Lew The Machine
|
| posted on 17/9/14 at 09:56 PM |
|
|
Adjustable rear geometry for haynes roadster?
Ok, so I'm about to start cutting steel for my rear wishbones and i realise I only have camber adjustment on the rear!
Two questions...
1. How important is adjustment at the rear?
2. What's the best way to achieve this?
Here's my current design....
(Green circled bits are staying, red circled bits need changing... Possibly)
Any feedback is welcome!
ITS FINE! i welded it!
|
|
|
|
|
rdodger
|
| posted on 17/9/14 at 10:15 PM |
|
|
Being able to adjust rear toe is handy. It's difficult to build it with tight enough tolerance to set it without adjustment.
I have it on mine via a cammed bolt on the inner lower wishbone (similar to how MX5 wishbones adjust though my bolt is from a Ford). It adjusts enough
to give me a tad of toe in. Alternatively a rose joint on the upright would do it.
|
|
|
Lew The Machine
|
| posted on 17/9/14 at 10:28 PM |
|
|
That's exactly what I was thinking, I know I'd be annoyed when I took it for alignment and they told me one side was 1mm out haha! Have
people done similar mods on their cars? I'm thinking of changing all 3 outer links with rose joints!?
ITS FINE! i welded it!
|
|
|
ettore bugatti
|
| posted on 17/9/14 at 10:31 PM |
|
|
Ah, you found the diff.
Here a JBA Falcon IRS with a rosejoint for toe adjustment
http://youtu.be/cRD1jIoBkE4?list=PLOD18N_fBFiNJuXU5HSJY4j4flVYUuXJ1
I would add some more mounting point on the upper suspension mount on the chassis (like the coilovers) so you can optimize the geometry for the
specific application.
How is your IRS assy mounted to the ladder frame?
[Edited on 17/9/14 by ettore bugatti]
|
|
|
ashg
|
| posted on 17/9/14 at 10:34 PM |
|
|
I put rose jointed rear lower wishbones on my roadster. It allowed boss racing to setup the car perfectly to fractions of a mm
Anything With Tits or Wheels Will cost you MONEY!!
Haynes Roadster (Finished)
Exocet (Finished & Sold)
New Project (Started)
|
|
|
AdrianH
|
| posted on 17/9/14 at 10:43 PM |
|
|
The old fashioned method was to shim the hub mounting.
Washers if way out, generally thin (a few thou) strips of brass or tin.
Adrian
Why do I have to make the tools to finish the job? More time then money.
|
|
|
snapper
|
| posted on 18/9/14 at 05:36 AM |
|
|
My Robin Hood uses the full Sierra rear end so the only option ( until I replace with Haynes set up) is camber wedges
I bought these off here a while back
Oval racer boys use washers under the hubs on Sierra and Granada
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
|
|
|
Ben_Copeland
|
| posted on 18/9/14 at 06:27 AM |
|
|
I'm doing what Ash did, but gonna rosejoint all the joints top and bottom. I didn't put the rear wishbone brackets on my chassis so I
don't know how accurately installed they are. It's a pain to get the wishbones in so I'm assuming not very accurately aligned.
Ben
Locost Map on Google Maps
Z20LET Astra Turbo, into a Haynes
Roadster
Enter Your Details Here
http://www.facebook.com/EquinoxProducts for all your bodywork needs!
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 06:46 AM |
|
|
I don't really fancy shimming, plus it's not necessary considering I can change the design to avoid it!
I've already changed the design of the rear upright once (now a 5mm laser cut and bent plate using 106gti calipers) so another change is no
problem!
quote:
Originally posted by ashg
I put rose jointed rear lower wishbones on my roadster. It allowed boss racing to setup the car perfectly to fractions of a mm
Do you have any photos of said rose jointed wishbones?
Cheers for all the input guys! It's nice to get options of people who've been through the same process haha!
ITS FINE! i welded it!
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 07:07 AM |
|
|
quote:
Originally posted by ettore bugatti
Ah, you found the diff.
Here a JBA Falcon IRS with a rosejoint for toe adjustment
http://youtu.be/cRD1jIoBkE4?list=PLOD18N_fBFiNJuXU5HSJY4j4flVYUuXJ1
I would add some more mounting point on the upper suspension mount on the chassis (like the coilovers) so you can optimize the geometry for the
specific application.
How is your IRS assy mounted to the ladder frame?
[Edited on 17/9/14 by ettore bugatti]
Haha yeah I found it! Big thanks for pointing me in it's direction!
What do you mean by add some more mounting points? To change the shock angle?
The IRS will have a "male" box section piece both sides which slides inside the "female" ladder chassis.
It will all be braced to the rollcage/spaceframe so it's not going anywhere, the only problem I'm having is torsional stress throughout
the length of the chassis, hoping to sort that with more bracing though haha!
ITS FINE! i welded it!
|
|
|
Mr C
|
| posted on 18/9/14 at 07:30 AM |
|
|
If you can change the design I would make a "Z" wishbone. Basically an A frame from the the forward hub mounting point rose jointed at the
hub end, to both chassis points, then a turnbuckle with L/R handed joints from the rear hub mounting point connecting to the A frame just forward of
the rear chassis mounting point.
Girl walks into a bar and asks for a double entendre, so the barman gave her one
|
|
|
Camber Dave
|
| posted on 18/9/14 at 07:37 AM |
|
|
ARB Mount
A detail perhaps, but I would mount the antiroll bar droplinks as far outboard as possible.
That way it will be more effective with a light gauge bar.
|
|
|
Slimy38
|
| posted on 18/9/14 at 08:56 AM |
|
|
I've probably come into this a bit late, but both the ARB and coilover mounting seem wrong. With the forces they will apply, having them in the
middle of a tube seems like a bad idea? I'm guessing there is a reason why the coilover is mounted mid wishbone rather than on the top of the
upright as per the original Haynes design?
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 09:16 AM |
|
|
quote:
Originally posted by Mr C
If you can change the design I would make a "Z" wishbone. Basically an A frame from the the forward hub mounting point rose jointed at the
hub end, to both chassis points, then a turnbuckle with L/R handed joints from the rear hub mounting point connecting to the A frame just forward of
the rear chassis mounting point.
Similar to the "JBA Falcon" design that ettore bugatti posted? It does seem to be quite a popular design for rear lower wishbones!
Does anyone have a good source for ordering rose joints? (and possibly a spec sheet for them so I can do some 3D work before I order them)
ITS FINE! i welded it!
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 09:23 AM |
|
|
quote:
Originally posted by Slimy38
I've probably come into this a bit late, but both the ARB and coilover mounting seem wrong. With the forces they will apply, having them in the
middle of a tube seems like a bad idea? I'm guessing there is a reason why the coilover is mounted mid wishbone rather than on the top of the
upright as per the original Haynes design?
Definitely not too late... No metal was harmed in the making of this design ;-)
The ARB mounts are still floating, and the connection from them to the wishbones via droplinks can still be changed!
Good question about shock position, again it's not confirmed but I've seen it done that way on other rear ends so thought it
wouldn't be a problem? The reason for having it low down was to avoid having to fabricate a relatively heavy duty shock mount at a high level, I
thought I'd try and utilise the rear wishbone & diff mounting frame for as many purposes as possible!?
ITS FINE! i welded it!
|
|
|
loggyboy
|
| posted on 18/9/14 at 09:35 AM |
|
|
Similar looking wishbones on a IRS striker - showing adjustable mounts. (albeint limited to increments of 0.5 x the thread pitch)
Mistral Motorsport
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 09:53 AM |
|
|
That looks EXACTLY like the design I looked at when doing mine, only difference being that has holes in the side of the upright!? Weight saving?
ITS FINE! i welded it!
|
|
|
loggyboy
|
| posted on 18/9/14 at 09:57 AM |
|
|
quote:
Originally posted by Lew The Machine
That looks EXACTLY like the design I looked at when doing mine, only difference being that has holes in the side of the upright!? Weight saving?
Standard Raw design, but yes, I would expect that's the reason.
Mistral Motorsport
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 10:11 AM |
|
|
quote:
Originally posted by loggyboy
quote:
Originally posted by Lew The Machine
That looks EXACTLY like the design I looked at when doing mine, only difference being that has holes in the side of the upright!? Weight saving?
Standard Raw design, but yes, I would expect that's the reason.
What brakes are you using on that?
Are there any cad files available for those uprights?
looks like a good quality build!
ITS FINE! i welded it!
|
|
|
loggyboy
|
| posted on 18/9/14 at 11:21 AM |
|
|
That's actually 2 builds, top one is mine, which has sierra disc hubs and carriers. The 2nd is a chap called Mikes whose using the Golf rear
brake setup that will mount to the 2 extra holes on the upright, that used the sierra drum hub carriers.
The uprights are Raw supplied, so I doubt a CAD file is readily available unless some one has drawn up their own.
Mistral Motorsport
|
|
|
mikeb
|
| posted on 18/9/14 at 11:23 AM |
|
|
Nothing wrong with Shimming it, but its a pain to change once set if you want to change to a different set up.
If you have the time rose joint it.
|
|
|
ettore bugatti
|
| posted on 18/9/14 at 06:37 PM |
|
|
quote:
Originally posted by Lew The Machine
What do you mean by add some more mounting points? To change the shock angle?
The IRS will have a "male" box section piece both sides which slides inside the "female" ladder chassis.
It will all be braced to the rollcage/spaceframe so it's not going anywhere, the only problem I'm having is torsional stress throughout
the length of the chassis, hoping to sort that with more bracing though haha!
No, more mounting points on the chassis so you change the top wishbone angle (and thus rollcentre height and 'swing arm length' .
I could only find any example of a RC car:
I was thinking that when the subframe was hung underneath the ladderframe leg you maybe could design something like a MX-5 subframe from sheet metal.
|
|
|
Mr C
|
| posted on 18/9/14 at 08:15 PM |
|
|
Apologies I missed the JBA post. yes similar.. though I would use a turnbuckle and rose joionts at both ends of the adjustable arm. This will alllow
you to adjust the toe by slackening off two lock nuts and rotating the turn buckle, rather than having the dismantle the roase joiny and screw it in
or out and resaassemble. I'll try and find an image of what I mean.
Girl walks into a bar and asks for a double entendre, so the barman gave her one
|
|
|
Mr C
|
| posted on 18/9/14 at 08:21 PM |
|
|
Found an image, this is looking towards the back of the car.
Girl walks into a bar and asks for a double entendre, so the barman gave her one
|
|
|
Lew The Machine
|
| posted on 18/9/14 at 08:48 PM |
|
|
quote:
Originally posted by Mr C
Found an image, this is looking towards the back of the car.
Yeah that pretty much the kind of setup I was thinking of, the JBA design is limited to adjustment by the thread pitch but using a rotating link bar
makes it possible to get it perfect!
Interesting to see those rose joints bolted vertically rather than horizontally? Is there a reason for this?
[Edited on 18/9/14 by Lew The Machine]
ITS FINE! i welded it!
|
|
|
