Tuesday, February 05, 2013

short stroked ?

rear trailing arm and torsion beam which has a separate coil spring and absorber setup, the spring tends to sag when the suspension drops... how much the arm drops depends on the length of the absorber... if u have a short stroked absorber, its fine because the drop is not significant... but if u have a normal stroke absorber, u have to becareful if the spring might just drop out of the seats... yes, a fairly shortened spring can drop out when the arm drops too low... this is what exactly happen to my current myvi rear spring + HWL absorber setup... when the car is jacked up, the rear trailing arm drops and the spring can be easily removed from the spring seat... this is very dangerous as the car hops over bumps, the spring might drop out and hit other cars... apparently this problem was also faced by our early batu tiga super saga racers... what they did was to tie a belt around the arm to the chassis so it does not sag that much... it was a crude but effective method... so, here is an innovation of their creation...
its kind of noisy when the suspension hops around... so if u can find a thicker and beefier belt or strap is much better...

oem rear spring

as most saga iswara owners who had coilovers knew our adjustable suspension ain't really a full adjustable suspension kit... the front one yes... but the rear ones are just normal absorber and sport spring... if u buy off the shelf coilover kits its perfectly fine for street use... but if u are looking for something slightly more motorsports (stiffer rate springs), u are going into a headache... front ones u can swap to any aftermarket coilover springs with stiffer spring rate as most coilovers shares the same dimension... as for the rear ones, manufacturers usually just make 1 spring rate and they did not even bother to specify the spring rate for that... as my previous post mentioned i did uprated my front springs to 8 kg/mm... this will upset the handling a little, depending on how u want the car to be setup... for my preference, i hate understeer... i prefer the car to be a little more tail happy... hence, uprating the rear springs is a must... picture below is comparison between HWL rear spring and saga iswara OEM spring... stiffness is more or less the same... only difference is the lowered height... hence u will get a slightly lowered ride height after installing it...
fortunately for us, saga iswara has been on our soil for over 20 years... many many of our elder generations had spent countless time and money on improving and upgrading them... as aftermarket support is not strong during the early days, many resort to searching for compatible halfcut parts... a few popular rear spring choice were from Mitsubishi SuperTouring, Honda SM4 as well as Mercedes W124... these are plug and play springs but requires some trimming to achieve the correct ride height... many do not realise saga iswara rear springs do share the same dimension with Perodua myvi rear springs... and much to my surprise, myvi rear springs are far stiffer compare to saga iswara oem rear springs, considering myvi is a small hatchback car... credits have to be given to my long-time friend Zaini for the information as well as his sacrificial springs for me to test it... so here we are comparison between HWL spring, saga iswara OEM spring and myvi OEM spring... note that the myvi spring had been trimmed to achieve the same ride height as before...
actually i've trimmed even more than this... total of 2 loops each side.... now the car fender sits flush with the wheels...
the car now handles beautifully on flat corners... noticeable decrease in body roll and much more confidence through the corners... with further tweak on the front camber and toe angle, a balanced handling can be achieve...

Saturday, December 29, 2012

6k to 8k spring

during the previous dato sagor track day i did addressed that my front suspension setting need to be revised... current 6k spring is suitable for street application but when it comes to track day racing, the body roll is just tremendous...
in such situation, the sensible thing to do is to upgrade the anti roll or front sway bar to beefier ones... unfortunately, the only available sway bar upgrade for my car is costly and only improves a tad bit... weighing the performance per cost ratio, i went for aftermarket uprated springs...
these were 220/80... which translates to 220mm in height with 8k static spring rate load... comparison between my 6k HWL spring and the new aftermarket 8k spring...
it is mostly a direct swap as both spring has same diameter... in fact, most aftermarket coilover springs have same diameter unless specified... thus, no harm getting them checked to make sure they are the same diameter... or else they will not sit well on the spring seat...
how it looks like when assembled... i got the spring seat adjusted to the lowest position...
take note that when u increase the spring load rate with same height position, ur car will eventually sit higher than before... this is because the car weight remains constant... when u increase the spring rate, the spring will no longer compress as much as before... so much so in my case after i've swapped to 8k spring with spring seat adjust to the lowest position, the car still sits 2 finger gap in between wheel and fender arch...

shift extender

why would you install a shift extender with a short shifter??... wouldn't it defeats the purpose of installing the short shifter in the first place??... these were a few common questions came when i custom fabricated this 3 inch shift extender...
as those who installed or even used common aftermarket short shifter before, it generally takes a little more effort to change gears due to the shorted pivot point to the gear knob... with the shift extender in place, there are a few added advantage... first foremost, it reduces the effort slotting in and out gears... travel distance from your steering to the gear knob shorted significantly... some might not view this is as important but fast upshift/downshift requires your hand to locate the shift knob accurately without looking at it...
as for shift travel, i would not say back to stock standard... it is some sort in between stock shift travel and normal short shift travel... all in all, this definitely improves the driving feel to the car... makes shifts in between gears much more pleasure...

Sunday, December 02, 2012

Top overhaul (pt III)

continue from part II... with the some help and a special tool, valve seal were snapped into place, valve spring were compressed and retainer was locked in place... apply lubricant generously all over the camshaft before u slit it in...
double check the engine bay... rewire and retuck those messy hoses and wirings...
1mm metal head gasket were used... copper spray were sprayed generously to the front and back of the head gasket to ensure even seal all across the head gasket... this is the most vital part of the head assembly...
a friend of mine who works at proton service center overlook my head assembly process... he even smuggled proton torque wrench so i could get my cylinder head torqued down properly...
there were a few steps (which i could hardly recall) in torquing the head down... starts from a relatively lesser torque, only to move on to the specific required torque... this allows the head to pre-sits evenly on each corner before proceeding to further tightening all of them...
after the cylinder head were torqued down, the intake manifold were next in place... i sandwich 2 normal paper gasket in between the teflon gasket to ensure no vacuum leakage... PTFE (or teflon) intake manifold gasket were made popular because it reduces heat soak on the intake manifold... teflon melting point is way above 200 deg Celsius... it acts as a good heat insulator to prevent heat from the cylinder head transferred to the intake manifold... cooler intake means denser air, which means more horsepower...
thermostat were also replaced with lower temperature rating ones from SARD... normal ones were rated at 82degC while this is at much lower 71degC...
there were not many photos after this as my hands were dirty and oily... its basically bolting on back parts and connecting the wires accordingly... a little wire tuck was done and cam cover studs were replaced with visually pleasing stainless steel allen key bolts... thick mineral engine oil were first poured in for the first 1000km run... thicker oil allows better lubrication on rotating parts because most of the old oil dried up 1 month since the top overhaul project started... initial start up was a little hard as we cranked the engine until battery flat... got the battery charged up at nearby workshop and resume cranking the next day... eventually it fires up... after the 1000km engine seasoning, the oil were drained and new TOTAL 10w40 fully synthetic were poured in... tappet were re-adjusted and everything ran smoothly afterwards...

Top overhaul (pt. II)

continue from part I...
the cylinder head was cleaned thoroughly with chemical to remove away all oil and carbon residue... because this cylinder head was from the old carburetored engine, the intake studs were shorter than those on fuel injection cylinder heads... i removed all of the intake studs and had them replaced with slightly longer stainless steel ones... this allows me to use teflon intake manifold gasket...
the next all important step is valve grinding... bought some grinding paste and took the whole afternoon grinding down each valve to make sure they sit well and no compression loss allowed...
and then finished by using AUTOSOL to ensure perfect seal...
valve spring were also uprated to stiffer ones from JASMA... they were claimed to have the same spec with RPW valve spring... see if you can differentiate between them both...
retainers were also replaced with light weight titanium retainers from JASMA... they are definitely lighter in weight compare to oem ones... unfortunately i forgot to scale them before installing...
viton valve seal were called in to prevent oil seeping into the combustion chamber...
to be continued...

Sunday, August 26, 2012

Top overhaul (pt. I)

this is probably my most ambitious DIY by far... top overhaul done at home... i'll break it down part by part as it took me ridiculously 1-2 month time to complete... i could not progress much daily as i only able to work on the car at night after work and during the weekends... with limited appropriate tools and knowledge, i dived into it... well, u'll never learn until u get your hands dirty right??...

first stage... stripping... remove all cables, wires, belts, pulleys, cam cover, rocker arm, camshaft, distributor, intake manifold, exhaust manifold, etc... it may sound easy but true to say that it will never will when u get your hands on it... in fact there are some steps and procedure to follow, in which i didn't... among all, is u must remove the water pipe before loosening the head studs... if the water is not drained out from the water jacket, it will get into the combustion chamber when u loosen the cylinder head...



u will also need good quality tools to remove the head stud... u don't want your tools to flex and break apart when removing the head studs... i damaged most of the head studs because i was stupid enough to use the wrong box socket... great relief with the help of expert in hand, i manage to get all damaged head stud out safely... it is important to have all damaged head studs replaced with original ones... original studs are built in a way if it snaps during tightening, it snaps at the center of the rod... in this way u will still able to get the cylinder head out and the broken studs out...

after the cylinder head is removed, it is washed thoroughly with petrol and chemical... all carbon cake "baked" over the years were scrubbed off... i took my time to clean the external of the block and gearbox from oil stain and dirt with strong chemical... it is important that after cleaning the piston and combustion chamber, u coat it with a layer of WD40 to prevent the sleeve from rusting away... spray generously all around the combustion chamber when the piston is at bottom dead center... rotate the crank and do the same for the rest of the chambers...



to be continued...

Achilles 123

Achilles 123... Was once used as official tyre for the MME endurance race in Sepang... tread wear rated at 200 with traction and temperature rated at A respectively...



i bought this pair for Rm240 each prior to the Dato Sagor track day held earlier this year... on the up side, the grip and traction is very good for normal street use... its cheap and cheerful compare with other UHP tyres that have similar performance level... but on the down side, it is ridiculously noisy especially cruising at 80kmh above... the tyre roar is somewhat similar to those military 4x4... grip level also reduce when it overheats, which is weird for a semi slick tyre... i've got to test the tyres out on heavy downpour... surprisingly it isn't as bad as people say it will... on standstill water at reasonable speed, it does not hydroplane much....

all in all, 123 performance in dry is hugely dependent on the tread pattern and huge chunk of shoulder block... rubber compound is no where near semi slick level... when the temperature gets too hot, u will lose traction... on wet, it is reasonably good... if u can live past the tyre roar, it is a cheap and cheerful UHP tyre...

Monday, June 18, 2012

mid bullet replacement

speed bumps and sagging exhaust does not go along well... all "low-life" car enthusiast knows it... so, here is the aftermath... shaved and almost punctured center bullet...



got it replaced with a rather cheap center bullet from JASMA... inlet/outlet measures 2.0 inch...



if u notice the new bullet has a bigger displacement compare to the old one... this does slightly affect the throttle response... but all in all, its a cheap and cheerful replacement bullet...

RACETECH smooth shift

in most manual transmission engine, there are 2 gear linkage which connects the shifter to the gearbox which engage the gears... at each end of the linkage is a rubber bushing which minimize vibration and shock each time u engage gears via push-pull movement of the cables... these rubber bushing sits in a hot and humid environment inside the engine bay which will harden and crack... worn out shifter bushing will cause gears hard to engage and missed shifts... these can be very frustrating especially when u are driving enthusiastically...



RACE-TECH has produced one-of-a-kind aluminum shift bearing called smooth shifter... these one piece billet aluminum bearings replaces the rubber bushing and sits flush with the linkage with minimal clearance... this reduces free play and makes shifting gears more solid and precise...



smooth shifter also comes with necessary snap on clips and instruction guide...

installation is very straight forward... remove the old worn out rubber bushing and replace it with the new smooth shifter bearing... remember to apply some grease during installation...





the old rubber bush...

Thursday, March 15, 2012

absorber mounts

anyone who has saga iswara and had changed to adjustable coilovers will understand how it feels having your absorber top mount bush to go bust in under 6 months... that is only on normal careful driving... if u drive around like a maniac, it will not even last 4 months...



unlike other more popular chassis-based cars, saga iswara strut towers design does not allow the use of camber plates or pillowball mounts... well, at least its not plug and play without and drilling works done to the chassis... the only choice so far is actually no choice but to change the mounts more regularly... this wouldnt be an issue because this involves removal of the whole coilover assembly... which means readjusting the camber angle is compulsory...



i took initiative and headed down to the local warehouse if i can find any polyurethane block which i can machine it to be exact fitment of the original mounts... little that i know, polyurethane material in larger block form can be rather expensive... due to some budget constrain and machining difficulties, i opt for a smaller diameter bush... and this is what i came out with...



comparison with original mount...



first trial fitment... the mounts are slightly thick although i machined it to the exact same height with original ones... after installed, the top metal plate was scratching against my strut tower as i turn my steering... had it removed and lathe it shorter by 2cm... it fits snugly now...



after installation and alignment, i took a quick test drive round the neighbourhood... had a couple of high speed hard braking, no wavy or unsettle feelings... going over bumpy roads feels slightly stiffer compare to brand new oem rubber bush... high speed cruise is also stable...

the downside is, only one or two issue... first, it creates some knocking sound whenever i accelerate or brakes... second, turning any corner more than 90 degrees (U-turn for example) will also emit knocking sound... which is weird because it only emits sound from the right side... suspect the mounts freeplay to be the fault of it because it is not a tight fit into the D-shaped strut tower... currently still using it as i'm still working on the design of it to get the best cost-efficient design... hopefully... cross-fingers light bulb will appear in my brain soon...

solid engine mounts

engine mounts are the thing that holds your engine and gearbox in place... most cars have 3 to 4 engine mounts... and most if not all original factory engine mounts are made of hollow rubber which allows certain degree of flex in order to absorb any vibration generated by the engine... this is crucial because any slight vibration from the engine will be transferred to the chassis and u will experience tremor inside the car...



so, why solid engine mounts??... many did not know that whenever we step on the pedal, the engine rocks about on its platform.. this is due to the torque exerted from the engine to the wheels to get the car moving.. this rocking movement will somehow reduces the engine respond and eagerness to go.. rocking left/right or front/back will also damage the hollow engine mounts in long term...

solid engine mounts can be made of many material... race cars will go for solid nylon or teflon while most enthusiast will opt for slightly less solid polyurethane mounts... another step less hardcore ones will be solid rubber engine mounts... these engine mounts have similar material with original mount, minus the hollow part which minimizes free play...

tadaa... here are my new engine mounts... i only changed the front and back engine mount which locates at the cross member... both of this mounts will receive most of the rocking sensation from the engine as all horizontally mounted engine (most FF vehicle) will rock front and back vigorously...



installation was rather easy as well... instead of change one at a time, it is best to loosen both bolts holding the engine to the mounts and drop the whole cross member... this is because changing one mounts at a time will have difficulty aligning the engine to the mounts to slot on the bolt... tight space will also be another factor as your long spanner and sprockets will not have enough room to maneuver...

comparison between solid mounts and original mounts...



and check out my torn engine mounts...





difference after installing them... dashboard vibrates even more vigorous at slight drop in the revs... have to keep them at 1000rpm and above... i think i made my car worse... haha...