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Angus Bruce

Universal to CV joint swap

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 Sorry if this has been covered before, but what would be the advantage of swapping Universal joints for CV joints in the final drive shafts? My understanding is that Universal joints have been used in pretty much all vehicles without issue.

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I don't think replacing UJ's with CV joints will solve the main TR6 rear end problem which is the half shaft splines can stick when cornering. I have modified Datsun 180B half shafts with UJ's in my TR6 and they've worked well for maybe 30 years. The Datsun half shafts have ball rollers to stop the binding up when cornering.

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my experience is that fitting cv shafts makes a considerable difference to the suspension’s ability to propel and suspend the car independently

my test drive after fitting CDD cv shafts a few years ago was a revalation, powering out of a roundabout that had a big camber change the car was significantly more able to cope than with the standard setup.

A new set of standard halfshafts with the coated splines might have had a similar effect, but i doubt it.

i have had an issue with failure of one cv gaiter, but other than that they have been good.

hth

steve

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I echo what Steve has found.I rate them very highly and found also the steering was more direct (the normal uprated driveshafts were locking up in twist giving a rear wheel steer and subconsciously corrected by the driver) and nearly caught me out. So, so much better drivability and transformed the ride.

Regards HarryTR5 Nutter

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The CV jointed shafts have 2 advantages in that a CV joint transmits power more evenly than a Hardy Spicer joint and  allows for the change in shaft length without the tendency to lock up. The coated shafts do a good job of dealing with the locking up. 

I put them on the 6 when I needed to replace a hub having put Teflon shafts on years ago. I decided that rebuilding the hub with a new stub axle was less cost effective than to change the whole lot. I was genuinely surprised by the difference the shafts make on wide sweeping fast bends such as you get entering continental motorways.

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8 hours ago, Mike C said:

I don't think replacing UJ's with CV joints will solve the main TR6 rear end problem which is the half shaft splines can stick when cornering. I have modified Datsun 180B half shafts with UJ's in my TR6 and they've worked well for maybe 30 years. The Datsun half shafts have ball rollers to stop the binding up when cornering.

In 30 years the engineering world has moved on, CV joints as used on modern cars  (and their derivatives offerings used on our IRS TRs, Stags and Triumph Saloons) are engineered to deliver torque without sticking or snatching throughout their range of movement. On modern vehicles do you think the UJ driveshaft would be considered to be the correct engineering solution ? I think not.

The Datsun Nissan driveshaft offerings work well but now are in short supply and require a significant degree of engineering to suit (well on Stags anyway), CVs are the way to go.

Mick Richards

 

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36 minutes ago, barkerwilliams said:

 

This example doesn't really apply to U-joints in a TR or other real-world OEM application. Designers know that the mating flanges at opposite ends have to be parallel to avoid velocity variations; a single joint will produce them at the slightest angle; in pairs they cancel out - if the ends are parallel and the crosses are aligned. Agreed that the TR IRS doesn't comply perfectly since the camber passes through the parallel position under load/ unload. Can't say I've ever felt vibrations from this however.

I don't flog my cars to within an inch of their life but do give them WOT on a regular basis ( they have 6 throttles ) and take them through curves a lot faster than my wife will tolerate so the U-joints have served me OK until now ( 200K miles between 2 cars ). The only reservation I have is the half shafts see almost 2X the torque of the drive shaft but have the same size on them. GOODPARTS offer an uprated U-joint setup for these ( aside from CVs which I saw there first ); maybe they're supplying the usual suspects in the UK.

Tom

Edited by Tom Fremont

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Tom,

 

My PTO's on the tractor seems to work exactly that way with velocity changes, and they are only doing 540 rpm. Muck spreader particularly prone with rhythmic showers of … out the back

 

Alan

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3 minutes ago, barkerwilliams said:

Tom,

 

My PTO's on the tractor seems to work exactly that way with velocity changes, and they are only doing 540 rpm. Muck spreader particularly prone with rhythmic showers of … out the back

 

Alan

One U-joint?

 

Tom

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1 hour ago, Tom Fremont said:

One U-joint?

 

Tom

No they will have two, one either end of the PTO shaft

Stuart

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2 minutes ago, stuart said:

No they will have two, one either end of the PTO shaft

Stuart

Bet the mating flanges at either end  aren't parallel

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The  camber of the IRS wheels changes as the wheel is deflected up and down so much of the the inner and outer ends of the drive shaft will not be parallel.

Not sure the vibrations of the PTO on a tractor are going to upset its handling too much!

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Yes OK tractors and TRs not that similar however using a tractor it is really, really apparent even a couple of degrees off square a UJ has marked  velocity changes. A CV joint as the name implies has a constant velocity.  One of the drawbacks of the original design is the sliding centre splines lock up with UJ's and release with an unpleasant bang. The Triumph Stag suffers from the same UJ shaft spline lockups but I understand from a supplier that the Stag Owners Club has changed the splined shafts so that lock-ups do not occur.

Presumably the original design of the UJ shafts accommodated enough parallelism in the flanges and angle change and torsional load  in the sliding splined shafts to work "reasonably" throughout the suspensions designed operating movement, however what years of wear together with  lowered suspension and some owners quite extreme camber angles together with increased HP do to the smooth running under load of UJs is a different matter.

Returning to the original question from Angus I would suppose a new TR with original spec HP, suspension etc would have very little difference to a CV joint.  But wear and suspension changes make a difference and the 20 minute swap out to CV joints is a no-brainer. Fit and forget.

 

Alan

 

Edited by barkerwilliams

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CVs on my car made a fantastic improvement. Apart from the cornering improvements they don't clunk on takeoff or gear changes, are quieter, don't need maintenance and come with hubs that don't break up when the bearings wear. 

However, the Mitsubishi based ones I used (they are very popular here, made in Brisbane) only vary in the length of the diff end stub between the Stag and TR6. The one on my drivers (RHD) side was too long and the CV would bottom out under power on hard fast bends causing vibrations through the car. It took two replacements to get it right.

I took the car on a 50km run yesterday to meet the sidescreen guys for a coffee. The route north of Sydney includes a few kms  on the M1 freeway at 'around' 110kph then up the Old Pacific Highway from Berowra to a place called Pie in the Sky, Cowan.

Do a Goodle Earth drive from Wahroonga to the Pie on the M1 and the old Pacific Hwy section. It is a wonderful TR drive usually traffic free, it was yesterday, and with a smooth surface.

The TR6 with the CV axles was brilliant on the freeway and the winding road. 

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On 9/4/2019 at 8:21 PM, Motorsport Mickey said:

In 30 years the engineering world has moved on, CV joints as used on modern cars  (and their derivatives offerings used on our IRS TRs, Stags and Triumph Saloons) are engineered to deliver torque without sticking or snatching throughout their range of movement. On modern vehicles do you think the UJ driveshaft would be considered to be the correct engineering solution ? I think not.

The Datsun Nissan driveshaft offerings work well but now are in short supply and require a significant degree of engineering to suit (well on Stags anyway), CVs are the way to go.

Mick Richards

 

I have to agree with Mick!  There is no comparison in my view in the operation between CV v UJs, mine have done 15k miles now and my rear suspension now works as it should and the chance of one of the rear wheels flying off has gone and that maybe reason enough to change to CVs, as I have witnessed this happening?

Bruce.

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I changed to CV joints when Moss were selling them at a greatly reduced price...

in addition to losing the clunk of my poor original joints the hubs were replaced at a time when stories were common of damaged hubs causing TRs to lose their rear wheels

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After multiple rebuilt hub failures and two broken differentials I swapped out all of the rear end (axles, hubs and diff) for the Goodparts kit. Infiniti Q45 lsd diff, cv axles and modified Ford hubs. I did this reluctantly but could no longer trust the stuff coming from well known rebuilders.

Stan

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 OK so looks like I am also going to have to go down this route.

Two outer UJs have lasted <6000 miles. Last one began to go after the 10 countries rally.. perhaps a result of the extra torque of the supercharger going up the mountain passes.  Don't really want to have to change them every year.  

Tim

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2 hours ago, TRTOM2498PI said:

Hi Stan,

 

Do you know which Ford hubs are used ? I have this kit on my 6.

 

Cheers.

Based on the part numbers stamped on the hubs we think they are from a Ford Taurus.

Stan

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4 hours ago, Tim D. said:

 OK so looks like I am also going to have to go down this route.

Two outer UJs have lasted <6000 miles. Last one began to go after the 10 countries rally.. perhaps a result of the extra torque of the supercharger going up the mountain passes.  Don't really want to have to change them every year.  

Tim

Are you using the cheap ones or the decent quality ones from the likes of Revington.

I was getting through cheap joints in about 3000 miles on my Stag powered TR, but started swapping them out with the quality ones several years ago as the cheap ones failed, and have not had a single one fail since despite some serious track day and autosolo abuse.

The quality ones have bigger bearing surfaces and more rollers, the differences are clearly visible

Neil

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Using GKN ones.  But perhaps they are not the best grade.  Will have a look at the boxes. 

Tim

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