TR6 Changing a TR4A fan to a TR6 fan

[Paulus]

I've come across several postings where the author has replaced their TR4 and 4A fanblades with TR6 fanblades and have had success in controlling the engine temps of their cars better.
My question is this, is it simply a matter of removing the original impellor and reinstalling the new or is there an adapter or conversion process to make this change?

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[TR4nut]

On my TR4, the cleanest way to change to the TR6 fan was to also change out the fan extension and dog bolt to ones from a TR3. The TR6 plastic fan is thicker and there wasn't enough room in front of the radiator. Here is a picture comparing the old setup vs the new, you can see that the shorter TR3 extension makes the total length very close to the original. With this setup is a complete bolt on modification, but I did have to pull the radiator. Not positive about the 4a setup - let me know if you need it and if so I'll measure the TR4 extension length so you can compare to your 4a.

Randy

installed:

 

[Paulus]

Thanks Randy, I like to know what I need before tearing things apart and your pictures and reply could not have been more helpful.
Paul

 

[MichaelG]

I replaced the original fan with the TR6 fan in my TR4A. No adapter required, and I used the original extension. The fit is very tight...less than 1/2 " clearance. That said, no problems to report...and no overheating concerns...even on hot summer days for more than 25 years. The TR3 extension looks like a good idea if your results differ.