How to get access to replay option? (Forza Motorsport 3 & Forza Motorsport 4)

Hello guys,
I’m new to the forum so please bear with me a minute.

A few days ago I just bought a used Xbox 360 E, the one with 4GB internal storage (I think it’s also known by the name of Arcade)
I am using it wih an external HDD storage via USB. It is a Western Digital of 1 TB (formated of course via Xbox360).
The Xbox can see this external HDD an works well except one thing: for Forza Motorsport 3 or Forza Motorsport 4 the games don’t offer replays to be saved.
Normally, after finishing to play a session, the game was having 4-5 option: continue, view leaderboard… and view replay. This last one is missing now
Previously, I was able to successfully save replays, for these games, on the same HDD, using same discs, but on another console that I sold: it was a Xbox slim with 250 GB internal.

The question is:
what can I do to get access to replays for Forza Motorsport 3 or Forza Motorsport 4 with my current configuration since I don’t want to change/trade my actual console?

I understood (not sure if it’s correct) that this is due to the “absence” of space, something like no storage = no replyas, although I’m using this external HDD

See here a similar situation:
"Okay, I traded in the 4gb model for a 250gb, and that did it. I now have replay. "

Thank you in advance for any sugestion

Oh that’s funny. It’s one of those things you’ll notice only when it happens to you.

But if there’s no solution, you don’t need to trade your Xbox, you can buy an internal HDD. You can find 320 and 500 GB and they should be cheap.

Sorry for not really being of help but I’m really surprised it disables the replays because of that. n_n’