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DAMPER POWER/MANUAL STEERING

Posted: Wed Aug 07, 2019 5:39 pm
by Dennis Nicholas
:w :w
MY GTC WITH POWER STEERING, Girling Decarbon damper (possibly the originals!).
When putting the damper/spring unit back on, bottom bolt into bottom bracket first, I found it a bit difficult to get the top bolt through the bracket and into the damper bush then difficult to get it all the way through and out to put nut on. I was apprehensive that I might damage the thread. Once in I tried jacking up the suspension to take weight on damper/spring to get to normal position so I could torque tighten all bush nuts/bolts. The damper/spring would not compress so I feared that somehow the damper rod had maybe become bent and was sticking so would not go into body.
I had taken the spring off the damper to clean and paint the damper and spring. While taking it all off again I noticed that the top damper bush eye looked very slightly out of alignment with damper body centre line (C/L). I had previously noticed this when putting back on but thought nothing of it as all had been working ok previously. Closer inspection with a set square and ruler confirmed there was a very slight miss-alignment. The bottom eye also seemed to be also not in alignment. Top one slightly clockwise and bottom one slightly ant-clock. A half inch rod through each of the damper eye bushes showed that indeed on one side the rods were closer than on the other side. I twisted one eye through 180 degrees and the rods now became parallel and the damper top bolt went in much easier and on jacking up, the spring/damper unit compressed till taking the full weight of the car.
I removed the damper unit again to further inspect and on putting a straight edge against the top chassis bracket front face this aligned about halfway back from the bracket front face of the bottom damper bracket. The bottom wishbones/trunnions/damper bracket all fitted and tightened in place.
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With the bottom wishbone brackets in the power steering position (offset bolts to the rear) the wishbones and thus bottom of the damper are 3/4 inches further forward compared with the non power steering. Since the top brackets are welded to the chassis then in one or other of the power/non power positions means the bolts in parallel damper eyes are not going to be parallel with bracket eyes. Was it standard that the damper eyes had complimentary twists to get the bolts parallel again (assuming the chassis for power/non power steering were the same with the top brackets only ever welded in one position??

I do have the spacers in their correct position on the inside of the brackets top and bottom and the bushes are the correct 1 1/8 inches wide.

How do modern replacement dampers cope with this offset? I have only previously dealt with new dampers on a non power GTE.
I don't like the idea that there is a side load put in the damper rod if the eyes are not slightly offset.

Dennis

DAMPER POWER/MANUAL STEERING

Posted: Wed Aug 07, 2019 7:53 pm
by scimjim
I imagine the damper bush is designed to take that small misalignment - the upper and lower wishbones can move fore/aft during normal operation (I wonder how much twisting moment you get when emergency braking?)

DAMPER POWER/MANUAL STEERING

Posted: Wed Aug 07, 2019 10:29 pm
by Dennis Nicholas
The two miss-alignments in opposite directions added up to very noticeably non parallel bolts which became parallel once the eye on the plunger rod was turned 180 deg....the normal static average state. A constant side load on the damper plunger rod would be further increased under certain conditions (as well as decreased under others), that can't be ok?

Dennis

DAMPER POWER/MANUAL STEERING

Posted: Wed Aug 07, 2019 10:39 pm
by JoeySully
Maybe save it as a jpeg or other image format. I dont think placing a .pdf inline is possible. It could contain several pages.

DAMPER POWER/MANUAL STEERING

Posted: Wed Aug 07, 2019 10:52 pm
by Roger Pennington
Yes, Joey is correct, PDFs always appear as attached files, as yours has, so you need to download and open them in a PDF viewer to see them. The best solution for your sketch diagram, if you want it to appear inline in the post, would be to save it as a JPEG image file, then attach that to your post.

DAMPER POWER/MANUAL STEERING

Posted: Wed Aug 07, 2019 11:54 pm
by Dennis Nicholas
Ah-Ha....getting the hang of it a bit more......post edited.

DAMPER POWER/MANUAL STEERING

Posted: Thu Aug 08, 2019 8:34 am
by scimjim
If the chassis is designed to take different trunnions (with the same damper for each), the damper top mount would presumably be aligned with the centre point of the lower two positions - ie giving a maximum of 3/8” misalignment in the static position?

As for the misalignment of your damper eyes, they don’t come like that, they’ve presumably bent over 40 years of use.

DAMPER POWER/MANUAL STEERING

Posted: Thu Aug 08, 2019 6:34 pm
by Dennis Nicholas
scimjim wrote:
Thu Aug 08, 2019 8:34 am
If the chassis is designed to take different trunnions (with the same damper for each), the damper top mount would presumably be aligned with the centre point of the lower two positions - ie giving a maximum of 3/8” misalignment in the static position?

As for the misalignment of your damper eyes, they don’t come like that, they’ve presumably bent over 40 years of use.
Re IF damper top aligned with central point.....yes I can see that would be either 3/8 too far forward or 3/8 too far back. Wheel back on ready to get back on road tomorrow and collect 2 new tyres so cant check the position.......that has been 10 months without the GTC.....I have huge withdrawal symptoms and can't wait to get back driving it......still a bit difficult getting in and out while 2 hip replacements recovering.

RE damper eye misalignment, the eyes have a pretty substantial join to the main body and I would say that the force to bend them would cause considerable damage elsewhere so perhaps Reliant were better with their design requirement than we give them credit for?

Note where I say
Dennis Nicholas wrote:
Wed Aug 07, 2019 5:39 pm
on putting a straight edge against the top chassis bracket front face this aligned about halfway back from the bracket front face of the bottom damper bracket
Too tired and emotional to do the maths now......its fish and chip van in Shebbear square night and wife has just gone to collect + I hear the SAM'S zyder bottle calling me :D

Denis