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Upper Fulcrum Pin

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fad64b

fad64b

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I have found it best never to assume anything especially with a 50 year old car. I believe the DPO rebuilt the front end on my TR3 but I am having unusual tire wear so I plan to go through it again. Does any one have a picture of the proper position of the Upper Fulcrum pin, I see that this could be installed backwards. I just want to be sure.
 
On the TR3, I would think that is just about impossible to install backwards. Anyway, the arch in the pin should be facing towards the motor.
 
fad64b said:
Does any one have a picture of the proper position of the Upper Fulcrum pin,
Click to expand...
Unless I'm misunderstanding the question, there's one right in the factory workshop manual.

Edit : Note how the upper wishbone (aka A-arm) can be seen extending downwards in the diagram.
 
Art,
This is where I am confused in Dale's photos it shows what I would call the arch facing the motor. But the diagram in the work shop manual that Randall posted looks like the arch is facing the wheel. On my car the arch facing the wheel would give more clearance for the shock hard ware.
 
I think we're getting the 'arch' description confused. I'm talking about the inner part of the fulcrum has an arch to it. The middle section of that faces in toward the engine, like it shows in Randall's diagram. Below is a pic I just took. That should clarify everything. /bcforum/images/%%GRAEMLIN_URL%%/smile.gif

Edit: Like I said, it looks like it's impossible to get backwards, as it would intefere with the shock mounting.
 
Not sure I can clarify any, except to say I think the confusion is over which way the arch "faces". The convex side of the arch goes towards the motor; the concave side towards the shock hole.

Dale's photos are not that clear to me, but seem to show it backwards; while Art's photo is correct for a TR3.

Installing it backwards does make it difficult to install the shock on a TR3; but I've seen it done.

One other point to mention, I now believe it's important to have the suspension in the 'loaded' position when tightening the nuts on the upper fulcrum pin and using the stock rubber bushings. I never did that, which in retrospect may be part of the reason my bushings never lasted very long. But that shouldn't be an issue with Nylatron or Poly bushings (like Art's photo shows).
 
Thanks, It is clear now mine are correct. I wonder if Dale installed his backwards?
 
I think we are all correct !!

"Roger Wiliams excellent book on how to restore a TR3a goes into the subject in some detail on page 126 where he explains that for a 3a the apex of the central bar's curve should face the centerline of car. That's fine because that was how my vehicle was before I dismantled it."

As in Art's fine photo

The TR4A, 250, TR5 and TR6 had their suspensions
reconfigured with the fulcrum pin reversed( curve apex
facing outward.) As in Dale's photo

Art's TR3 fulcrum is correct and my TR6 fulcrum is correct.
My bad, thinking Triumph used the same pin design for the TR3 and TR6.

But a good tidbit of education for us all.

regards,

dale
 
fad64b said:
Thanks, It is clear now mine are correct. I wonder if Dale installed his backwards?
Click to expand...

Well, now that brings us to why are your tires wearing so badly? /bcforum/images/%%GRAEMLIN_URL%%/hammer.gif
 
I think it's important not to confuse TR models. TR3s are DIFFERENT than TR6s in many details. F&R suspension is totally different. As is the frame, body panel construction, and so on.
 
Art- I've got 1,400 miles on my new tires and the nubbies
are still not worn off. My car handles like a dream.
Three professional Triumph mechanics pronounced my
fulcrum pins installed correctly for a TR6.

On a SIX, the upper A-Arms ARE NOT interchangeable.
Get them reversed and you will have severe tire wear
and an unstable ride. Maybe the Threes are similar?

d
 
According to Moss the Upper Fulcrum Pin is the same part # 661-000 TR2 through TR6.

As for the front tires the inner 1/3 is wearing and more on the drivers side tire. I thought I would start with ball joints and upper bushings. I am planning to change to the TR4 uper control arms and ball joints I think this setup is more durable. Has any one else done this to a TR3?
 
fad64b said:
According to Moss the Upper Fulcrum Pin is the same part # 661-000 TR2 through TR6.
Click to expand...
That's true, but it doesn't prove they were all installed the same way.<div class="ubbcode-block"><div class="ubbcode-header">Quote:]As for the front tires the inner 1/3 is wearing and more on the drivers side tire. I thought I would start with ball joints and upper bushings.[/QUOTE]Why the uppers ? The lower joints are much more apt to wear, since they carry the weight of the car. Personally I would want to check the toe & camber first, to know what I'm looking for. You can do an effective camber check with just a reasonably flat floor, a carpenter's square, some C-clamps and a pair of rulers.<div class="ubbcode-block"><div class="ubbcode-header">Quote:] I am planning to change to the TR4 uper control arms and ball joints I think this setup is more durable.[/QUOTE]Don't forget that you also have to change the trunnions to the later TR4 parts (which are different from side to side), and that your steering will get heavier due to the 3 degrees of castor induced by that setup.
 
Randall

I believe the upper arms and ball joints were the only change TR3 to TR4, the lower trunnions change in the TR4A.

You are right I need to check it all, the camber seems to be 0. I have not checked the toe.
 
fad64b said:
I believe the upper arms and ball joints were the only change TR3 to TR4, the lower trunnions change in the TR4A.
Click to expand...
I disagree. The trunnion change only altered the angle between the pin & the vertical link. But when the vertical link was tilted, the upper pivot point had to move as well. The change in the arms moved the pivot point (as well as mating to the new ball joint).

Hence both the arms and the trunnions changed at the same time, which was NOT at the TR3-TR4 transition, but early in TR4 production (CT6343/CT6389, depending on whether wire or disc wheels were fitted).

Just had a quick peek in my TR4 SPC, which confirmed the above and also reminded me that the steering lever also changed. If memory serves, the upper ball joint moved to the rear (creating the 3 degrees positive caster), and the steering lever got longer to retain the geometry. But I could have that backwards, and I'm too lazy to go check my own parts. The change points are also listed in the Moss catalog.

The TR4A did also get a redesigned trunnion (similar if not identical to the TR6 unit), but the later TR4 got the 'handed' trunnions at the same time as the upper A-arms changed. The later TR4 trunnions look almost identical to the earlier ones, except for the change in angle (which is visible if you look closely or compare sides).
 
Hi Frank,

Sometimes high tyre wear is due to improper alignment of a front suspension tower after an accident. There are a few things to check out for tyre wear on a TR2 - 3B.

1. Toe in or toe out if incorrect can scrub tyres quickly. The correct setting is from zero (parallel) to 1/8" toe in.

2. If the inner upper rubber suspension bushes are chopped out, then you can get negative camber. This causes the inside of the tyre to wear quickly. The solution is to replace the rubber bushes with polyurethane, but make sure you get the two piece bushes per end, as some suppliers sell one piece which are not correct. The inner fulcrums go back exactly as per Art's photo. Two piece bushes can be changed without taking the spring out.

3.Check that the bottom inner bushes have been upgraded to nylon sleeve from the original rubber. Replace if still rubber.

4. Once the above is OK, check each front wheel for camber. At static load it should be 2 degrees positive. In other words the top of the tyre is further out than the bottom. There is no camber adjustment other than to re align the suspension tower. One other cause of incorrect camber can be a bent suspension upright.

5. If you are dismantling the suspension it is worthwhile to get the uprights crack tested as (very rarely) they can fail at the start of the thread into the trunnion.

6. If doing the suspension check the front wheel bearings as they are just of marginal size. Replace with genuine Timkin if possible as there are some dodgy bearings out there.

7. Worn out front shockers can be a cause of high tyre wear too.

Hope this helps,

Viv.
 
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