Spent this afternoon tacking in the top suspension mounts using a jig inspired by some I've seen on here. Pretty please with the results but I have a couple of questions...

In order to get zero camber (I want to run slicks at some point) I had to wind out the top transit drag link and the top rose joints a fair bit. At zero camber both rose joints are in by 5 whole threads which is 10mm in to the wishbone of the full 30mm available. Also the transit drag link is also only 5 whole threads in to the top bush of the wishbone. I can't move the lower wishbone in any further and in order to get the current state of play I've had to wind the lower rose joints in so far I'm going to have to find some half nuts to use as locking nuts. Basically is this state of play safe? If not can I get some longer rose joints so I can wind them in some more, wind the transit link in more and basically shift the wishbone out a bit if you see what I mean? The rose joints are M10s.

Secondly, suspension travel... I have tons of movement upwards in the arrangement but it only moves down 3" (from the lower wishbone being horizontal) until the assembly binds. The thing binding is the lower balljoint. I imagine this is plenty but just wanted to check.

The lower shock mount seems a long way out and with the top one fitted under the top rail the shock will be at quite an angle. Is this normal?

The wishbones are supplied by ace sportscars by the way.

Here's some pictures so you can see the arrangement I've got...







Thanks for any advice.

Regards,

Mark

[Edited on 10/6/07 by dern]

I wouldn't like to drive your car!
I personally would not use M10 rod ends and if I did they would be wound most of the way in.
I use 1/2" unf on my projects and I have not had a failure.

3" droop is adequate, you can set the spring to prevent the balljoint binding.

How much further in would the top link be if you had 2 degrees of camber? Not muhc id guess. With this in mind, id remake the top bones maybe 20mm longer - doesnt seem right to me having them that far out.

Also, 10mm roses seems more suited to trackwork, i cant see the benefit on the road of making them that small. My trackcar has 10mm roses, so that i can use a mix of 3/4" and 7/8" tubing.

Martin, whats the narrower dimension of your oval tubes?

I would worry about the top BJ/TRE being so far out, and as said M10 for the rod ends may be a bit on the small side, I asked this question myself a while back and the consensus seemed to be 1/2 for road use.
And you could fit the top shock mounts on the outside of the chassis to steepen the angle up a bit

Cheers

Alex

Looking at your setup there is nothing unconventional.

Even if your shock is slanting at say 45 degrees - you are still getting around 70% of the upward motion of the wheel transferred to the shock, depending on what the car is for, you may not notice this compared to a slightly more upright shock.

In terms of suspension movement - you are right in thinking that 3" in droop is plenty for 7s.

You would be well advised to source some different rod ends with longer shanks though. I think the rule of thumb is 1.5 x the diameter of the fixing needs to be threading into the wishbone or fixing.

You might want to double check the quality of the rod ends themselves too - Nick Skidmore on here sells goldline rod ends which would be more than up to the job in question as M10s but a check to their static UTS would be well worth it.

Geoff

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Originally posted by nitram38
I wouldn't like to drive your car!

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Couuld you not raise the mounting point of the upper wishbone mount sligtly?
Or make a bigger mounting bracket?

i also would only use 1/2" minimum rose joints. In fact, all the rose joints on my car are 5/8", but thats beside the point. I've been told and recommended to use 1/2" minimum. that was for racing use though, so 10mm should be alright. I always prefer to over do things though.

I'd also like to see the top ball joints screwed in more. I'm surprised the the wishbones would be supplied so short.

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Originally posted by dern

PS. The car will be predominantly for track use and some sprinting. I'm not that bothered about driving it on the road.

[Edited on 10/6/07 by dern]

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are you sure they arent sierra upper bones?

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Originally posted by blakep82

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Originally posted by dern

PS. The car will be predominantly for track use and some sprinting. I'm not that bothered about driving it on the road.

[Edited on 10/6/07 by dern]

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remember the stresses on raci e suspension are a lot higher than road cars. I remember a racing driver tell me the stresses on road suspension is only something like 30-40% of that on a race car.

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^ also, not sure it would make a whole lot of difference (it maight make enough though) seems you have the wrong side upright on there. you seem to have the left side one on the right

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Originally posted by JoelP

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Originally posted by blakep82

quote:

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Originally posted by dern

PS. The car will be predominantly for track use and some sprinting. I'm not that bothered about driving it on the road.

[Edited on 10/6/07 by dern]

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remember the stresses on raci e suspension are a lot higher than road cars. I remember a racing driver tell me the stresses on road suspension is only something like 30-40% of that on a race car.

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My thinking is that, on a road car, failure is unacceptable. On a track car, you try to push the envelope to improve it. Ie lighter/thiner bones etc. I believe chapman used to weaken stuff til it broke than back up a few gauges/grams.

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quote:

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Originally posted by blakep82
i also would only use 1/2" minimum rose joints. In fact, all the rose joints on my car are 5/8", but thats beside the point. I've been told and recommended to use 1/2" minimum. that was for racing use though, so 10mm should be alright. I always prefer to over do things though.

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lol, true

cross posting, we're going too fast! That was to blake.

Mark, i wouldnt worry myself. Just dont overtighten the lock nut! Thats more likely to cause a failure than anything else.

[Edited on 10/6/07 by JoelP]

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Originally posted by blakep82
^ also, not sure it would make a whole lot of difference (it maight make enough though) seems you have the wrong side upright on there. you seem to have the left side one on the right

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Mark,

How much movement would you gain by making new chassis brackets for the wishbones?
You could move the bolt holes outwards (horizontally) maybe 5-7mm, keeping your geometry correct but allowing you to wind your rose joint 5-7mm further into your top bone.

may be a lot less work and a lot cheaper.

good luck

Steve

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Originally posted by dern
Really? How can you tell?

I tried both and the other one makes the state of affairs worse.

Regards,

Mark

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Originally posted by JoelPUnless im mistaken, blake's correct. Cortina is a front steer hub, ie the steering arm should point forwards. Doesnt HAVE to be, but you would affect steering geometry if you swapped them.

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Simple answer - top bones are too short and I wouldn't consider them to be safe enough.

I'd be happy with 10mm rose joints if they were good quality and screwed nearly all the way in and the track rod end definately need to go in a lot more.

I think the easiest and cheapest solution would be to get some new top bones made.

Volvorsport (off here) made some very similar ones to my spec and did a fine job.

http://locostbuilders.co.uk/viewthread.php?tid=35371

Pat...

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How much movement would you gain by making new chassis brackets for the wishbones?
You could move the bolt holes outwards (horizontally) maybe 5-7mm, keeping your geometry correct but allowing you to wind your rose joint 5-7mm further into your top bone.

may be a lot less work and a lot cheaper.

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Oops, typed to slow - but you get the same conclusion.

Pat...

stepping back a bit, the further inboard of the 2 ball joint holes should be at the top. and yes, cortina's steer from the front. so the steering arm should be at the front also. i gather you haven't started on steering rack mounts yet, as this could cause a whole lot of confusion later

No bends in my top bones. These are GTS (Yes GTS and well made too ) items, but theres no rocket science in the design..........

My eliptical bones are 40mm X 16.7mm X 2mm, bought from Ralt racing.
10mm rod ends are ok for a single seater but a car that can carry two people, I would not go under 1/2".
I am not sure but I think the sprintR has 5/8".
Rod ends at full extension create more of a leverage point on the threads and a thread is a natural cut into the material to help with causing a break. The material that is taking the load is actually only about 8mm when you take off the thread thickness.
Remake your top bones if they are too short. I re-made mine to give more castor and it didn't take long.
I also remade my cast uprights in steel as originally they were made in aluminium, because on the finished car, they looked too weak. That mistake cost me another £400!
To remake your bones, you are only talking about £20-30?
There is hardly any weight saved by using 10mm over 1/2", only more of a risk of failure.
Go with 10mm if you must, but wind them in.
My other advice is that your camber should be about 0.5 to 1 degree.
It does make your tyres wear, but it also helps with grip in corners.

different car, same components, same idea. viewed from the front

wishbones


top view

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Originally posted by ReMan
No bends in my top bones. These are GTS (Yes GTS and well made too ) items, but theres no rocket science in the design..........

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Originally posted by dern

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Originally posted by nitram38
I wouldn't like to drive your car!

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Very encouraging.

The 10mm rose joints were supplied with the wishbones. Apart from the fact that you use 1/2" and wouldn't personally feel happy with 10mm rose joints is there any engineering reason why they aren't strong enough? If so I'm surprised that they were supplied but I can always drill and tap the bones out to take bigger rose joints.

Is there any alternative to making up new top bones? I can do it but it seems a waste to chuck the ones I've bought. Can these be extended in any way?

Thanks,

Mark

PS. The car will be predominantly for track use and some sprinting. I'm not that bothered about driving it on the road.

[Edited on 10/6/07 by dern]

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quote:

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Originally posted by nitram38 My other advice is that your camber should be about 0.5 to 1 degree.
It does make your tyres wear, but it also helps with grip in corners.

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Originally posted by nitram38What I mean is that I wouldn't like to be driving your car hard with 10mm rod ends that stuck out that far!

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You can use straight lengths and rose joints - just like MNR.

Pat...

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Originally posted by dern

quote:

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Originally posted by ReMan
No bends in my top bones. These are GTS (Yes GTS and well made too ) items, but theres no rocket science in the design..........

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The only problem I can see is that the chassis ends of my brackets need to be perpendicular to the axis of movement so I can mount some inserts for the rod ends.

Either I need a bend to get in to the balljoint mount, an angle welded in to the legs to achieve the same or weld the legs at an angle to the threaded insert... if you see what I mean?

Regards,

Mark

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quote:

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Originally posted by ReMan
Though there must be quite some angle available in the rod end itself, if they were to be made just out of tube like yor existing ones but straight.
Or am making it too simple

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have u got the right castor angle ? worth checking before u weld them up i now from personal experience lol

That's the beauty of rose joints.

Loads of adjustable castor!

Pat...

Had an idea (please excuse the picture, seem to have mislaid my scanner)...



The thing on the left is the end of the bone as it stands. There's a threaded insert welded in to the tube.

On the right I've got a bit of high tensile threaded rod (a bolt with the top cut off) and some threaded bar/stock. I've inserted the stud in to the existing insert and held it there with thread lock to hold in place for the next bit. I've then wound on the threaded bar on to the stud which then extends the bone.The stud winds in to the existing bone and the extension by 15mm giving me 25mm (40mm extension) in to which I can fully wind the rod end with a lock nut in place. I then weld the extension on to the existing bone end and then wind in the rod end.

Firstly does this plan look any good?

Secondly where can I get some threaded round/hex bar like in the picture with an M10 1.5 thread? I'd need 4 of them each of which is roughly 40mm long (I'll measure more accurately if this is a goer.

Thanks,

Mark

I'd only do that if I were to then sleeve and weld over the top of the joint as it is a recipe for disaster. At least sleeving it it will add the strength and prevent the possibility of it unscrewing.

Steve

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Originally posted by Howlor
I'd only do that if I were to then sleeve and weld over the top of the joint as it is a recipe for disaster. At least sleeving it it will add the strength and prevent the possibility of it unscrewing.

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It may well work fine, but it just has that 'feeling' of being not the right solution and with something as safety critical as a wishbone I'd personally rather do it properly.

Why not fix the probelm properly?

Set the car up on blocks to give the front ride height you are looking for. Then put the wheels on the hubs on the uprights......... attach the bottom balljoint.....then set the wheels at the required camber......then put the drag link in the top hole of the upright........measure the length that a new wishbone needs to be to do the job properly.............then make new top wishbones that fit properly and do the job safely.

Not difficult at all. And safe as well.

Cheers,
Syd.

You'll get more clearance for your coilovers with properly made wishbones, as well.

[Edited on 11/6/07 by Syd Bridge]

You're right of course.

I just want to avoid the shag/cost of having to find/make the inserts for the rod ends and the transit drag link.

Cheers,

Mark

Give (???) the present top w/bones back to who made them. With the distance that they are short, they'd never be any good, except for someone wanting about 15 degrees negative camber!!

They're junk to start with.

Sorry.

Cheers,
Syd.

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Originally posted by Syd Bridge
Give (???) the present top w/bones back to who made them. With the distance that they are short, they'd never be any good, except for someone wanting about 15 degrees negative camber!!

They're junk to start with.

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rose joint inserts can be bought from rally design for a few pounds each. drag link tube can be bought from lolocost

And get some tube bent up.

A lot of the manafacturers will do it for you like MK, MK Engineering or any tube bending place.

Pat...

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Originally posted by dern
[Unfortunately I bought them quite a while ago and the guy's website has now gone....

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Originally posted by MikeRJ
Flog them to someone using Sierra uprights? I reckon that's what they muct have been made for.

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Originally posted by blakep82
rose joint inserts can be bought from rally design for a few pounds each. drag link tube can be bought from lolocost

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Nick Skidmore (on here) is good (and quick) at making inserts.

Pat...