The Brumbyrunner Project

brumbyrunner · Post by **brumbyrunner** » Wed Jan 14, 2009 1:37 pm

Under the rules he's limited to 16" wheel travel but what's that got to do with it?
Biggest problem with a coilover is that it doesn't have any external bypasses so it's sort of 15 year old technology.

Wilbur · Post by **Wilbur** » Wed Jan 14, 2009 5:32 pm

More oil volume before it gets too hot ?

brumbyrunner · Post by **brumbyrunner** » Wed Jan 14, 2009 10:13 pm

A longer stroke shock is not nessessarily going to run cooler as it will be moving faster. There are lots of opinions on what is the best motion ratio. Close to the wheel the shock must move faster and heats up, further away and it works harder and heats up (and blows apart).

Anyway, back to the business at hand.
You can see the outline of the trailing arm in this pic. It's not much but it's a start.

Looks too short yet it's twice as long asthe original. Any longer and I'd have to channel the floorpan and raise the seats so this is it until I go full tubeframe. This is where the tyre will sit.

Wilbur · Post by **Wilbur** » Wed Jan 14, 2009 11:07 pm

You mean close to the wheel as in verticle ie the front of the hummer, and further away like the rear end of most buggies ? How about bore size or is that something you leave for old mate to work out ?

Is the rear wheel staying at factory position, appart from the extra track?

Suspension is a curiousity of myne

fredsub · Post by **fredsub** » Thu Jan 15, 2009 8:43 am

has anyone invented water cooled shocks ?

typed "water cooled shocks" in google and surprisingly a few hits.....

could be what you need

interesting read http://www.patentstorm.us/patents/53928 ... ption.html

the full pdf is a good read, register to get it (free) or PM me an email to send it to.

looks like Aussie inventor for that patent:) and yes for rally application.

Outback bloke · Post by **Outback bloke** » Thu Jan 15, 2009 9:03 am

So is that trailing arm fitted in place? I mean permanently, or are you still designing?

brumbyrunner · Post by **brumbyrunner** » Thu Jan 15, 2009 9:27 am

White_Lightning_Rex wrote:You mean close to the wheel as in verticle ie the front of the hummer, and further away like the rear end of most buggies ? How about bore size or is that something you leave for old mate to work out ?

Is the rear wheel staying at factory position, apart from the extra track?

Don't really understand what you're asking? There are a lot of talented suspension gurus out there to ask (ok, maybe not that many) who know so much more than I do.
I was merely pointing out that Robby Gorden finds it better to run a single shock per corner in his Dakar cars when the trend is to use two. One serves as the coil carrier and the other can be massive and have external bypass tubes that the coilover cannot.

The rear wheels are staying in the wheelarch where they were before. If I move them rearwards as everyone suggests, it moves the balance point forward (bad).

fredsub wrote:has anyone invented water cooled shocks ?

I've spoken to a few racers that've tried it. None with any success. Water boils to easily and it's heavy and complicated. It is better to build the shock larger with more oil to stay cool. Here I go talking about stuff over my head again.

brumbyrunner · Post by **brumbyrunner** » Thu Jan 15, 2009 9:34 am

Outback bloke wrote:So is that trailing arm fitted in place? I mean permanently, or are you still designing?

What you can see is the outside wall of the trailing arm. It is welded to the Subaru bearing carrier and hangs off the new mount in the back of the cab. I still have to design and build the inner part of the arm.

Outback bloke · Post by **Outback bloke** » Thu Jan 15, 2009 10:13 am

If I move them rearwards as everyone suggests, it moves the balance point forward (bad).

I agree. The bad bit that is.

So it is coming together as planned? Looking the goods?

Wilbur · Post by **Wilbur** » Thu Jan 15, 2009 1:55 pm

I wasn't going to suggest moving the rear anywhere. It seemed to be fairly well weight balanced on the scales at Alice.

I only ask you about suspension because you know more than me. Might just sit back and let you get on with it.

brumbyrunner · Post by **brumbyrunner** » Thu Jan 15, 2009 2:18 pm

Outback bloke wrote:I agree. The bad bit that is.

So it is coming together as planned? Looking the goods?

It's slow going. Trying to get everything lined up and square. Changed the trailing arm shape 3 times this morning and found that the rear track will still be narrower than the front or I will lose wheel travel. The rear guards need another 100mm cut out of the top and the fuel tank might have to be raised to clear the driveshafts.
I'll get there.

brumbyrunner · Post by **brumbyrunner** » Sat Jan 17, 2009 10:48 pm

Got some progress to report. After days of pondering and trying different setups I've tacked together the pass. side trailing arm. Feels good to be able to see it. Looks good too. I've got a bit more sheet to cut out and then finish welding. I'll try to get some pics tomorrow. I have managed to duplicate the front track width and still have at least 14" of wheel travel. Took a lot of mucking around to get it right. I wonder if there would be a market for long travel rear suspension?
Anyone want to increase their factory 5" of wheel travel (more if you've got a lift kit)?

brumbyrunner · Post by **brumbyrunner** » Mon Jan 19, 2009 7:17 am

I took these pics last night but I thought they'd turn out better. I'll get some new ones once I finish sanding & painting.

And a comparrison with the factory MY trailing arm.

fredsub · Post by **fredsub** » Mon Jan 19, 2009 8:10 am

How will the "sprung" weight compare with the original ?

also consider putting another support from the apex of the triangle for additional strength?

good work btw

vincentvega · Post by **vincentvega** » Mon Jan 19, 2009 10:30 am

awesome Stuart. Looks solid as

im back by the way - need to get this LCD screen up to you

brumbyrunner · Post by **brumbyrunner** » Mon Jan 19, 2009 4:07 pm

fredsub wrote:How will the "sprung" weight compare with the original ?
also consider putting another support from the apex of the triangle for additional strength?

I will weigh the two arms when I'm finished but it's not as heavy as it looks.

I have considered that a lot but there has to be a compromise between strength and weight. I also considered boxing the whole area but it would be very suseptible to dints, especially the bottom. Once I mount it back up or maybe after a test drive I might decide it needs more support but at the moment I think it's strong enough. The main advantage in building these myself over buying them from a supplier or fabricator is that I know whats underneath and what material I've used.

vincentvega wrote:awesome Stuart. Looks solid as
im back by the way - need to get this LCD screen up to you

Welcome home.
The package I wanted to post to you got delivered to Brett's house instead. You just need to pick it up (and hang it somewhere).

Post by **Captain Obvious** » Mon Jan 19, 2009 5:06 pm

looking good, what pivot are you using to attach the arm to the car?

stamp_licker · Post by **stamp_licker** » Mon Jan 19, 2009 5:11 pm

Looks good Stuart.Kind of like these v dub ones.

brumbyrunner · Post by **brumbyrunner** » Tue Jan 20, 2009 2:51 pm

Captain Obvious wrote:looking good, what pivot are you using to attach the arm to the car?

Say what?

stamp_licker wrote:Looks good Stuart.Kind of like these v dub ones.

Ahhh, do you really think so?

Post by **Captain Obvious** » Tue Jan 20, 2009 4:50 pm

[quote="brumbyrunner"]Say what?

what sort of joint is the a frame linked to the car with? eg rose joint or just a bush type setup?