MTFCA Forum

Does anyone know and can share just how much stiffer the special round wire Watts clutch spring is over the stock Ford flat wound spring?

I've not used a spring compressor scale to verify but the wound round Watts is/was considerably stronger than an original. The new springs are around 100 lbs. +. I've removed a couple Watts springs from transmissions that had the clutch throw-out collar stubs nearly worn through from so much spring pressure.

RajoRacer wrote: ↑

Fri Mar 31, 2023 11:01 am

The new springs are around 100 lbs. +.

It has been several years since I tested a reproduction spring, but they always used to be 135# at 2”. The watts spring is heavier than that. Good used original springs are 95 to 105 pounds.

The Ford engine and transmission is engineered for about a 100# clutch spring. Any stronger spring than that and you will have accelerated wear issues in other areas.

The problem with the watts clutch is the fewer number of disks.
Not enough clutch surface, so to compensate it requires a stronger spring.
Not the most successful "improvement" for a model T.
Good luck.

Hi Mark,
I have recently installed a Watts clutch in my speedster. I was lucky enough to find a new one with the round spring & one with the square
spring. The round one was 122# @ 2" the square sping was 114# a used round spring I picked up was 108#. The instructions say you will/may
need to adjust as it wears in, I have done this twice and found a little axtra preassure will still leave a free nuetral @ 15/16"-1" and gives a
very smooth & positive engagement. ( I can push the car out of the garage with one hand )
Craig.

As I recall, The Watts round spring can/did expand on the throw out sleeve & cock out of place.
Later versions added a "cup" to retain the spring.

Hi John,
If you find that info please share it OK. Thanks.
Craig.

Great input guys, thanks!

I have an original set of Watts clutch disks on the shelf, but no spring.

Judging by the spring rates provided, a new higher tension square spring would work fine
with possibly a little extra tension via the 3 finger adjustment.

Do check the new springs tension. I have found a wide range from 110#'s to 130#'s
The stiffer tension preferred for the Watts disks.