Top gear moans...

[GreySVO]

Hi all,


Need some of your expertise.


I have a 1985 Mustang SVO with the original T5 transmission. I am the original owner with about 85,000 original miles. I am having a top gear groan at anything under about 60mph. The noise and groan goes completely away at 65+ mph. In 4th at the lower speeds, the noise is not present. Mostly under high loading of engine in higher gears, and especially in 5th.


I never hard shifted this vehicle and rather babied it. I've recently installed royal purple ATF.


Any recommendations on diagnosis or possibilities?


I have installed oem motor mounts with the original dampers this year.


Thank you,
Barry

[MikeFleming]

Really difficult to tell form the limited info. Afaik that should be a WC box. You can tell from the number tag on the box.

Things to check:
- Main shaft and counter shaft end play
- Bearing wear on main and counter shafts

That usually covers 90% of noise issues.

Checking / adjusting main shaft end play requires taking our hre box, not much for disassembly. While checking / adjusting the counter shaft end play is lots more work - requires partial dis-assembly of the box.

4th gear is straight-through - it merely conencts the input shaft to the output shaft while the cpuntershaft and gears are not under any load at all.

[GreySVO]

Hi Mike,

thanks. Anything I can do otherwise to check before pulling transmission?

Barry

[MikeFleming]

^
Nope.

[Mike S]

The expert at Hanlon Motorsport told me that the Royal Purple ATF was to slick for the T5 and not to use it. Change the fluid back to Ford ATF.

[svono50]

I know our T5's can be finicky with the fluid used, could be the easiest test before pulling the unit out. I have had good luck with Mobile 1 ATF as well as the Dextron juice over the years, no groaning at 113K miles (knock on wood).