Pops out of 1st gear

[Last TR]

Going very slowly down a steep drive in first gear, using both the engine and the brakes to keep it slow, my TR8 occasionally pops into neutral. I have not had the experience in 2nd or 3rd going downhill at somewhat greater speed. The car had a used 5-speed transmission installed shortly before I bought it last year. Do I need new synchro rings, new motor/trans mounts, or maybe a bungee cord around the lever?

Ken
Anchorage, Alaska

1980 TR8, 1973 TR6, 1965 Volvo PV544, 1958 MGA, Jeep Cherokees

[windy one]

When I had that same problem, it was an internal issue. I just swapped out my trans with a known good one, all cured.

Johnny

[Underdog]

You could check for binding in the gear lever area...boot around the lever ect. Not likely but worth a look. Rubber bushes that attach the shifter are also prone to deteriate. That's the easy stuff to check.

Worn syncros will cause pop out. Not usually the blocking rings as much as slop in the whole assembly or teeth worn on the slider and gears.

Be patient and Mildred will be along soon I'm sure. The resident expert on LT77s.[:)]


72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

[V8Wedgehead]

I would check the shift bushing that hold the shift lever assembly onto the transmission. Secondly if they look to be in good shape change the gear box fluid to the GM Synchromesch Transmission fluid. I fit has not been changed to this fluid it may help prolong the symptons. Typically if after you go to the GM fluid and it still pops out of gear or will not go into a gear your synchros are done! You will have to either do a swap or get yours rebuilt. Good luck!

Michael
1980 TR8 FHC/Works Rally Project

If it is broken then fix it....if it is not then make it faster!"

[Workshop Help]

Why, thank you Underdog. You're so sweet.

Let us analyze what is happening inside the gearbox. We have two whirling masses of fine British steel interspaced with five brassy-alloy synchros and a fixed rod with sliding forks. All this rotating steel is supported by four large taper roller bearings and one small taper roller bearing. Lubrication is by a combination of traditional splash and an oil pump shooting oil forward thru the main shaft to the small taper roller bearing with bleed-offs along the way for the synchronizer assemblies. That, in a nutshell is it.

We won't go into the swarf issue as this as been done to death already, except in a minor indirect manner. As the LT77 ages thru even normal and very well maintained use, wear & tear does occur. Bearings begin to wear down, their matching races developing grooves, the soft metal of the synchronizers wear off the outer nubs and inner groove edges, the gear teeth themselves wear gouges in each other. The whole assembly loses it's orginal design tolerances, it loosens up. Just like our hot little bodies over time. Ain't that right, Hasbeen?

Ken, in the original post, says this is a used transmission. Folks, As we have previously discussed, there is no such thing in this Celestial Universe as a good, used LT77. What is happening is the effects of time and/or lack of frequent oil changes have come to the fore with a loose assembly flexing in the bearings/races. The layshaft and mainshaft are bouncing around and POP! The reverse torque load from engine braking slips it from in-gear to neutral.

What does this mean? It means you must cork up that volcano, heat up the barn, securely and safely elevate the car, slip a floor jack under the gearbox and with wrenches in hand, pull your transmission. Place it on the clean workbench, disassemble it, and go forth to the local quality bearing house to buy new bearings as well as order new gaskets, oil pump, synchros, polyurethane shifter washers, and all the rest of your cars various needy items.

That is what all this means. As others here have said, you gotta worn out gearbox. Please research the threads hereabouts for our previous articles on the LT77 and report back on your progress. I must repeat, the only way to know you have a good LT77 is for you to rebuild it yourself, or stand over and watch someone else do it, every step of the way.

Mildred Hargis

[Underdog]

I'd just like to add that having rebuilt a few MGB OD boxes and 3 of these 5spds, I feel the 5 spd to be the easier of the two. A universal type gear puller to get the 5th speed gear off and they come apart without much drama. Only downside to them is no side cover to pull off for a looksee. You have to dismantle them to inspect the internals. At that point it would be foolish to go back together without at least new brgs and oil pump. That's why I would never pay much for a used one unless it was rebuilt or had some sort of documentation as to it's condition.

Several years ago a fella in our club bought a used one to replace his ailing 4 spd. He asked me about checking it out for him. I quoted 3 or 4 hundred dollars for the labor plus the cost of brgs, pump and whatever else it needed. He says..."but how much to just check it out?" I explained what I just said in my previous paragraph but he couldn't seem to grasp the concept. I finally said that I don't haxe X-Ray vision and if I did, I wouldn't have to make money working on gear boxes.[:D]

72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

[bmcecosse]

If the only problem is this ocassional popping out on overrun in first gear, and the box otherwise performs ok - leave it be ! It will last for many many miles yet. Treat it to a good oil change by all means. And don't hold it in gear or tie a bungy round the lever - that will only wear out the selector fork and add even more gunge to the bottom of the box! Just rely on your brakes for going down hills - that's what they are for!

[Last TR]

It's too bad the previous owner didn't rebuild the old transmission (which I also got with the car) instead of replacing it. I've been through the transmissions in both my TR6 and my MGA, and I suspect I can do this one too. The nice thing is I can rebuild the spare transmission while continuing to drive my car. But unless it gets to be a problem in the higher gears on the road, I probably will leave it be for now. Thanks everyone.

Ken
Anchorage, Alaska

1980 TR8, 1973 TR6, 1965 Volvo PV544, 1958 MGA, Jeep Cherokees