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MG MGB Technical - 2nd Gear Problems

Upon driving my freshly restored '64 MGB, we found that it ran beautifully, with one exception. We can't get it into 2nd gear when moving, as if the synchro is bad, but all (3) synchros were replaced when rebuilding the gearbox. We've noticed that the clutch "engage/disengage" point is very near the floorboard, so we suspect maybe we have a hydraulic problem. I found a wealth of information in the archives about bleeding the system...is it possible we don't have the system free of air? If so, why are all other gears ok? Any other ideas?

Thanks,
Rich
http://64mgb.home.mchsi.com/
Rich

The key ,as I see it is the low release point on your clutch pedal. Address this first, as most other repairs would involve powertrain removal.Bleeding the system even rebuilding both the master and slave take a lot less time, and at least if done correctly, the hydralics can be ruled out.
RIC
Ric

There should be about 1/2" of travel of the slave piston. If you have less than this then the system needs bleeding. If you find it difficult to get full travel try emptying the system then refilling it with a gunsons on very low pressure connected to the slave bleed nipple. If you have 1/2" but still a low biting point the pedal, master push-rod and clevis pin are probably worn. You can replace the clevis-pin and push-rod but if the pedal is ovalled it will need some weld in the worn area (don't completely fill the hole, leave the unworn part clear so you can get a file in) and filing out bit by bit.
Paul Hunt

Thanks for the input, Ric and Paul. Both the master and slave cylinders, as well as the pushrod in the slave are all new, so unless Moss sold me bad pieces, I think we can rule them out. After reading about all the problems others have had bleeding their systems, I'm hopeful that we just aren't getting all the air out of the line. When we bled the brakes, we rigged up a way to pressurize the system by drilling a small hole in the top of an extra master cylinder cap, then inserting an air nozzle with the compressor set on low pressure. Would a similar setup help with the clutch bleeding?

Thanks,
Rich
http://64mgb.home.mchsi.com/
Rich

Rich - Try the following on your slave cylinder: With the bleeder screw on the slave cylinder shut, push the actuating rod all the way back into the cylinder, then rebleed the system normally. You may want to repeat this process a couple of times to insure that all the air is out of the slave cylinder (watch the level of fluid in the master cylinder to insure that it doesn't overflow when pushing the actuating rod into the slave cylinder). The other thing to check for is all of the holes in the linkages. Since bothe slave and master cylinders are new, the holes in the actuating rods should be ok, but the holes in the pedal end that attaches to the master cylinder rod and the actuating arm in the bell housing are probably worn oblong and are probably contributing to your problem. Good luck - Dave
David DuBois

Rich,

There are two types of 2nd gear the original type with a plain steel cone and a bronze synchro ring - the later type has a coted cone and use a steel ring.

The two types are interchangeable only as a set with the corresponding ring.

What rings did you replace - a steel ring on a plain steel cone won't work!
Chris Betson

Hey guys, we just found something else to throw into the mix. We compared the new actuating rod in the slave cylinder to the one that came out, and the new one is about 5/8" longer that the original. Will this be a factor? Here are the measurements from the center of the hole to the end of the rod:

New: 3 1/16"
Original: 2 7/16"

Thanks,
Rich
Rich

As long as the rod does not force the slave cylinder to the end of its travel, then it will make no difference.

The system is self compensating.
Chris Betson

Rich - applying pressure to the top of the m/c is exactly what the EeziBleed does, but that on its own is not sufficient to fully bleed the brakes on either of my cars, and I didn't even try with the clutch based on others comments. But it was 100% effective when used to fill the system from the slave nipple. Check the travel you are getting, that will tell you whether it is hydraulics or mechanical. Hope for hydraulics.
Paul Hunt

Thanks, everyone, for all your input. Unfortunately, we've determined that we're going to have to pull the motor/transmission and find out what's going on in the gear box. After more bleeding, we're convinced that the hydraulics and clutch are working properly. We can feel the throwout bearing contacting the pressure plate right at the top of the pedal travel, releases where it should on the way up, and all other gears work fine. A real bummer, since everything else in the drive train seems to be working so well. My theory is that someone replaced 2nd gear at some time, with the gear that needs the steel synchro ring (see Chris' comments above), and when we replaced all the synchros we used the brass rings.

We'll see what happens.
Rich
http://64mgb.home.mchsi.com/
Rich

This thread was discussed between 27/04/2002 and 02/05/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.