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Tr4aJim

Tr4a- mounting the fulcrum/upper wishbones

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Folks, I’m installing a Moss (US) “Major Suspension Kit” on my TR4a. https://mossmotors.com/major-suspension-kit-repairs-both-sides?assoc=75084

I just started mounting the upper wishbones to the fulcrum, and if I’m reading it right, the Tr4 shop manual says, for a Tr4a, the castellated nuts should be torqued the same as a Tr4 (26-40 ft lbs). So I did a trial fit of the upper wishbones and fulcrum on the bench. However while tightening the castellated nut, I found the retaining washer bottoms out on the fulcrum pin shoulder before I reach even 26 ft lbs. 

In addition, to get the cotter pin hole to align with the castellated nut, I then had to back the nut off the pin shoulder slightly. Yet in this config, the rubber bushings appear fully compressed and the wishbone arms are stiff to move. Does this sound ok? There doesn’t appear to be a way to torque the nuts per the manual, and also get the cotter pins in. 

I also did a trial fit of the fulcrum/wishbones on the car, and noticed that there was insufficient room between the castellated nuts and inner fender, to fit a socket/torque wrench. 

Finally, I have read that the various suspension bolts/nuts should be tightened with the car sitting on its wheels, so as to compress the bushings in their “at rest” position. I just don’t see how to reach these bolts/nuts with the car on the ground and with the tires in the way. Is there something I’m missing here? (probably!:huh:)


Thanks 

Jim

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Finally, I have read that the various suspension bolts/nuts should be tightened with the car sitting on its wheels, so as to compress the bushings in their “at rest” position. I just don’t see how to reach these bolts/nuts with the car on the ground and with the tires in the way. Is there something I’m missing here? (probably

Hi Jim,

 for this part - simply support the axle stubs on jacks or stands. This will simulate tyres on the ground.

Roger

 

 

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The fulcrum nuts bottom out on the shoulder. Torque up to the bottom limit torque and see where the slot is relative to the hole then you can set the torque wrench to top limit tighten up a little bit to get the pin in without it ‘clicking’. If it’s some way out you can mix and match nuts and washers until it’s right.

Assemble it on the bench and then fit the fulcrum to the tower  

Ive skimmed the back of nuts in the past to get slots to line up. Aircraft use a range of slightly different thickness washers to achieve a good fit. 

Edited by Drewmotty

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Thanks Roger, I will do that.

Drew, could it be that the hole in the washer is too small, and it should be able to slide over the fulcrum pin as the nut is tightened? Now the washer hits the pin shoulder and the nut snugs up against it tight before 26 lbs is reached. I could just continue to tighten, but the nut is at the end of its travel.

Also, as I mentioned, the Tr4 shop manual shows the torque range as 26-40, which seemed pretty broad to me. So I checked a Tr6 torque chart and it just says 40. Since the Tr4 manual is vague on Tr4a torque values, can I use Tr6 values as a better guide?

thanks

Jim

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The washer is supposed to hit the shoulder.

Bob.

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Make a good record of how you do this as you will be doing it again in 12 months time, the rubber bushes dont last the course and you would be better off using poly on those top inners at least.

Stuart.

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Stuart, you know I thought it was odd that Moss supplied nylon bushes for the lower wishbone/trunnion pivots, but rubber ones for the lower wishbone pivot brackets, as well as the upper wishbones. Was that how they came from the factory?

Anyway, a quick look at the Moss site shows them listing both nylon and poly bushes as options over the rubber ones. Is there a durability difference between nylon and poly?

Jim

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Hi Jim,

both Nylon and Poly are quite durable. The poly can give a more comfortable ride. The nylon is a bit hard.

 

Roger

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Sorry, one more question. Do the nylon or poly bushes also require torquing with the suspension loaded, or is that just for rubber bushes?

Jim

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Just the rubber. Both the nylon and polybushes can be easily rotated by hand even when fully tightened. 

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Hi,

when I was a youngster and changed over from old rubber to PU this first PU bushes have been for the bin.

They fitted much to strong on the falcrum pin and glued there after a short time - I did not realize this.

No problem at all - until I jacked up the car the first time. The PU bushed turned under the load of the coil spring and glued again in a very low position. 

This I also did not realize. But with the wheels back on the ground my TR looked "high heeled" at the front any very ugly. This because the PUs still glued in the lower position and pushed the car up.

I needed some time to realize the reason and had to do the job again with better fittig  bushes.

With the look on some other "high heeled" TRs I think also other TR drivers have this problem but do not realize the reason.

Ciao / Cheers, Marco 

 

 

Edited by Z320

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Folks,

Well I’ve hit yet another snag in my suspension rebuild. :wacko:

The good news is I have successfully assembled the right hand suspension (using nylon bushes). The bad news is I’ve run into an issue on the left hand side. The new fulcrum doesn’t fit!

 It’s a bit hard to see in the picture, but with one bolt threaded in, you can just see that fulcrum bolt hole on the other side doesn’t line up with the threaded hole in the tower, (maybe 2 mil or so out), and the fulcrum is up against the dome of the shock tower.

I have the fulcrum oriented with the “shallow” side toward the tower. Though it looks like the fulcrum should have the “deep” side toward the tower (and the shop manual Tr4a supplement bears this out), I remember reading a thread on this forum that this is incorrect for a Tr4a, and the “shallow” side should face the tower (please correct me if I’m wrong about this). 

Anyway, what’s odd is the new fulcrum on the right side went in with no issue. Yet the tower and dome on the left side look in good shape with no evidence of being deformed.

Do you think it would be ok to grind some of the fulcrum enough to clear the dome, or would this weaken the part too much?

BTW - I forgot to mention that I compared the new fulcrum with the old one I removed from the left side, and the middle “bridge” is narrower on the old part.

BTW #2 - I just tried the old right side fulcrum onto the left shock tower, and it doesn’t fit there either! It is offset by the dome just like the new fulcrum. I compared the two old fulcrums, and the one that fits the left has a bit more bevel on the lower edge than the one from the right. Strange

thanks

Jim

44705B55-E93D-4263-B6BA-9725054C27CC.jpeg

Edited by Tr4aJim

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It looks by your pic that the tower may have been repaired on the mis aligned side, I would repair the tower top and re-align the hole. 

Paul

.

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Hi Paul, so you think the point where the top of the tower meets the dome was repaired at some point, and the distance from the threaded holes to the dome was shortened slightly?

If true then maybe the PO ground some of the inner surface off the left fulcrum to make it fit. I took a picture of the old left fulcrum on top of the old right one (I put some white paint on the right one for contrast). You can see the left one is slightly narrower.

Also, both of the old ones are narrower than the new ones.

Jim

EFA5ACF1-9B88-4617-9455-91037C59C7FF.jpeg

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Below is a pic of the recess in my original fulcrum which is ~ 4mm at the deepest point. Both sides are very, i say very snug fit with the turret dome on both old and new chassis. But is there a recess in it ? If so i suppose you may grind it a bit to make it fit. The other thing is that the central axle sits higher by 2 mm than the bolt-on stands. Check your new fulcrum if the same applies.

 

WhatsApp Image 2019-05-13 at 23.55.40.jpeg

WhatsApp Image 2019-05-14 at 00.13.00.jpeg

Edited by Geko
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Geko, I checked the vertical pad gap, and the old and new fulcrums have the basically same as you show.

However I placed the old and new fulcrums pad to pad, I found the the cross bar on the new fulcrum is offset almost 3 mil further toward the tower dome, than the old fulcrum. This must be why the new one fouled badly on the dome. I also compared the two old ones, and cross bar of the one that fits the left side, is about 1 mil further from the dome. So it is possible, the PO May have ground away the difference to get the left one to fit. The new ones are too far off.

thanks

Jim

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It would interesting to know if you bolt the old and new brackets together, is it the bolt holes are drilled in the wrong position, but more importantly do the pins line up,  could you post a few pictures of them bolted together, that way we may be able to see which bit of the parts are wrong please.

John

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John, here are some pictures of an old and new fulcrum bolted together. The mounting holes in both line up ok, however the “bridge” in both are slightly different.

In the first picture the old fulcrum is on top. You can see the new one underneath is slightly offset toward the shock dome side. In the second, the new fulcrum in on top, and you can see the old fulcrum is offset slightly toward the engine side.

Granted its not much of a difference, but its enough to have the new one foul near the bottom of the shock tower dome.

Jim

309F0973-3936-4B17-850C-16809789B47C.jpeg

38F013DA-3EF0-4A25-A6E2-25FBD1E36C0F.jpeg

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Same supplier as above ?

Edited by Geko
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Why not just fit it the other way round?  the difference in camber angle will be minute, & actually in the desired direction i.e less +ve

Bob.

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Geko, the new fulcrums are from Moss (US), I don’t know where the old ones were sourced.

Bob, I was under the impression that by reversing the fulcrums, the front end can’t be aligned to 4a specs. Is that not correct?

Which begs the question, what was Triumph trying to “fix” by flipping the fulcrums? Could it be the differences in the frame geometry from the Tr4? If the Tr4a supplement in the shop manual shows them in the same orientation as the Tr4, the decision to change them must have come late in the process. 

Jim

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