absorber is what controls the spring when it releases that tension. If you have the rebound turned to full soft, it will not be able to control the spring and your car will bounce. That will make the bump seem larger then if the rebound on the shock was turned stiffer. I hope that makes sense.

[ThickCobra]

RRussellTx,

Thanks for the feedback as I also have about 740 miles on mine.

Clover,

Your feedback inspired me to do a bit of research on the topic of Bump & Rebound. And, as you know these shocks can be adjusted for both. I came across this "Car Suspension Tuning Guide" at www.rapid-racer.com that covers this topic. I thought I'd share the link with you all. It suggested that you should generally have more rebound than bump. The guide explains why. I have no idea whether this guide is authoritative but it was interesting reading.

Again, maybe my desire for a softer ride, without sacrificing performance may be a bit optimistic, but I enjoy the pursuit.

[edwardb]

Went to a Cars and Coffee this morning (about froze, but that's another story...) and the GPS took me on a couple roads I hadn't been on before and were in incredibly bad condition. Winter around here does that but these were especially bad. Was reflecting on your feedback about these riding rough. Was impressed though (again) that the car handled it pretty well. As one of the responses here suggests, I'd want to make sure you don't have something hanging up. I do find Clover's comments about the shock adjustment interesting, and the link you provided tracks with that response exactly. I might give the rebound a click or two and see if I notice any difference.

BTW, and I suspect you know this already, the IRS Roadsters sold since the new IRS was introduced with our 20th Anniversary versions are all exactly the same suspension setups. I've seen a number of builds on here that selected all the same options as we have, e.g. sway bars, double action shocks, etc. Even without those options, I would expect they behave very similarly. My Gen 3 Coupe, delivered this past December, is an IRS version, and has exactly all the same components (e.g. spring weights, etc.) as our cars. So this discussion isn't unique to the Anniversary Roadsters.

[ThickCobra]

You are adventurous as I can imagine it's still as cool in the mornings, as it is here in Wisconsin. Brave soul comes to mind. But, tomorrow 61 mid day and Monday 73 high so I'll be out testing.

As I read the guide, I too found that it tracked with the response. I will adjust the rebound a few clicks and at the same time revisit whether anything is hung up.

Thanks.

[ThickCobra]

Thought I'd provide an update on my suspension adjustment. I thought I would start with simple items and surprisingly, I have a much more enjoyable ride. And, with the weather turning nice this last weekend, I am trying to add some miles. First, I verified and adjusted if necessary, tire pressure to 22 lbs all around. Next, I adjusted the double adjustable Koni shocks. I initially had them on full soft for both bump and rebound. After doing a bit of research, I decided to add 4 possitive clicks to the rebound.

As a side note, I read that you need to be careful while setting the stops full soft or full pressure, not to jam the adjustment. If you jam it, it will make it difficult to adjust in the future. I almost could not adjust one shock but got it to free up. So, I set the rebound on all to 1 click positive.

And, as I start to accumulate more miles , I believe it will get even nicer. Thanks to all for your input.

[AC Bill]

So FFR made a special 20th Anniversary edition kit, including brakes, that prevented one using 15" wheels and tires..? Pretty goofy idea..

[Clover]

Thought I'd provide an update on my suspension adjustment. I thought I would start with simple items and surprisingly, I have a much more enjoyable ride. And, with the weather turning nice this last weekend, I am trying to add some miles. First, I verified and adjusted if necessary, tire pressure to 22 lbs all around. Next, I adjusted the double adjustable Koni shocks. I initially had them on full soft for both bump and rebound. After doing a bit of research, I decided to add 4 possitive clicks to the rebound.

And, as I start to accumulate more miles , I believe it will get even nicer. Thanks to all for your input.

Glad the stiffer rebound settings helped. It is kind of counter intuitive and I bet most people turn the shocks to full soft compression(bump) and rebound not realizing that that will actually make the ride harsh. I am waiting on my kit to be delivered and I am certainly a novice car builder, however, I do have a good amount of performance driving experience and was a driving skills coach for a few years. That really helped me learn about setting up car suspensions, which is much more complex then most people realize. I plan to spend a lot of time refining the suspension on my 65 coupe and I will write up a detailed guide for everyone when I do. I am sure it will take some time tinkering with things, however, I think there is probably plenty of room for improvement from the recommended settings from Factory Five. I know the alignment recommendations are pretty conservative and not suited for going around turns quickly in my opinion. I am not saying the recommended settings are wrong, they are just set for a different sort of driving then I enjoy.

[ThickCobra]

Clover,

I appreciate your input which certainly helped with my suspension. As I recall, the kit did not recommend any suggested settings nor guidance on setting preferences. Your feedback prompted me to do some research. And, a great topic to share with owners.

Jay

[lahrs37]

So this is a little different because I have the standard koni's that come with MK4 IRS complete kit. They are non-adjustable and it looks like they are 750# front and rear. Is this right? If so, could I go down in the rear without upsetting the balance of the car? My car rides so rough that I literally don't want to drive it here in Philly, which is a total bummer. And I am 35 and in good shape! I have also been thinking about replacing my Kirkey's with standard seats and my 17" wheels with 15" - though replacing springs is probably the cheapest, easiest place to start.

[ThickCobra]

So this is a little different because I have the standard koni's that come with MK4 IRS complete kit. They are non-adjustable and it looks like they are 750# front and rear. Is this right? If so, could I go down in the rear without upsetting the balance of the car? My car rides so rough that I literally don't want to drive it here in Philly, which is a total bummer. And I am 35 and in good shape! I have also been thinking about replacing my Kirkey's with standard seats and my 17" wheels with 15" - though replacing springs is probably the cheapest, easiest place to start.

The springs with my kit are 500lb each for the front and 400lb each for the rear.

[lahrs37]

The springs with my kit are 500lb each for the front and 400lb each for the rear.

This is where I am getting the 750# number:

http://www.factoryfiveparts.com/1468...retro-fit-kit/

[edwardb]

This is where I am getting the 750# number:

http://www.factoryfiveparts.com/1468...retro-fit-kit/

Those instructions are 10 years old, and I question whether that 750 number is correct any more. Your springs should be clearly marked (multiple times) with the weight rating. My experience with two new 2015+ IRS kits is 500 front and 400 rear same as ThickCobra describes. Don't overlook tire pressure. Guys routinely over-inflate the tires on these. For street use, I use 22 front and 22-23 rear. It makes a huge difference.

You should be able to get this sorted out without changing wheels/tires IMO. We have lots of bad roads here in Michigan too. Some I avoid they're so bad. But in general, no reason you can't make it so you'll want to drive it.

[lahrs37]

Those instructions are 10 years old, and I question whether that 750 number is correct any more. Your springs should be clearly marked (multiple times) with the weight rating. My experience with two new 2015+ IRS kits is 500 front and 400 rear same as ThickCobra describes. Don't overlook tire pressure. Guys routinely over-inflate the tires on these. For street use, I use 22 front and 22-23 rear. It makes a huge difference.

You should be able to get this sorted out without changing wheels/tires IMO. We have lots of bad roads here in Michigan too. Some I avoid they're so bad. But in general, no reason you can't make it so you'll want to drive it.

Ok, I will check the springs when I get home. I am also pretty sure I am at 35 in the tires! Hopefully that does it.

[Jim Schenck]

The 20th Anniversary cars all come with the street style silver double adjustables that were configured to be able to adjust over a wider range than the standard red body shocks. On full soft these shocks are softer than the standard shocks but can also adjust to be stiffer for track days or just sharper handling. The biggest difference between the two is the red shocks (or black double adjustables) are mono-tube which gives a slightly harsher ride but a more responsive handling feel when they are set to roughly equivalent stiffness. The other main difference is mono-tube shocks can be mounted in any direction where the twin tube silver shocks must be mounted with the body down, if the shocks are upside down then they will not work well, if at all, and the ride will be awful.

If your settings and mounting seem correct then you can also check for binding, if the bushings don't have enough grease in them or you miss a ball-joint with the grease gun the ride can be noticeably harsher. To check for binding unbolt one end of the coil over and lift the suspension with a jack (until it is compressed a couple inches past ride height but careful not to lift it off the jack-stands) and drop the jack a moderate rate to see if the suspension drops evenly or if it comes off the jack or not down at all. If it is binding the most likely culprit is grease, however if an alignment shop adjusted the front upper arms without loosening the jam nuts they can put those arms in a very tight bind as well.

If you think it is just a matter of preference in the end and the car is stiffer than you would like I would recommend swapping the rear spring to the front and getting 300lb rears (that is the configuration we use on the 33 since the 20 inch rear tires have less give to the sidewall) and/or swap to a set of 17s. I would think you could find someone on the forum willing to do a swap fairly easily, your 18s for a set of 17s.

[edwardb]

Ok, I will check the springs when I get home. I am also pretty sure I am at 35 in the tires! Hopefully that does it.

Whoa. That will not only give you an incredibly harsh ride, it's potentially dangerous. Get them down into the 22-23-24 range and I think you're going to feel a big difference.

[Dave Howard]

Ok, I will check the springs when I get home. I am also pretty sure I am at 35 in the tires! Hopefully that does it.

35 psi will definitely rattle your teeth and jar your back. Typically you can run 1 psi per 100lbs of car weight. And like others have said, you will notice a world of difference when you drop the tire pressure.

[lahrs37]

I was at 31. I aired down to 20 and it was a HUGE difference. I will air back up to 22ish. And because the roads are still so bad here I would like to try the stock FFR lowback and maybe 50# less spring rate at each corner. Thanks for the insights everyone!

[ThickCobra]

I was at 31. I aired down to 20 and it was a HUGE difference. I will air back up to 22ish. And because the roads are still so bad here I would like to try the stock FFR lowback and maybe 50# less spring rate at each corner. Thanks for the insights everyone!

Glad you're on your way to a nicer ride.