This subject sort of 'hijacked' Ian's thread on problems with his gearbox, so I thought that we could give the subject its own thread.
I am in contact with a couple of colleagues who are Polish and carry out 500/126 business with their contacts in Poland, and have asked them to try to ascertain if 'Motomax' are still a viable company---I will advise the forum of the outcome of those enquiries.
A couple of questions to Andrew, who has already fitted the Motomax C/V couplings to his 500. (a) what size socket did you use on the nut--measuring with my micrometer, it would seem that the nut is 26.5mm(!) Did you use an Imperial sized socket, and if you did, can you remember what size it is (1-3/64ths?) and, (b) the effort required to tighten up the rear hub nut is quite considerable when it gets to the point that you are trying to 'crush' the spacer to get the correct pre-load on the bearings. Were you able to do it all with the new (relatively small, when compared to the 'normal'30mm) nut, or did you do the bulk of the tightening with the original setup (ally/rubber coupling and 30mm nut) and then fit the coupling and 26.5mm nut for the final pre-load tightening? Your input on this would be much appreciated Andrew. :worship:

I'm glad that you've explained the setup so well Tom, because this has eliminated any latent thoughts I mught have harboured of ever fitting these joints on a 500. Perhaps the compromised engineering you describe is the reason why they have been discontinued because the company website illustrates a continuing, large and thriving business.
It seems odd to create a workaround for a common weakness in the the drive-train only to replace it with a possible weakness further along the system.
That contentious bearing preload, and the two alternative types of nut that go with it in original specification, is a subject that recurrs here with regularity. I hadn't thought deeply enough about how you fit the Motomax to have realised that the reversed nyloc replaces the original nut:bang:.
It is obviously very important that the bearing preload is properly set and stays that way. A nyloc nut is no different from any other securing nut in that the friction created at the flat interface with the component it is securing is the primary mechanism that prevents it from working loose. So I wouldn't be happy with having to rely on what sounds almost like a taper-seat, interference fit.

PS. They are still available here:

http://www.ebay.co.uk/itm/Classic-F...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

I discussed these joints some time ago with my Italian friends....
their views were as follows...
unless you have a massively tuned engine and drive it really hard the std setup is fine, Abarth used it and they chucked out more than most people use and more than a 126 engine.
The second point the make is that they do not consider the setup to be that much stronger.

There are alternatives... but they do cost.

as for me.. I will not be tuning or driving to a point the std setup needs to be changed.

just my 2p

Tom et al, I had a funny feeling that my concerns would bring comment!!! Just some thoughts, the supplied nut is quoted in the Motormax instruction as 27mm But, as Tom points out they are just under this, and I wonder how much potential for the socket slipping around the nut when under the strain of preloading there is ??? I have not come across any adverse comments on the 500/126 forums or elsewhere against these CV kits or the fitment procedure, but that in itself means nothing. I'm not sure I totally disagree with BigV regarding the standard rubber joints and their in service life. The point is if you rag the nuts off of the car they will not last and as this kit is from another mass produced car (I think Citroen but I'm checking) probably front wheel drive, with greater power output they must be stronger and last longer when driven hard. The jury is out regarding the 27mm nut and fitting it the wrong way with me, if there is another secure way of achieving the same result then I'm all for it.

Ian.

My understanding of these drive couplings is that they can handle a lot more power if required without breaking up like the standard ones have been known to. But also being purely mechanical if looked after they will never need replacing.
I have never dealt with Motomax directly but they have a long reputation for being hard to contact and get a dialogue going. As far as the couplings go I believe that every so often when it suits them they get tooled up and turn out a batch. I do not know how many or how often. As the manufacturer I think that they may be more interested in selling in batches rather than one offs which suits the middle men who seem to be putting prices up by the day.
If someone can get their foot in the door and a number of interested guys get together then you might have a chance of getting a good deal when they become available again.

here you go...
if you want the business......
but it comes with a price tag.....

http://www.bacciromano.com/?p=prodotti&l=eng&cat1=25&cat2=79&mar=4&pcd=4598

I'm sure that a similar kit could be made cheaper...

I know on Lotus Elans the CVs on the replacement for the rubber doughnuts are from a VW

I was contacted by Motomax after leaving an enquiry. Price was acceptable. I fitted mine as per instructions- but to different hubs. My set up uses disc brakes at the rear. There was no " crush" tube as per standard setup - proper bearings in housings.
26mm socket proved ok.
The trickiest job was getting the driveshafts in with the supplied rubber dowel - to prevent the shaft hitting the coupling.
I used racing grease over the supplied graphite type - as this is digusting stuff to work with.

I installed these units some 10 years ago and they are still performing without any problems. The reason I used them was the poor quality of replacement standard units, I only managed to get approx 350 miles out of the standard replacements. There are other alternatives out there but are very expensive. I looked for a cv unit which had the correct number of splines and offset to fit, even went to my local driveshaft repair service to see if he could recommend something but to no avail.
Ralph

Motomax also make a driveshaft with CV's at each end ( which does away with the boots I've changed three times) the price was extreme at £800.....
Maybe a future upgrade.....

Thank you for your input Ralph---very reassuring. Can you remember how you got round the considerable load needed on the nut (to crush the pre-load spacer)--did you do it in 2 parts as I suggested, or just kept tightening the 26mm nut until the pre-load was to the correct level required?:worship:

I know we have a bit of a laugh at times on here, but this type of thread really is the benefit of this forum...

Ralph has used the tripod joints for 10 years... but what mileage, and how do you drive and what spec engine...

And the Std replacements do seem to vary in quality as we know from many of the rubber/metal components.

I do have a tuned engine with a Panda head and 5 speed box I could fit at some point so I would like to understand the real benefits of these joints, the advantage of double Cv shafts is clear... but do they have problems?

thepuddlejumper said:

I installed these units some 10 years ago and they are still performing without any problems. The reason I used them was the poor quality of replacement standard units, I only managed to get approx 350 miles out of the standard replacements. There are other alternatives out there but are very expensive. I looked for a cv unit which had the correct number of splines and offset to fit, even went to my local driveshaft repair service to see if he could recommend something but to no avail.
Ralph

Click to expand...

Hi Ralph, can you please detail your use of your car at present i.e. - type of driving, speed, gearbox (4 std, 4 hi ratio or 5 speed) and if you had any problems with fitting the CV joints. Just to reiterate what Tom has asked, did you torque up the pre-load crush tube using the supplied nut or not ????
I have discovered that these CV joints may well be modified Citroen 2CV items ????

Ian.

Bigvtwin996 said:

Ralph has used the tripod joints for 10 years... but what mileage, and how do you drive and what spec engine...

And the Std replacements do seem to vary in quality as we know from many of the rubber/metal components.

Click to expand...

I had bad experiences with the rubber couplings in the past, so when restoring, I invested in genuine Fiat replacements. I can say that so far, after three years and a whisper under 20,000 miles of hard motoring, (the last 4,000 with a pretty powerful engine in the back), I haven't had any problems.

I am inclined to think that there had to be a mechanical purpose in the buffering effect of the rubber in the coupling. The elasticity works both on the drive action and on the over-run when engine braking is being used via the gearbox. So it will reduce the twisting effect on the splines of the axle shaft and graduates the strain imposed on the crown-wheel and pinion teeth etc.
I'm unsufficiently versed in mechanical engineering to know if my observations are relevant, but if it ain't broke etc....

Bigvtwin996 said:

I know we have a bit of a laugh at times on here,

Click to expand...

Speak for yourself...

There's even an Italian noun to describe a component with this function.
....from Wikipedia:

"The giubo is made from flexible synthetic rubber and is designed to allow some angular misalignment while reducing driveline vibration in mechanical power transmission applications."

Why the modern Rubber stuff fails so quickly.... as in the drive Joints etc

We all complain, we all look for cheap... but I have looked at how and why the modern repro stuff like engine mounts etc fail...

The reason is the manufacturing process is different... as classic car owners many have seen these DIY products for doing everything from Zinc plating to Rubber mounts.. and for little things they are fine...
Well the Rubber mount kits are a 2 part mixable rubber material that you pour in to a mound having coated the metal parts with a primer..
Quick, easy no special tools .. perhaps some Lego to make the mold..

Repro parts are made a similar way using 2 part rubber compounds...
but Originals were not...
The rubber is a solid material and a steel mold is made, the components primed in a similar way.. but the rubber is forced in under pressure and heat, in a process as we know as Vulcanizing... and the end result is much stronger.. obviously different grades of rubber can be used...

The tooling can take 40-60 hours to make and recouping costs would take a long time, so most repro parts are simply made using cold cure as cars are not normally driven as hard and as often, so we make do....

The is why Factory Drive couplings are better than the cheap crap we buy from the cheapest supplier.. it is not their fault they fail...

Came across this set as another option.
https://www.500mania.it/kit-giunti-con-crociere-tripodi.html

This kit looks very much like the system that the factory Abarth 1000tcr racing saloons used. In those applications they, like this kit, still used a rubber/ally coupling between (in this case the U/J coupling) the drive-shaft and the stub axle. Abarth used to manufacture specially up-rated couplings for the racing saloons. I think that the main purpose of fitting the U/J coupling is to eliminate the flexing that normally takes place within the bi-material coupling.

If you notice most of the Solid type kits are listed as performance/racing...

The lotus ones were famous for the ~"wind up" on pulling away and gear changes... and could result in "Kangarooing" and if one of the "Doughnuts" let go a right mess at the rear....
but the "solid/sliding" joints with CVs had a side effect.... that was and hash gear changes etc were felt through the drive train as the Doughnuts added a cushioning effect for bad changes etc.
The result being that it was common for diffs to take the brunt of the shocks on Solid conversions....

This is all fine for Race use where max performance is required and a strip down/rebuilt isn't an issue but for road use.....

this is my concern with these kits on a 500...
the Original joints provide a cushion within the transmission to the wheels... and that would be removed..

Rusty, I installed the cv units without replacing the bearings and distance piece. So in effect it was a 2 stage compression of the spacer. I also screwed the nylon nut on before fitting the cv unit.to thread the nylon part, this allowed the nut to be fitted more easily. I also used red loctite to secure the nut. I did have one problem when fitting the axles back. The axles were too long to fit into thr joint, the green steel cover section would not allow the axle past and into position. I therefore had to slacken off the gearbox mounts to manipulate the shafts into position.
I have a 126 engine fitted with panda 30 head and carb setup, so the Gamine goes very well and I use it to the max when I can in saying that over the last couple of years I have only done a few hundred miles per year.