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 Lowering amount on the front and back

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mickB
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PostSubject: Lowering amount on the front and back    Fri Aug 26, 2016 8:24 pm

Well this weekend sees the mazda rx8 wheels hopefully being fitted so I want to drop it too, can others who have done it tell me what amount of drop I will get with winding the nuts down on the torsion bar, on a vw t4 10mm on the locking bolts will equate to 25mm at the wheel, is this similar on the SC, also what drop will I get cutting 1 coil out of the rear spring to
Cheers all
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GPW
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PostSubject: Re: Lowering amount on the front and back    Fri Aug 26, 2016 10:16 pm

If you compare the length of the adjuster (from pivot to bolt) with the length of the wishbone (from pivot to ball joint) you'll get the ratio.
I.e. if the wishbone is 2.0 x as long as the adjuster I'd expect a 10mm change on the bolt to result in a 20mm drop at the balljoint/wheel. Please let us all know though - I'd certainly find it useful info as I want to add 1/2" back to mine!

You can't cut coil springs, they'll almost certainly have a flattened section at each end - e.g.



so if you do cut them they don't sit properly, causing serious side loads. You may find a firm that can squash them for you properly, or you may even find the spring from a different car or van may fit - there's not so much weight on the back of a Hiace.

BTW - any idea how tight to torque the wheel bolts?
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mickB
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PostSubject: Re: Lowering amount on the front and back    Fri Aug 26, 2016 10:27 pm

Darn it, I was hoping the springs would be same diameter all the way down without any tapering, I'll try and work out drop on nuts to drop at wheel and let you know
As for the nuts, I tighten by hand using breaker bar, always have done since I was a teenager, I'll make sure the nut washer is correct for the wheel then tighten as I normally do
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GPW
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PostSubject: Re: Lowering amount on the front and back    Fri Aug 26, 2016 11:28 pm

mickB wrote:
Darn it, I was hoping the springs would be same diameter all the way down without any tapering, I'll try and work out drop on nuts to drop at wheel and let you know
As for the nuts, I tighten by hand using breaker bar, always have done since I was a teenager, I'll make sure the nut washer is correct for the wheel then tighten as I normally do

They may be the same diameter all the way along - have a look first!
The issue is the proper support of the cut end, somehow - perhaps heating with a torch - the new end would have to be shaped to match the spring pad.

Maybe some lowered springs can be sourced from Japan? The problem we have is that we're keeping 20 years old machines made by a country famous for progress - so all the add on hop-up parts are out of stock now, I think wandering around a few scrapyards with the original spring may yield some results though - it's not a super unique spring.
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PostSubject: Re: Lowering amount on the front and back    Fri Aug 26, 2016 11:32 pm

Pic here:

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toldsimply
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PostSubject: Re: Lowering amount on the front and back    Fri Sep 09, 2016 1:02 pm

You can get suspension spring clamps, which you can use to lower the springs, rather than replace the springs. You don't have to take the whole kit and cabboodle apart for that. A quick internet search pulled up these http://www.ebay.co.uk/itm/2x-Coil-Spring-Clamps-Raise-Lower-suspension-Kit-Car-GE7-/301560588868

It also pulled up articles on the worst mods you can do to cars, so you might be better off getting new springs in the long term. Just a thought though...
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GPW
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PostSubject: Re: Lowering amount on the front and back    Fri Mar 10, 2017 10:05 pm

Ok, slight thread resurrection here regarding lowering.

There is a device on the back of my van with some springs and stuff, which I assume is used to balance braking force between back and front brakes.

I think it sends more pressure to the back when the back is loaded down.



If you look at grouping 10 above, you'll see it.

So my van is lowered quite a bit which will simulate quite a big load. If no one has adjusted this device then I'll be getting too much braking force to the back, so does anyone have any ideas how to test or set this?
Probably anyone lowering their van needs to adjust this bit.

Perhaps someone has a technical manual that describes it?
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mickB
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PostSubject: Re: Lowering amount on the front and back    Sat Mar 11, 2017 7:15 am

It'll be a pressure regulator and I hadn't thought about it either, some more work to do before dropping the back
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PostSubject: Re: Lowering amount on the front and back    Sat Mar 11, 2017 9:47 am

Yes after I posted that I watched a video about brake systems and the little valves.
https://www.youtube.com/watch?v=qzUk8W1-2pw

There are three major valves it seems: One to close off a failing circuit (fault tolerance), Two to stop lower pressure getting to the front before the back is braking (anti-spin), Three to limit back braking (anti premature lockup).

What we seem to have is like you say: a pressure regulator whose pressure depends upon the sinking of the suspension. It will pass everything right through up to possibly 100-300psi and stop it going above that, the exact amount depending upon the level.

Some people seem to be making plates so that the level sits where it would have before they lowered the vehicle, which sounds good, but there are clearly two adjusters on it. I'll take a photo later.

So what we need to know is the magic PSI or Bar number: The van-empty max pressure allowed to the back brakes. Then any van can be setup with a pressure gauge to be correct. We need either someone to find it in the technical manual, or someone with a stock suspension (ideally of a matching van - 2WD SC for me), to unhook a rear brake hose (hose to cylinder is probably the more robust connection) and screw it into a pressure gauge.

Gauges are fairly cheap, but the adapters can be quite pricey. I recently bought a lovely 63mm glycerin hydraulic gauge for 8 and have had to fork out over 10 for the steel 1/4 BSPP gauge to 1/4BSPP adapter to be able to use it - doh!). Once we have that pressure number we just get someone on the brake pedal, the gauge in view and adjust one of the adjusters until we reach the standard number for a no-load pressure limit.


Last edited by GPW on Sat Mar 11, 2017 10:10 am; edited 1 time in total (Reason for editing : readability)
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PostSubject: Re: Lowering amount on the front and back    Sat Mar 11, 2017 10:12 am

Photos of the regulator.










free upload

I was thinking it may be possible to permanently attach a small gauge to the pressure line, but it would have to be done well for safety reasons and to be bleedable.
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GPW
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PostSubject: Re: Lowering amount on the front and back    Sat Mar 11, 2017 11:23 am

Just as a thought Mick:

Could you measure vertically from the centre of your back wheel to the metal of the wheel arch?
Mine is 345mm

That would give a good baseline for the 'normal' position, then me or any lowered van can be jacked up to match it, so the position of the pressure regulator's lever can be determined, measured with a caliper and corrected.

This would be much easier than tapping the pressure, especially if we compare readings as I'm only 60% certain mine has not been changed.

Thanks in advance!
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mickB
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PostSubject: Re: Lowering amount on the front and back    Sat Mar 11, 2017 9:33 pm

GPW wrote:
Just as a thought Mick:

Could you measure vertically from the centre of your back wheel to the metal of the wheel arch?
Mine is 345mm

That would give a good baseline for the 'normal' position, then me or any lowered van can be jacked up to match it, so the position of the pressure regulator's lever can be determined, measured with a caliper and corrected.

This would be much easier than tapping the pressure, especially if we compare readings as I'm only 60% certain mine has not been changed.

Thanks in advance!

I'll take some measurements and photos but I have dropped the front down a bit, the back readings should be the same just worth remembering
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PostSubject: Re: Lowering amount on the front and back    Sun Mar 12, 2017 10:51 am

Thanks!

I had another thought as well after reading the 1978 Hiace manual on here
http://www.toyotavans.org/community/tips/tips.html

in which they use gauges on the front and back, but the limits are quite sloppy.

The idea is to buy a small IR thermometer (from Hobbyking etc) that remotely takes the temperature of things.
Than after some driving you can check the temperature of all 4 discs and drums and adjust the adjuster to even out the heat from the front and back.

In that way we'll know for certain that they are sharing the work.

Perhaps I'll have a go and see when my car does with that, as that's standard and has rear drums and front disks so would be a good model. Brakes on it work well too.
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PostSubject: Bit of info   Mon Mar 13, 2017 5:37 am

This is an aside to your topic but what size rx8 wheel you fitting???,any idea 18's fit??? ,what size tyre you going with??,I'm looking to upsize my wheels & would be helpful to know what other folk manage to get under there lol
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PostSubject: Re: Lowering amount on the front and back    Mon Mar 13, 2017 7:03 am

countzero1978 wrote:
This is an aside to your topic but what size rx8 wheel you fitting???,any idea 18's fit??? ,what size tyre you going with??,I'm looking to upsize my wheels & would be helpful to know what other folk manage to get under there lol

They RX8 alloys are 8x18 with 225/40/18 tyres, et50 so they rubbed the wishbone on full lock, and that was with it not lowered, they won't fit now even with just the front dropped, they are just too big. I have Mitsubishi 6 x 16 on now with 225/55/16 tyres, its not ideal I could do with 7" wide rim so I'm always looking whats on ebay. I think the perfect size would be 7 x 17 with et35 and shod with 225/45/17 front and 225/50/17 rear give it a slight rake with it lowered all round
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PostSubject: Re: Lowering amount on the front and back    Mon Mar 13, 2017 9:53 pm

Got some more spring measurements today under the van.

My lowered springs are 15mm steel, and 128mm dia coil, so like the RAV4 springs but a bit thinner. No idea of free length as they are on the van!!

Mick - did you get a measurement of your rear wheel centre to wheel arch?
Mine is 345mm and my brake proportioner adjustments look like they hasn't been touched.
At normal (lowered) ride height the proportioner is against the stops - I.e. all pressure goes to the back drums (simulates fully loaded van).

So that measurement of a standard SC would be _very_ useful to me so I can setup my proportion valve to what Toyota thought it should be.

If anyone else has a stock Hiace super custom 2WD could they also measure rear wheel centre to wheelarch? I just need a number to work from as mine was already lowered when I got it.

Thanks in advance!!!
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 7:26 am

GPW wrote:
Got some more spring measurements today under the van.

My lowered springs are 15mm steel, and 128mm dia coil, so like the RAV4 springs but a bit thinner. No idea of free length as they are on the van!!

Mick - did you get a measurement of your rear wheel centre to wheel arch?
Mine is 345mm and my brake proportioner adjustments look like they hasn't been touched.
At normal (lowered) ride height the proportioner is against the stops - I.e. all pressure goes to the back drums (simulates fully loaded van).

So that measurement of a standard SC would be _very_ useful to me so I can setup my proportion valve to what Toyota thought it should be.

If anyone else has a stock Hiace super custom 2WD could they also measure rear wheel centre to wheelarch? I just need a number to work from as mine was already lowered when I got it.

Thanks in advance!!!

Sorry GPW we've had all new central heating system fitted last week so forgot this

Just checked and mine is 400mm Shocked [I gotta get it lowered.....] that with 16" alloys and 22/55/16 tyres that go through them speed displays you see bang on at 30mph on my speedo
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 12:53 pm

Would it be fun if I measure the distance on mine? It is with somewhat tired leaf suspension in a 4wd version, before it will be raised in the next couple of weeks Very Happy

(my wheels are already having 372mm from the center hehe)
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 1:10 pm

Thanks!

400mm - is that the average of both sides? The LHS is what counts in fact.
The beauty of that measurement is that it's independent of wheel/tyre size Smile

As my load sensor was on the stops and the thread looks untouched I'm now fairly confident I can use your number to set it up as it left the factory. There is exactly a 5mm gap when on the stops (see green arrows):



So I'll measure that gap when I've pushed it up to 400mm on the jack so we have a basis to work to. If you did the same (when you next happen to be underneath with some calipers Wink) we'll have a second to confirm.

Then - whatever that measurement comes out as - e.g. 7.5mm or something - we'll be able to set the unloaded valve position correctly so the braking is safe with any ride height. So it's a win win!

BTW: It'll be a few days until I jack it up as the front's in the air at the moment for new discs+pads.
BTW2: I think stock RAV4 springs should give you a mild drop and are cheap, but I still have no way of telling how much of a drop you'd get from those, if any. I did find poly spacers on the internet though to jack up springs a little - in 5mm, 10mm, 20mm etc sizes which I may use. i also need to work out where the bump-stops are...

Hiace4wd: 372mm? That's low for a 4wd, but leafs are great for adjusting! Have you also got this load sensing valve?
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 1:25 pm

GPW wrote:

Hiace4wd: 372mm? That's low for a 4wd, but leafs are great for adjusting! Have you also got this load sensing valve?

372mm is the tyre. The wheel arch is now something like 5 cm above it. So should be 430mm or something.
I should have it raised to 480mm probably.

The load sensing valve is on my agenda to check! (I also needed to adjust it on our Landcruiser)

Leafs are great, I would actually want to stick the axle under the leafs. But it is no good because the torsion system in front won't keep up.
Anyway offtopic.
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 1:36 pm

GPW wrote:
Thanks!

400mm - is that the average of both sides? The LHS is what counts in fact.
The beauty of that measurement is that it's independent of wheel/tyre size Smile

As my load sensor was on the stops and the thread looks untouched I'm now fairly confident I can use your number to set it up as it left the factory. There is exactly a 5mm gap when on the stops (see green arrows):



So I'll measure that gap when I've pushed it up to 400mm on the jack so we have a basis to work to. If you did the same (when you next happen to be underneath with some calipers Wink) we'll have a second to confirm.

Then - whatever that measurement comes out as - e.g. 7.5mm or something - we'll be able to set the unloaded valve position correctly so the braking is safe with any ride height. So it's a win win!

BTW: It'll be a few days until I jack it up as the front's in the air at the moment for new discs+pads.
BTW2: I think stock RAV4 springs should give you a mild drop and are cheap, but I still have no way of telling how much of a drop you'd get from those, if any. I did find poly spacers on the internet though to jack up springs a little - in 5mm, 10mm, 20mm etc sizes which I may use. i also need to work out where the bump-stops are...

Hiace4wd: 372mm? That's low for a 4wd, but leafs are great for adjusting! Have you also got this load sensing valve?

I'll grab some measurements when under it, that 400mm was passenger side too so I'll get t'other side aswell
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 3:42 pm

Excellent!

Passenger (left) side only should be fine as the sensor is on that side, you can see the valve if you look just in front of the back wheel past the chassis/frame rails.

That precise 5mm + measurement (green arrow) will be interesting as that will be what we aim for. I think we just need to use the adjuster for the big spring (and any bracket etc required if we run out of adjustment) to correct for any lowering.

This valve also means that bleeding the rear brakes will be tricky with a drooped suspension, so jacking on the diff would be needed for that.

Thanks again!
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 8:16 pm

Hiace4wd wrote:

372mm is the tyre. The wheel arch is now something like 5 cm above it. So should be 430mm or something.
I should have it raised to 480mm probably.

430mm on my unmolested 4wd (leafsprings). That's with a rear heavy camping interior and parked pointing upwards.

I'd like a lift and bigger wheels, but don't want to start cutting the bodywork. Transfer box is a bit close to the ground though. Will worry about it when I've finished all the other jobs though.
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 8:49 pm

Yeah it is like that. So we have pretty much the same height on the rear axle. I just have a bit more height because of the bigger tyres.
Probably next week the leafs will come off, they will be heated, smashed back into shape and a leaf added.
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PostSubject: Re: Lowering amount on the front and back    Tue Mar 14, 2017 9:09 pm

TwentyOneThirtyFive wrote:
Transfer box is a bit close to the ground though.

You may also want to guard the front coolant and AC rad stack just under the front, if you are off-roading they look a bit vulnerable and there seems to be plenty of chassis there to attach a bolt-on protective cover/cage for them.
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