diff' torque rods

[miked]

Today I was given an old magazine from the late seventies and it had articles about Elans. On an exploded view I noticed (what looked like) some sleeve through the rubbers fitted either side of the diff' torque rod bushes. This was a poor picture but looked like some kind of tube that the rubbers shove over. I have had 2 plus two's and have 2 Elans but have nevers seen anything here before. Is this a mistake or is there meant to be a small close fitting tube.

Anybody seen this

Mike

[lotusfan]

Somewhere on this forum I once found a .pdf file of a Series 2 Elan service parts list. The illustrations are very much clearer than the more modern parts lists. On the differential torque rods a spacer is indeed shown as you say. I had assumed that maybe the early torque rods were threaded all the way back to the fixed washer and the purpose of the spacer was to prevent the rubber bushes wearing on the threads.

[RotoFlexible]

Well, I'll be. My S2 has no such spacer but the "Elan_S1_S2_Coupe_Masterpartslist" shows that spacer, illustration key CB14, part no. AT-7613, "Spacer (mounting bush washer)". That's not a Lotus part number but the list doesn't indicate a different manufacturer. The parts manual available at rdent.com doesn't show such a spacer.

[garyeanderson]

I have taken the diff out of a lot of Elan's, from early S2's on and have never seen these distance tubes in use. If Lotus used them they were probably a S1 only part. The rest of the diff torque rod parts are from the front anti-sway bar where it mounts to the bottom of the shock absorber. Anyone else actually ever seen them in use?

Gary

[lotusfan]

On second thoughts maybe the spacer is to limit the amount of crush on the rubber bushes? The length of thread on the rods is more than is needed for the usual 2 threads out of the nyloc nut. Perhaps we should have a spacer?

[RotoFlexible]

The "modern" torque rod has the equivalent of that spacer built into it. You build up the metal washers and rubber bushings just as you would when attaching the anti-roll bar to the bottom of the front shocks. The first three washers, and the two bushings, slide over the built-up (unthreaded) section, with the diff bit in there as well of course. The final washer has a smaller hole: it comes down against the unthreaded part but won't slide over, and the nut comes down hard against it.

The stack, starting with the flange on the torque rod, is:

Washer - bushing - washer - diff ear - washer - bushing - washer (small hole) - nut.

At least that's how I recall it. I installed the diff a few months back, but then I can't always recall what I had for breakfast, so I stand to be corrected.

[miked]

Interesting!

I suppose the fact that the bottom of the front shocker arrangement is the same diameter (I think) kind of proves it to be right without.

Will check, as I have a half built car to look at.

Mike

[cabc26b]

my guess is that take up the difference in diameter between the rod and the hole in the lug on the casting for the diff.

[miked]

I was thinking this but would it cause vibration by becoming metal bound.
??

[RotoFlexible]

There's no direct metal-to-metal contact between the torque rod and the diff housing; the holes in the housing ears are significantly larger in diameter than the rod. The dished metal washers snuggle into the recesses of the ears, with the compressed bushings providing a sight amount of longitudinal compliance and the flexibility of the rods providing whatever lateral compliance is needed. That, and the Frustcone top mounts, and the three-micron clearance from the bottom of the housing to the chassis ensure that there's no metal-to-metal contact anywhere between the diff and chassis, hence no transmitted vibration, on a good day.

[miked]

Andrew, I understand fully what you are saying and agree but refer to the subject of the existance or not of the sleeves. They dont look needed. If they did exist, they would surely only tighten the rubbers slightly.

Mike

[RotoFlexible]

My guess (and it's only a guess) is that the sleeves were needed at first to make up the diameter difference between the torque rod (perhaps it was threaded all the way to the flange) and the bushings. At some early point, they must have reworked the torque rods to have the correct diameter for the correct length so the need for the sleeves was eliminated - adding simplicity as it were. Like I said, just a guess!