Props and articulation

[Shackleton]

... cause now that I've fitted the front prop to my RRC, with Defender Td5 R380, I notice that its almost at full articulation. The prop should be err in the short position until such time as the axle moves downward and demands the prop to stretch, right?

So if I now do as little as bounce the Rangey hard over a speed bump the prop might come in two?

Assuming that I'm assuming that my assumptions arent making an ass out of me what are my options? Have the prop cut and elongated by the inch or two it gains when stretched, or is a double carden prop the answer or whah?

I searched the forum and to add to my problems I'm reading stuff about props vibrating cause of misalignments and stuff. I just hope whoever made up my modified gearbox mounts knew about that sort of thing.

George

[Mo Murphy]

First things first George, your propshaft is too short.

What propshaft are you using ?

Do you have lifted suspension ?

A double Carden prop is usually used to allow the propshaft to run at a steeper angle, if the double carden prop is the same length as your existing prop then you'll still have the same problem.

Mo

[Shackleton]

Mo

The prop is a standard RRC front. I say that without knowing for sure, but it's exactly the same length as my original prop I took off. It must have been running at full extension like this when I got the car, I just didn't notice. Unless the diff housing on late RRC's is slightly longer then the early cars?

My suspension is standard, saggy offside et al. In fact when I replace the dead springs this problem will obviously get a little worse

Is there a standard front prop that is just a little longer then the RRC item?

[Bowie69]

Are the splines showing?

There are 3/4 different props (probably more tbh!) for the 'standard' RRC front prop.... early, late, late with viscous coupling, and the latest with viscous coupling and cats.

Yours is a late or early one? The differnce in prop length is normally down to a combination of gearbox and transfer case length -the diff nose doesn't change.

[Shackleton]

I should paint the pic more clearly,

The car is a '73 RRC, I was lucky enough to find a '92 RRC that someone had fitted a Td5 complete with Disco R380 into. They mounted the lump basically square where the original RRC V8 mounts had been which left the R380 sitting a few inches further forward mount wise. They used the original chassis mount holes but fab'd offset mounts so that the R380 mount lies under the forward bolt rather then square between the triangle of bolts. (I realise that explantion doe's nothing to give you an idea of where the flange of the gearbox actually lies )

I decided to use the prop that came on the R380 purely by virtue that it wasn't in any worse condition then my original one and when stood together they were exactly the same height. I can't tell if the splines are showing cause of the boot but I doubt it, I tried to pull the shaft apart and couldn't if you get me.

I replaced the Disco R380 with a Defender unit cause it suits the car better. The dismantlers I got the Defender unit from use an oxy torch to take scrappers apart so the unit came with the severed end of a rear shaft still attached. Should I be going to my blacksmith and have him let that into my front prop? It's the splined end - does that matter?

[vinny]

Whats the distance between the flange on the diff and transfer box?

[Shackleton]

643mm / 25.314909999999997"

[JST]

from the G box position it sounds like a one off so I would be tempted to give someone like D4x4 a ring and ask them to make one up for you.

[vinny]

643mm / 25.314909999999997"

Just out measuring the rear prop on my 90 its approx 26"... Thats on std suspension!!! might be an option?

[filthy boy]

Double cardon props do not allow more angularity. In fact usually less. Because they have a big extra bit in the middle.

They are only needed when the diff pinion points at the transfer box rather than being parallel so UJ angular acceleration isn't cancelled out.

You need a longer prop if it is too short.

[bishbosh]

Just out of curiosity, is the rear prop jammed shut?

[Shackleton]

Thanks Vinny, I'd say though that unless you're 'approx' is approx 3/4" out then I wouldn't be able to squeeze it in. But yeah I'll take your rear prop if it comes to it

Bish I'd my original '73 rear prop cinched up too before I noticed it was at full extension so I offered up the prop that came on the '92 and yes it's longer and seems to be a perfect fit. What are you thinking?

[LR90]

Think again about what Vinny has said. His rear prop in situ and with room to stretch or compress is close (ok within .75") of your at rest length. And from what you are saying yours is at its limits of stretch in this state.

One other thing you need to bear in mind though is coiler props have an easier life than leafers as the radius arms or rear links tend to cause the axles to swing in an arc of near constant distance from the transfer box prop flanges. Try disconnecting the front prop (one end only) and lifting the car until the axle is hanging off the ground. Can the prop be stretched far enough to make the flanges meet?

[honitonhobbit]

92 RR is a viscous T box - 73 is a 4 speed.

Three lengths of RRC front prop, longest is viscous prop.

Don't bother with D4x4 as they get there props made by outside contractors

use these guys: http://www.propshaft.co.uk/

[bishbosh]

I was thinking that perhaps your engine mounts were welded in in the wrong place..... just like I did with mine!!

[Shackleton]

I was thinking that perhaps your engine mounts were welded in in the wrong place..... just like I did with mine!!

Yeah, and there I was all happy that the gearbox had been mounted in such a way as to use standard props...

I'll be jacking the car with the prop dislocated at one end tomorrow to see what the story is. Fingers crossed on the possible use of a D90 rear prop.

[Shackleton]

Just to put this to bed - I got a chance to lift the car and drop the front flange of the front prop shaft. It was perfectly happy to be extended to the diff nose so alls well that ends well. Sure I'd prefer if it were a little less extended but there seems to still be a little in it.

In reality the O/S shock and probably the brake lines would max out before the shaft...