THM-400 hard shift into reverse
Thread Starter
Intermediate
Joined: Sep 2016
Posts: 29
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From: Columbus Ohio
THM-400 hard shift into reverse
Hello,
I am picking up a 73 L48 Auto for my wifes birthday. The motor has been rebuilt once (pretty stock rebuild) and the trans has a "shift kit" in it. Driving down the road it acts like a typical shift kit with very firm positive shifts. The problem I have is that shifting into reverse from park it really slams into gear. No metal on metal noise just a very hard jerk. I know the THM-400 is reliant on good vacuum, over 15inches to operate effectively. My question is could it be a vacuum problem or just the function of the shift kit? My plan is to put the trans back to stock buy replacing the shift kit valve body with a stock one.
I have checked the fluid and it is very clean with no burnt smell of a typical burnt clutch pack.
I am familiar with ford transmissions and 200-700R4 but not these older ones.
Thanks
Chuck
I am picking up a 73 L48 Auto for my wifes birthday. The motor has been rebuilt once (pretty stock rebuild) and the trans has a "shift kit" in it. Driving down the road it acts like a typical shift kit with very firm positive shifts. The problem I have is that shifting into reverse from park it really slams into gear. No metal on metal noise just a very hard jerk. I know the THM-400 is reliant on good vacuum, over 15inches to operate effectively. My question is could it be a vacuum problem or just the function of the shift kit? My plan is to put the trans back to stock buy replacing the shift kit valve body with a stock one.
I have checked the fluid and it is very clean with no burnt smell of a typical burnt clutch pack.
I am familiar with ford transmissions and 200-700R4 but not these older ones.
Thanks
Chuck
