Rear upper arm nip... Fitting Powerflex. have I lost a bit?

[TVR Beaver]

Here again... as it says.. fitting Powerflex and just come to fit the rear uppers (the top of the triangle)only to find that the gap between the clamp tube and the arm is massive.. this won't nip up... so I can only assume I've lost a bit?.. may be some big washers or something??
I have all the old rubber bush units I took out and have just been through them... all 12 are the same length and the same length as the Powerflex.. so it's not this (2 smaller fatter ones on the rear where the shock mounts also)...
So what goes in here.. any thoughts????

[carsy]

Just done mine and guess what!. yep exactly the same. we must have the same wishbones. I rang powerflex and they sent me some more thrust washers. Some 1mm and some 3mm thick. I packed one side with 2 x 3mm washers and fitted a 1mm on the other side. Fitted nice and snug then.

[TVR Beaver]

But how did you torque it up?... the inner steel tube is a lot less than the gap... you must nip on this to make it solid... Id assumed there were steel washers in here as the inner face is not chewed up on the arm... Its not a Powerflex issue as the std bushes are all the same length and would sit the same (with a gap)
But you must clamp the inner tube.. or it will turn on the bolt?.. and with this amount of clearance you've no chance of doing that...

Edited by TVR Beaver on Friday 28th January 21:06

[carsy]

Yes i here what you are saying and totally agree. Having done the whole car now with these bushes i am not totally convinced they will all work as intended. ie on the internal bearing rather than on the bolt. Everyone i have fitted seems to differ on gap dimensions and on how much the lugs need pulling up etc. As a few people have recently stated i dont think these type of bushes are that well suited to the car.

I thought about fitting metal washers just big enough to go over the bolt and so grip the metal tube as you rightly state. As of yet though i have just put the plastic washers in, but as you say the bearing will not operate as it should.

I am in the middle of a complete body off at the minute so may well alter this yet. Other than the metal washers i dont know what can be done.

[TVR Beaver]

But how did it work before we pulled it in bits???.. the original set up must have had something in there as they did not float about (I know they can't on the rubber ones easily unless they are knackered).. and the inner facesare not indented by the small inner tube... as I said above, I've kept the remains of the old bush units and the inner tube used in this position is the same length as the Powerflex ones...
What we need is an original set up and see whats in there... I guess mine went to the blasters stuck to the arms and are now in the bottom of the shot blast machine although I'm sure I'd of seen them.. and didn't find any 'special' washer on the floor when cleening up... but they must have something or the lot would not be held......
Also.. you must get a nip here or the first bump you see will push your camber well out...

[carsy]

My old wishbones were completely shot and are now in the bin. From what i can recall they didnt have the rubber bushes but some kind of plastic bush, not the poly`s,and these clearly worked on the bolt. From what i know the rubber bushes will have had some kind of thrust washer. These thrust washers will have taken the slack. The metal tube will not have hit the wishbone sides probably because they didnt have to be as long because the bearing worked on the bolt and not by the wishbone grabbing the metal tube.

[chris52]

Mine are the same but when I dismantled the origional rubber bush it had a metal washer on either side, I re-used these wahers when I rebuilt the arm using the powerflex bush. Geo was set by TrackvRoad and 1 year on no problems.



Chris

[TVR Beaver]

carsy said:

My old wishbones were completely shot and are now in the bin. From what i can recall they didnt have the rubber bushes but some kind of plastic bush, not the poly`s,and these clearly worked on the bolt. From what i know the rubber bushes will have had some kind of thrust washer. These thrust washers will have taken the slack. The metal tube will not have hit the wishbone sides probably because they didnt have to be as long because the bearing worked on the bolt and not by the wishbone grabbing the metal tube.

No.. It would never hold on just rubber.. first pot hole and youd be -5deg on camber as the bolt moved to the back of the slot...

Chris.. so you used the existing washers (metal) and the thrust washers (plastic) from Powerflex?.. assume this is how you did it... Any idea how thick the metal washer is?? I'll have to re-make some...
cheers..

[chris52]

Pretty sure they were the same size washer on the outside as the inside, don't seem to remember them being anything special. You will need to fit the arm to the chassis first then measure the gap and the bush sleave I do remember one side was a fairly loose fit and the other I had to lightly tap the washer in.

Chris

[TVR Beaver]

Cheers Chris... Will crank the old lathe up and get some made... Can't believe I've lost them.. There again the amount of waxoyl on mine.. it's a wonder i could find the arms

There is an issue at the other end of this arm where the Powerflex fits the big bore.. the thrust washers are too thin (the tube fits okay).. so need to give SH the details once measured... thats why I was trying to clamp up the front end.. to see if it moved the rear!..

[carsy]

TVR Beaver said:

There is an issue at the other end of this arm where the Powerflex fits the big bore.. the thrust washers are too thin (the tube fits okay).. so need to give SH the details once measured... thats why I was trying to clamp up the front end.. to see if it moved the rear!..

This was also the same on mine. Just fitted some of the additional washers powerflex sent me to take up the gap. They were quite helpfull over the phone.

[Adrian@]

This is a camber adjusting joint....I have been making bespoke washers for this assembly for 5-6 years IMHO any additional washer added as packer needs to be the ID the bolt AND OD of the shoulder of the thrust washer as a support or the upright will punch straight through the plastic across the top of any smaller washer and clash with the wishbone on acceleration and braking. This is not anything special to these bushes, as if you use OE spec thrust washers that also occurs, BUT with the OE bush the metalastik bush stop this until it sheers will want to draw the upright central.
Adrian@

Edited by Adrian@ on Saturday 29th January 13:22

[TVR Beaver]

Adrian@ said:

This is a camber adjusting joint....I have been making bespoke washers for this assembly for 5-6 years IMHO any additional washer added as packer needs to be the ID the bolt AND OD of the shoulder of the thrust washer as a support or the upright will punch straight through the plastic across the top of any smaller washer and clash with the wishbone on acceleration and braking. This is not anything special to bush as if you use OE spec thrust washers that also occurs, BUT with the OE bush the metalastik bush until it sheers will want to draw the upright central.
Adrian@

Yes.. agree.. I've been to the shop to get some washers but they are smaller OD than the plastic thrust washer.. so can't use them... as you say over time it will push over the top, cutting the plastic off...
So guess the only option is to try make some (unless you have some for sale??)
What thickness did you make them...?
If you look at the pic Chris put up (its the same as mine).. the trust washer only just gets to the OD of the tube and the triange... These also would be better a tad bigger... but I can't find any old washers this size that came off??.. strange ...

[Adrian@]

I was never able to find anything off the shelf, so I would turn them up bespoke each time...as long as the joint is then captured between 4 washers that then clamp to the slots of the wishbones, (capturing the internals of the bush) without bending the arm, I was never too fussed....my thought are here, is that the gap has a relationship to the welding tolerances of that top wishbone and the chassis lugs and even the coating on the wishbone so worked with as best as I could get size.
Adrian@

[TVR Beaver]

Well, spent the afternoon tweaking the top arms.. When you look at what’s going on there the original set up is not nice….

The larger of the arms sets the scene sort of speak (the one from the rear mount) as this one is solid.. and the other arm must move to accommodate it…

When I measured the gap in the front nip, it had about 3mm run out back to front!! Not good for straight clamping of the bearings etc…

So I set about getting this right first… but then found when I adjusted this, it moved the other ends (chassis end)…. So I’ve had to jig with studding and washers both front and back to get them set right…

Both arms done now.. and ended up with two spacer washer on each in the front nip of about 3.2mm wide each… so a gap of 6.4mm to fill… a bit bigger than when I started but at least everything is all square now…

Surprised how easy the arms bend…. And what a lash-up the initial design is… !!

[V8NRG]

TVR Beaver said:

Well, spent the afternoon tweaking the top arms.. When you look at what’s going on there the original set up is not nice….

The larger of the arms sets the scene sort of speak (the one from the rear mount) as this one is solid.. and the other arm must move to accommodate it…

When I measured the gap in the front nip, it had about 3mm run out back to front!! Not good for straight clamping of the bearings etc…

So I set about getting this right first… but then found when I adjusted this, it moved the other ends (chassis end)…. So I’ve had to jig with studding and washers both front and back to get them set right…

Both arms done now.. and ended up with two spacer washer on each in the front nip of about 3.2mm wide each… so a gap of 6.4mm to fill… a bit bigger than when I started but at least everything is all square now…

Surprised how easy the arms bend…. And what a lash-up the initial design is… !!

I'm not sure i'm understanding this. Any chance of some pics of what you've done to sort it ? (just for those of us that will be doing this soon )

[TVR Beaver]

Basicaly the original set up works on 'bending metal'.. not the best.. I'll do some pic's tomoro....
May be one question... ive made washers equal both sides... to get the original position, it may be worth doing say 2mm / 4mm?.. Just a thought...

[Adrian@]

The joint is as this...bolthead-washer-WB-washer-bush centre tube (1a/1b or2)-washer-WB-washer-nut....where 1a is the OE design it is a bonded metalastik bush with an outer casing pressed into the rear upright, which in twist sheer (once set at ride height) is a good design but in shunt forward and back is poor, TVR see this and after 3-4 years and add thrust washers on the ends of all the cars rubber bushes creating 1b. BUT if you look at old thrust washers from this position you will see that there has been shunt pressure from the eyelet of the upright combined with tube of the bush (which are both larger that the metal washer that abuts the WB creating a stepped thrust washer) Where joint is 2 poly then there are zero forces to stop shunt through the bush so the eyelet of that is the top wishbone can and will punch over the top of the washer leaving the upright free to float...My method of stopping this on this joint only (rubber or poly) has been to create a bespoke washer on the inside of the wishbone that is as large as the thrust washer it needs to support (adding that TVR dress the inside of the WB to allow a sliding washer of THEIR size to slide along the elongated holes, this must too!)
Adrian@
I too have never like the fact that I find that once in position these joints can have be wild in the gap size due to the design..I would never want to bend the WB, this is why they are bespoke, equal, to mount the upright centrally.

Edited by Adrian@ on Sunday 30th January 09:11

[TVR Beaver]

.



(Drawing exagurated so you can see but the two faces of the nip are not parallel)

This is all im saying.. the smaller of the two arms actualy gets pulled into the bigger one creating a nip that is not parallel (so not good for clamping)...
The bigger of the arms is solid so won't move... but jacking with nuts and washers will move the smaller one so you can get the nip parallel.... but take care as doing this moves the mounting end.. so you need to hold these at the right gap (or may be even a bit wider to allow for spring back)
Once you have them near parallel and your happy with it... made the faces flat and measure the gap size... then taking the bearing tube length off this gap gives you the size you need to fill with washers.. so make 2 washers to fit.....
.
the only question I have and I'll see when it goes together is, to get it in the correct position are these washers the same thickness?.. in thoery the bigger arm has not moved so it's relationship to this should remain the same?.. so if you've now got 6mm to fill... you may find you need 1 washer 2mm thick (gap fron the thrust washer and bearing to the large arm to keep distance as before).. and 1 at 4mm (gap from the other thrust washer and bearing to the smaller arm).... we'll see...
.
however, getting a paraller nip here will increase clamping force massivley, make it easy to adjust, and stop the bending / twisting of metal localy to get it to clamp....
The actual strength in all this back end set up is in the lower frame wishbone.. and this will dictate where the upper one needs to be... the upper one must conform to the lower as all it's doing is steadying things relative to it.....hope this helps

(all measurements are examples and not what I actualy had... )

Edited by TVR Beaver on Sunday 30th January 10:12

[Adrian@]

You have to assume equal, when the wishbone is in the car and the inner bushes fitted the flex in that gap can be so variable, depending on how close it is made + or - of it's spec. I'm 100% sure that the bolted assembly WILL draw the wishbone parallel at the slotted holes when done up, the wishbone material is not strong enough not to deform.
Adrian@
Something to note....the brace tube across..both ends butt welded, but the other elliptically butt welded and that is totally solid ....

Edited by Adrian@ on Sunday 30th January 10:32