Strut mount/bearing question

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fordem
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For the guys who have changed their struts or springs - or anyone who has disassembled a front strut.

The struts have (I believe) a 22mm diameter piston rod which then steps down to a D shaped section and then the threaded portion for the nut - how closely does the D section fit in the bearing on your mount?

I had my struts apart late last year and noted that there was a fair bit of clearance where the strut passes through the bearing, which I think should not be that way - on every other vehicle on which I have disassembled the strut, the strut was a close fit in the mount, on my iO I had several mm clearance, once the nut is tightened down there is no play so I was not to concerned, but as I am now preparing to replace the struts, I plan to correct this, possibly by replacing the strut mount, or by having a tube spacer made to take up the clearance.

NZIO
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Struts

Hi, for a close up view of the threaded portion look at the pics of my strut extenders in my NZIO lift thread - last I looked it's on page 2 of the suspension forum.

I suspect you're right that there is a small amount of movement possible as its quite a basic bit of engineering, but there was no obvious wear on my old struts and this is how it's designed so not sure how much of a problem it really is?

fordem
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I know what the top of the strut looks like.

The question more relates to the tube in the strut mount - none of the ones I've seen have as much clearance as this seems to - for example, on my GV, one strut had to have the mount tapped off with a heavy block of wood, there was just enough corrosion to make it a tight fit - the iO has several mm clearance.

Claude io
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Strut mount

Just to make sure that I understood (don't shoot me, if I haven't!) I think that you are talking about the free play between the threaded part of the insert and the inside of the bearing? If it is, I have notice the same and it is not uncommon, but Kmac (my new adjustable plate) have modified the washer under the nut  with a shoulder to fix this and center the insert, but a small tube, as you mentioned would be just as good.

I have the original plate and I can measure them to see if we have the same gap...

Happy io

My build: http://www.pajerio.com/forum/claudes-io...02 ZR, diff lock,  225/75/16, sport exhaust, and a bit more...

fordem
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Close ...

 

Here are the strut rod extenders that NZIO made from his old struts - you can see 22mm piston rod, and then you can see where it steps down to the D section, (although the flat itself is not shown), and then where it steps down again to the threaded portion.

The diameter of the D section is not a snug fit in the inside of the strut bearing.

From what you say yours had a similar clearance - thanks - you've answered one question - but raised another - I can't help but wonder why Mitsubishi did that. 

 

NZIO
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D section

I know I must be missing something but here goes... All the D section being held in the top spring hat needs to do is stop the strut rod from spinning around, which it does OK albeit not with a not very precise fit. Is your concern that the slack in the fit could get worn over time and allow the strut rod to spin and possibly undo itself?

Claude io
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Why?

Fordem, hard to say but if I would have to guess, Mitsubishi likes to use the same part on several car, and I wouldn't be surprised that the top strut might be used on another car, with a wider "D" section, and decided that it would be fine for the io the way it is? I don't know, just an idea!

Nzio, I think that the issue is more that the "D" section is smaller than the inside section of the bearing. From memory about a couple of mm, maybe more...

Happy io

My build: http://www.pajerio.com/forum/claudes-io...02 ZR, diff lock,  225/75/16, sport exhaust, and a bit more...

fordem
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I wish that were the case.

Claud io wrote:

Fordem, hard to say but if I would have to guess, Mitsubishi likes to use the same part on several car, and I wouldn't be surprised that the top strut might be used on another car, with a wider "D" section, and decided that it would be fine for the io the way it is? I don't know, just an idea!

Nzio, I think that the issue is more that the "D" section is smaller than the inside section of the bearing. From memory about a couple of mm, maybe more...

Happy io

One of the things I've done very frequently over the past few weeks is look a part number for an iO specific part, and then put that part number back into Mitsubishi's inventory system to see what other vehicles it fits - and it's not often that I find it used on another vehicle - case in point - there are six different Mitsubishi part numbers for the front struts, replaceable by two different Tokico numbers of two different KYB numbers, and those part numbers are specific to the iO - they are not used on any other Mitsubishi vehicle.

I tried to find another vehicle, preferably a US market vehicle (it's fairly easy for me to get parts out of the US), that used the same strut, spring, strut mount, strut boot, etc. - and drew a blank on every item - the only suspension part I was able to find is the sway bar end links, which are also used on the Diamante.

NZIO
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part numbers

I think I've previously relayed the comment made by the local shock absorber specialist I got my KYBs from - he said he has more manual annotations and cross outs in his Mitsubishi catalogues than any other manufacturer, by a long way.

fordem
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My concern is alignment

NZIO wrote:

I know I must be missing something but here goes... All the D section being held in the top spring hat needs to do is stop the strut rod from spinning around, which it does OK albeit not with a not very precise fit. Is your concern that the slack in the fit could get worn over time and allow the strut rod to spin and possibly undo itself?

I'm not really concerned with the fit of the D section in the upper spring seat, but more in the strut mount bearing - it is my suspicion that the alignment (caster/camber) can be affected by where the strut is in the bearing when the nut is tightened down.

You can remove the plastic cap from the bearing and unscrew the nut and move the top of the strut maybe 2mm or so side to side/front to back - I have no idea how much this affects the caster/camber - but in theory it will - maybe I should measure it, maybe I'm focusing too much on minutia.

NZIO
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Aha!

I knew I wasn't quite getting it... OK I hadn't noticed it myself but know what you mean now. A couple of mm though? I would have thought for a 4x4 it's beyond the threshold of meaningful error, and the nut is torqued down hard enough to ensure movement shouldn't happen without a significant shunt. Having said that - its just my opinion, perhaps you're right.

ktm300
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.

There should be maybe .03mm difference between the Bearing ID and the shaft OD, resulting in a clearance fit.

'Several mm' sounds excessive.

Cheers.

 

 

 

"It should be assumed everything I say and do is incorrect ".

Claude io
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Several mm

Agree, several mm is way too much, and my 2 mm probably too, but it was not a nice fit... Ktm is putting doubt in my mind...So I have just measured the inside diameter of the bearing 's plate, 15 mm and the threaded part, 12 mm that is all I can measure today... I will measure the "D" section on Thursday (a bit more involve). But at this stage, the "D" section being visually bigger than the threaded section, I think that it will be closer to 15 mm than I remembered.

Happy io

My build: http://www.pajerio.com/forum/claudes-io...02 ZR, diff lock,  225/75/16, sport exhaust, and a bit more...

Claude io
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"D" section diameter

Hum, I couldn't stop thinking about this....so I just measured the "D" section, and it is 14.7mm may be 14.8 mm (hard to put the caliper between the spring), so I was way out and wrong about the 1 or 2 mm gap, sorry. Anyway, I hope it helps...

Happy io.

 

My build: http://www.pajerio.com/forum/claudes-io...02 ZR, diff lock,  225/75/16, sport exhaust, and a bit more...

fordem
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Agreed - several mm, is, in my mind, excessive.

ktm300 wrote:

There should be maybe .03mm difference between the Bearing ID and the shaft OD, resulting in a clearance fit.

'Several mm' sounds excessive.

Cheers.

There is considerably more play than would be considered a "clearance" fit - I can't tell you how much more, but I would say several mm - if it were a clearance fit, as on my other vehicles, I would not have been asking about it

I know the struts are the Mitsubishi OEM part number, because it's stamped into the body - I can't say the same for the strut top mount/bearing, hence my question - if they are not the correct part, the time to replace them would be whilst I have the strut assembly apart.

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