Lotus Elan and Lotus Elan Plus 2 Forums

Hi all.

I know this is one of those subjects that has been covered many times before but unfortunately that is the problem.

I am just about to fit the Rotoflex Couplings to my Elan and frankly i only want to do it once so i have been reading up which direction the Bolts go in.

The first version is as suggested in Mr Bucklands rebuild manual which states all the bolt heads should face the road wheel (outwards) for those with the guide page 306.


The second version i read on here was that all the Bolt heads face the road wheel except the Drive shaft - Diff side Rotoflex which are the other way round (Head faces the diff) and is how it appears in the manual.



Then there is the third version, According to a picture in the Elan brochure all the nut's face the Drive shaft but as it was a picture of a show chassis i can't be sure it wasn't assembled like that to look nice.

Of the three options i'd usually just go with the manual (option two) but it worry's me that there may have been a change in procedure since my manual was produced in 1970.

On the up side of all the searching i found i had the wrong standard HT Bolts which promptly got changed for a set of Sue Millers finest with the correct shank length.

If you fit the diff end bolts with the heads towards the diff,I think you then cannot get them out one at a time and you have to get all 3 in at the same time. Indeed there may not even be enough clearance between the diff output shaft 'spider' and the diff case to fit a bolt that way around.


I have always fitted all my bolts with the heads outwards i.e towards the tyre.

Only 3 bolts are the other way around in that diagram and contrary to it being later.. that diagram was probably drawn in the early days of the car, maybe before they even built one. And they may have found the all-heads-outwards to be desirable after the cars were built.

billwill wrote:Only 3 bolts are the other way around in that diagram and contrary to it being later.. that diagram was probably drawn in the early days of the car, maybe before they even built one. And they may have found the all-heads-outwards to be desirable after the cars were built.

That is why i put this post up. I was going to fit them as per the Workshop manual but i hold Mr Bucklands manual in good stead hence the confusion.

I seem to recall there is TEXT in the workshop manual which says fit heads to the outseide.

Workshop manual version has never failed me. The nuts are never against the doughnuts apart from on the outermost bolts which feed through the brake discs.

Bill: "When fitting bolts, their heads MUST be in contact with the 'low' bosses in the couplings. The exception to this is the bolts which secure the brake disc .... when ALL bolt heads are towards the wheel."

Sounds sensible to me, keep the head of the bolt against the low boss of the Coupling as per this thread lotus-suspension-f42/handbrake-pull-rods-t24008.html and this picture from the manual.



So this is correct.


Just hope i can get the torque wrench in between the coupling and the Diff

Thanks guys.

Just for reference i thought i'd put a picture of the wrong bolt next to the right one (note how the Shank comes through the Coupling) don't use the bolt type on the left.

Absolutely right, Chris. Very important!

The bolt is essentially a 'fitted' or 'fit' bolt so that there is no movement of the bolt in the 'spiders' or the brake disc. Movement there will bring rapid bolt failure.

Looking at those couplings reminds me that in the 'good old days' the metal around the bolt was solid with the hole drilled/bored through instead of the two piece later/current offering. I expect that contributes to the lack of longevity of the current product.

elj221c wrote:Looking at those couplings reminds me that in the 'good old days' the metal around the bolt was solid with the hole drilled/bored through instead of the two piece later/current offering. I expect that contributes to the lack of longevity of the current product.

I agree the later design is a little odd, the Bolt is quite loose in the later coupling holes. I had a set with drilled holes on my +2 and found they wound up more than the later ones but did last longer.

Just hope these Rotoflex's last couple of years because i'm not a fan of the CV type shafts (well not the ones available in the UK anyway)

Grizzly wrote:Just for reference i thought i'd put a picture of the wrong bolt next to the right one (note how the Shank comes through the Coupling) don't use the bolt type on the left.

P1040222.JPG

If the thread on the left hand 'bolt' goes all the way to the head then it is actually a screw

stevebroad wrote:

Grizzly wrote:Just for reference i thought i'd put a picture of the wrong bolt next to the right one (note how the Shank comes through the Coupling) don't use the bolt type on the left.

The attachment P1040222.JPG is no longer available

If the thread on the left hand 'bolt' goes all the way to the head then it is actually a screw

Well the problem being the proper bolts are unusual, if you just buy 3" x 7/16 bolts the shanks are usually 1 1/2" rather than the correct 2" shank.

It is imperative that the shear force does NOT go across the THREADS of the bolt but ONLY across the shank/solid part non-threaded part.

Where the bolt is fitted with the thread exposed to the joint/joining/mating face between the doughnut and the flange then the bolt WILL undoubtedly shear.

Understand this simple point - shank of the bolt through/across the joint/joining/mating face - and you can't go wrong

45bvtc wrote:It is imperative that the shear force does NOT go across the THREADS of the bolt but ONLY across the shank/solid part non-threaded part.

Where the bolt is fitted with the thread exposed to the joint/joining/mating face between the doughnut and the flange then the bolt WILL undoubtedly shear.

Provided the nut is tightened correctly there isn't any shear on any part of the bolt.

If the nut is loose then there may well be a problem but it makes a noise to warn you (I know)!

There is no Mechanical lock between the Drive Flange and Couplings so the bolts are the only thing stopping the joint from turning, the tightness of the Bolt has nothing to do with the point the shear force is applied.