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Correct Length of standard shock absorbers


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Hi Mark,

Best is to remove one front shock and measure its length in both positions (longest and shortest length).

Measure from centre of lower bolt hole to the position between the two rubber discs for the top mount.

Max. Length should be 300-305 mm, compressed length approx. 250mm, see earlier post in this topic.

An alternative, easier method, since the issue was "too long shocks" is to jack up the front of the car on the chassis, both wheels hanging free in the air, and test if the steering goes heavy; this is what happened to my 6.

I think due to the trunnion contacting the lower spring pan, resulting in very very high lateral (sidewards) forces on the trunnion and resultant friction, but Moss indicated it is due to the upper ball joints, some cheap repro's limit the travel of the front suspension. Moss may be right, who am I?

I appreciate they investigated the issue after the PQI was raised, unlike another supplier.

Regards,

Waldi

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Hi Mark/Waldi,

this was quite an alarming issue - you don;t want the steering to seize when flying off that hump back bridge.

 

There are some rather poor quality top ball joints on the market and that may be the biggest offender in this problem.

I found out today that Revington supply a quality top ball joint but at a price. But! how often do you change a ball joint, worth every penny.

 

Roger

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Hi Mark,

have you contacted the supplier. Those boots should have been very good quality.

 

It is odd that even Moss boots last quite a good time when fited to a running car but are hopeless if the car is static.

 

Roger

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Sorry Roger,

I replaced the rotted ones with the ones you recommended, which are still in excellent shape.

Just removed one shock,measured from centre hole bottom to centre of two top rubbers 335 mm fully open. Fully closed 235 mm.

If all like for like oem parts are all coming over size. what are the best aftermarket correct size shocks available?

Mark

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Mark,

Back to shockers....

I finally have gone for GAZ...fitted them and they are the correct dimension when fully extended and nothing binds.

Seen good and some negative reports on this make..will only know when rebuild is done.

 

Richard.

Edited by Richard Young
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Hi Mark,

I installed Koni Classics, part no. 80-1784, they were 200 euro incl. shipping from Germany (to Holland).

Their length in full extension was 305 mm.

There is an not so old topic called " Trunnions..."

with relevant info.

Regards,

Waldi

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  • 4 weeks later...

My new KYB gas shocks from TR shop are also 330mm extended i.e. 30mm too long, causing trunnion to contact wishbone and jam steering on droop, trying new QH upper ball joints to see if it free's up steering, even if it does, not ideal using trunnion as travel limit stop. Using standard shock upper bushes instead of the KYB's position the shocker a couple of mm higher and with 4 x 3mm spacers above the lower shock brackets gain about 5mm but still not enough to cure the problem. As detailed previously orig shocks were 300mm extended and no issues.

 

Regards,

 

John

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Hi John,

Went through the same issues months back,I would advise you send KYB's back for refund.The only way the problem will be solved is with 305mm length..same as original.I would go for Konis or GAZ as they are correct length....just my two penn'th worth.

 

Regards

Richard.

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Now tried QH ball joint, had less articulation than the originals, also they were about 1.5mm narrower than the originals and the bolt holes slightly larger diameter, i.e. all in all much poorer than the originals (they also have no grease nipple).

It is def not a ball joint articulation problem, if you remove the front ball joint fixing bolt which allows the ball joint to articulate as much as it likes it is still very stiff steering on droop. It's because the trunnion is tensioned between the lower pivot bolt, the upper pivot point(ball joint) and the point at which the trunnion is being forced outwards by the lower wishbone. It's bad enough without the weight of hub/disc/caliper/wheel and tyre so will only be worse when all this is installed.

So it looks like a set of shocks of the correct length is the only proper solution.

 

John

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John,

I also had the same issue, with standard shocks from TR-shop, also 330 mm long, see earlier post above.

I too thought it was the trunnion pressing against the lower seat pan, but Moss (who also supplied these shocks thought it was the top ball joint. Your simple test shows this is probably not the case.

I returned my shocks to TR shop, their response at that time was disappointing to me.

Moss took more effort to resolve.

 

Regards,

Waldi

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Hi Waldi,

when the issue was pointed out to the TRShop all their suspect stock was thrown in the bin.

Admittedly there were only a few items but off they went.

 

The TRShop did not want to compound any problem.

 

I understand Rimmers did nothing.

 

Moss spent a great deal of time evaluating the problem and came to the conclusion that the main suspect was the top ball joint.

However this hasn't stopped them selling the cheaper TBJ.

 

From a practical point of view this stiffening of the steering due to the pressure on the trunnion would only surface if the front of the car is airbourne.

This is not a common event,but does happen.

 

There is a problem so be careful in what you buy.

 

Roger

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Hi Roger,

Thanks, this is also what I recall.

 

John,

When did you order your 330 mm shocks from TR Shop?

 

Regards,

Waldi

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Waldi,

 

They were ordered early June, But they were not the same as yours they were KYB's.

 

I looked into this and the manufactures spec for the original part numbers show an extended length of 330mm. It seems that the use of these and slightly modifying the length of the lower bush is a way of providing a quality shocker at an attractive price that will fit the TR6, they have been used like this in the US on TR's for a while and people are pleased with their damping quality but they were not specifically designed for the TR6 by the manufacturers, hence the 330mm length.

 

My concern was not the airborne issue during use, as if that unlikely event did occur, most people (including me) would just hold on tight to the wheel until landing, turning the wheel airborne is not a wise move and when you land everything works as it should. My concern was the large amount of continuous sideways pressure on the trunnion when on droop not designed for that force, my car has had the wheels off the ground for months. More of a concern was the MOT where they check my suspension/steering on full droop. I have had reports of my steering rack going tight on another car I owned which was due to a slightly bent rack, so they are bound to pick up this level of restriction, probably fail it and rightly so.

 

As previously mentioned the ball joint articulation was not my issue either with the original or QH ball joint.

 

I would add that I am happy with TR shop's initial response to my raising the issue.

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John,

Thanks.

I am not familiar with UK MOT requirements (I am Dutch), but overhere it would be hard to convince the inspector that all is ok during normal driving.

Glad to hear the TR Shop response was good now.

It may be a quality shocker, but it is not fit for purpose.

Hope you find an acceptable solution.

 

I am prepared to pay extra for a correct item, and that is what I did.

Regards,

Waldi

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Agree with Waldi and Roger...also looking at my original post on this issue,at the time I did find that by taking one of the bolts out of the top ball joint and slightly loosening the other it assumed a steeper angle (with sus drooped) and did remedy the steering tightness to a degree,so my earlier comment on this post regarding the effect on the trunnion being the prime cause of the stiffness of the steering might in fact also point to the top balljoint adding to the problem.

I was wondering about the MOT question also.

 

Richard.

Edited by Richard Young
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