T50 gearbox help

[totta crolla]

I have recently installed a used Toyota gearbox into my car but it will not change 4th to 3rd with the clutch depressed. If rev matched, driving in 4th then into neutral and a blip on the throttle it will go in o.k without using the clutch at all. The clutch is fine and it selects gears o.k when stationary.
My suspicion is worn synchro rings but could it also be the synchro hub ?
Thanks

[jdm86gtz]

Is it blocked? Chances are the baulk ring isn't gripping the taper on the gear any more due to wear.
If you split the box and compare the baulk ring grip with slight inward pressure applied on 3rd and then on a different good gear. Pop out the layshaft when you do this.

[totta crolla]

Yes it's blocked.
I will be removing the box soon and I will do as you say.
Can 3rd - 4th be done without taking the complete shaft apart ?

[davew7]

I had a simular problem with a T-50. There is a spring inside the hub that holds 3 dogs in place. One end of the spring had slipped out from under the hub and block the gear engagement. I was able to push the spring back in place and re-assemble. But after just 300 miles I had the same problem again. In the USA the dogs and springs where no longer in stock. You might have better luck in EU, or finding a good used trans or one for internal parts. Dave W

[jdm86gtz]

You only need to remove the 3rd/4th gear hub and one snap ring to get at the 3rd gear baulk ring.

[totta crolla]

This seems to be a common problem on the T50 and mine is now the third gearbox I know of with the fault. I will check very carefully the springs and dogs as it may be a simple fix for a few gearboxes.
Thankyou both for your input.