View Full Version : TR4/4A TR4 Slips out of 3rd gear

04-01-2012, 09:38 AM

I searched a little bit, but thought I'd ask just the same. I have a small problem with the car slipping out of 3rd gear. Not always, but more often than not. Just wondering what is causing this and how easy it may be to fix.

..........Thanks, Alex

04-01-2012, 10:45 AM
How does it slip out..under pressure..or driving ..or gearing down? Its going to be a rebuild job anyway..Takeing the tranny in and out is easy enough..but the rebuild should be dont by someone in the know thats for sure.

04-01-2012, 11:23 AM
Mine in my TR4 slipped out usually on deceleration. The problem was a worn spring and detent in the top shifter cover for the 3/4 rod. I just rebuilt my cover and I'm really a bit anxious about how those detents will work. I tested mine with a weight gauge after installing new springs, balls and plungers. The 3/4 rod uses a plunger now instead of a ball, but you could go either way.

I'm told you can remove and rebuild the cover without removing the transmission but I haven't done that.

Remember, if you do this, those tapered setscrews or bolts in the shifter rods will not remove easily (putting it mildly), and will likely sheer off, unless you are extremely lucky or careful. My strong suggestion is that you use an impact driver and socket to remove them. Any other method could result in you visiting a machine shop. My visit was last month.

Good luck.

04-01-2012, 01:18 PM
your shifter forks could be worn past min thickness, 0.260 is min,
the forks from VB on 1st and 2nd gear are made incorrectly, the 3/4 fork seems to be ok, you could look at those too


Simon TR4a
04-04-2012, 09:25 AM
These gearboxes more commonly jump out of second under heavy braking, this is a common problem among vintage racers and can sometimes be solved by use of different transmission fluid.
Usually the pressure on the gears will hold them in place when you are accelerating, I am not sure if this is relevant to your 3rd. gear problem.

04-04-2012, 05:34 PM
I like the detent idea. There could be internal causes for slipping out of gear but the detent seems most likely and the only easy fix. The cover comes right off. A new spring and ball would be in order but it's probably just sticky with crud.