-
Please only use these forums for blogs, they are not a discussion forum
1400 rally car shenanigans
- Thread starter Huggy444
- Start date
pollyp
Club Member
with the gtir calipers and tiny stock MC, mine used to brake ok when cool on public roads but only applied approx 60% braking on the first pump when it's fully hot on track (felt like boiled air, the MC simply couldn't push enough fluid).
so I had to always double pump the pedal to get full braking, which upsets balance & confidence.
afew tips:
- firstly, if any air has ever entered the MC or tis been disturbed, fully bleed all air out the MC
- most MC I seen have a gap between when the pistons fully resting extended out, and when the piston shuts off the reservoir and begins pumping fluid to the brakes.
eliminating this dead-zone gap will result in a shorter pedal travel, immediate braking, braking bite-point moves higher & sooner.
1. adjust the threaded piston shaft / pedal bracket nut till the bite point feels right,
2. now connect a long clear tube to the MC outlet port nearest the booster,
3. push the pedal down once to pump some fluid partially along the visible tube (not to the end) and hold,
4. blow into the open end to apply & maintain pressure, the fluid shouldn't move whilst pedals held down,
5. now slowly raise the pedal until the fluid just begins to move and set this pedal position as ur rest stop point (with ziptie or fit an adjustable rest stopper),
6. adjust brake switch position.
- the throttle & brake pedals relative travel range & resting points are quite adjustable but too long for me to explain.
- if it only feels stiffer & brakes harder after double pumping, even after eliminating the dead-zone, u need bigger MC.
OP
OP
Bloody hell, a good few things for me to play with!
You say bleeding all air out of MC, by that you mean just bleed the whole system I assume?
And how would I adjust the dead-zone gap, is it another screw/thread on the on MC?
I'll play around next week as I'm off college and work
You say bleeding all air out of MC, by that you mean just bleed the whole system I assume?
And how would I adjust the dead-zone gap, is it another screw/thread on the on MC?
I'll play around next week as I'm off college and work
pollyp
Club Member
look at video at bottom of this post and the posts afterwards
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-126#post-716153
just explained how to adjust dead-zone there
there are many things to tweak when u know how they all work
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-126#post-716153
just explained how to adjust dead-zone there
there are many things to tweak when u know how they all work
OP
OP
look at video at bottom of this post and the posts afterwards
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-126#post-716153
just explained how to adjust dead-zone there
there are many things to tweak when u know how they all work
If I double pump when driving the bite point stays the same so I guess that is kind of good news
I'll reread all the above and watch the video in the morning, tis a bit heavy to read at this time of night
Thanks Paul, I'll be sure to pester you if I have any more questions haha
I can see the benefits of the progressive feel, just makes the bite point a bit lower making it feel odd when heal/toe'ing on shifts...
Haha, the logical solution then is to buy myself some AP callipers?
It's probably a little different for me as I run servo-less, so there's a bit more sensitivity with respect to pedal loads than with a servo.
I'll have to carry out an on track test for sure, as you really can't use this particular setup in anger on the road
OP
OP
It's probably a little different for me as I run servo-less, so there's a bit more sensitivity with respect to pedal loads than with a servo.
I'll have to carry out an on track test for sure, as you really can't use this particular setup in anger on the road
So with the primera MC you'd have a stiffer pedal due to it displacing a larger volume of fluid with one pedal depression? Got it.
Those callipers do look nice, usually used on mk1/2 escorts if my reading is correct? Very fancy!
Still want to organise a micra trackday meet, get the trackday/turbo/rally micras together for a bit of fun
pollyp
Club Member
the pedals stiffness / travel vs braking force is a subjective personal preference.
at the point where the brakes begin to bite:
- some drivers like a stiff/short pedal travel (to keep it level with throttle pedal for consistant heel toe)
- others like a soft / long travel pedal for better threshold braking control
- and various levels of pedal force vs braking force (sensitivity)
its all affected by many parts of the braking system combined, hydraulically & mechanically, including at least:
caliper/MC volume ratios,
caliper/MC travel range,
servo size & travel,
front/rear pad CoF & working temps,
disc cooling,
brake hose stiffness,
brake pedal total travel,
pedal vs MC shaft leverage ratio,
rest point - bite point deadzone,
bite point vs throttle rest point relation,
throttle pedal total travel & rest point,
etc etc
I found the primera MC to be wayy too long and fouled the engine.
I upgraded to a citreon C3 MC so that the moment I stamp on those brakes I can be guaranteed I have 100% braking which boosts confidence.
when things are all stone cold on street roads, the pedal will obviously feel alot stiffer & begins biting at slightly higher point.
whereas wher they're all very hot & soft & grippy when pushed on track, the pedal will soften slightly, bite point lowers till it levels with the throttle and the sensitivity increases as the pads & tyres all get in their grippy working temp zone.
also note that given enough time, we all tend to eventually adapt to the various car control sensitivity (like going between the hard responsive kasandra and the super assisted & floppy french peugeot 307). some drivers adapt faster than others.
when there's no time to adapt, such as rushing between spare cars or quickly prepping a new car in motorsport, then we adapt the cars control factors to suit the drivers expectations & preference to quickly get on with it.
tis been a loooong time since we been to blyton
at the point where the brakes begin to bite:
- some drivers like a stiff/short pedal travel (to keep it level with throttle pedal for consistant heel toe)
- others like a soft / long travel pedal for better threshold braking control
- and various levels of pedal force vs braking force (sensitivity)
its all affected by many parts of the braking system combined, hydraulically & mechanically, including at least:
caliper/MC volume ratios,
caliper/MC travel range,
servo size & travel,
front/rear pad CoF & working temps,
disc cooling,
brake hose stiffness,
brake pedal total travel,
pedal vs MC shaft leverage ratio,
rest point - bite point deadzone,
bite point vs throttle rest point relation,
throttle pedal total travel & rest point,
etc etc
I found the primera MC to be wayy too long and fouled the engine.
I upgraded to a citreon C3 MC so that the moment I stamp on those brakes I can be guaranteed I have 100% braking which boosts confidence.
when things are all stone cold on street roads, the pedal will obviously feel alot stiffer & begins biting at slightly higher point.
whereas wher they're all very hot & soft & grippy when pushed on track, the pedal will soften slightly, bite point lowers till it levels with the throttle and the sensitivity increases as the pads & tyres all get in their grippy working temp zone.
also note that given enough time, we all tend to eventually adapt to the various car control sensitivity (like going between the hard responsive kasandra and the super assisted & floppy french peugeot 307). some drivers adapt faster than others.
when there's no time to adapt, such as rushing between spare cars or quickly prepping a new car in motorsport, then we adapt the cars control factors to suit the drivers expectations & preference to quickly get on with it.
tis been a loooong time since we been to blyton
OP
OP
Yeah I've only driven the car a few times since the brake upgrade, and it's only when I slam on the brakes hard that I notice the extra travel... I guess I'll have a quick play around before the rally on the 20th at Blyton, and see how it fares
@pollyp im usually always good to go and do a track day, might set up a thread and see if we can get a few people along
@pollyp im usually always good to go and do a track day, might set up a thread and see if we can get a few people along
Mat Humphries does a larger m/c that is a straight swap. Its around £150.
OP
OP
Yes... But, that MC is from another Nissan of some make, and is worth like £20/30 from a scrap yard
pollyp
Club Member
aye could do with trackday round april when it starts warming up, whether andys ready or not
prefer the days where blytons bout £100 all daycould do more to improve kasandras suspension cos I now realised her roll center was actually dropped far below her CG from lowering abit and having such high braking/power force, which may partially explain why she rolls SOO much and inherently understeers badly unless I intentionally deflate the fronts.
but that's a later to-do list, she's always ready to go at will.
OP
OP
aye could do with trackday round april when it starts warming up, whether andys ready or not
could do more to improve kasandras suspension cos I now realised her roll center was actually dropped far below her CG from lowering abit and having such high braking/power force, which may partially explain why she rolls SOO much and inherently understeers badly unless I intentionally deflate the fronts.
but that's a later to-do list, she's always ready to go at will.
Ohhh getting very technical, you've increased the moment between the RC and CG so get more roll.... Try telling this to most people, 'The lower the better' is there reply
March would be better for me as no rallies, but I'll look at some dates for Blyton
I know but you're getting a brand new part. I thought £150 was quite cheap. For that price I just can't be bothered messing in Scrapyard's. Not at my age now anyway. Lol.
pollyp
Club Member
citreon C3 MC was just £15 at scrappy, micra reservoir pops on, with some minor tweaking it'll slot into the k11 servo
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-124#post-714406
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-124#post-714406
Ohhh getting very technical, you've increased the moment between the RC and CG so get more roll.... Try telling this to most people, 'The lower the better' is there reply
March would be better for me as no rallies, but I'll look at some dates for Blyton
One of the reasons why I've never lowered a K11 below ~35mm even when upgrading to BC BR coilovers.
I'd be up for a track day but only on a dedicated track and not an old aerodrome.
I'll likely eat my words at some point re: M/S size. Having swapped the APs out over a set of AD22VF I can say there's significantly less dead zone and a firmer pedal. I'd expect that to be primarily down to much tighter running clearances and no doubt better rigidity within the caliper itself. It is however a fresh start, so I'll see how I get on...
I'll have a closer look and see if there's any room for improvement based on Paul's experiences on adjustment.
All I can now is they're plenty powerful enough from cold on a run of the mill M1144 pad and when hot your face comes off pretty easily
OP
OP
Tis a fair point, makes it nice and easy as you know it'll fit straight on with no issuesI know but you're getting a brand new part. I thought £150 was quite cheap. For that price I just can't be bothered messing in Scrapyard's. Not at my age now anyway. Lol.
So me, you and Polly all run the BC's - Very nice coillies imo
The track we usually go to is Blyton Park, re-tarmacked recently and is beautifully smooth, open pit lane track day is around £109 midweek, and a few pennies more for a weeken day. Nothing to hit there either,very nice runoff space on all corners
pollyp
Club Member
Ohhh getting very technical, you've increased the moment between the RC and CG so get more roll.... Try telling this to most people, 'The lower the better' is there reply
March would be better for me as no rallies, but I'll look at some dates for Blyton
was just reading more into suspension & roll centres, which I found interesting to explain kasandras symptoms & how to fix but can read so much that the brain stalls lol.
most ppl may assume that lowering the whole chassis ride height will lower the CG for less weight transfer, or better aero, or just looks nice cos it tries to replicate those dedicated race car from a different environment onto a street car.
but not many ppl are aware of or even consider all the other hidden consiquences for each action, such as roll center and real-world obstruction ground clearances, which could actually work against the main assumption and end up with a worse car.
takes alot of knowledge, skill & experience for a designer/engineer/technician/team to "balance" every single aspect of the vehicle to obtain the best solution "formula" to suit that user/client/team/customer needs.
just like balancing / moderating the right amount & quality of ingredients for a tasty food. you don't just simply shuv a tanker full of salt over a bag of chips with no considerations or it'll be ruined.
looks like blyton does the £109 full days on feb 21 and wednesdays march 9, apr 13/27
pollyp
Club Member
One of the reasons why I've never lowered a K11 below ~35mm even when upgrading to BC BR coilovers.
I'd be up for a track day but only on a dedicated track and not an old aerodrome.
I'll likely eat my words at some point re: M/S size. Having swapped the APs out over a set of AD22VF I can say there's significantly less dead zone and a firmer pedal. I'd expect that to be primarily down to much tighter running clearances and no doubt better rigidity within the caliper itself. It is however a fresh start, so I'll see how I get on...
I'll have a closer look and see if there's any room for improvement based on Paul's experiences on adjustment.
All I can now is they're plenty powerful enough from cold on a run of the mill M1144 pad and when hot your face comes off pretty easily
this roll center issue is one of kasandras biggest issue holding her back. was considering buying/making some lower balljoint & tie-rod joint extensions to correct the arm angles & roll centers for the new height.
luv it when the semislicks & pulsar pads are all sticky hot and from left-foot braking hard as I can, I feel my cheeks being ripped off lol
pollyp
Club Member
it could either be an £££ custom balljoint, Or tis just as simple as a lathed threaded extension. would be nice if roll center adjustment kits exist for micras but can't imagine a simple lathed bit will be too dear. need to look at afew machinists.
it's a "nice to have" mod cos imo this is the next weakest link holding back her potential but it ain't essential and just part of the development cycle.
h701micra
Deactivated Account
But apparently because I don't know much in the professional sense of engine tuning and power. I'm deemed clueless by know-nothing-done-nothing wanna-bes who seem to know everything about my job
Give me suspension any day of the week
Paul, do you remember this webpage:
http://www.motoiq.com/MagazineArtic...in-the-Geometry-Part-One-The-Roll-Center.aspx
There's a picture on the last page is a picture of modified B14 Sentra bottom arms that had been modified with "longer Chrysler parts".
Nissan likes sharing parts between models and a B14 doesn't seem that much larger than the micra, so it might use the same taper as the Sentra?
The bottom arms seem similar to the Micra's so it would seem the same mod might work... you've got a couple spare bottom arms don't you?
pollyp
Club Member
Paul, do you remember this webpage:
http://www.motoiq.com/MagazineArtic...in-the-Geometry-Part-One-The-Roll-Center.aspx
There's a picture on the last page is a picture of modified B14 Sentra bottom arms that had been modified with "longer Chrysler parts".
Nissan likes sharing parts between models and a B14 doesn't seem that much larger than the micra, so it might use the same taper as the Sentra?
The bottom arms seem similar to the Micra's so it would seem the same mod might work... you've got a couple spare bottom arms don't you?
ah yea I was looking at that too, something to look into.
I've chucked my old arms away
I was thinking last night about this, there's something about that setup I don't understand, if when you are working out the roll centre you join the lower ball joint and the lower arm pivot then the arms pictured seem to change neither of these?Paul, do you remember this webpage:
http://www.motoiq.com/MagazineArtic...in-the-Geometry-Part-One-The-Roll-Center.aspx
There's a picture on the last page is a picture of modified B14 Sentra bottom arms that had been modified with "longer Chrysler parts".
Nissan likes sharing parts between models and a B14 doesn't seem that much larger than the micra, so it might use the same taper as the Sentra?
The bottom arms seem similar to the Micra's so it would seem the same mod might work... you've got a couple spare bottom arms don't you?
Yes the arm now points further down (which makes it look as though things have changed) but the ball joint / pivot point is still at the same position??? so the bottom arm has just sort of changed shape?
Where have got it wrong?
h701micra
Deactivated Account
Roll centre is the imaginary line through the centre of the wheel and inboard mount/pivot of the lower armI was thinking last night about this, there's something about that setup I don't understand, if when you are working out the roll centre you join the lower ball joint and the lower arm pivot then the arms pictured seem to change neither of these?
Yes the arm now points further down (which makes it look as though things have changed) but the ball joint / pivot point is still at the same position??? so the bottom arm has just sort of changed shape?
Where have got it wrong?
You're correct in what your saying with that arm not having much difference except it's area of travel altered
I only skim read the article, I'm going off your previous post) but if somewhere in there they did lengthen (or even shorten) that arm then you'd affect Roll Centre
I understood that the relevant points were the a line going through the ball joint and the centre of the inboard suspension pivot... the other line comes at 90 degrees to the strut from the top of the strut.
It's an awful picture but shows what happens to roll centre for a lowered car with Macpherson struts
They are trying to readdress what's happened to the roll centre as the car has been lowered, if they can move the ball joint down it will help, my question is: if where the ball joint pivots remains the same relative to the hub it won't make a difference how long the ball joint or how far down the arm because the instant centre is a line joining the pivot points not a line along the suspension arm.
I don't know if they lengthened the bottom arm but I imagine it would effect camber more than anything? but yes would effect roll centre too...
My brain is saying that where the ball joint pivot needs spacing down rather than the lower arm being moved down (but the pivot remaining at the same spot) which seems to be what the longer ball joints would do, maybe you'd have to have them in your hands to really see what's going on...
h701micra
Deactivated Account
You're quite right. I almost quoted my own posts and corrected it then realising it was me that said. Things we say in a rush eh. I'm not even sure how a line through tyre centre and inboard mount would even help
That's a much clearer photo of roll centre (if it works)
Now I'm back on track,
Their idea checks out for raising roll centre as the point of intersection is sooner for the drawing
When you consider the equation involving roll centre the length of the arm comes into play. It'll affect camber curve for sure, but it'll also affect the moment radius in the equation. It'll also affect scrub radius. Lower moment radius = higher roll centre
Food for thought
Considering that manufacturers aims for low front roll centre and high rear, and you see the length of the moment arms involved vs front to rear its a real world example if you was to notice it
That's a much clearer photo of roll centre (if it works)
Now I'm back on track,
Their idea checks out for raising roll centre as the point of intersection is sooner for the drawing
When you consider the equation involving roll centre the length of the arm comes into play. It'll affect camber curve for sure, but it'll also affect the moment radius in the equation. It'll also affect scrub radius. Lower moment radius = higher roll centre
Food for thought
Considering that manufacturers aims for low front roll centre and high rear, and you see the length of the moment arms involved vs front to rear its a real world example if you was to notice it
Last edited:
OP
OP
Jack Neal Blyton 2016 rally Summary:
Had to drive the car to the event as had no parents around to tow the car for me, so packed it full of stuff and drove the hour and a half journey - got there slightly deaf but all good
Unpacked and met Andy, @h701micra, who was servicing for me out of the kindness of his heart! Seeded 4th in class of 10.
Stage 1: first corner of first stage, I pressed on my brakes and just span around like a ballerina... This was a recurring theme throughout this stage! That is until I cooked the pads and lost some liquid through a leaky bleed nipple. Back in service and Andy tried to sort in the 15 minute break.
Stage 2/3: good pace but still struggling with brake issues, soft pedal and no matter how much I pumped the brakes did very little - leading us to assume the pads were glazing so Andy cleaned the pads up the best he could.
Stage 4: better braking but pedal still lost feel, and Andy spotted a leak from a nipple.
Over lunch Andy bled the whole system and got a bit of air out, pedal felt better but still not quite right.
Rest of stages: struggled on with the brakes, made the best of it. Pace was still very good, made it back to 2nd in class and 4 seconds off 1st in class - we caught 1st in class, John Savage in his mini clubman, on the stage where we saw him pull off with a mechanical issue.
So we finished up 1st in class with a lead of 2 minutes, very good day apart from the brakes!
Day was made all the better as I had a freind from college codriving for me (his first event) so was good to win him a trophy.
Had to drive the car to the event as had no parents around to tow the car for me, so packed it full of stuff and drove the hour and a half journey - got there slightly deaf but all good
Unpacked and met Andy, @h701micra, who was servicing for me out of the kindness of his heart! Seeded 4th in class of 10.
Stage 1: first corner of first stage, I pressed on my brakes and just span around like a ballerina... This was a recurring theme throughout this stage! That is until I cooked the pads and lost some liquid through a leaky bleed nipple. Back in service and Andy tried to sort in the 15 minute break.
Stage 2/3: good pace but still struggling with brake issues, soft pedal and no matter how much I pumped the brakes did very little - leading us to assume the pads were glazing so Andy cleaned the pads up the best he could.
Stage 4: better braking but pedal still lost feel, and Andy spotted a leak from a nipple.
Over lunch Andy bled the whole system and got a bit of air out, pedal felt better but still not quite right.
Rest of stages: struggled on with the brakes, made the best of it. Pace was still very good, made it back to 2nd in class and 4 seconds off 1st in class - we caught 1st in class, John Savage in his mini clubman, on the stage where we saw him pull off with a mechanical issue.
So we finished up 1st in class with a lead of 2 minutes, very good day apart from the brakes!
Day was made all the better as I had a freind from college codriving for me (his first event) so was good to win him a trophy.
Last edited:
OP
OP
We were also chasing a subaru throughout the day, at one point we were 11 seconds in front of him but we backed of after John and his mini had a mechanical (no point binning my car and not being able to get home as no trailer). Subaru ended up beating me by just 2 seconds!
Just ordered a new almera p10 master cylinder to try and improve the brakes.
Still having an engine stutter at high RPM even with new coilpacks and throttle body - will replace the fuel pump and change the injectors to see if this helps.
Just ordered a new almera p10 master cylinder to try and improve the brakes.
Still having an engine stutter at high RPM even with new coilpacks and throttle body - will replace the fuel pump and change the injectors to see if this helps.
Last edited:
OP
OP
16€ from China, supposedly good quality according to reviews, might get one myself.
DYNO RACING - New Brake Bias Valve Lever Type Adjustable Proportion Porp Valve For racing Car
http://s.aliexpress.com/JNv2IBB3
(from AliExpress Android)
DYNO RACING - New Brake Bias Valve Lever Type Adjustable Proportion Porp Valve For racing Car
http://s.aliexpress.com/JNv2IBB3
(from AliExpress Android)
SuperUno
Buy & Sell Member
Do it! They are very useful for altering handling, probably the best brake 'upgrade' after moving to vented discs.
Are they any use on a stock setup?
frank
Club Member
I'll pm you so not to clog up the post as its off topic
OP
OP
Saw them, nice and cheap - next time I destroy a mirror I'll buy them
pollyp
Club Member
load compensators were fitted for road safety just to prevent the efficient rear drum brakes from locking up first by delaying the flow.
rear discs are inherently less efficient so need more pressure.
in motorsport you need reliable consistant adjustable brake bias,
so I'd agree with all the guys that I'd very highly recommend removing the old compensator and fit a bias valve to control the braking balance. it's importance is right up there with the adjustable dampers.
and remove the old ABS system, no good for braking stability or braking performance.
is the P10 MC non-abs? cos an ABS mc will have 4 ports while the non-abs only has a simpler 2 for the front & rear.
to fit a bias valve you'd need to remove/bypass the load compensator and delete the cross-diagonal brake plumbing by joining both sides at the front & rear then run the rears through the bias valve.
rear discs are inherently less efficient so need more pressure.
in motorsport you need reliable consistant adjustable brake bias,
so I'd agree with all the guys that I'd very highly recommend removing the old compensator and fit a bias valve to control the braking balance. it's importance is right up there with the adjustable dampers.
and remove the old ABS system, no good for braking stability or braking performance.
is the P10 MC non-abs? cos an ABS mc will have 4 ports while the non-abs only has a simpler 2 for the front & rear.
to fit a bias valve you'd need to remove/bypass the load compensator and delete the cross-diagonal brake plumbing by joining both sides at the front & rear then run the rears through the bias valve.
OP
OP
Cars a non abs car anyway, and the p10 mc is also non abs so that's all good
I think Andy sorted the system to make installation of a bias valve fairly easy when my brake pipes went internal, but I'll be leaving installing a bias valve to either Andy or a local company (don't trust myself haha)
pollyp
Club Member
Cars a non abs car anyway, and the p10 mc is also non abs so that's all good
I think Andy sorted the system to make installation of a bias valve fairly easy when my brake pipes went internal, but I'll be leaving installing a bias valve to either Andy or a local company (don't trust myself haha)
nice, should be a doddle to fit then
