Timing Chain tensioner Thread size

[bloodknock]

In amongst my parts accumulated over around 40 yrs ive spotted a couple of used spare tensioners that are of a different thread size to my sprint one ....what were they used on? The old rope seal twinc?

[rgh0]

I am not aware that the standard front covers changed. All the ones I have seen have the same threads for the tensioner. Maybe some have been modified due to the threads stripping? But is was made by Lotus so anything is possible

cheers
Rohan

[2cams70]

I posted previously about the same topic. I've got the same issue. Can you post a picture of your tensioner?Is it the tensioner plunger or the tensioner sprocket pivot you are referring to? (my issue concerns the tensioner sprocket pivot)

[bloodknock]

It the tensioner spring plunger not the pivot.
I'll get some photos
Bob

[bloodknock]

Tensioner spring preload screw. Two distinctly different thread sizes. The smaller thread is from my sundry spare bits box, there are two the same size. They must be from earlier Twincs as these were stashed away in the TC Escort days.
The larger is from my sprint, which as I have previously said was stripped very early in its life.
I have also included a photo of a spare tensioner pivot pin i have in my bitsa box.
Bob

[rgh0]

I believe the smaller 5/8 inch fitting is the standard. This is whats on all my front covers and spares including the original cover from my 73 Plus 2.

The standard thread appears to be either 5/8 Whitworth or UNC. Its hard to tell given that their are only a couple of threads and as the only real difference is the thread angle and I don't have the equipment to easily measure the 5 degree difference quickly. My guess would be UNC. I am not aware of any other Whitworth threads on an Elan.

I would guess someone has stripped the front cover thread and re-tapped it to 3/4 UNC and made a new adjuster fitting to suit for your Sprint at some stage

cheers
Rohan

[bloodknock]

Hmmm thats interesting, since i aquired the car very early in its life, its a 71 car and I recall that it had around 9k miles on it when purchased in 1972.
I am now concerned about the integrity of this area. Ive been messing with TCs for years on and off, with parts of various engines in storage, some were older lotus cortina elan and escort engines. I wonder if ive mixed front covers and used an earlier one that had been mackled. I now have no spares of this item, as the old engines have been sold on!
Great! So how much are remanufactured front cover assemblies and who does the best version?
Bob

[Chancer]

What concerns do you have about integrity? The modified tensioner thread will be stronger.

Or is it an originality thing? If so would a modern reproduction make things any better?

The quality and dimensional conformity/tolerancing of most modern reproductions is at best marginal very few have the integrity of an original part.

[bloodknock]

Thanks for that, i assumed that modern manufacturing technology would be on top of the job quality wise.
The tensioner looks identical externally, I was thinking more of the remaining thickness of the surrounding casting, but thinking about it and reviewing the thread, theres plenty of meat there.