Rods 'n' Sods - UK Hot Rod & Street Rod Forums banner

41 - 60 of 122 Posts

·
Registered
Joined
·
685 Posts
Ripped all the wood out of the countryman, boxed the B posts and will fit a roll bar behind B post with tube running down header and below side windows all tied into the frame of 1ins box around tail gate . Having driven it before it needs a lot of stiffening so I would say but as much bracing in as you can.
 

·
Premium Member
Joined
·
2,242 Posts
Ditto to all the above comments re wood.
my Austin Ruby had wood strengthening, some was rotten or falling out, so I replaced it with steel box, some places I kept the original wood and added the box section.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #43 ·
quick update. Front suspension is located. Changed plans. Orginally I'd have had to modify the wings to clear the A arm pivot and the upright. Decided that was ugly so pushed the pivot out 35mm and shortened the top arm. I know I'll get a bit more (0.7deg) camber gain at full compression, and a bit more positive on droop. But it's not a race car, so go with it.
Rear suspension is also located, just need to remake the brackets as I put a 12mm hole in them rather than 10mm!

 

·
Registered
Joined
·
140 Posts
Discussion Starter · #46 ·
rear suspension stuff

So, moving to the rear. I hadn't fully drawn this area as I couldn't find all the dimensions I needed.
The first go was built from the drawings I had done;



But once I'd put it together I realised the half shaft would have enough clearance. So, remade it with a notch.

Then I started thinking more about diff mount, and how the rear seats would mount. Why am I thinking about seats now? Well, the front seats are Ford B max, cos they have integral belts. It makes sense to use the matching rear seats. These also have some inbuilt belt mounts. That means the mounting points have to be super strong.

At this point I had enough info to redraw and remake. The new rear has chassis rails in the right place for the seat to sit on, and makes the diff mount much simpler. I also made the A arms mounts/shock mounts/upper to lower chassis brace as single parts where possible.

 

·
Registered
Joined
·
140 Posts
Discussion Starter · #47 ·
The modified rear also gives me a bit more room for a petrol tank. Will need think more about that before I put any cross bracing in.

Jobs on the (maybe at the weekend) list:
Even tacking this together it's gone out of square so, measure everything and tweek it till it's all as square as it can be.
Remake the passenger front lower arm mounts. The drivers side ones also double as a brace- much better. Everything is just tacked, and it'll take half an hour to make new ones.
Plan and make the diff mounts, fit the diff.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #48 ·
So, I remade the lower arm bracket, and did the diff mount brackets. Pics will follow when I get out in the garage later. It finally came off the axle stands and rolled a couple of feet. That's a milestone to celebrate.

I've also been sthinking about steering. Rack needs to be 583 to 615mm wide. I've a little space to move it up and down to get zero bump steer. Mini rack is 615 so I ordered one. Then realised it's rear steer so that's cancelled.
I can either go back to the original plan Mk2 Escort with inner tie extensions...or shorten the Mazda rack.

QUESTION:
Why am I trying to find a manual rack? Why don't I have power steering? I can't think where I got the mantra to not use power steering. Is it just that people don't like the extra pipework/doesn't look right? Anybody know a good reason not to use the shortened Mazda power rack?

QUESTION2:
Akerman. I understand the wheels need to follow different arcs, and this is acheived by forward/backward placement of the rack. But I'm not sure what I'm aiming for. I'd tend toward neutral to oversteer, rather than understeer. It's a long wheelbase so it's never gonna turn very quickly.
What do I need to draw to work out the rack position? I know there are hundreds of resources for this, suggest a couple that spell it out!

Thanks all
Andy
 

·
Registered
Joined
·
327 Posts
The Ackermann is not to do with the rack position but the size and shape of the steering arms. If you draw a straight line from the centre of the rear axle to the centre of the front hub pivot (ie the kingpin) then your track rod ends should fall on that same line.
 

·
Registered
Joined
·
685 Posts
Thats correct, bump steer is more important, with ride height set, inner joint on rack has to be on the line between top and bottom inner wishbone centres . Rack arms need to be parallel with wishbones. The forward /rear ward rack position will make a difference to Ackerman , the only way to check is with turn/degree plates. Its so long since I checked one cant remember what the difference side to side should be but think its 20deg to 18deg.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #53 ·
yep, rack inner joints lie in line with the wishbone centers. I've seen the drawings of the steering arm angles intersecting at the rear axle but the fore/aft position of the rack affects how much each wheel turns. The length of the arms also has an effect. Got some more measuring to do.
I think I can draw it on my chassis plans. I'll post a sketch when I think I have it. Must be possible to draw it!

Thanks for input, some extra eyes on whatever solution I come to is always a good thing
 

·
Registered
Joined
·
327 Posts
The position of the rack and the rod lengths do affect the amount the wheel turns but surely that change would be the same side for side, i.e. would not affect Ackermann.
 

·
Registered
Joined
·
550 Posts
This guy is a bit annoying to listen to, but if you can put up with him these videos are pretty useful:


 

·
Registered
Joined
·
140 Posts
Discussion Starter · #56 · (Edited)
The position of the rack and the rod lengths do affect the amount the wheel turns but surely that change would be the same side for side, i.e. would not affect Ackermann.
I'm not an expert yet- I have just the right amount of info to be dangerous!

Well, I just wrote an explaination, and did a drawing. And my drawing doesn't match my explaination. There's always a difference of turning angle on the inside and outside wheel. I'm still convinced that the rack offset from the centerline of the steering arm balljoints affects how much that difference is.

I'm off to do some viewing/reading of the links provided.

Thanks all
 

·
Registered
Joined
·
685 Posts
In a perfect world the arms (looking from above ) will be the same distance from centre of TRE to hub pivot as inner rack end is to centre line.
 

·
Registered
Joined
·
140 Posts
Discussion Starter · #58 ·
In a perfect world the arms (looking from above ) will be the same distance from centre of TRE to hub pivot as inner rack end is to centre line.
Got to think about that...
If you can do a sketch, that might lift the fog.

I'm still arguing with steering rack lengths. I think I'm going back to the MK2 Escort rack again. I can position it for zero bump steer, and get the track rods parallel with the lower A arm.
The LHD mini one I've got coming is gonna limit mounting options too much.
 

·
Registered
Joined
·
327 Posts
On reflection I think you are right, moving the rack fore and aft would affect the Ackermann slightly but only if the steering arms have Ackermann geometry as well. In this case the track rods end up at different angles so their effective length must change too. For symmetrical steering arms (no Ackermann at all) moving the rack fore and aft would not have this effect. (I think!!)
 

·
Premium Member
Joined
·
7,462 Posts
Moving the rack wont change Ackerman angle.

Thats pre built into the steering arms.

If its a front rack set up the track rod end pivot will be to the outside of the lower ball joint.on a rear rack the tre will be on the inside.

On our cars for road use,and how we drive,there really is a lot of leeway as to what will work..

The biggie as stated is getting the rack at the right height and width
 
41 - 60 of 122 Posts
Top