Thread: Superior Engineering Superflex arms for Rovers.

The problem is, when taking in to consideration the original propshaft, its out of phase-ness and angles of T/case and diff, what are they??? So in best practice, a custom drive shaft would be used and the pinion set to the angles for its type, i.e. conventional or DC.

This would be, AFAIK, for:

DC type shaft: pinion pointing at just above the centre line of the t/case flange centre. This is only just above as the centre line is to meet the centre line of first uni coming from the t/case. The DC being at the t/case end

Conventional: Pinion angle parrallel with the t/case flange.

Note, that does not allow for the original out of phase propshaft.

Originally Posted by uninformed

The problem is, when taking in to consideration the original propshaft, its out of phase-ness and angles of T/case and diff, what are they??? So in best practice, a custom drive shaft would be used and the pinion set to the angles for its type, i.e. conventional or DC.

This would be, AFAIK, for:

DC type shaft: pinion pointing at just above the centre line of the t/case flange centre. This is only just above as the centre line is to meet the centre line of first uni coming from the t/case. The DC being at the t/case end

Conventional: Pinion angle parrallel with the t/case flange.

Note, that does not allow for the original out of phase propshaft.

I've never measured the stock angles, they are worse for the puma and later engined Land Rovers as seen in the many problems with front drive shafts and transfer cases.

Leaving aside the puma and later engined LR, with the front drive shaft the operating angle at standard height is large, and gets worse with any suspension lift.

Also if front suspension travel is increased (here we are talking of supeflex arms to free up the front for better balanced and increased articulation), then we run into the problem of the universal at the TC binding.

With a double cardan drive shaft, the alignment criteria is not so much pointing at the TC, or the first uni, but the operating angle of the uni at the opposite end to the double cardan joint. This angle should be 1 degree (note I was incorrect before when I said 0.5 to 1 deg), and if it is achieved by pointing the pinion above the drive shaft, it reduces the working angles of the double cardan joint.

With a conventional drive shaft, the criteria is for the working angles of the uni joints at both ends to be equal within 1 degree, and the working angle to be 1 degree minimum to 3 degree maximum (see table below for larger angles). The common way to achieve this is with parallel pinion and TC shaft, but it is not the only way. It is perfectly acceptable to use what is sometimes referred to as a 'broken-back', where the shafts are not parallel but the working angles are equal (within 1 deg).

The following from Spicer:

Few more details for all to ponder.

First of all I think you will noticed more vibration from a set of mud tyres then you would a slightly out of alignment drive shaft.

He are my angles of operation from my front tcase output down to the diff.

Tcase output at 0°
Driveshaft operating angle (in relation to tcase output) 20°
Differential flange 14°

This is well out of recommended specs. To my surprise the angle of operation at the differential universal is much more then I was expecting (twice as much).

So I have 20° shared between the two universal joints in the custom CV driveshaft.
With 6° of operating angle at the differential uni.


This could well be due to having too much castor correction.

I am interested in comparing the castor correction applied to my current cranked arms, against the castor correction of each SF arm.

when I put my first spring lift in, which was pretty much 3 inch, I had pretty new MTRs. Front prop vibed at approx 85km/h. Disco 2 DC shaft went in and vibe was gone.

I just checked mine, and with approx. 1 1/2-2 inch lift (115mm between BS) I have:

Propshaft 12.5*
Diff pinion 73*
T/case 91.5*

Even though the ground was not perfectly level, it was flat in both directions, and its the relation of those 3 items to each other that count.

So, by my calcs I have 13.5* shared at the DC and 4.5* at the diff pinion uni. How ever, as I have stock RA, my pinion is pointing higher then the shaft (opposite to Grimace's)

And a further FWIW, you don't need the Super Flex arms to get uni bind.

My old shaft did it just with TLC Koni's in the front.

Just a quick bit of info for the guys that asked, 2" arms give ~3.38deg and 3" arms will give ~5.1deg of castor correction over a standard arm.
BTW I should have about 20 sets of arms ready to go in 2-3wks max.
I will also do a few sets of 3" arms in the next lot which will be about 2 weeks after the first batch.


cheers
Greg

Grimace

Who made your DC shaft? - should have had a good look at it last weekend.

Got some vibration in Bumblebee - not sure if front or rear or both. So interested in this discussion to learn basics prior to trying to solve vibration for on road use.

Skiboy