Do the sunroof equipped R56 cars have different front and rear springs than the non sunroof cars?

I drove two new cars back to back over a 100 mile loop and I found that the sunroof car deals with directional changes in a significantly more direct manner and with far less lean than the non sunroof car.

Any advice much appreciated.

 

Did they have the same suspension? You can order the cars with both "standard" and "sport" suspension from the factory, or go one more and have the JCW suspension installed at the dealership.

If the R56 sunroof weighs about the same as the R53, it'll add about 65 pounds to the car between the glass, motors, tracks, and wiring. If the suspensions were apples-to-apples you'd feel the difference. That said, it has been theorized MINI uses different spring rates between sunroof and non-sunroof cars in their factory suspensions, though nobody [to my knowledge] has taken the effort to measure them.

 

Both cars had the standard non-sport suspension.

I could find no prior discussion about different spring rates on the two cars which is why I am posting this. I strongly suspect that the sunroof car has stiffer springs and they make for a much improved handling over the non sunroof car.

 

Very interesting. The added mass of the sunroof when countered with stiffer spring rates and corresponding damper firmness, would yield the same suspension frequencies unless MINI intentionally tuned the two configurations differently.

Ok, I just checked RealOEM, and they recently updated it and removed all the spring part numbers. That said, damper part numbers are still there. There are no different dampers other than a set for standard and a set for sport. This leads me to believe there are no different spring rates unless MINI opted for the uber cheap/non-ideal spring swap. This would mean the cars would feel different in transision due to one of them being less damped [the sunroof car in this case]. Since the sway bars are the same, the sunroof car will pitch and roll more too.

I'm still a bit baffled how you could experience less body roll with the sunroof car if the suspensions are "the same". Are the tires the same between cars? How about limited-slip diff? Are they otherwise stock? [no poly FCAB]

 

Funny this is mentioned, it reminds me of a recent experience. I recently took a road trip and my car was loaded with about 7 suitcases and a set of golf clubs. We made a stop of a couple of days at my sisters place. While there we got to drive some local roads.

My car actually handled better with the load in the back. The car visually sat about 3/4" lower. I'm sure this was more weight than a sunroof but this incident surprised me.

The only conclusion I could make from this was perhaps because the vehicle rode better with a load (just like pickups always ride better when loaded) it only felt like it handled better.

 

...about the sunroof and added weight. If it weighs 65 lbs, it is weight worth adding. I use the sunroof all year, both for the added light and the air.
The times when the weight would be objectionable is really never. Also, I have seen post claiming 65 to 80 lbs for the unit. I have no data, other than experience with the weight of various materials from 30 years in construction, but I am willing to bet 5 cents or so, that the net difference between a car with and without a sunroof is closer to half or less of the claimed weights I have read in posts. Reguardless, the added weight in the hands of the average owner, is meaningless unless you are racing at a very high level.

 

Excellent point and we agree that while glass panels weigh more than the simple metal skin that they replace they will not add the claimed 65 lbs. Generally the roofs of cars with sunroofs are not reinforced in significant ways but the Mini roof opening is very large and it is quite possible that the combined glass and structural weight addition is indeed in the 65 lb range.

Is it possible that engineering dialed in less overall lean with progressive springs to provide an added safety margin?

That being said, the difference in transition handling between the two cars was far more significant than anything induced by differences in tire side wall stiffness. Driving a straight line at 35 mph while turning the steering wheel by 100 degrees, as if driving around cones, was all the proof one needed. The sunroof car was far superior to the other, the proverbial night and day.

We are dealing with a difference in springs here and I intend to get to the bottom of this as soon as I visit the dealer's parts counter with two VINs, one from each car. I hope the answer is in the springs otherwise I will be left scratching my head.

 

Both non-sport, same size wheels and tires, no limited slip, both stock w/o aftermarket parts.

It is a head scratcher but I would not be overly surprised to see a modest spring rate change without an accompanying dampener valving change.

I will however be sure to check the respective dampener part numbers as well as the spring numbers.

 

Please post here when you find the results of your part number search.

 

The ETK that we use to look up BMW/MINI parts has a spring table that requires the user to put in the last 7 digits of the VIN to determine what options are on the car, which in turn shows a specific spring part number. Spring part numbers can't be accessed without a VIN.

A few of the more popular options that determine the spring part number that I can remember right now are Xenons, H/K sound, and of course, the sunroof.

I can run the two VINs for you...but not until Tuesday(my Monday) when I go back to work.

 

Thank you PARTSMAN

We agree on the need for the VINs and I will be at the Dealership today armed with both VINs.

Different springs for the Xenons? I don't doubt you but what is going on with that?

Anyway, I should be posting something by tonight.

 

OK PARTSMAN, here we go:

VIN last 7 of the car with sunroof: TT80017

and the car w/o sunroof: TT94241

The parts counter at the dealership looked them up and found all six part numbers to be different between the two cars:

Car with sunroof: Front Strut LH: 6 782 209
Front Strut RH: 6 777 142
Rear Strut LH: 6 778 567
Rear Strut RH: 6 778 568
Front Spring: 6 777 190
Rear Spring: 6 777 194

He did not give me the part numbers of the car without sunroof but he did say that none of the six were the same.

I asked for color codes on the springs and lb/in rates but his list did not show that information.

Somebody would do us all a big favor if all the various springs could be listed with lengths, color codes and lb/in rates.

And a word of advice to autocrossers. If you intend to race a car in totally stock form get a sunroof equipped car and amaze the rest of the Minis.

 

The xenon headlamp assemblies are heavier than the standard headlamp. I'm not sure if it makes any kind of real difference, but they are listed in the spring table option list.

Thanks for posting the info. I will run the VINs tomorrow to see if I can get any specs on the springs.

 

Thank you very much.

 

I'd never heard any mention of varying spring rates on the stock OE and sport OE suspensions, but I do know the JCW Suspension kit has three different spring rate options based on if you have certain options. Your findings confirm this is the case with all of the factory suspension setups.

Congrats on this interesting discovery! I don't think these small variances will really change anyones laptimes but it is a great observation on your part and I do suddenly feel better about opting to get the sunroof and hi-fi system now.

 

It is a significant difference in favor of the sunroof car and it would make a significant difference in lap times.

 

I have been looking all morning, but neither my techs or myself have any info available to us regarding the spring rates and/or color codes. Sorry.

Depending on how deep you want to get into this...you could have someone dyno the springs on both cars to get their true rate.

 

Thank you for trying PARTSMAN.

 

"Significant difference"? Is this relative to the suspension tuning watering-down between '02 and '05 MCS's, or are you being perhaps a bit dramatic in your description? I've driven lots of both sunroof and non-sunroof MINI's, and have never noticed a marginal difference in suspension tuning that wasn't related to the car simply being heavier, let alone a significant improvement. From what you've described so far, it sounds like you're being overly sensitive. What other MINI suspension setups have you driven? I'm just looking for relativism to add credibility to your statement.

What kind of situation were you in that allowed you to drive two different MINI's in 100 mile loops? Based on the VIN you've provided, the sunroof car was noticably older. Perhaps all the extra miles have settled the suspension where the new non-sunroof car was still stiff from assembly?

Ok, so the part numbers are different. Now what? Are you planning on dyno testing the springs and dampers to prove they're tuned significantly different beyond the weight difference? Furthermore, why would MINI conciously tune a luxury option [adding the sunroof] to have more sporting handling? Wouldn't those that get the sunroof generally want a more compliant ride that wouldn't rattle the delicate sunroof components?

 

many years ago, someone on MINI2 that work(ed) at Oxford looked at the weight difference between a moonroof and non-moonroof equipped R53. Taking into account the weight of the moonroof cassette and glass, and the weight of the portion of the roof that's not there, the diff was something like 25 lbs, give or take a few lbs. so the weight diff is negligible, really.

 

I have an '08 Clubman, standard suspension (with the sun roof). My local dealer will swap out my springs, shocks, and sway bars for a "full sport" suspension, which is supposed to have better spring rates, dampener rates, and tighter handling. They tell me the springs and shocks on the set they want to sell me are 1 step below the JCW set up. Is this worth the swap? They want a fair bit of $$ to do it, and I contemplating whether or not this would be an upgrade or just $$ ill spent...? Any ideas? If I did this swap out, I'd have everyting but the turbo, yeah I know, should have bought a Turbo.

 

Sort of bringing a thread back from the dead, but has anyone ever located a color code guide for identifying mini springs? Trying to put my JCW back to stock with sport suspension and I want to make sure I have the correct springs. Fronts have a red and wht stripe while the rears have two grey or white and one blue stripe. I believe them to be sport suspension springs. Can anyone confirm?

 

Yes, different option packages have different springs. This is VERY common, I'd say most cars are designed this way. A stripped down version of a given car can weigh hundreds of pounds less than a loaded version, and OEM's do this to keep the ride and handling consistent between differently optioned cars.

 

That said, buying a sunroof car to get better handling is not a smart move. The added weight on an R56 is DEFINATELY more than 25lbs, and the weight is up high, the worst place for it.

The way the springs are typically chosen is by vehicle weight. For example:

A car between 2400 and 2450 has x spring rate
A car between 2451 and 2500 has x + 3% spring rate
etc.

So, in theory, a car that weights 2451lbs might have a handling advantage over a car that weighs only 1 pound less because it has relatively stiffer springs. However, this would be difficult or impossible to nail down to a particular option or package, especailly on a car like mini with so many combinations. And most cars would fall within the middle of a given springs' weight range, so the differences would be minimal.

Many other things can cause the variation you experienced. For example . . .

Alignment settings from the factory typically vary quite a bit, and "factory specs" are often very wide to allow for that. A car with a toe setting near the high end of the spec will feel very different from a car with toe at the low end. When the cars are aligned at the factory, the springs/bushings typically haven't settled yet, so it's not uncommon for toe settings to actually be out of spec once the car is actually in a customer's hands.

Also, bushing rates can are typically allowed to vary by up to 15%, and shock damping can vary about as much as well.