Thread: Uni's out of phase?

Originally Posted by garrycol

Juddy sells them

http://www.aulro.com/afvb/verandah/1...ropshafts.html

Just because someone makes them does not make it good practice. Just because someone sells them does not make them good practice. While they may do "A" job it may also be a mask or band aid. BTW there is some not so good results of those "flash" BM propshafts running on a few AULRO members vehicles currently.....something about "not for hwy use" and failing DC's doesnt shower me with confidence.....

Originally Posted by uninformed

I thought double dc shafts were a no no.........

Never heard that before. Is it an aussie specific thing?

With a DC on each end, the shaft is a true constant velocity and has no rotational pulsing going on. A CV shaft will do exactly the same thing.

yep I have seen a true "cv" joint used on comp turck prop-shaft. No I dont think it is an aussie specific thing, I cant remember where I read it. I was hoping an engineer could shed some light ...

Im happy to be wrong on the double DC. I would how ever stay away from BM shafts after reading the woes here on Aulro.

Originally Posted by uninformed

yep I have seen a true "cv" joint used on comp turck prop-shaft. No I dont think it is an aussie specific thing, I cant remember where I read it. I was hoping an engineer could shed some light ...

Im happy to be wrong on the double DC. I would how ever stay away from BM shafts after reading the woes here on Aulro.

A double DC shaft could make a bigger mess if it came apart. But compared to the mess a normal cardan **** makes if one end lets go, it's not a whole lot different.
I'm not aware of any production vehicle using a double DC shaft. Single ended DC are common enough. Most double DC applications I've seen were people trying to sort vibrations from modified suspension.

Originally Posted by uninformed

Just because someone makes them does not make it good practice. Just because someone sells them does not make them good practice. While they may do "A" job it may also be a mask or band aid. BTW there is some not so good results of those "flash" BM propshafts running on a few AULRO members vehicles currently.....something about "not for hwy use" and failing DC's doesnt shower me with confidence.....

Wasn't commenting on their appropriateness or otherwise - just in indicating they are available - nothing more.

However - I to have not heard that they are a 'no no' - where does this come from. If I put on a double carden on my 101 it will force the other end out of specs as the shaft is actually steeper than before - this is because the actual double carden is much longer than the the single UJ. While angles of the UJs are softer at the DC end they are steeper at the single UJ end.

Garry

as I said, I read it somewhere, but cant remember. That was the reason I asked Dougal, as I thought he would have the smarts and non-bias to know.

In your case, I see what you are saying but a wrong length shaft of any type is not a good idea. Is there a reason you used your 101 as an example? have you changed things that require a non OEM type shaft? I dont see any point to put a dc shaft in an application that doesnt need it. You have pointed out one reason, another is its an extra moving part that can fail.

In the OP's case, his lift has increased the required "static" length of his prop-shaft, AND angles are now probably beyond that of a stock UJ through his range of travel.

Originally Posted by uninformed

Is there a reason you used your 101 as an example? have you changed things that require a non OEM type shaft?

The 101 has by design the very problem discussed here and others have found when they lift their defenders etc. In the 101 it is termed the "101 Rumble" and all standard 101s (GS) will have it. It happens above about 80kph on trailing throttle and is the result of a 101 having about the equivalent of a 4 -5" lift. As built, the Ujs in a standard 101 shaft operate outside the design parameters of the UJ and Army service specs indicate a service life of only 17,000km.

In the 101 (note the Ambo version is much heavier and doesn't seem to suffer as much) the ways to deal with it seem to be a DC shaft, lower the drivers side engine and gearbox unit or rotate the front axle. I have not actually found anyone who can honestly say they have fixed the issue. Rotating the front axle is almost impossible without some major engineering.

In my case I had a different drive shaft made - the UJs are much larger with fine needle bearings, they have a much larger operating range, the splines are much longer and the tube is rubber filled - it damped the vibrations a bit but they are still there. A DC on the end might be the go but I would need a even wider range UJ on the other end.

Garry

Originally Posted by goingbush

Think you'll find 45 out of phase is correct for front shaft on RRC Disco & Defender

A big thanks for the picture. I hadn't remembered to have a look at the CD I got from the AULRO shop and, sure enough, there it is in the '09-'94 and the 1995 manual. What a bunch of nits at that factory - earlier manuals just tell you to mark the two halves before you pull them apart.

Thinking about this thread yesterday, I took two old RRC front shafts out of storage and the two ends on both of them are aligned. And what really confused me is that they also both have the arrow markings like the factory put on: ------> <-------

So that's confusing.