Definitive answer to 172 vs. 172 Cup /182 castor difference?

[andy_casey]

I've been searching and searching on this subject but there seems to be a lot of ideas but I've not seen a definitive answer as to which component(s) give the increased castor on the 172 cup (and 182s) vs. the normal 172. Some suggest the hubs, others say they're identical (the 182 and 182 cup share the increased castor but have different strut spacing whereas the 172 and 172 cup appear to share the same strut hole spacing) and from what I've read, the lower ball joints are identical but I've not seen whether the lower arms are the same or whether the cup items shift the BJs forward a cm or so - perhaps there's a thead buried somewhere that I've missed? Is there a final answer on this or is it still a little bit of a mystery?

The other thing that interests me is the fact that the Full Fat, non cup 182 (same strut hole spacing as 172) shares the 3 deg castor that the 172 cup has and so perhaps this model will yield some parts which could be used to achieve the added castor with the ABS already being something that's designed in.

Reason for asking is that I'm fitting some 172 cup suspension (possibly with 182 cup rear springs) to my 172 ph2 and am interested in what's required to get a little closer to the cup chassis.

Cheers in advance for any replies.

 

[andy_casey]

I've been giving this some thought and applying some logic (always dangerous). Anyway, the front suspension is a simple MacPherson strut and so the number of components are few and the positioning limited, as I must make the assumption that the shells are the same and thus the upper mounting points are not moved.

From some further research, I noted that the quoted wheelbase for the 182 is some 13mm longer than that of the 172 (2485mm vs. 2472mm) and this is rather curious, as it corresponds approximately to the amount that the front wheel would move forward due to a 1.5 deg increase in castor! Here's some maths -

At small angles, 1 deg is approximately Tan-1(1/60) and so for a strut of approximately 600mm, 1 deg equates to the lower mounting moving ~10mm and 1.5 degrees equates to ~15mm of movement. As the wheel is approx 500mm from the upper housing, the wheel will only move 5/6 of that 15mm, thus 12.5mm. Curious. To achieve this movement and assuming that the top mounting point is the same, the lower arm or ball joint must move 15mm forward. From speaking to Tom @ Wests today, I've been informed that all lower arms are the same part no and as they include the lower BJs, it would point towards them being the same too.

Looking at the components -

• Top mount (common to all 1X2s)
• Strut (has no effect on Castor unless length is shorter)
• Hub (steering axis should pass through the wheel bearing cenre line to minimise torque steer and prevent excessively heavy steering)
• Lower ball joint (again, I believe these are common to all 1x2s based on information from Renault parts)
• Lower wishbone / arm (common to all 1X2s)
• Wishbone bushes (integral to common 1X2 lower wishbones)

So this only leaves the subframe as a candidate. Thus, I would like to know if anyone has a 172 and 182 subframe that they can look at and measure or compare the location of the wishbone mounting points relative to the mounting holes to see if it is different between 172 and 172 Cup/182 models, as this would achieve the extra castor.

Thoughts?

Cheers in advance.

 

[octavio.zl]

Hy Andy, I am writing down far away (Mexico). As I had a little accident with my car last week and I am going to repair it, I was on the quest of the correct chassis specs. Being a 172 Ph2, I was curious about its specific wheelbase, since the workshop manual I have does not mention it, and a complement that I found is only applicable for light weight versions (later 182 arrived to Mexico as Cup, formerly not the Cup version from Europe). As I started the quest I found that 182 had greater WB than 172's, from then the 2485mm was not applicable to my car.
I found your thread really interesting, since I had the same thought as you... what part is different between 182's and 172's to make that difference.
I know the struts are different indeed, but I have no acces to both parts to compare and measure. I am thinking also on the subframe mounting points for the wishbones.
I wonder why nobody else replied to this before, is such an interesting thread to improve handling on non-Cup versions.
Best regards, hopefully we will compare and measure the sub-frames and the struts. Even when this is a very old thread, I will try to come up with an answer for this.

 

[Tav]

Great question. The castor is certainly noticeable and makes front end feel lovely when setup properly.

 

[andy_casey]

I wasn't able to find a reason for this on the web so the only way to do it would be to get a cup and a 172 ph2 next to each other and measure various parts. I have to say that I did edge towards the idea that the ph2 172 has the higher amount of castor and it's another of those situations where an ambiguous Renault press release causes confusion... best of luck with it.

 

[Michael Woodford MST]

PH1 - 2.15
PH2- 1.5
PH2 cup- 3.0
182/ 182 cup- 3.0

 

[andy_casey]

Thanks for the numbers but the question is what causes the differences as most of the parts that could cause the castor change are common to all ph2 models according to the Renault parts system.

 

[Chip-mk1]

I'm interested as to what causes the phase 2 to have slightly less caster than the phase 1, as neither the hubs nor the bottom arms appear to be any different, and the top mounts are clearly the same too, so there isnt anything which I can see which accounts for the published figures Mike just quoted being different.

Cup though its the wishbones, very clear to see when you have them side by side, its mounted with the balljoint pointing forwards at quite a steep angle so very visibly increases the caster.

 

[andy_casey]

Thanks for that information. Do you have any pictures of the 2 side by side? As per post 2, I was told that the lower arms were the same when I inquired at Renault.

Is it the arms or the ball joints that are different? It would be good to know!

 

[Chip-mk1]

Thanks for that information. Do you have any pictures of the 2 side by side? As per post 2, I was told that the lower arms were the same when I inquired at Renault.

Is it the arms or the ball joints that are different? It would be good to know!

I havent got pictures, but Im sure me and Mike can get some soon as we're both altering our phase 1s in the near future.

Its the Arm, absolutely 100% guaranteed despite all the misinformation from the main dealer saying otherwise (it threw us too, so at one stage we thought it must be the hub as we got the same info as you about the arms being the same and we knew it wasnt the balljoint), but as soon as Mike got another customer in with a cup for some work it was really obvious you only need to glance at it and you can see that the outer bolt hole is sat much further forward than on the normal arms.

 

[andy_casey]

Be great if you could put up some pictures. Please let us know what arms are shown and any relevant dimensions.

 

[Chip-mk1]

There are pictures put up previously by p@blo


Cup:
View attachment 81803

Non Cup:
View attachment 81804


This is the difference in the arms, ignore the fact thats not running a standard balljoint, those arms are the standard non cup 172 arm versus the standard 172 cup arm.

Like I said, you can see that all that has happened is that the outer mounting hole has been drilled further forwards.

 

[mr.pink87]

Interesting. Difference between ph1 172 and ph2 172 is subframe related afaik. Mounting positions for the wishbones are slightly different.

 

[Chip-mk1]

Interesting. Difference between ph1 172 and ph2 172 is subframe related afaik. Mounting positions for the wishbones are slightly different.

So the wishbone mounts are a couple of mm further forward on the phase 2?


One trick I have used on a different car, is actually to elongate the holes slightly to move the entire subframe forward a couple of mm, doesnt make a big difference but its free and is easy to do if you have the subframe off for some reason anyway.

 

[bozothenutter]

Hmmm, could this be done on a 182 aswell?

 

[Chip-mk1]

Hmmm, could this be done on a 182 aswell?

Could what be done?

If you mean fitting 172 cup arms, then by the sounds of it renault already have.

Go out and have a look and see which of the two arms above yours looks like and let us all know?

 

[Tony Hunter]

There are pictures put up previously by p@blo


Cup:
View attachment 81803

Non Cup:
View attachment 81804


This is the difference in the arms, ignore the fact thats not running a standard balljoint, those arms are the standard non cup 172 arm versus the standard 172 cup arm.

Like I said, you can see that all that has happened is that the outer mounting hole has been drilled further forwards.

Ah Chip, that's what I've been waiting for, I can actually see the difference now, very interesting indeed.

 

[Chip-mk1]

Ah Chip, that's what I've been waiting for, I can actually see the difference now, very interesting indeed.

Its a nice simple solution, Ive done similar on various other cars just by plug welding the whole and drilling a new one or by elongating the existing hole and welding a washer on to cover the edge of the old hole.

Thats what I am thinking about doing on my phase 1.
Ideally I would actually like to add a little track width at the same time as well, but unfortunately there isnt a lot of metal left at the end to do so, so I might look at welding a plate over it first and then drilling that, or possible if I can get enough clearnace make up a plate to bolt into the existing holes that has 4 holes in it, 2 for where they were and 2 for where I want to move them to, but the problem in trying to do that is obviously the bolt heads need to clear and as I dont want to move it very far that might not be an option.

Will probably whip the arms off this weekend and take a look at them properly and decide which way to do it as Mike said he has some time free to pop round and is interested in it as well (and he's a better welder than I am, I can get by but he's a qualified coded welder etc)

 

[bozothenutter]

Could what be done?

If you mean fitting 172 cup arms, then by the sounds of it renault already have.

Go out and have a look and see which of the two arms above yours looks like and let us all know?

the subframe bit.....

 

[Chip-mk1]

Yes you should be able to elongate the holes and then mount the whole frame further forward a couple of mm easily enough as its only bolted up in 4 places.
You cant go far like that though obviously, as so many other things mount to it, but if you just want a couple of mm it should be ok, although I cant say 100% as Ive not tried on that specific vehicle.

 

[Tony Hunter]

I want to take ours apart now lol, but testing at Mallory tomorrow, so better not.

 

[Chip-mk1]

Yeah probably best not to pull it apart just yet, although you could just take the wheel off and get a reasonable picture from underneath to show which type of arm you have.

 

[Tony Hunter]

I'l do it tomorrow when we change the wheels and tyres over.

 

[Chip-mk1]

Nice one

 

[mr.pink87]

I don't think you'll be able to move the subframe on the Clio by elongating the holes as the rear 2 holes have some kind of fixing collar/cone.

 

[John Gordon]

Ph1 wishbone.

 

[mikekean]

Cup racer wishbones are somehwere intween cup and non cup wishbones, the outer hole sits pretty cental. I can get a pic if people are interested.

I fitted Cup wishbones on my Williams when i put the 172 widetrack on and you can tell there is a massive increase in castor as the lip on the inside of the bumper has been completely worn a way by the tyres!

 

[p@blo]

So the wishbone mounts are a couple of mm further forward on the phase 2?


One trick I have used on a different car, is actually to elongate the holes slightly to move the entire subframe forward a couple of mm, doesnt make a big difference but its free and is easy to do if you have the subframe off for some reason anyway.

Be interested to hear your feedback from comparing this Chip- i don't have my phase one subframe assembly anymore but having swapped the rack over previously (ball joints looked newer), was fairly sure it was giving a fairly noticeable toe out. Possibly narrower front track through either wishbones or subframe pickups?

Cup racer wishbones are somehwere intween cup and non cup wishbones, the outer hole sits pretty cental. I can get a pic if people are interested.

I fitted Cup wishbones on my Williams when i put the 172 widetrack on and you can tell there is a massive increase in castor as the lip on the inside of the bumper has been completely worn a way by the tyres!

Lol-step too far Mike? Be interested to see the images for the Racer wishbones Mike. Wonder if the clearance would be an issue on a mk 2? :S

 

[Chip-mk1]

I'll try and get some measurements at some point, trouble is when they are on the car and you havent got access above them to get at the holes cause there is an engine in the way (and the holes arent visible from underneath due to the frame itself) any subtle difference is going to be hard to spot.

 

[...]

be interesting to see what effect slotting the hole on the cup wishbone to give even more caster did , theory suggests it would increase bite on turn in but would take some playing around with ,

 

[Chip-mk1]

be interesting to see what effect slotting the hole on the cup wishbone to give even more caster did , theory suggests it would increase bite on turn in but would take some playing around with ,

What im planning at the moment is to redrill the phase 1 wishbones with the outer hole as far forward as possible. Will probably swap to a cap head bolt to mean that it takes up less space as well

Its just frustrating that there isnt anymore flat metal left to move it outwards as well as ideally I would like to increase the track a bit as I am doing it.

What would be ideal would be if we could find another balljoint with the same size pin but with a greater distance between the pin and the outer mounting hole.

 

[shiftspark]

Chip, how much castor do you think you can get with moving the mounting holes ? MF said to do this a while back but I never got round to it.

 

[Chip-mk1]

Chip, how much castor do you think you can get with moving the mounting holes ? MF said to do this a while back but I never got round to it.

By just moving the outer hole I dont think you will get anymore than about a degree more than the cup ones, if that, what you could do as well though is to move the inner hole further back as well as the outer one further forward, you could gain many degrees like that but the downside would be that you would marginally decrease track at the same time if you did so

 

[shiftspark]

I cant run different top mounts in my class so was thinking about trying re drilling to gain a bit of castor on my ph1 , this plus maybe also adjusting the inner mounts may give enough - unless it rubs the arches.
I only run revalved Konis and sportlines because I still use the standard top mounts and dont think coilovers are worth the extra cost.

 

[Chip-mk1]

This is that I am going to try out.

Outer hold slightly further out and moved further forward, inner hole I will just slot by a couple of mm to allow the bolt to still go through.

 

[shiftspark]

Looks good chip, get a move on then as there's a few waiting on the results

 

[Chip-mk1]

Lol, sadly mate Im in london and the car is in somerset, so bear with me.

What I will aim to do is work out how many MM its moved the balljoint itself forward once I have done it, then based on the distance between the ball joint and the bearing within the top mount its some pretty simple trig to calculate the change in caster with a reasonable degree of accuracy

 

[bozothenutter]

This is that I am going to try out.

Outer hold slightly further out and moved further forward, inner hole I will just slot by a couple of mm to allow the bolt to still go through.

will this require the existing hole to be closed? Or any strengthening?

 

[Chip-mk1]

will this require the existing hole to be closed? Or any strengthening?

As the new hole looks like it will have good clearance from the previous one I do not believe thee is a requirement to close it.
I dont beleive its presecense will signficantly weaken the arm which is sacrificial in nature anyway, it the deliberately weak part of it further down the arm near the bushes which is designed to bend in an impact anyway.

 

[Chip-mk1]

Mike has just had his Phase1 geo'd after fitting some Cup arms to it, it now has 4.8 degrees of caster.

So certainly a good mod for a phase 1 is just to fit the cup arms.


Sadly wont be able to make a direct comparison to my modded phase 1 arms im going to do soon, as obviously front versus rear ride height and stuff will be different between the two cars.

If I end up in a similar ballpark though I will be happy, and anymore would be a bonus.
(id run 8 if I could!)