T45 pops out of 2nd gear

[Duke66]

Hello Gentlemen,
My MK4 is a donor build (circa 2015 with a 98 Mustang GT donor)
4.6 2v with T45 five speed transmission.
As my car is in body shop jail, body off now after body work and almost ready for paint I brought the chassis home for cleaning, wire tidy up, etc.
I drove the car 5000 miles in gel coat before taking it to body shop and never having driven the Mustang as it was a crashed car I discovered that the transmission would pop out of 2nd gear while cruising or decelerating if I hit a small bump (or big bump).
Does the forward slanting shifter handle play much of a part in this?
It stays in gear fine under throttle.
If transmission is in need of parts now is the time.
Any insight into this situation is greatly appreciated.
Thank you,
Dave

[Jeff Kleiner]

Do you have the accordion style rubber shifter boot on it? Sometimes it can sort of preload the shift lever which lets it pop out of gear when the conditions are right. If you have it installed take it loose and see if the problem still occurs. If that cures it try repositioning the boot or replace it with a vinyl or leather type.

Jeff

[Duke66]

Do you have the accordion style rubber shifter boot on it? Sometimes it can sort of preload the shift lever which lets it pop out of gear when the conditions are right. If you have it installed take it loose and see if the problem still occurs. If that cures it try repositioning the boot or replace it with a vinyl or leather type.

JeffGood info about where to start.
Thank you Jeff