Another green laner build

Some air springs arrived in the post. I have been having issues with the back end bottoming out so these may help. They are Chinese copies of Firestone units. The Chinese supplier's dimensions were more than a little optimistic but I expected that. Going by a mixture of my own measurements and Firestone's data I should be able to get nearly 6" of travel, which is a step up from the standard 4" travel. It's going to be really tight in the back. I may end up raising the floor an inch to make room. That combined with about a 1" lift should be about right.

   

Here is one of the springs next to the modified Range Rover springs I use on the trials car and Copelander.

 

I contacted Jimnybits about their Black Raptor premium shocks a while back. They seem to be reluctant to give me open and closed dimensions for the shocks, which is a bit disappointing. I'm not going to buy expensive shocks without knowing if they will be suitable.


I built this valve block for the Copelander but never fitted it. The 'temporary' manual valve block I fitted does the job well enough on that car but I want a more automated solution on the Jimny. I'll probably get rid of the 4 pressure sensors on the top of the block and rely on Range Rover wheel height sensors instead. The original plan was to use both but I think that's probably overkill.

 

This is the circuit board I designed for the controller. I didn't allow for an IMU (basically a 3D level), which would have given me the option for basic active roll control. However it looks like I can now get an IMU that would be pretty easy to add on. I used one of these boards as the controller for rear wheel steering on the Copelander.

 
 

Progress has been a bit slow recently as I have a lot of work on and I've also been doing a lot of work on the trials car. This weekend I had a bit of spare time to start shoehorning the compressor and valve block under the bonnet.
This is the cage that holds the pump, relocated washer bottle and valve block. The steel was a bit thicker than I would have liked so I added some lightening holes.

 

Here is the cage installed in place of the washer bottle. You can also just about see the curved air tank mounts.

 

It's getting a bit busy under the bonnet. There isn't enough room for the expansion tank in it's original place so I relocated it next to the power steering reservoir. By the way, the red wires tying the tank in is only temporary. They will be replaced by heavy duty cable ties.

   

Changing the headlight bulb is going to be... challenging. I think the only solution will be to pull the headlight out. Not ideal but I've seen worse as standard in other cars.

 

Oh wow... air bags for real..... This just got serious.
I'm also a big fan of keeping stock suspension geometry.
PS. Amazing sheet metal fab skills.

I had a bit of time today so I did some more work on the suspension. With the springs out I can get a good look at the spring seat. The black cleaner bit keeps the spring centered. It has to go. Unfortunately it is welded to the main bracket with about 20 spot welds. I recently got my old cheapo plasma cutter back from a friend who had it on long term loan. With the power turned down and with a bit of care it will 'wash' away  the top layer of steel, leaving the layer underneath untouched. The Hypertherm I use on the CNC table is great for cutting but it's too powerful for a job like this. It would go straight through the lot and the floor as well. Take a deep breath, there's no going back now...

 

Well, that was fun. Standing directly under a shower of molten metal is not my idea of a good time. Modern Dickies FR overalls are junk. They are fire resistant but they do nothing to stop the splashes of metal going straight through. I dug out an old pair of Dickies FR overalls which are at least twice as thick and do a much better job.
I think I did a pretty good job of getting the plate off without damaging the main bracket.

 

First the good news. The bag just fits and it will collapse far enough that I don't need to move the bump stop. Now for the bad news. It won't extend far enough. It runs out of travel even before the standard shocks run out of travel.  I had hoped to gain at least another inch of travel.  It's very difficult to estimate the true travel of an air spring until it's under load and it looks like my estimate was quite a bit out.  I may be able to gain a little by spacing the lower mount point up a bit but it can't go far. Fu... er, oh bother.

 

Well, I can't go back now. The spring seat is a pile of slag on the floor. I suspect I may end up going with my fallback plan - Land Rover Discovery II springs. They have over 8" of travel which is nice but they are also 30mm larger diameter and quite a bit longer then these springs when fully compressed. They are going to be a really tight fit in the limited space available.

 

Air bags.
There used to be a guy out in East Anglia who did airbag & hydraulic suspension for hot hatches. 
Ray Vern hydraulics. He may have what you need.
 

Thanks for the info. I might have a chat with him. Looking at his website he seems to use crimped bellows type air springs which won't handle long travel combined with awkward angles as the axle moves. In fact Firestone specifically say they shouldn't be used for vehicle suspension. The advantage they have for car lowering applications is that they are very compact.

I'm leaning towards Land Rover air springs as I have experience with them on three other builds. I didn't go with them in the first place because I didn't think they would fit. However on further investigation I think there is just enough room. I should receive a couple in a few days so I can take some measurements. The biggest issue is finding room for shocks that can handle the over 8" of travel that these bags are capable of. I may need to raise the floor about 1". It's a bit of a pain but the existing floor has a bad case of tin worm so it could do with being replaced anyway.

Jimnybits still won't give the the open and closed dimensions of their shock kits so it looks like I'll be going with AVO adjustable shocks designed for Land Rovers. They are rebuildable so if need be I can play with the valving to suit the lighter Jimny. Another alternative is to get Gaz to make some shocks to my specs but they quoted me a lead time of 7-8 weeks, which is not ideal.