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nordoceltic
14-05-2015, 05:14
Sorry for the noobish question but how does one tune the bump stops ? Most guides online don't talk about using bumpstops, and we all know the default set ups on all these cars leaves a lot to be desired.

JimStick1
14-05-2015, 05:38
I could well be wrong, but I think bump stops are used to control spring rates near the end of the springs travel. It can be used to be make soft setups feel less sluggish, or to limit suspension travel (keeping the car off the ground) amongst other things. There can be a fair amount of math involved in figuring out the ideal way to go about setting them up - you'd probably need access to telemetry to do it right.

MikeyTT
14-05-2015, 09:13
For me personally I always take them out. I find that they unsettle the car too much. I've found the car more stable under almost all conditions without them. The C9 for instance I can run over a second faster around Oulton International with just removing the bump stops, than with them in.

Jim is right in that when you're nearing the end of the suspension travel they should provide a less jarring effect than just hitting the end of travel. I tend to adjust a line or avoid a curb though if that's really a big problem.

That said I've never spent huge amounts of time playing with them. I tend to spend more time looking at the damper rates than anything else.

menaceuk
14-05-2015, 13:51
I am no master tuner, but IMO...

...Both Slow & Fast Bump stop are important.

Fast Bump Stop is only really needed on bumpy tracks. If a car oversteers(decrease rear or increase front) or understeers( Increase rear or decrease front)over a bump then Fast Bump needs changing.

Slow Bump Stop is very handy for weight transfer so can help with understeer(increase rear or decrease front) & oversteer(decrease front or rear) in corner entry & exit

It should also be noted that rebound is tied to both Slow & Fast Bump Stop. I personally tend to make the same adjustments to rebound as I do with Slow & Fast Bump.

hkraft300
14-05-2015, 14:21
I am no master tuner, but IMO...

...Both Slow & Fast Bump stop are important.

Fast Bump Stop is only really needed on bumpy tracks. If a car oversteers(decrease rear or increase front) or understeers( Increase rear or decrease front)over a bump then Fast Bump needs changing.

Slow Bump Stop is very handy for weight transfer so can help with understeer(increase rear or decrease front) & oversteer(decrease front or rear) in corner entry & exit

It should also be noted that rebound is tied to both Slow & Fast Bump Stop. I personally tend to make the same adjustments to rebound as I do with Slow & Fast Bump.

What you're talking about are the dampers aka shock absorbers - they limit the rate of compression/extension of the spring as the wheel travels up and down relative to the chassis.

I have no idea what part the game refers to as a "bump-stop"

I thought "bump stops" are rubber/poly/alloy bushes that restrict suspension travel.

Thomas Sikora
14-05-2015, 14:52
That is an bumpstop
202341
This limit the spring travel, background is to have a low ridehigh but not to touchdown the street e.g. by override of road bump=>there fore bumpstop :)

If you have a low ridehigh and hear a touchdown on street or see it by flying sparks then grow up the righhigh or increment the bumpstop.

hkraft300
14-05-2015, 15:57
That is a bumpstop


That's the part I was thinking of.

menaceuk
14-05-2015, 16:08
What you're talking about are the dampers aka shock absorbers - they limit the rate of compression/extension of the spring as the wheel travels up and down relative to the chassis.

I have no idea what part the game refers to as a "bump-stop"

I thought "bump stops" are rubber/poly/alloy bushes that restrict suspension travel.

That they are.

Roger Prynne
14-05-2015, 17:33
Have a look at these images....

https://www.google.co.uk/search?q=bump+stop&es_sm=122&source=lnms&tbm=isch&sa=X&ei=IdxUVeaGM4npUu7KgOAE&ved=0CAcQ_AUoAQ&biw=1345&bih=745&dpr=1.25

And have a read of this....

http://www.autoanything.com/suspension-systems/what-are-bump-stops.aspx

JeyD02
15-05-2015, 04:23
https://youtu.be/5JyKQyAVCfI

Watch it'll illustrate you and give other aspects of the suspension side :)

TMoney
15-05-2015, 04:39
I believe the setting is the actual length of the bumpstop (ie. 25mm). Increasing this will reduce maximum suspension travel or decreasing it will increase travel, or rather not limit it. Setting this too low could cause the suspension to bottom out but too high could unsettle the car.

MULTIVITZ
16-05-2015, 15:22
For a controlled ride a road spring must have a straigt gradual rate through its compression not a peaky rate as it runs out of travel/movement. This is done by way of linkages in the positioning and movement ratio of the road spring. It was found that a low bodied car had more grip by way of the aero effects, but having the body hit the road stopped grip. Riding the car on bumpstops is ok if the dampers can handle the kick back and you're at a speed that generates downforce, but for clean transitions into corners I would not recommend hitting the stops, especially short ones! Off road cars have long bumps that are progressive to protect the occupants and vehicle from extreme shocks, you can tune the bumpstops it makes for much fun. This game has fast and slow bump damper settings, there's no excuse for bottoming unless you like it!!

JeyD02
16-05-2015, 19:01
It's like an extra feature for spring height and "final" stiffness. Usually used when you want to use normal suspension settings but then there are some bumps, holes that maybe harm the cars balance so these bump stop will kick in specially in those tricky bumps and manage to stabilize the car when the travel of the the suspension reaches almost maximum. It just about tame those bumps.

MULTIVITZ
17-05-2015, 01:33
Sorry but no, they should not be used as extra springing for bumpy parts. The setup has to be tailored for bumpstop use if you're going low and soft with high downforce, high bound damping and camber that works with compressed ride height. Its when you see positive camber setups and high caster settings. Makes a car hard to drive, but can give amazing grip from the downforce, I wouldn't recommend it for bumpy tracks as you may get jacking!

JeyD02
17-05-2015, 02:27
Sorry but no, they should not be used as extra springing for bumpy parts. The setup has to be tailored for bumpstop use if you're going low and soft with high downforce, high bound damping and camber that works with compressed ride height. Its when you see positive camber setups and high caster settings. Makes a car hard to drive, but can give amazing grip from the downforce, I wouldn't recommend it for bumpy tracks as you may get jacking!

That's the point.. A "kick baxk" effect otherwise soft and low spring settings sticking the car on ground with bumlstops.

nordoceltic
18-05-2015, 14:46
Thanks for the replies. So far what I am gathering is that bump stops help soften the impact of bottoming out the suspension. That and adding bump-stops compresses the springs leaving less room for suspension travel.

It sounds like adding Bump stop and then re-tuning springs will help is if crossing a kerb or other bump in the track is sending you into the wall/off track but you still wanna run a hard spring rate. Also seems if one is not having a problem it might be best to leave them set to zero. Am I somewhat correct here?

nordoceltic
18-05-2015, 14:53
Thanks for the replies. So far what I am gathering is that bump stops help soften the impact of bottoming out the suspension. That and adding bump-stops compresses the springs leaving less room for suspension travel.

It sounds like adding Bump stop and then re-tuning springs will help is if crossing a kerb or other bump in the track is sending you into the wall/off track but you still wanna run a hard spring rate. Also seems if one is not having a problem it might be best to leave them set to zero. Am I somewhat correct here?

Also I found this: http://www.hotrod.com/how-to/chassis-suspension/ctrp-1106-bumpstops/

According that article bump-stops kinda of increase the progression of spring force as the suspension travels. Thus you can run a softer spring force for better compliance and grip, but the bump-stop lessens body roll to keep more weight on the inside tires during cornering.

MULTIVITZ
25-05-2015, 10:42
Yes. But not all cars can be tuned that way, beause of camber angles getting unstable at the suspensions extremities of movement, or the angle goes out of range for a good contact patch size for the tyre (downforce stops this problem, but tyre can get burnt!). It can hamper direction changes and bumps give the tyres a hard time to. Bound is used to compensate the rebound effect and increased spring rate effect of heavy downforce when its generated. That last sentence is such a massive peice of puzzle to the car tuning picture I'm lucky I don't get shot for writting it in a public forum lol

Doug914
25-05-2015, 14:22
Don't use the bumpstops for anything other than keeping the car off the track. As others have said, start at zero if you can. Their best use is in a low downforce, very low ride height setup for top speed (think Qual F/A at Monza) where everything esle for a lap time takes a back seat. When it comes to handling track, you want to stay off the bumpstops as much as possible. A better compromise is almost always raising the ride height.

DJBLITZKRIEG
31-05-2015, 16:24
Go to youtube and look up a channel called Suspension Truth. a guy called Sheikh, he has whole videos dedicated to bump stops.

Schumi01
02-11-2015, 08:11
Don't use the bumpstops for anything other than keeping the car off the track. As others have said, start at zero if you can. Their best use is in a low downforce, very low ride height setup for top speed (think Qual F/A at Monza) where everything esle for a lap time takes a back seat. When it comes to handling track, you want to stay off the bumpstops as much as possible. A better compromise is almost always raising the ride height.

"Stay of the bumpstops"
Does that mean leave it stock or set them to 0? I've read your post a couple of months ago and I'm tuning them to 0 all the time,but I've found some world record tuner who's using bump stops. So, I'm confused now...

Ian Bell
02-11-2015, 08:19
Sorry for the noobish question but how does one tune the bump stops ? Most guides online don't talk about using bumpstops, and we all know the default set ups on all these cars leaves a lot to be desired.

Basically, they're a last resort to stop you from grounding out. They work better on circuits like Le Mans where running on the bump stops will ensure you have some clearance and aren't grounding and thus losing speed due to grounding friction on long straights. They are a nightmare in corners though if you're leaning on them as they provide little suspension acuity and your car will therefore handle horribly.

Schumi01
02-11-2015, 08:54
Basically, they're a last resort to stop you from grounding out. They work better on circuits like Le Mans where running on the bump stops will ensure you have some clearance and aren't grounding and thus losing speed due to grounding friction on long straights. They are a nightmare in corners though if you're leaning on them as they provide little suspension acuity and your car will therefore handle horribly.

Ah, that's why my car bottoms out on certain tracks...
I've tried raising the R.H, stiffen suspension, dampers ect... but nothing seemed to work.

So, if I understand it correctly: flat tracks=0 bumpstop. Wobbly tracks= 0 bumpstop ---> tune the car, if the car still bottoms out, I add some Bumpstop...?

Ian Bell
02-11-2015, 09:00
Ah, that's why my car bottoms out on certain tracks...
I've tried raising the R.H, stiffen suspension, dampers ect... but nothing seemed to work.

So if I understand it correctly, flat tracks=0 bumpstop. Wobbly tracks= 0 bumpstop ---> tune the car, if the car still bottoms out, I add some Bumpstop...?

Yes but don't lean on the bump stops in fast corners where you need subtle suspension reactions.

Ian Bell
02-11-2015, 09:02
I'd use bump stops sparingly at tracks like Monza (particularly old Monza :) ), Le Mans and others with long long straights and a dearth of very fast well loaded corners.

RTA nOsKiLlS
02-11-2015, 09:03
Basically, they're a last resort to stop you from grounding out. They work better on circuits like Le Mans where running on the bump stops will ensure you have some clearance and aren't grounding and thus losing speed due to grounding friction on long straights. They are a nightmare in corners though if you're leaning on them as they provide little suspension acuity and your car will therefore handle horribly.

Hmmmm, I may have to make some bumpstop changes to my Mclaren Longtail for Nordschleife. I think I have it completely wrong. I'm fairly sure mine are set to max, still managed a 6.09 though. But it could explain why I cannot drive in the Karousel. ;)

Invincible
02-11-2015, 09:13
I'd use bump stops sparingly at tracks like Monza (particularly old Monza :) ), Le Mans and others with long long straights and a dearth of very fast well loaded corners.

You tease, you...

Ian Bell
02-11-2015, 09:16
Hmmmm, I may have to make some bumpstop changes to my Mclaren Longtail for Nordschleife. I think I have it completely wrong. I'm fairly sure mine are set to max, still managed a 6.09 though. But it could explain why I cannot drive in the Karousel. ;)

You're clearly a great driver. Using rubber cones (which basically is what bump stops are) as opposed to standard coil suspension is a tough ask. If you've been successful there I'd suggest raising your ride height and dropping the bump stops as you'll then have much more finesse in the faster corners. Another option is retaining the ride height but stiffening the springs (with an increase on dampers all around to match). This might lose you some mechanical grip in the slower stuff but give dividends in the faster corners. You can mediate this by dropping tyre pressures a tad to get some back in the slow stuff.

Schumi01
02-11-2015, 09:17
I'd use bump stops sparingly at tracks like Monza (particularly old Monza :) ), Le Mans and others with long long straights and a dearth of very fast well loaded corners.

Because of the low R.H, low D.F and soft suspension, right?
I think I get now...

Thx for the info, Ian!

Schumi01
02-11-2015, 09:28
You tease, you...

Lol

Didn't get It until I've read your post...

Ian Bell
02-11-2015, 09:38
Because of the low R.H, low D.F and soft suspension, right?
I think I get now...

Thx for the info, Ian!

Correct.

Jussi Viljami Karjalainen
02-11-2015, 11:38
Just to add, bump stops aren't necessarily super stiff in many cases, for example on the 12C GT3 they're barely stiffer than the springs (though they do obviously add to the springs, so the end result is quite stiff). There's also a big difference between running tall, progressive bump stops and short, sudden ones, you'll hit tall bump stops more often but the overall effect will be smoother. Many road cars in real life have quite soft suspensions and rely on their bump stops to carry them through heavy cornering (Mazda MX-5's for example seem to eat through their bump stops, check Fat Cat Motorsports on YouTube for more on the subject), and many high downforce racing cars with softer suspensions can also easily run into their bump stops at high speeds. Bump stop tuning is also one of the key points of modern NASCAR setup, they want the car to sit really low down after all.

So it is a bit situational (depends on the car, track and overall setup you're running) if they're only a last effort kind of thing, you can use them effectively in other situations as well.

EDIT: Nifty stuff about bump stops: https://www.youtube.com/playlist?list=PL75DC8BAD62876251

Schumi01
02-11-2015, 12:48
Don't make this harder than it already is, Jussi :p

Thx for the info bud.

Umer Ahmad
02-11-2015, 13:31
There's some heavy bump stop R&D in NASCAR. Indycar pretty close to a spec series also has intense focus on dampers as thats where teams are allowee to deviate a little.

"The front shocks on cars are what we like to call 'aero inhibitors,' " Golder said. "On the front shocks, we have bump stops and we fine tune them to affect the attitude of the race car, to try to keep the nose down. There's a great comprise between running a softer bump stop, which is going to feel better to the driver, verses a stiff stop that's going to keep the nose down and keep the car sealed down to the race track and help improve the aerodynamics."

http://www.nascar.com/en_us/sprint-cup-series/nascar-nation/nascar-edu/mobil1-technology-hub/nascar-mobil1-technology-shocks-profile.html

Video here
http://www.nascar.com/en_us/news-media/franchises/race-center.sprint-cup-series-phoenix-international-raceway-race-center-extra-bump-stops.3876850892001.html

havocc
02-11-2015, 13:51
I'd like to point out that "bump stop" is translated as "paraurti" in the italian client and this can be misleading since "paraurti" means "bumper" http://www.revozport.com/mclaren/images/products/rhz-front-bumper/mp4-12c--rhz-front-bumper.jpg

Schumi01
02-11-2015, 13:56
Does this approach for bumpstop tuning also counts for openwheelers? Or is it more a street/race car thing?

Jussi Viljami Karjalainen
02-11-2015, 14:12
It applies to everything, but if you suspension is already super duper stiff (as it often is on high end open-wheelers) it's probably less likely to crop up.

hkraft300
02-11-2015, 16:38
Are they a set stiffness? Variable (softer with increasing size, judging by the rubber cone reference)?
Still not hard to squash them and bottom out.
The GT3 cars don't need them. The LMP900 cars sit on them comfortably down Mulsanne or any long straight. The P30 needs ~25mm bump stop and it's of little benefit to reduce scraping. At that size they seem so soft you may as well up the ride height and stiffen the springs by a click or 2.

Schnizz58
02-11-2015, 16:45
Are they a set stiffness?
I think the smaller they are, the stiffer they are.

Jussi Viljami Karjalainen
02-11-2015, 16:52
Yeah, thicker ones are more progressive, ramping up in stiffness slower, while thinner ones get stiffer really quickly. Hence the trade-off of hitting the more often with thick ones but the effect being more subtle, vs. hitting them rarely with thin ones but it being more noticeable.

Umer Ahmad
02-11-2015, 17:10
I think he means "in the game are the bump stops all the same thickness/resistance and are we only adjusting the heights?"


I dont exactly know (Casey?) but i think we do not have access to this, we can only control the heights.

Jussi Viljami Karjalainen
02-11-2015, 17:25
I think he means "in the game are the bump stops all the same thickness/resistance and are we only adjusting the heights?"


I dont exactly know (Casey?) but i think we do not have access to this, we can only control the heights.And IIRC Casey explained that thicker settings result in more progressive, softer responding bump stops. We can't adjust the stiffness directly, but the thickness does affect it already.

Schnizz58
02-11-2015, 17:35
While we're on the subject, I have a question about the bottoming out sound. Obviously that happens when you bottom out for real but my question is do you also hear that scraping noise if you hit the bump stop? Early on someone said that you do but I never saw any confirmation of that.

Jussi Viljami Karjalainen
02-11-2015, 18:19
Yeah, I'd love to get confirmation on that myself. I seem to recall that one of the sound devs said that that's how it works, but I can't remember for sure.

EDIT: Ach, managed to actually find the post I was talking about:


For some reason we have audio when the bumpstops make contact in the travel. So it almost sounds like you are bottoming on the track. It's confusing and of course they don't make any noise IRL as they are a sponge rubber type material or just rubber depending.. Should be removed IMHO.This was in Dec 2014, so I'm not sure if it was changed or not, but I'd guess not.

RTA nOsKiLlS
02-11-2015, 18:36
You're clearly a great driver. Using rubber cones (which basically is what bump stops are) as opposed to standard coil suspension is a tough ask. If you've been successful there I'd suggest raising your ride height and dropping the bump stops as you'll then have much more finesse in the faster corners. Another option is retaining the ride height but stiffening the springs (with an increase on dampers all around to match). This might lose you some mechanical grip in the slower stuff but give dividends in the faster corners. You can mediate this by dropping tyre pressures a tad to get some back in the slow stuff.

Cool, thanks for the tip.....I'll have a go later on. :)

RTA nOsKiLlS
03-11-2015, 12:40
http://s22.postimg.org/b533b9s69/telemetry.jpg

What is the red part telling me? Bottoming out?

Umer Ahmad
03-11-2015, 12:50
means you're hitting the bump stop.

azidahaka
03-11-2015, 12:51
I think no more suspension Travel .

Fong74
03-11-2015, 12:52
means you're hitting the bump stop.

Correct. But there is a bug with the left front bump stop for quite some time now. It lights up occasionally on almost all cars without your car really bottoming out.

hkraft300
03-11-2015, 13:06
http://s22.postimg.org/b533b9s69/telemetry.jpg

What is the red part telling me? Bottoming out?

You're not bottoming out in that pic. Your height reads 1.8" so that means you still have clearance from ground. Travel is also at 1.8" so you still have room for your suspension to move.

RTA nOsKiLlS
03-11-2015, 13:33
Correct. But there is a bug with the left front bump stop for quite some time now. It lights up occasionally on almost all cars without your car really bottoming out.

Ahhh, maybe that explains why I couldn't stop it happening. I put it to full ride height, and tried the springs on various rates and the front left kept flashing red.