MGB steering rack play

Buzz · #1 (**permalink**) 10-11-2011, 10:20 AM

Any gurus or others familiar with the workings of the MGB rack and pinion? On inspecting my front suspension about a year ago, I found that the rubber boot on the left side (its a right hand drive rack) of the steering rack had torn right at the inner end and was riding back and forth on the tie rod. Since it was near the end I was able to squirt some grease in and reattach it using a couple of tie wraps.

It eventually worked its way off again and now I have some play in the steering. Only with the steering centered, I can turn the steering wheel to the left a good 2.5 inches before the wheels start to move. Turning to the right there is no play at all.

This does not noticeably affect the steering at all when driving except during a transition from turning right to turning left. As the steering wheel crosses center, there is a split second of looseness in feel as it takes up the play.

Standing next to the car with the hood open, I can turn the steering and see that there is no play in the shaft or u-joints, but turning left from dead center, I can see the left tie rod move upwards slightly before it starts moving the wheel. Turning the steering wheel back and forth in the "play zone" makes the left tie rod move up and down about 2 inches in total travel.

Is this likely an adjustment issue, a replaceable worn part or do I need to order a whole new rack?

PS: the tie rod end on that side looks like it needs replacing as well - the rubber is torn. Could that be the culprit?

There is no shimmying or steering vibration at any speed.

mickmate · #2 (**permalink**) 10-11-2011, 11:24 AM

The inner tie rod ball is held in with an adjustment nut that sandwiches it in its socket. It sounds like it may need adjustment to tighten it or possibly replacement. They should be tight enough they are snug but can still be easily moved by hand.

Buzz · #3 (**permalink**) 10-11-2011, 11:36 AM

Thanks Nick. I'll download a steering rack diagram online and see if I can make the adjustment.

mickmate · #4 (**permalink**) 10-11-2011, 11:39 AM

56 MGB Inner Tie Rod Adjustment - YouTube

Buzz · #5 (**permalink**) 10-11-2011, 11:41 AM

Thanks again Nick - I really appreciate that. I'll check it out.

strictlypersonl · #6 (**permalink**) 10-11-2011, 11:53 AM

The vertical movement on the driver's side indicates there's probably something amiss.
I'm pretty sure that there are a couple of gear designs, but most have a spring-loaded nylon cup that pushes the rack onto the pinion (stabilizing the vertical movement). There may be a screw adjustment or shims to adjust the pressure. Pull the cover plate off to see how things work. I don't think that there is a replaceable rack bushing on the driver's side.

Buzz · #7 (**permalink**) 10-11-2011, 12:06 PM

Thanks Bob - getting ready to head down to the garage now so I can check it out. I'll report back on what I find.

Buzz · #8 (**permalink**) 10-11-2011, 07:29 PM

I jacked up the car and found two things wrong with the steering rack.

The first and most obvious was that the outer tie rod end on the left side was adjusted all the way in to the point that there was no room for further adjustment and there was plenty of adjustment available on the other side.

The second thing is that the rod on that side also seemed excessively loose at the inboard end compared to the other side. With the steering wheel centered, I could easily move the outer tie rod up and down and, to a lesser extent, back and forth.

After watching the video that Nick linked to, I checked the jam nut on the inboard end and found it to be loose. I tightened up the bushing and the nut per the instructions which stiffened it up a bit. The jam nut on the outer tie rod end on the right side was also loose so the next thing I did was to center both tie rod ends and did a quick realignment making sure there was no slack on either side.

The play in the steering is gone completely. I still need to get someone else to do a proper alignment now, but at least I don't need to buy a new rack.

The bad news is my radiator (Griffin aluminum cross flow) developed a bad leak on the test drive; halfway up the outlet tank where it appears to have been making contact with the aluminum shrouding and wore through. It never came close to overheating, but half my coolant drained out and I had to stop at a little bar & grill to relax for a couple of hours while it cooled enough to add some water and head home.

Overall, a good day. The car ran and handled like a dream. The parlimentary representative for my constituency lives across the street from where I was stopped and he came over to check out the car. So I made some new friends discussing cars and politics while I waited.

The Cobra got me home easily with the leaking radiator and now I can look forward to pulling the rad and taking it in for patching.

Thanks again Nick and Bob for your help - another big part of the joy of Cobra ownership.

Rick Parker · #9 (**permalink**) 10-11-2011, 08:00 PM

There is also a replaceable bushings in the end of the rack opposite the pinion. It can wear and allow the rack to move up or down or front to rear before steering wheel input impacts the wheel angle (steering).

Buzz · #10 (**permalink**) 10-11-2011, 08:34 PM

I think I will order a pair of replacements, Rick, along with new tie rod ends. They both appear intact but the left side must have taken a beating. I have a new set of rubber boots and I will have them all installed when I have a proper alignment done.

mickmate · #11 (**permalink**) 10-11-2011, 08:42 PM

Sounds like a good plan. We have seen them break a ball off the end of the tie rod. It could have something to do with work hardening after rattling around loose in there.

Rick Parker · #12 (**permalink**) 10-11-2011, 09:59 PM

Yes, check the inner tie rod ends. There is a very short heavy spring behind the race that the ball rides on. There is a tightening spec that keeps the inner tie rod in compression so it will not permit the wheels to dart around when they hit irregularities in the road. The later MGB racks also had an adjusting screw and jamb nut art the pinion to adjust the tension imposed by the rack onto the pinion. This was used in lieu instead of shims.