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I want to keep this about rebound damping. So to make sure we are all looking at the same information, here is the article and YouTube video (by Mike Kojima) I’m using to learn about rebound damping adjustments.
Dampers are like weight transfer capacitors. *like capacitors delay the change in voltage (by storing and releasing energy), dampers delay or modulate the rate at which weight shifts during acceleration, braking, or cornering.
Dampers (shock absorbers) control the rate at which suspension compresses or extends.
More damping = slower weight transfer.
Less damping = quicker weight transfer.
Front Shocks:
Increase in front rebound
1. makes the turn-in more crisp and sharp.
2. More response to steering input.
3. Feels good and responsive in transitions
4. Feels good for most drivers but, this can fool them into adding too much.
5. Most things happen at the corner entrance
Too much increase in Front rebound:
1. Tire shock
2. Poor harsh uncomfortable ride
3. The front suspension packs down progressively on bumps, getting harsher and harsher. Front of the car bobs and jiggles around.
4. The front of the car skips under cornering and braking and has no traction.
5. The front of the car has poor traction in bumpy turns.
6. Sometimes poor corner exit traction due to poor dynamic weight transfer to the rear wheels (noticeable in drifting the most).
7. Poor off-the-line traction for drag launches.
Too little Front rebound:
1. The front of the car feels floaty and scary when going fast, especially under undulations or pavement height variations. Feels like a boat.
2. Slow sluggish turn-in, the steering wheel feels like it’s leaning the car rather than turning it. grinding understeer.
3. The car gets blown around in the wind.
4. The front of the car gets light at speed.
5. The front of the car rears up and loses the front grip on the corner exit. Front of the car pushes to the outside of the turn.
Rear Shocks:
Increase in the rear rebound:
1. Slows rear rotation, can make use of trail braking or lift throttle to rotate car easier to manage and catch
2. Adds rear stability in high-speed turns.
3. Can add traction at the corner exit, the car hunkers down on throttle.
4. Reduces braking dive and rear wheel lock-up.
5. Adds stability on transitions
6. The back of the car follows the front better
7. More traction in a drag launch
Too much rear rebound
1. Tire shock & Poor harsh uncomfortable ride
2. Car loses rear grip in general
3. The rear suspension packs down progressively on bumps, getting harsher and harsher. Rear of the car bobs and jiggles around.
4. Delayed corner exit oversteer, the car can understeer on the corner entrance and oversteer the corner exit, this is very undesirable!
Too Little Rear Rebound
1. The rear of the car feels floaty and scary when going fast, especially under undulations or pavement height variations. Feels like a boat.
2. The back of the car feels unstable and scary, especially in cornering and transitions, car wants to suddenly snap into oversteer, not good.
3. The car might drag launch ok but loses traction past 40 feet or so.
4. The car has a generally unstable feel, even if the front feels good.
This all makes sense to me and we’ll see next trip to the track if I’m able to feel these changes in the car.
Eddie
I am aware of your stance on sway bars and I understand weight transfer and how it relates to understeer and oversteer. Most of what you said I understand and agree with. But when it comes to rebound damping I’m not sure I follow… which is OK for now. Mike’s article is pretty clear and that’s good enough for me to take to the next track day.
I think you just tied up suspension tuning in a nut shell… It’s not simple. Springs and sway bars are easier to understand. The dynamics of shocks, less so. Add to shocks 2 and 3 way adjustability and you are at another level. Overall, none of it is simple.
I once asked the the owner of BimmerWorld and professional race car driver how to set up shocks. His response was simple… set them to the point that the car starts to skip across the pavement then back them off a click. Not having adjustable shocks, I never tried that one.
On the other hand, a mentor that I had raced stock cars and stock trucks at the professional level. He didn’t know how to set a car up, but he did know what a really good setup was when he was out on the track and he did know what a poor setup was. One of the things that he looked for was to be able to set the front end down on initial hard braking to maximize front camber and then have the shocks hold it there while he released the brakes durning turn-in (trail braking). Clearly this took a balance between shocks and springs and driving style and well beyond my level of ability.
However, my take away from that was the importance to the MINI. The MINI naturally increases front camber with braking. Being able to retain that camber to the apex is important and is a combination of driving technique and car set up. It is also important to generally not be on the gas before the apex as the front will lose that camber and start to “push”. For me, it is all about driving technique as the car’s setup if fixed. Seat time and instruction.
I did note one thing in your list:
Increase in the rear rebound:
… 3. Can add traction at the corner exit, the car hunkers down on throttle.
This strikes me as being applicable to rear wheel drive cars; not so much to FWD if at all. While the general dynamics of a car is independent of drive wheel location, the usefulness or benefit of a particular part of that dynamic may be different. This is also true for driving technique in some situations. Just be mindful of that.
Again, words aside, I think you are at the point of being comfortable with making changes. It will be interesting to see where you get to in your progress of knowledge and technique.
Tire Rack has the RT660 on close out because the new RT660+ are the latest & greatest. For me, I won't be able to tell the difference anyway so I'm going to save a few bucks.
I did a few more adjustments this weekend mostly checking on where everything settled out and see if my measurements were correct. I actually raised the front just a little bit.
Here's where the ride height landed... Very happy with this.
Track Day at The Ridge in WA. Time Attack Group.... Lots of GT4s and GT3s!!
First day on the new tires ~ RT660. They are awesome. My old tires were the Falken RT615 and they were 5+ years old... still had some tread but the rubber was getting stiff. The RT660 were significantly better. Sticky and forgiving. New Fortune 500 suspension and new tires made a noticeable difference. Made some changes & lots of notes on tire pressure and suspension rebound adjustments. Sway bar is at 19mm stiff and may go back to the 22mm soft... going to do one more track day before I decide.
I know very little about the Lotus line but this one was super cool.... super low and tight.... gota be super flexible to climb in but such a rad little car.
Love the 944 chassis. This was a 944 S2 so normally aspirated with the larger 3.0l engine. If I had a bigger garage, this would be something I would go after.
The Lotus cars are very cool looking. On the other hand, Porsche has done a monumental job with designing their GT3 and GT4 cars to be really good on the track, right off the showroom floor. In some respects, the GT4 is the better car to have.
My brake reservoir has had a small leak for about 6 months now... After pressure bleeding (just under 15psi) and even heavy braking at the track I find a little brake fluid running down the back of the reservoir. So time to change it before it implodes.
It's a pretty easy job and you shouldn't need to bleed the clutch or the brakes if you're careful. It is messy though... no way to really get all the brake fluid out of the reservoir so get as many rags as you can under it.
Clutch line is a little tricky... it has a rubber gasket that keeps the line on the reservoir nipple. You can see in the pictures.
Separate the gasket and the line to get it off. Putting it back on ~ it was easier with the rubber gasket already in the line and push the whole thing on the nipple.
Pelican has them for about $100 and they are on the West Coast so shipping is 2-3 days.
I think it was leaking from this back seem... but I can't really see any signs of breakdown.
Even though I had a bunch of rags under the reservoir, I still managed to get brake fluid down in the compartment which has a hole and ends up draining behind the wheel well. So put down some cardboard and maybe even take off the wheel liner before you start.
Came down roughly where the yellow arrow is.... I've already cleaned it up at this point.
Oil Catch Can dump:
Poured about a table spoon of oil and then the metal scouring sponge probably had another 1/2 tablespoon in it.... I feel like this mod is well worth the time. All that oil NOT going back into the system seem like a really good thing. My only negative with the OCC is there is a slight oil smell when I turn on the heat or AC in the cabin because the air intake goes right by the OCC. I've got Teflon tape on all the threads but still a slight smell.
Good catch on the brake fluid reservoir before something bad happened.
Doggy pee pads are a great way to catch fluids you don’t want to get around.
Also, you can get most of the fluid out of the reservoir using a hand vacuum pump (I use a Harbor Freight one). I have a hose from the pump to a hole in the lid on a catch jar and a separate hose from the catch jar lid that goes into the reservoir. Make the holes in the catch jar lid slightly smaller than the OD of the hoses so the hoses seal to the lid. This is what I use to make a full brake fluid change/flush before going out on the track.
Last edited by Eddie07S; Jun 1, 2025 at 01:56 PM.
Reason: edit
It is summer and it's hot. The Mini AC has never been great. Couple years ago I put a can of AC recharge in it and it helped. Well, this summer the AC was again lackluster so I checked it and it was slightly low on the low side pressure. So grabbed another can and..... long story short.... over charged it! CRAP. Compressor started to struggle and the clutch would dis-engage and then re-engage.
So don't be like me and just pop another can in the old AC to get it cooler. And even more important don't use one of the AC recharge kits with fake stuff or sealant.... Guys at the shops really don't want to deal with that.
Good news is I found a local family owned shop who only charged me a $180 to do a full refresh on the AC system. Drained it and re-loaded it up. Now it's awesome. Significantly colder.... so all is well that ends well.
I have now owned the Mini for 8 years. Bought it Dec 2017 / First post here was Jan 2018.
I have changed the oil religiously every 4-5000 miles. More track days, shorter intervals.
The Mini has 82,000 miles and I've done about 3 track days every summer.
The questions is how is the oil holding up and more important how is the engine holding up?
Decided to do an oil analysis. Blackstone Oil Report
So based on this report, primarily the Comments....I'm feeling pretty good. And I have a baseline for going forward.
If I start doing more track days I might switch to a 5W-40 oil. Maybe Liqui Molly? But the Castrol seems to be holding up fine.
The LF of the mini has always been a little low when measuring the ride heights at each jack point & wheel arch. It's not really noticeable to anyone but me. But I started extending the length of the LF coil over to raise the LF to be more level. Then I started thinking.... am I adding weight to the LF and RR diagonal? Rabbit Hole!
Ordered another bathroom scale on Amazon. If you want to do it get two 450 pound max scales because the fronts could be close to 900 pounds.
This one is 450 max but some times I would have to re-wake it up... but it worked well.
Put 130 lbs in the drivers seat.
Leveled the garage floor with plywood.
Disconnected the sway bars. Corner Balance the DIY method
I will save you the details of the 3 hours of rolling the car on and off the scales.
Yes ~ by increasing the length of the LF coilover i.e., ride height via the threaded body, was adding weight to FL and the diagonal. So I reset both front coilovers to the same length and confirmed the spring preload. (I had the coilovers out to replace the bumpstops anyway) I also confirmed the rear were the same and re-weighed the car.
The bathroom scale method is not fast but it is actually pretty accurate. I would roll the car on and off the scales for each wheel. I would get 4 weights of each corner and most time it would be within 2-4 pounds. Which for me, was close enough.
I was able to estimate my car weighs 2850 pounds with 7/8 tank of gas and 130 pounds in the drivers seat.
LF / RR corner weight was 1437 pounds and RF / LR was 1413 pounds after resetting the front coilovers.
I was able to shift 60 +/- pounds from the LF to the RF by setting both front coilovers at the same height.
Front Left is still a little low but that's OK... rather be balanced than look perfect.
Oh, more question…
I have thought about doing the bathroom scale thing, but not as of yet. These questions come from a few things I have pondered before attempting it.
- Did you just do one wheel at a time?
- How did you make sure the wheels not on the scales were at the same height as the wheel on the scales? I know you said you leveled things, but just checking to see if that meant with respect to the scales.
- You appear to have driven onto the scales in such a way that at first one scale would see the full weight that the wheel is supporting. Maybe the answer is obvious, but a scale rated for 400+ was ok with being loaded to about 1000 lbs with no issue? Or did you have some way for the 2 scales to share the load as you drove up?
Coilovers.
I have Fortune Auto 500 series Coilovers with 6K front and 6K rear. I am super happy with this set up but I would like to note.... You can NOT have your cake and eat it too. This suspension took 4 seconds off my best lap time a the track BUT big hits / dips on the backroads are hitting pretty hard into the bumpstops. For me, it is very good (but not great) on the street and good enough on the track. I am definitely straddling the fence between street and track.
Corner balance. (there was some trial and error here but this is where I landed)
First I used plywood to level each wheel on the garage floor. I have tape marks on the garage floor for each tire position and then used a laser level to get all 4 points level.
Next I made sure both scales were the same height and got a piece of plywood to span the two and measured the total height. For simplicity I made the height of the wood + scales 1.5 inches.
Then I had some 2x8s. Three long ones over 5 feet and 1 short one of about 2.5 feet. The short one is paired up with the scales.
Trying to drive the car on this mess was not happening so I just pulled the car in, jacked up one side put all the wood in, jacked the other side and put all the wood in, let it down, rolled it back and forth 3-4 feet at a time and settled the suspension.
Remember tire pressure, sway bars, drivers seat weight and fuel depending on how detailed you want to be.
I then jacked up one side and replaced the 2x8 with the scales+wood and put the short 2x8 just in front of the scales to roll the car on and off the scales.
Rolled the car on and off a few times to get the suspension to settle (this is crucial, the weights changed as the suspension settled) and then do it 4 more times to get the weights. Then jack the car up and do it all over again for the other 3 corners. I used a little block of wood and some shims under the lip of the plywood on top of the scales to make sure the wood was supported when the wheel rolled on but not height enough to hold weight.
Yes, rolling the car onto the scales sends the first scale over and the scale screen would show and ERROR or OVER but then once I got the tire between the 2 scales it comes back and registers the weight. I was a little leery but every time I added up the two weights they were with in 3-4 pounds.
I always had 2 chalks going to make sure I kept the car on the wood when rolling. Two people pushing back and forth helps a ton.
Technically you subtract the weight of the plywood you have on top of the scales but let's be real here, we are going for ballpark numbers.
Now it took my brain awhile to comprehend what he is saying here, specifically at 6:20 where he talks about the same ride height with two different length coil overs. But I think I'm going back down to the garage to do some measurements this evening. Here we go again, I will report back.
*MotoIQ has backed this video in the comments which I have been learning a lot from him too.
Pads were almost done, rotors were getting close, wanted to try some more aggressive rear pads and install the caliper guide bushings I purchased last year.
Over the years I've been focused improving the rear end of the car under heavy braking (long straights into hard corners)
To this point I have replaced the rear trailing arm bushings with poly, switch out the suspension to Fortune Auto coilovers 6k front 6k rear, worked on alignments as well as stiffened up the chassis. My next step is a little upgrade to the rear brakes.
Going with the Carbotech 1521. I change out the front pads between 1521 for the street / XP10s for track days, but I'm not changing out the rear pads every track day. Pressing the rear piston is kind of a pain. If you have not done it before.... watch Mod Mini's video and go slow... you need to get the piston turning before you get too much pressure.
Suspension travel/pre-load update: I did spend an another day on the front spring pre-load and summarizing a long day down to one sentence: I added some preload to the front springs to give me, what I think is about 3/4 inch more compressions travel.
What issue are you working on resolving with the change in brake pads?
I have experienced an issue out on the track with the back end wanting to dance around under heaving braking. The solution that I came up with was to use the same pad front and rear. I also leave the rear track pads in all the time and just change out the fronts from the track pads to the street pads. Personally, I would suggest running the XP-10s both front and rear.
Yeah, I'm looking for a more consistent brake feel from the rear. The old pads were Hawk, (can't even find what they were specifically) but nothin special. My XP10s on the front are awesome but sometimes squeak if I leave them on for a few days after a a trip to the track...I don't want deal with squeaking through the neighborhood with the rear pads.
So the closest I can come to the performance of the XP10s(more bite and temp range) without the risk of squeaking are the 1521s. These will be much better than what I had on before.
The rears don’t make noise on my R56 (Hawk DTC60) or on my F56 JCW (Carbotech XP20). I once tried the 1521s and thought they had a lot less performance than the XP10s. Maybe they have changed them since then.
However, all of that said, I spent a long time and tried a lot of different pads in the rear of my R56 before I found a combination that worked with the front pads. The only thing I can say for sure is that a pad with more bite was better than less bite and it needs to have a pretty high heat range. It will be interesting to read how you make out.
You sir, have the same level of autism I have with my car...
I love to see this though. It is such an undertaking to care for these cars and their quirky behaviors, in a world of amazing cars.
Will you be joining the MTTS rally on the west coast? Maybe we can do a track day after the event ends in Tahoe at Sonoma Raceway lol... I currently lap Sonoma (Sears PT) in 2:00.42 (Garmin said 1:59.7 theoretical time)
Will continue following, seeing a lot of good info. Shoot me a follow if you have IG, would love to stay in touch! @chuchoshoots
The rears don’t make noise on my R56 (Hawk DTC60) or on my F56 JCW (Carbotech XP20). I once tried the 1521s and thought they had a lot less performance than the XP10s. Maybe they have changed them since then.
However, all of that said, I spent a long time and tried a lot of different pads in the rear of my R56 before I found a combination that worked with the front pads. The only thing I can say for sure is that a pad with more bite was better than less bite and it needs to have a pretty high heat range. It will be interesting to read how you make out.
I don't think they have changed the compound on the 1521s. My old rear pads were Hawk HPS and they were almost worn out, so I feel like the 1521 pads will be an upgrade in both temp and bite. Still not a track car so can't be squeaking like a garbage truck through the neighborhood.
