Can 5-speed Simplex TDF rear derailleur work on a 4-speed cassette?

[BlackRockJohhny]

Maybe it's a dumb question, but I'm wondering if a 5-speed Simplex Tour de France (TDF) rear derailleur work on a 4-speed cassette? I have a (actually, am anticipating that I will soon have) a 1960 Schwinn Varsity with a 4-speed cassette. It comes with a 4-speed Simplex Tour de France.
However, if it ever happens that the 4-speed TDF fails, could I use a 5-speed TDF (which I have laying around) on that 4-speed cassette? The throw of the 5-speed is 23-24 mm, so I assume that it will have more throw than the width of the 4-speed cassette (maybe not, just an assumption on my part).

Are there any issues that would prevent my 5-speed TDF from working on a 4 speed cassette?

Thanks!

 

[bulldog1935]

it should work fine - friction shifting doesn't require any kind of index steps.
I have run several different RD from the 5-sp era on 6- and 7-speed, and heard of them running fine on 8-speed cassettes.
All you have to set up are the limit screws that keep the RD aligned with the limits of the freewheel cogs.

 

[BlackRockJohhny]

it should work fine - friction shifting doesn't require any kind of index steps.
I have run several different RD from the 5-sp era on 6- and 7-speed, and heard of them running fine on 8-speed cassettes.
All you have to set up are the limit screws that keep the RD aligned with the limits of the freewheel cogs.

 

[BlackRockJohhny]

Thanks for the reply, bulldog1953.

Actually the Simplex TDF doesn't have limit screws as far as I know. It's a plunger-type derailleur.
Here's a pic:

 

[bulldog1935]

Hopefully there's a way to limit it to keep it out of the spokes - bad things happen.
But otherwise, there's nothing that will keep it from working with 4 cogs.

 

[rhenning]

I going to tease you a bit about your terms used. There is or never was a 4 speed cassette used on a Varsity. There was a 4 speed freewheel and they are indeed different. The derailleur should should work with a 4 speed freewheel. I have a 1960 Continental that would have come with a TDF derailleur but some time early in its life it was replaced with a 1962/3ish Huret. Talking to old Schwinn dealers that was apparently pretty common. The Huret will stay on the bike as long as I own it. Roger

 

[rhenning]

As long as I brought it up here are some pictures of my Contienta. Roger