healey

Hi all,
I am doing a WP/TB service in my 1979 OB. The last time I did this I did not service the tensioner as the car only had 35K miles. This time I decided to "rebuild" the tensioner, primarily to clean out the old oil. When I dissembled the tensioner and removed the bi-metallic springs/washers I notice that one of the washers was broken. See photo. Any thoughts on how one washer would break when inside the tensioner cylinder??

Also when I strung the rest of the washers together as seen in the 2nd photo they do not appear to be arranged in 8 groups of 5 in opposing direction. The broken washer is were the pointer is and would be the last(10th) one in that group which has nine washers.

Questions? 1. Will the tensioner work with one missing washer? 2. Is the arrangement of the washers correct. Manual calls for 8 groups of 5, however the sequence seems to be 5 groups of 5-10-10-10-5 washers. The 3rd photo shows the washer sequence from another rebuild of a '79 tensioner that I got off of this forum so my sequence seems to follow this sequence.
Any help/advice would be appreciated.
I may have to install a Porken Tensioner which will require modifications to my AC bracket to get it to fit.
Thanks,
Bob


washer sequence

Washer seqence from another '79 Tensioner

linderpat

Call Mark at 928 International and get a used set of the bi-metallic discs. Stay with the stock system. Don't reassemble without the full set of discs in the tensioner. My $.02.


BTW, the WSM manual shows the correct arrangement of the discs.

FredR

Your tensioner has 40 washers and the assembly is correct- 8 sets of 5 washers- what you should note is that the assemblies that have 10 washers are two packs of 5 back to back as in 5 pointing one way and the other 5 pointing the other way.

The total assembly is critical to achieve the correct spring rate resistance as designed. On the later model tensioner like mine that overall spring rate of the pack is equivalent to 0.6 of the spring rate of one washer- yours will probably be different but not by much I suspect.

Given one has failed I would acquire a new pack from one of our suppliers as used units have no provenance albeit they may be perfectly OK-your risk as it were.

healey

Ok, Roger had a washer in stock so he is sending it to me to complete the set of 40 washers. Also looks like the sequence of washers is correct per the manaul. I should be all set once I get the replacement washer.
Thanks,

FredR

If one washer has failed like that one has to wonder why such happened and whether it is feasible that the other 39 washers are OK.

For metal to crack like that the only logical engineering reason I can think of for such to happen is some form of embrittlement and if so why would it impact only one piece?

Flexing back and forth for 44 years maybe work hardening but with only 35k miles that is nothing use wise so some kind of environment issue- possibly corrosion of some kind?

GregBBRD

Not common for one of these "washers' to break...at least I've never seen one.
You will find that the replacement part is different visually.
I'm not sure why Porsche changed the design, however at this point in time, I am replacing more and more "sets" of washers, due to wear.

Tony

temp changes and pressure...ask the guy that built the sub. Eventually stuff fails.

PorKen

ROG100

At $10 a washer that gets expensive fast.

FredR

At $400 a set are there any cheaper options?

ROG100

Fender washers maybe.

FredR

Roger,

You are getting a bit slow on the uptake in your old age!

GregBBRD

Sorry, but 40 pieces of anything from Porsche which cost $400 doesn't knock me over....especially when they are 40+ years old, continually changing shape, and constantly under pressure, which is trying to make them flat.
Compared to other, simpler pieces, which come from Porsche, these seem like a bargain.

GregBBRD

Worth noting:
If one is replacing or considering replacing the bi-metallic discs in their stock tensioner,
It's really not as expensive as the aftermarket tensioner people would like you to believe.

There's only 35 discs required (and one spacer if you are updating from the early 40 discs to the updated 35 disc recommendation) and they retail at $8.88, not $10. (And it is very quick to find someone who will give almost anyone a 20% discount, which makes them $7.10.

That's less than $250, for a complete set of new discs.
Add in a new boot, a clamp, and a new tensioning bolt (to keep the tensioner from leaking oil out the threads) and your total cost is less than $300.

kamaro

@ $400 for rebuilding stock tensioner, wouldn't be more viable to get a Porken tensioner instead?