General Multilink Suspension

Discussion in 'General Discussion' started by ArcticFire-Account Closed, Wednesday 12th Feb, 2014.

  1. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    Are there any multilink rear suspension gurus on here?
     
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  2. Ichiban Founder Staff Team

    England CJ Leeds
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  3. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    I don't have permission the view it. Need to pick some brains but it could be challenging
     
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  4. Ichiban Founder Staff Team

    England CJ Leeds
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    Really let me see why that is
     
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  5. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    Works now cheers, interesting read.

    Ok, I'm having a very annoying problem with my rear suspension and so far the mechanic at work, the rally mechanics I use and also the guys on the Mazda forum haven't been able to figure out what's wrong! lol

    Mind it's a Mazda 6 MPS so the rear is multilink suspension setup with gas shocks and it's AWD so there's a diff back there also with drive shafts etc.

    Basically, it's making a clunking sound but there doesn't seem to be any pattern as to when it makes this clunk and strangely potholes tend not to cause it but more things like speed bumps, lateral forces, rise and dips in the road and road imperfections. It's almost constant clunking away over bumps when the car is cold but after being on the motorway it tends to fade away. It also clunks when the rear is coming off the kerb, even when doing it very slowly. The rear doesn't seem to be absorbing the bumps very well, it's a bit jarring which makes me think it must be related to something that's connected to the dampers. There's no excessive roll with the car.

    I've replaced the rear shocks and the rear drop links. The rear diff bushes are fine as that would only clunk when launching. The ARB bushes look mint and there's little movement but I'm getting them replaced next week anyway. Nothing else seems to have any unexpected play and the bushes all appear to look good. We can't seem to replicate the noise when up on the ramps or over the pit and tonight I tried it on axle stands so the suspension is dropped down but it's all even stiffer then with no play anyway.

    It's a mystery and made worse by how many bushes this car has in the rear. It's been suggested that it could be the rear trailing arm bushes although again there's no unexpected play with them.

    Any thoughts or has anyone experienced this as it's doing my head in!




    I suppose this may be appropriate....

    :BavarianTractor:
     
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  6. PeteMM Premium Member Club Supporter

    Northern Ireland Pete Belfast, UK
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    Unfortunately you will never be able to exert the forces seen when driving onto suspension components when on a ramp or lift. Making issues like this a nightmare to diagnose.

    My initial thoughts were drop links, but you say they are replaced. Having read the rest of your post, I would be almost tempted to say top mounts for the shocks. A lot of bushes will clunk and jump around if they were not correctly greased or fitted. Have you greased the spring plate and top mount?

    Have you considered looking at the diff or propshaft? it could be something as simple as a bit of dirt on the splines coming out of the diff. It may also be a sign of wear in the rear diff but I am imagining at this stage you can determine the difference between the mechanical noises of suspension and rotating drivetrain. As the suspension moves, there will be an element of lateral slip of each rear driveshaft, allowing it to slide in and out of the diff as the suspension bumps and rebounds. If it is a setup like Honda driveshafts then it will run on bearings inside a cup and they can become worn and knock. Alternatively if it is bolt on like the WRC cars then there has to be a CV or other joint to allow the lateral movement.

    Just a thought.
     
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  7. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    Cheers, the top mounts of the shocks was mentioned on another forum but I figured that as these guys had literally just put new shocks in a few weeks ago it would have been noticed. They cover regular mechanics right through to building rally cars so I'm confident they know their stuff! lol

    The car has 30K miles so I'm hoping it's not the rear diff, although I did replace the oil in it a few months ago. It takes a litre and I remember using Comma GL-5 but the bottle was crap for pouring (access is poor) and I could only get 1/2 litre in. I could only get Castrol GL-5 locally on the same day so I finished off with this. Is it possible that even though they are both GL-5 the different brands could be causing some problem? (it's been bugging me btw since doing it as I don't like mixing brands).

    There is tiny movement in the drive shafts but they checked it and said it's all good. There doesn't seem to be any parts listed for rear CV joints but the drive shafts have something called a Rotor Sensor at the end. I've attached a screenshot showing a parts diagram.

    I think I'll get them to check the shock mounts, it does sound like something is tapping on the underside of the boot so that would make sense. Unless it's the rear diff oil?

    Screenshot.
     
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  8. AndyB1976 Valued Contributor ★ ★ ★ ★ ☆

    United Kingdom Andy Aberfoyle
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  9. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    Way hey, love the name! Arctic Tools! hehe

    Do you think it actually works? Worried that there would be too much interference what with being wireless.
     
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  10. PeteMM Premium Member Club Supporter

    Northern Ireland Pete Belfast, UK
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    Was GL5 the recommended oil to use in the diff?

    I am sure you know Hondas make funny noises and self destruct when people use crap tranny fluid, the same applies for almost every diff/axle I have ever worked on.

    We stick to Millers stuff because they genuinely work alongside clubman motorsport guys to create their products but everyone has their favourites and it is hard to persuade them otherwise. Find out what weight of fluid you need and do another change there to the right stuff, all one brand. Get a length of hose that fits in the fill hole but also slides over the end of the bottle. Leave the fluid on a radiator for an hour before doing the job, means you can hold the bottle up in the wheel arch and it flows out easily instead of spending 4 hours trying to drain 250ml from an airtight bottle full of syrup.
     
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  11. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    lol it wasn't as bad as the gearbox but I fashioned an awesome tool so I could fill the gearbox easily from above the engine bay!

    GL-5 is the right spec and I used the correct weight - all straight from Mazda's own technical book (a beastly 3,000 pager!). I'm not a fan of mixing though so I think I'll drain and redo. People have recommended Motul but then others don't. I figured Castrol can't be all that bad as it's part of BP.

    - - - Updated - - -

    Here's the spec:

    Rear differential oil type Grade: API service GL-5
    Viscosity: SAE 90, SAE 80W-90, SAE 75W-90
    Capacity: 1 Litre
     
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    PeteMM likes this.
  12. AndyB1976 Valued Contributor ★ ★ ★ ★ ☆

    United Kingdom Andy Aberfoyle
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    There are some complaints online about interference, I guess it depends maybe where you have them hooked up. As other have said there is really no other way to replicate the driving experience on a ramp or axle stands. A handful of diagnosis per year and you'd probably save the money spent in garage inspection fees. You can also listen to injector solenoids and pump bearings aswell.

    I was going to try and wire my own up with 4 or 6 walkie talkies on different channels, VOX enabled with small battery clamps wired to a mic input, onto the walkie talkie lol. I then thought about hooking up the walkie talkies to FM transmitters so I could just use the radio to scan rather than multiple walkie talkie channels but then the cost was getting close to buying the tool outright.

    Here is a short vid, basically getting to the point

     
    Last edited by a moderator: Saturday 22nd Feb, 2014
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  13. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    I'm not sure if I'm sold on these things, there must be some way of making the suspension work without having to actually drive it. I'm thinking gigantic lever under the tyre and work that baby up and down? I know of an MOT station that has a one-man suspension test kit. I'm sure it was like plates that either sat on the ramps or was built into it and it shiggles all the wheels in different directions to test the suspension components. I remember watching it in action on my Accord and thinking it was wrecking my suspension because it was quite forceful!
     
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  14. AndyB1976 Valued Contributor ★ ★ ★ ★ ☆

    United Kingdom Andy Aberfoyle
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    Yeah I guess any good garage and mechanic will always have the tools and knowledge to pinpoint noises.

    If its a drive shaft/CV joint (not in your example specifically) you can hook these clamps in the vicinity and its something you can buy and own - unless you have space for a suspension shaker or don't mind the inconvenience and costs to go to the garage :Niceone:
     
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  15. ArcticFire-Account Closed Banned Getting Started

    Scotland Graham Scotland
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    Well they found out what was wrong and it turned out to be the rear diff mount - something I was hoping it wouldn't be! lol

    It's apparently a 5 hour job but these guys reckon it will only take 3 - it's a similar job to the Subaru's which they specialise in so I'm guessing this along with their rally heritage helps. It's also given me an excuse to upgrade the rear diff mounts to a poly bush kit and whilst they have it off I'm going to upgrade the rear ARB also :Smile:

    It knocks like mad now so I'm glad they've found the problem before my rear diff suffers from axle damage!
     
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    AndyB1976 likes this.