Restoring 172 Cup - Help Required

Hi all

I’ve spent the last two years restoring a Clio Cup, which has been owned by a couple of members on here already. It was a solid car to start with and had been stood for a few months prior to me becoming the custodian.

Anyway, it went for its MOT and everything was going great, until we got to the brake testing… long story short, the brake servo decided to give up and split in half. Thankfully it happened there, not on the road, but now I’m stuck trying to source a replacement.

I’ve spoken to my local dealer, Mick at Diamond Motors and Pure Motorsport. We’ve concluded the servo should be the same as the 172/182, based on historic part numbers. The problem I’m finding is;

Several different part number crop up
The part number on the servo that gave up is different to the ones coming up on the likes of Autodoc, online car parts and an eBay seller in Lithuania.

I’m hoping someone can help me keep this 172 Cup in mint condition and on the road by confirming if the servo is generic across the RS Clio 172/182 range or if it is indeed unique to the 172 Cup?

Thanks for reading and hope someone can help.

Many thanks
Sean

Sounds like Mick has got a dose of amnesia & forgot all about the exact same nightmare I had with with mine just over 2 years ago

I'll have to go through my old photos to help properly explain but the short version is that I found it impossible to find a servo with the same part number as what was on the car and what I managed to find on Autodoc from cross referencing the Bosch part numbers was different & wrong.

I ended up getting a used servo from someone breaking a 172 Cup then scrubbed it back to bare metal, repainting it then running a thick bead of silicone sealant around the bottom where the 2 halves of the servo join together. It was probably started from spilled brake fluid sitting in the crease of the join, eating the paint away then combined with that area getting exposed to water & other crap which sits in the creases and it got rusty & eventually failed.

These are the part numbers from mine & what I got from Autodoc.
You can see the side by side pic that the servos are different. I reckon it's possible to swap the rod over to make it right but I chickened out because the new servo was really expensive, took ages to arrive, if it didn't work it'd be obvious that I'd messed around with it and there's a good chance they'd tell me to piss off if I sent it back asking for a refund 🤣

Not sure if the silicone is visible in these pics tbh but you get the jist of what I was trying to do

Hi mate. Thank you for your detailed reply, really appreciate. Ah man, so it looks like the Cup is unique and I can’t just use any servo. The one or two I’ve found are rotten and look in worse condition than mine, so I just don’t understand how it split in half.

I suppose as it’s in two pieces, I can sand it down, rust restore, attach and then run a bead of seal round like you have.

Looking at how they’re joined, you’d just need to use a punch to secure them back together. After what happened, you can imagine I’m a little reluctant in case it happens again… just in the road next time.

Also, as you say, I’m very reluctant to buy and split a brand new one.

So… back to the hunt or restore.

Thanks again for your help and advice, really appreciate it.

You've got no chance of restoring yours, the rust has completely compromised the metal at the point it needs to be it's strongest (that's why it split in 2) it's just like rust anywhere else on the car, the only way to repair it is to chop it out & replace the metal itself.

On top of that you can't even weld it back together as you'll trash the rubber diaphragm inside.

I only gave up looking to use a different servo & modifying it as I dropped lucky finding a Cup servo that happened to be in good nick

If that’s what’s needed, then I guess that’s my only solution. I can’t believe the servo is unique to the Cup. I’d be interested to find out what else that servo is used in, as surely it can’t be unique to just a 172 Cup. The development alone would have cost a fortune for a small number of units, in comparison to the 172/182.

On another note

Your cup looks great

Sean Collingwood said:

If that’s what’s needed, then I guess that’s my only solution. I can’t believe the servo is unique to the Cup. I’d be interested to find out what else that servo is used in, as surely it can’t be unique to just a 172 Cup. The development alone would have cost a fortune for a small number of units, in comparison to the 172/182.

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Like you said I’d imagine it will no doubt be on other (probably non abs’d?) french cars. It’ll just be a headache trying to figure out which ones that is.

Advikaz said:

On another note

Your cup looks great

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Thank you… it’s a lovely looking ornament at the moment 😅

Matt Cup said:

Like you said I’d imagine it will no doubt be on other (probably non abs’d?) french cars. It’ll just be a headache trying to figure out which ones that is.

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That’s my thoughts, surely another non ABS car. Were the early 172 phase 1’s non ABS?

Sean Collingwood said:

Thank you… it’s a lovely looking ornament at the moment 😅

That’s my thoughts, surely another non ABS car. Were the early 172 phase 1’s non ABS?

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Relatable mate

Sean Collingwood said:

If that’s what’s needed, then I guess that’s my only solution. I can’t believe the servo is unique to the Cup. I’d be interested to find out what else that servo is used in, as surely it can’t be unique to just a 172 Cup. The development alone would have cost a fortune for a small number of units, in comparison to the 172/182.

Click to expand...

If I was in this situation again I'd be getting my hands on some other servos & dismantling them to measure & compare stuff inside (I was about to scrounge some from a local scrappy that had a load of pov spec Mk2's in) with a view to making a good 1 that fits & works.

As far as I can think, it's the length of the rod the pedal attaches to that is different and it appears relatively easy to swap those out so that's the route I'd be going down - as well as desperately looking for a used one from a Cup

Sean Collingwood said:

If that’s what’s needed, then I guess that’s my only solution. I can’t believe the servo is unique to the Cup. I’d be interested to find out what else that servo is used in, as surely it can’t be unique to just a 172 Cup. The development alone would have cost a fortune for a small number of units, in comparison to the 172/182.

Click to expand...

You can't use sensible logic like that with French cars
You'd think that's the case but there really are a load of things that are annoyingly unique to the cup - which I have discovered the hard way - and probably a load I don't know about too.
A brilliant example of this kind of silliness is the driveshafts & CV joints, ph1 shafts are the shortest length, next shortest are 172 Cup shafts and ph2 shafts are the longest (no idea about 182 stuff though but it's not really relevant on this subject)
On top of the shaft lengths, in their infinite wisdom Renault also decided to put 32 teeth splines on the outer part of the ph1 & ph2 shafts but the 172 Cup ones have 23 teeth so CV joints are a swine to find

16v_paddy said:

If I was in this situation again I'd be getting my hands on some other servos & dismantling them to measure & compare stuff inside (I was about to scrounge some from a local scrappy that had a load of pov spec Mk2's in) with a view to making a good 1 that fits & works.

As far as I can think, it's the length of the rod the pedal attaches to that is different and it appears relatively easy to swap those out so that's the route I'd be going down - as well as desperately looking for a used one from a Cup

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I think that is what I’m going to do. I’m going to get a servo from Stu at Renomotive, as he has an few and see what I can ‘create’.

When I’ve been thinking logically, the fork that holds the pedal is shorter, so this would affect the pedals resting location.

Also I found that the amount of servo assistance on the Cup was reduced, due to the lack of ABS (now is that due to no ABS, or the actual servo?)

If it’s a case of the pedal sitting in a different location, it should be sat in the same location as a 182, as the pedal assembly is the same - on the grand scheme of things, that isn’t a problem.

As for servo assistance, is it really going to be so different, that it makes the car un-drivable? Probably not.

So best case, I can cobble something together to make a 172 Cup spec set up. Worst case, I’d have to get used to a slightly different pedal feel… as for my OCD… I’ll have to just accept ‘it is what it is’.

I’m realising the Cup is a lot more unique than what you read in a brochure… which leads me to think that Renaultsport in the 90’s/00’s were pi$$lng money to develop unique parts for a special car… although homologation for rallying, I guess it was a blank cheque!

I

Sean Collingwood said:

When I’ve been thinking logically, the fork that holds the pedal is shorter, so this would affect the pedals resting location.

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I'm thinking this could also be related to the master cylinder being different on the Cup - I could also be talking a load of b****cks but it's something that seems plausible from my experience

16v_paddy said:

You can't use sensible logic like that with French cars
You'd think that's the case but there really are a load of things that are annoyingly unique to the cup - which I have discovered the hard way - and probably a load I don't know about too.
A brilliant example of this kind of silliness is the driveshafts & CV joints, ph1 shafts are the shortest length, next shortest are 172 Cup shafts and ph2 shafts are the longest (no idea about 182 stuff though but it's not really relevant on this subject)
On top of the shaft lengths, in their infinite wisdom Renault also decided to put 32 teeth splines on the outer part of the ph1 & ph2 shafts but the 172 Cup ones have 23 teeth so CV joints are a swine to find

Click to expand...

It’s things like the fabric seats, thinner glass, 172 Cup offset Turini wheels… the list of unique parts/set up… how on earth did they afford to sell them for circa £13k

But then rumour has it, each Megane R26R cost £1m in development and look how much they were brand new (can’t confirm if this is actually the true figure, but I did read each was sold at a loss).

16v_paddy said:

I


I'm thinking this could also be related to the master cylinder being different on the Cup - I could also be talking a load of b****cks but it's something that seems plausible from my experience

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I’ve also heard that. The master cylinder is supposedly different, but I will see how it fits up to the 182 servo. As long as a vacuum can be generated and there’s no leaks, the servo will work. It’s all down to just how much assistance the 182 servo will give.

I might buy a 182 master cylinder too, to be safe, but years ago I did remove the ABS from a 182 and it still braked absolutely fine… and in all honesty, it was an absolute bodge job.

From driving both, the 182 never felt over assisted, but the Cup for day to day normal driving, could do with a little more. Great for modulating brake pressure on track, but it was never restored to be driven balls to the wall… also, I’m awfully close to 40, so those days are long gone 🤣

I thought the 182 master cylinder couldn't be used because it only has 2 ports where the non abs one from the Cup has 4 ports?

I was thinking more along the lines of the piston inside the MC being in a different position requiring a different length rod to press it while maintaining the same pedal position.
I'm starting to think that it all just comes down to these 2 bits circled in the pic, I'd be swapping those bits over into a different servo to see if it does the trick

16v_paddy said:

I thought the 182 master cylinder couldn't be used because it only has 2 ports where the non abs one from the Cup has 4 ports?

I was thinking more along the lines of the piston inside the MC being in a different position requiring a different length rod to press it while maintaining the same pedal position.
I'm starting to think that it all just comes down to these 2 bits circled in the pic, I'd be swapping those bits over into a different servo to see if it does the trick

View attachment 1719633

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Ah ok… thank you for letting me know about the 182 MC… that was a total oversight on my part. You’re right, it has two, Cup has four. So that idea is out.

I’d also agree with you on those parts needing to be swapped out too. How easy is it to remove the part the pedal attaches to? As the servo split in two all by itself, the smaller rod thing was easy to extract.

Also, when splitting the servo, what did you do regarding those indentations that attaches the two halves together? And reattaching them, did you use something like a punch to pinch the halves back together?

The servo in my pic is the 1 that split itself open so that bit was already easy to disassemble 🤣

The rod the pedal attaches to is really easy to remove, it sits inside the plastic sleeve & is held in place with the 2 black clips which are then secured into place by the circlip spring thing

On the replacement servo I didn't actually split it apart, I did pry apart the indentations a bit so I could get the silicone in there better then used a punch to pinch them back together - just make sure you use something to clamp & hold the 2 halves together 1st because as soon as you start to hammer the indentations in, the shock and spring pressure can make the whole thing explode apart

Brilliant, thank you for the advice, really appreciate it. I was beginning to think I had a very tidy and lovingly restored parts car.

So it sounds like securing in a vice will probably be the best solution while prying apart the indentations to stop bits of servo flying all over, then to fill with sealant when being built back up.

After Tuesday, I know all too well about the exploding apart bit 🤣

It has to be done, they’re becoming scarce now and deserve to be kept right. Shame they’re not classic Ford prices though, I bet if they were, places would be making pattern parts for them… and the investment value of course 🤣