Page 1 of 3

Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 12:38 am
by Anton
Heya, peoples.

I'm getting together the parts I need to convert my SJ to coils. Gonna use vitara trailing arms and a custom upper wishbone/A-arm (don't like the vitara part, but I plan on making something similar).

That is to say, I'm planning on a triangulated 3 link. Don't know if there's room for it up front, but that's what I'm going for on the rear.

The upper link is going to be attached to the axle in such a way as to maximise articulation and travel. Essentially it's going to be twin pivot points, at 90 degrees to one another. A bit like this:

Image

I say a bit, because I'm planning on making it bigger, stronger, and the lower part, much longer.

The mounting to the axle that I have planned would look a lot like this:

Image

Except that the wishbone/a-arm (whatever you'd like to call it) will connect to it without the long upward shaft or the triangulated piece. I hope what I'm taking about is fairly clear...

So, firstly, does anyone forsee any problems with that setup?

Then there's the trailing arms.

Initially I'm just gonna make it work just like Suzi made it work on the Vitara. Nothing different really. But down the line (once the car's roadworthy) I'd like to make super-flexy trailing arms on which the axle end bushing actually rotates. Now, to make them rotate is the trick. I was thinking of using tapered bearings, when I realised that what I'm thinking of is, in essence, a bike hub.

Image

Now, I can pick one of those up brand new for about a fiver. I'm thinking of getting one and building something around one ( :weld: welding it into a tube, with the bush on the end so it rotates), and then destructively testing it (not on the car! I like being alive too much) so I know if it'll stand up to the pressure. The other option I thought of was making use of a trailier hub:

Image

Now, that's gonna stand up to a lot more abuse, but it's also going to cost about £50 a corner. And since these things are going to be basically disposable (I can't open it up to service it - it's angle grinder time if I need to get inside) that's a lot of money to throw around, plus they're massive.

So the second question is, does anyone think the bike hubs would be strong enough, and if not, any ideas on a hub that isn't too big/heavy/expensive (and made of mild steel so I can weld it into a trailing arm!)

Thanks, peoples!

Re: Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 10:42 am
by twiss
I wouldn't use bike hubs!
I've snapped enough of them with the weight of me and a bike on top of them.
They wont take much abused with an SJ sitting on top.

Why don't you just use a whole vit rear axle for the back?

Re: Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 12:09 pm
by ScottieJ
Bike hub will be no where near strong enough!

I personally think it's best to use a tried and tested set up

just a simple 3 link with A-frame using proper hi-flex joints at at least the axle end of the links. Like creeper/johnny joints is the best way to go, yeah it costs a bit more but the results will be better!

Image

Re: Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 5:05 pm
by Anton
twiss wrote:I wouldn't use bike hubs!
I've snapped enough of them with the weight of me and a bike on top of them.
They wont take much abused with an SJ sitting on top.
I had a feeling they were probably too weedy, but I thought I'd ask... ;)
twiss wrote: Why don't you just use a whole vit rear axle for the back?
Because I don't have a vit rear axle. And if I did, the ratio in the diff would be completely mismatched to the front axle. And it's wider, which might make for trouble as the car is going to be road legal. The new body (jago geep) should match the track of the vehicle nicely as-is, but not so much with a vit rear axle.
ScottieJ wrote:I personally think it's best to use a tried and tested set up

just a simple 3 link with A-frame using proper hi-flex joints at at least the axle end of the links. Like creeper/johnny joints is the best way to go, yeah it costs a bit more but the results will be better!
I know what you're saying, don't reinvent the wheel - and I'll probably end up using johnny joints, but where's the fun in never contemplating something new?

Re: Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 6:16 pm
by twiss
Vitara axles are cheap ;)
People are always breaking vitaras.

Its not an uncommon conversion either...
Here is a pic of it done, there is a build thread for one but I cant remember where it is.
I'm sure someone here has it bookmarked.

Image

The Diff gears are interchangeable with Samurai and 413 diffs so ratios aren't too much of a problem.

As for the width, a Samurai axle is 1326mm wide. Vitara is 1460mm, so its only 134mm different, so only 67mm on each side, you will barely notice a 3rd of a centimeter!

The main reason I suggested the vit axle was because you get to keep basically the same Suzuki brakes, bearings, and diff parts... You could also use both the trailing arms, and the vitara middle link as well

All you really have to do is weld a new crossmember inbetween the chassis leg for the middle link to attach onto

Re: Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 6:23 pm
by twiss
I've just found the link to it on a thread on Difflock
The link shows the conversion in detail and exctly what theyve done

http://forum.difflock.com/viewtopic.php ... sc&start=0

Re: Vitara trailing arm mod...

Posted: Mon Mar 26, 2012 6:50 pm
by Anton
twiss wrote:Vitara axles are cheap ;)
People are always breaking vitaras.

Its not an uncommon conversion either...
Here is a pic of it done, there is a build thread for one but I cant remember where it is.
I'm sure someone here has it bookmarked.

The Diff gears are interchangeable with Samurai and 413 diffs so ratios aren't too much of a problem.

As for the width, a Samurai axle is 1326mm wide. Vitara is 1460mm, so its only 134mm different, so only 67mm on each side, you will barely notice a 3rd of a centimeter!

The main reason I suggested the vit axle was because you get to keep basically the same Suzuki brakes, bearings, and diff parts... You could also use both the trailing arms, and the vitara middle link as well

All you really have to do is weld a new crossmember inbetween the chassis leg for the middle link to attach onto
Essentially you've got a good idea, and I thought about it a while back (read that thread a while ago) but 67mm is nearly 7cm, not 1/3rd of a cm! It's about 2.5 inches both sides. The axle would simply be too wide for the body that's going on the car. The other problem is that the rear vitara diffs aren't interchangeable with sammy/413 diffs, only the front ones are - rear vit diffs are larger.

I like the diff ratio I have - and I'd have to go with a matching vit diff up front if I went with a vit rear. The car wouldn't do motorway speeds as comfortably with vit diffs.

Add to this the fact that vit springs would be way too stiff (taking a lot of weight off with the body swap) so I have to get new springs anyway, and it's as much work to do a complete swap as to stick with what I have and make trailing arm mounts and spring perches for the current axle.

Add to that the fact that I've seen a writeup on a vit axle conversion that claimed the vit axle isn't as strong as the sammy one and I'm inclined to stick with sammy axles.

I can't find the article, but someone chopped up a vit axle and added sammy front axle knuckles to it so as to make a front axle that was as wide as his vit rear axle. Basically he made a vit rear axle into a front solid axle, and put the pair of them under a samurai. Don't ask me how he made the halfshafts work, but he seemed to.

The rear was ok on the road, but the front one bowed under the weight of the car. That suggests to me that vit axles aren't as strong as sammy ones - and I'm a bit of a heavy right foot type when I'm offroad, so I'd rather not shove a vit axle in the mix.

If I can find the article, I'll post a link.

Re: Vitara trailing arm mod...

Posted: Thu Mar 29, 2012 12:08 pm
by muddymesser
stick wheel spacers up front then you dont have much diffence

the lower the gearing the more control you will have so if you get a vit back axle and matching diff jobs a jood un

also the vit axel already has mounting points for the 3 link so less fabrication is involved, and they use the same shafts on each side so you dont need as many spares ;)

Re: Vitara trailing arm mod...

Posted: Thu Mar 29, 2012 12:50 pm
by Anton
muddymesser wrote:stick wheel spacers up front then you dont have much diffence
But it'll still be too wide for the bodyshell that's going on.
muddymesser wrote:the lower the gearing the more control you will have so if you get a vit back axle and matching diff jobs a jood un
But I like the gearing I have! I could live with being a teeny bit lower (I have a 410 box for that) but not as low as a vit final drive ratio. And I have plenty of control already... ;)
muddymesser wrote:also the vit axel already has mounting points for the 3 link so less fabrication is involved, and they use the same shafts on each side so you dont need as many spares ;)
I'm not too worried about fabbing, that's no real issue. The spares thing is a good point, but it's not enough of an upside to get around the fact that it's just *way* too wide for the bodyshell I'm using, and so I wouldn't be road legal. And since the front has fenders, not arches, I can't just stick arch extensions on (which I don't want anyway), I'd have to make new front fenders too. Which would probably ruin the look of the vehicle...

Re: Vitara trailing arm mod...

Posted: Thu Mar 29, 2012 2:09 pm
by twiss
If you're fabbing it up then there's no point in using vitara trailing arms.
You could pick something with stronger arms, ones that are easier to fit rose joints onto

Also for the middle link I reckon that mount wont be very suitable.
An "A" section mounted with regular bushes onto the axle and a rose joint attaching to the new crossmember would be better

The question needs to be asked though, if you're going to all the effort why not go 4 link.
It will be much better than 3 link, and if you're fabbing it up yourself it seems like a waste of time to take it all off, fab up 3 link, then stick it all back on again.
Might as well get it bang on first time as its a substantial mod!

You should also remember that if you coil convert it you will need to SVA test it to use it legally on the road