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PollyMobiles Rebuild

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pollyp

pollyp

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gave her wheels & body a good wash.

ever since that local tyre shop fitted my new Falkens, the left side always deflates afew psi overnight, found out all the tyre valves were actually leaking a tiny amount, so yet another few quid to fix 🙄

fitted the rear spacers back on so they sit the same as the front.
brakes were tiny bit spongy so I bled them little bit more and now it's back to normal & feels firm (y)

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went for a late sunset drive to record more videos

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the wirebrushed battery connections definately fixed the issue.
alternator was outputting 14.2v and both the battery terminals and the ECU datascan are reading 13.8v :cool:
 
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pollyp

pollyp

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I've finally made a walk around video highlighting some key features of Kassandra using my Huwaei P20 Pro phone with shaky hands (some sorta gimble would help) and some editing. It's a shaky 1st attempt but real proud of how well it came out 😍

Been wanting to do such a video for soo long, especially these recent months when ppl in car clubs were doing simple quick virtual walkarounds of their cars during the lockdown.

The royalty free music from youtube makes such a difference to the video compared to just having silence. (picked this song cos it had a little mightycarmod feel to it lol)

Last night I went for a sunset drive to test the brakes, alternator & suspension.


Feels better, charging normal, still got the odd rattle in the bulkhead to sort out, gear stick is getting sticky so I'll need to make a ball bearing joint to replace this sleeve joint soon.
 
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pollyp

pollyp

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was a lovely day for a drive & few photos :cool:

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ever since this local small tyre&exhaust shop had fitted my new tyres badly in January
(dots didn't align to the valve, tyre bead didn't follow wheel rim, balanced it wrong, stacked 3-4 layers of weights at one point)
the valves have been leaking round the outside and I was sick of pumping em up every time I drive.

instead of going to the same place to fix the valve, who'll probably just do the same dodgy work, I decided to go to nearby kwikfit to get it fixed.

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they quoted me £15 to revalve & balance each wheel, I mentally choked on my tea inside but decided meh, least it'll be fixed.
damn error of going to a shoddy garage to fit online tyres ends up costing me an extra £47 🤬

next time I'll just pay bit extra and order/fit em from the tyre place instead 🙄
 
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pollyp

pollyp

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thought the rear speakers been getting quieter and less bass, turns out the rear left speaker stopped working 🙄

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anyone know the specs of these? I heared they're just 30W rms

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chopped it apart to find the fault

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going +ve to -ve, the 4ohm wires are coiled 40 times counter-clockwise

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this is where one of the wire had broken maybe from fatigue

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my sony headunit outputs 55w rms per channel and I'd like to upgrade all 4 speakers to improve the low end bass without adding extra amps or subs in the boot but with soo many different response from ppl and the billions of speaker choices, it confuses and hurts my brain and still dunno what to buy 🥴🤪
 
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pollyp

pollyp

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was curious to see if replacing the gear stick rubber mount with a solid one would help reduce movement?

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I made this solid bracket

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bolted it up.
hmm yeah that was a mistake lol 😄 it transmits soo much noise (clunking & whining of the gearbox and the engine firing) to the chassis like a huge speaker. similar to when I once tried a solid front engine mount.
immediately swapped that one back 🙃

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the gear stick has recently felt more sticky, which affects my 0-60
took the bushes out and yup all the grease had dried out and steel has rusted.
(this was suppose to be a temporary fix till I made a new bearing joint)

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wirebrushed & regreased and it feels alot better now

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I've planned and ordered the bits to machine a new joint using sealed needle bearings
 
was curious to see if replacing the gear stick rubber mount with a solid one would help reduce movement?
The one I use for my mini is a morris 1100 exhaust mount
I put this particular one in because it was the same width but a larger diameter than a mini exhaust mount which broke earlier. I expect it is firmer than the micra part but I don't get much noise and vibration.
 
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pollyp

pollyp

Club Member
The one I use for my mini is a morris 1100 exhaust mount
I put this particular one in because it was the same width but a larger diameter than a mini exhaust mount which broke earlier. I expect it is firmer than the micra part but I don't get much noise and vibration.
ah yes good point, I could use the same bobbin rubber exhaust mount I used on my rear backbox
 
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pollyp

pollyp

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Reading a few 'choosing speaker with amp' guides, they generally say:
pick a speaker with rated/nominal input RMS power close to the amps continuous RMS output,
peak maximum power ain't as important,
high sensitivity speakers for low RMS amp,
low sensitivity for high RMS amps.

Looking at the headunit manuals, my old JVC said 50w max and 19w RMS, meanwhile my Sony only states 55w max and left out the RMS (their user manuals are pretty poorly written & vague too imo)

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So with no info about what the Sony units RMS is and didn't wanna fit a low power speaker if the unit was able to pump a full 55w to fry the coils, I decided to investigate more into what the amp actually puts out to get a better overview.

Following a guide on how to test amps, I played a pure sine wave at various frequencies & volume on the headunit using a tone generator app on my phone via bluetooth, with the sound settings maxed out and measured the AC voltage coming out of one speaker channel.
recorded the voltage at every Volume level at various frequencies for both the JVC & Sony unit.

Initially I used a 12v 12.5amp power supply to run the headunit and discovered the amp can only output upto 12v max, same as what it was powered by.

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Since the max output is dependant on the input supply I ran the test in the car with the engine running.

I also measured the input voltage at every volume and various settings.
The JVC draws quite abit of juice and the input reads a consistant 13.4v
Sony began at 13.7v and drops to 13.64v when the volume is above 33/50 but it was surprising to find the headunits LCD display brightness had a big effect in drawing soo much power.

With the display colour set to it's darkest setting the input was 13.7v but when turned to full bright it dropped to 13.3v, which will affect the amps max output so I turned it very dim for the tests.

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Both units have a non-linear S-curve output vs volume.
The JVC has a wierd curve rising exponentially from 8-21, with the low freq being amplified more than higher freq.
Volume 21-31 oddly flatlines and then it slowly rises from 31-50 till it outputs a maximum of 14.5v (input supply is 13.64v during max volume)

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The Sony in comparison has a much smoother S-curve, amplifying low freq more than high freq equally, and reaches a max output of 14.3v with the input at 13.64v

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Using the equation Audio power = V(squared) / R
the JVC pushed out max 14.5v = 14.5 x 14.5 / 4ohm = 52.5watts (close to it's stated 50w max power)
It's RMS rating of 19w is approx 8.7v which according to the graph is around Vol 19, that's just above the volume I normally always listen at.

The Sony pushed out max 14.3v = 143.3 x 14.3 / 4ohm = 51watts (little bit off from the stated 55w)

So with the 'max output' figure meaning the absolute maximum juice the amp could constantly pump out with a pure sine wave, I could use the given JVC figure of 19w RMS to roughly estimate Sonys RMS as 21w

Later on I found on Sonys web site for their other headunit models that they stated 55w per channel and 20w RMS, so the estimate was close enough. wish they wrote it in the manual too :rolleyes:

After days of researching every speaker make & model till my head is pounding (not a pun :p ) I narrowed down my selection to this coaxial Kenwood KFC-E1765

It handles 30w continuous RMS power
300w max peak power
good freq range of 30-22000hz
highly sensitive at 92dB/w
fits within the front door
and good price at £34 a pair

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See how it goes when it arrives next week
 
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pollyp

pollyp

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Designed a new gear selector joint using a pair of 15x21x14mm needle roller bearings.

The needle bearings (purple) allow the (yellow) joint to rotate freely and maintains a precise tight alignment against the (green) inner 15mm bushing but also allows the (yellow) joint to slide along the axis of the bolt, this means the length of the (yellow) tube doesn't have to be as precise and I can fully tighten the nut/bolt without the risk of binding the bearings.

(the old ball bearing design required very high precision machining of the (yellow) joints diameter and length.
whenever the tolerances were a fraction wrong, it would either be too loose and rattle, or too tight and seizes/damages the ball bearing)
This needle bearing design is alot more forgiving.

To protect against the elements, the HK1514RS bearing features a rubber seal too.

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components arrived

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machined the 25 x 35mm round steel billets to form the U-joint and gearstick joint

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welded the 2 billets together as a solid 1st because there's zero chance of 'blowing through' or warping the precise tolerance fit compared to if I machined it hollow before welding the thinner tubes

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with the U-joint welded together, I intentionally chopped the round bars slightly longer beyond the 35mm needed so that now I can machine each end precisely until the other perpendicular rod sits exactly in the middle and it is precisely 34.8mm long

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slowly drilled a 19mm bore

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before precisely machining it out to 21mm so I can tolerance fit the 21.05mm needle bearing

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2 more holes to machine tomorrow

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pollyp

pollyp

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machined & welded the larger bearing tube onto a spare gear stick and whacked the ball joint further up to make it a short shifter

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the finished U-joint casing

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press fitted the needle bearings

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drilled & tapped the holes to an M12

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installed. the bolt is slightly 5mm too short for the locking nut at the end but at least it's still screwed tight onto the threaded flanges I tapped.

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went for a drive and it's soo much smoother, easier and sharper feeling with absolutely zero rattles and minimal vibration :cool:👌
 
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pollyp

pollyp

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ordered some Kenwood KFC-E1765 on monday and it arrived today thursday unfortunately they sent the wrong one! :mad:
they sent me the KFC-S1766 which is less sensitive at 89db/w and less range at 35-22000hz
everything else is the same spec and price and nicer looking.
I could've contacted & sent it back to be corrected but imho it wasn't worth wasting another £5+ postage and afew more days & energy for a slightly better model, I'm just gonna slap this budget speaker on to find out how it does

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2 holes already line up so I just needed to drill 1 hole and solder the new wires up, easy peasy.
the new speaker surround has a much firmer feel compared to the older softer standard foam speakers.

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initially did a visual bass comparison at 30hz and volume #35
you clearly see the standard cone moves a huge amount, maybe it's has a more sensitive coil than the kenwoods, but it begins to distort from vol #15
the kenwood is much stiffer and only moves 1/2 as much but can reach upto vol #35 without distorting :cool:


now playing music at equal volume and headunit settings all at default, initially it's kinda disappointingly flat & little quieter than standard but the key big difference is that the kenwood can go much louder.

on the sony MEX-N6001BD unit I'm able to apply a "rear bass enhancement" setting which sends a low pass filter to the rear speakers turning em into subwoofers and then turn the fader to 30/70% front/rear and now I can turn the volume upto #30 with a much punchier bass without distortion.

ordered another pair of KFC-S1766 speakers from another seller for £5 less to complete the fronts 😁
 
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