43 replies to this topic

[Bigfella237]

No worries Jason, happy to help!

 

You need to get yourself a terminal in the shed! My WiFi gets out there from the house but it's not a real healthy environment for a computer.

 

Anyway, I'll be online for a while yet so I'll keep an eye out for an update...

[Bigfella237]

Well after reading my gauge wrong I now have just over +2° caster and -1° camber both sides.

 

That sounds pretty much spot on, how many shims did you end up with in the UCA mounts? If you have too many on one bolt only it won't clamp flat on the K-member, but I'm guessing you'd be okay with only +2°?

 

As for toe in. With a string line from front to back through the center of the wheels I have 4ish mm gap at the front of the front wheel.. what this is in degrees I'm not sure?
What gap at the front of the wheel would people recommend for toe in?

 

Have a look at this thread: http://www.gmh-toran...gs/#entry530741

 

Toe is measured in millimetres, if you've got poly control arm bushes you'll probably want to set the toe at zero, but with rubber bushes (which flex more than poly) you'll be aiming for a little bit of toe-in, say 1 or 2 mm.

[Bigfella237]

Also, while you've got the gauge and the string-line out, it would be worth checking whether the arse end is tracking right too, bit hard to check for caster ( ) but have a look at the rear camber each side (hopefully zero), measure the total rear toe (again, hopefully zero) and then extend the string-line up to the front end and measure to see if the diff is sitting square in the car (if your rear track is skinnier than your front you may have to run the string around the front wheels and measure the rear)? I've seen this done with string-lines on race cars in the pits plenty of times.

 

Not sure if you have a diff conversion but even with a factory diff you might be shocked at the result?

[Bigfella237]

Depends what's out, if you've got any camber or toe then you're looking at a bent axle or tube, if it's an axle it will change with rotation.

 

Tubes warp when the various mounting brackets are welded on, usually you have a big length of round steel solid bar like an inch and a half thick that gets fed in one tube, through the centre and out the other, with adapters that neatly fit the bar and all four bearing journals. If the tubes are bent you can heat and press them back straight, I saw a website somewhere that showed how to do it, hang on I'll see if I can find it...

 

Yep, have a look at this: http://www.crankshaf...ear_end_housing

 

If the diff is straight but not sitting square, obviously you can get adjustable trailing arms, but they're not cheap, you can also get eccentric bushes, which come in several different offsets, but it's a tedious process especially if you're only guessing which bush you need.

 

BTW, those eccentric bushes aren't supposed to be use in front LCAs but they do fit, I believe 76lxhatch fitted them to gain a little extra positive caster, or maybe he made his own, I can't remember now?

 

One other really cheap mod you can do which will make a bit of difference is simply boxing in the rear trailing arms by welding a strip of steel along the bottom of them (you can even get all fancy and hole-saw holes in them too if you like). Standard arms are remarkably weak and this will help stop them flexing.

 

I guess if the diff isn't sitting square you'd be silly not to look for a bent trailing arm first too?

 

Also, have a good look at where the rear trailing arms mount to the floor, the lower mounts are fairly beefy because the lower arms are what push the car forward under acceleration, the problem is with the upper arm mounts.

 

Believe it or not, the upper arms actually pull away from the body under power (think of how a drag car wheel-stands, something has to actually pull the front of the car up into the air, that's the upper trailing arms at work).

 

There's a whole heap of other rear suspension geometry to do with rear-steer, anti-squat, roll centre, etc. but that's not really something you can do much about if you're using the factory mounting points so let's not even go there!

[76lxhatch]

Don't bother with the rear end unless you suspect a problem, you'll just drive yourself nuts. Sounds like you've sorted the caster, there's no way it would have been that far negative.

How do you find reading your camber gauge, looks like it would be difficult to get a fine reading? I use a digital angle finder which has 0.1 degree increments, which is OK, but could do with a little more accuracy on occasion.

Different shims on each side is pretty normal but it can make it harder to get the most out of it when one side has to compromise to match the other. Bent upper control arms can generally be carefully bent back as long as they are not damaged, its easiest to remove them but have used a bottle jack on the firewall in the past to match them up! The numbers you have look pretty good though, I'd leave it at that.

If you measure the track from the front wheels only, they are often not even so don't assume a mismatch left to right is caused by the rear end.

lazer would be awesome but expensive. im in the cheap options lol..

Just buy one of those cheapo levels which has a pointer built in, pull it it apart if need be and mount it on the side of the gauge so its roughly straight (this doesn't actually matter too much once you measure both front and rear on both sides as any error cancels itself out). Cut a couple of short lengths of something (mine are just MDF) that butt against the tyre and locate your tape measure at the outer tyre diameter, then point the laser at the tape to get your measurement.

Also very handy for centring the steering wheel, pivot the laser dot to the rear wheels and make it an even gap both sides.
 
 

BTW, those eccentric bushes aren't supposed to be use in front LCAs but they do fit, I believe 76lxhatch fitted them to gain a little extra positive caster, or maybe he made his own, I can't remember now?

Someone (Noltec I think) used to sell them as being suitable for the front, I don't know whether they were the same item offered for the rear or not. I made my own because I wanted Superpro bushings, but it also allowed me to keep the maximum amount of bushing material and set the ideal offset for the camber change I wanted.

[76lxhatch]

Removing the upper control arms with the subframe in the car is not really easy... I was only referring to the straightening part being easier :-(

This is all I meant with the MDF spacers, they just give the tape measure a nice even spot to sit at. Repeat for the rear and its guaranteed to be in the same place, also ensures that your measurement is at the outside diameter of the tyre.


A set of wheel plates is also very handy to avoid tyre friction causing incorrect measurements. Mine are just two layers of aluminium plate with grease in between, they don't need to be very big to get the tyre off the ground.


And this is the laser pointer, not pretty but functional

Imagine it placed against the wheel in the first photo above, swivel until the dot (or cross hair if you have one of those lenses) is on the tape measure, then record the measurement and repeat for the other side to get a distance. It doesn't matter what this distance is, after you repeat at the rear of the wheels just take the difference to get a nice accurate toe measurement. Less at the front is toe in, less at the back is toe out.

If your pointer is a bit crooked it doesn't matter using this method, as the four marks (left front, left rear, right front, rear rear) will all be equally out and thus cancel any inaccuracy.

[Bigfella237]

To be brutally honest, I wouldn't bother spending more $$$ on lasers & levels unless you plan on playing with your alignment on an ongoing basis, the tape measure method works fine for toe, the laser pointer just makes it easier if you don't have an apprentice handy.

[Bigfella237]

Saw this on the interweb, looks pretty simple to make and the only tools required are two tape measures and a digital level...

 

 wheel align 1.JPG   235.06K   8 downloads

 

...of course you still need the turntables with the degrees marked on them as previously discussed.

[76lxhatch]

That's pretty neat too, the bottom bar would not only help with the toe measurement but also make it easy to level the bracket so its straight up and down.

I always use the same 20 degrees turn for caster measurement so have a fixed triangle that lays on the ground and line it up with the laser pointer. Not sure why you are saying a laser pointer is expensive as it doesn't have to be flash, you could even re-purpose one of those freebie pens which have a dot built in?

[Bigfella237]

I just meant that it's money Jason doesn't have to spend if he stuck with the tape measure (I think he said somewhere that he was on a budget), but it sucks doing that by yourself so by all means go for it, doesn't have to be an adjustable laser sight or anything fancy like that (although that would make it easier to set up).

 

Some digital levels I've seen have magnetic bases so you wouldn't even need that extra right-angled bracket sticking out like above, the level should work just as well on the vertical plane as it would horizontal? One I was looking at even auto-rotated the display so it was always up the right way.

 

On that design, would the upright piece really have to pivot on the cross piece, couldn't the whole thing just be welded in a T-shape provided it was square? I was thinking that'd be one less thing you'd have to check/adjust on setup and that they probably only have it in two pieces for easy shipping?

 

Obviously you'd need to make a pair of them but the only semi-difficult part to make would be the lugs that mount in the bead, but nothing a half-dozen old bolts, a grinder and a lot of patience couldn't overcome!

 

EDIT: But you would need to make sure those lug bolts were all EXACTLY the same length otherwise the camber reading would be wrong.

Edited by Bigfella237, 18 March 2015 - 07:28 AM.

[76lxhatch]

On that design, would the upright piece really have to pivot on the cross piece, couldn't the whole thing just be welded in a T-shape provided it was square?

I didn't actually notice it wasn't, would need to be solid to help with level as I mentioned anyway

Obviously you'd need to make a pair of them

Didn't think of that either, that's a major drawback