TC Front End Improvements-Handling

[Steve Simmons]

Mark, Duncan covered it pretty well but I will add that while the TC steering will never be as stable or light as the TD, it should be be pretty good once it's been set up correctly. One thing that usually isn't set right is the centering. Don't set it at the center of play, set it at the center of the tight spot. The casting and even the machining of the boxes isn't always perfect, so the center of travel is usually not the actual center of the worm.

As for the rod ends, I'm hesitant to recommend replacing the factory spring-loaded ends with rose joints because the BC box isn't the most robust part of the car and those ends were likely, in my opinion, used to provide some shock absorption on rough roads. Whether they are needed today on our much improved roads is debatable, so I leave that up to others to determine. As for performance advantages, they will make a slight improvement, but they certainly don't look original.

Before modification I would recommend disassembling and inspecting your existing ends. There is any appreciable wear on the balls, turn them 90 degrees. Then grease them and adjust to their tightest point, then back off to the nearest split pin groove. On the pitman arm end end, there is only one split pin groove so I like to machine a second one to enable finer adjustment. Also be sure to look at the springs, as they do occasionally break. Once this is all done, and your reasonably confident the rest of the front end is set up correctly including the axle being installed the right way around (a fairly common mistake), no excess play in the bearings, kingpins nice and tight, etc give the car a run and see how it feels.

[Mark Strang]

Well, I must have done something right when I rebuilt the steering box. My friend who has a TC and has been driving a lot of different TC's for 30 years test drove mine today and claimed it was the best steering TC he had driven. I was pleased to hear his comments but I'd still like it better. I think I'll try the 1/2" toe in and see what happens. It won't hurt to try. How is the tire wear with that setting?

Mark

[Duncan M]

FWIW-- from what I have observed, the ball attached to the steering drop arm that goes into the drag link end, wears dramatically faster than the other balls. Too bad places like Moss never seem to have them (drop arm ball) in stock. FTFU has them in stock for $70 (ST280).

[Mark Strang]

Duncan, Yup, I had to replace that one and another rather than just rotate them. Wanted to eliminate any variables. The springs were good and the seats for the balls were fine on all of the joints. I set the steering up for the center of the tight spot with just a little tightness and as my friend was driving he took his hands off of the wheel and it tracked dead straight with reasonable turning response. You know, it might just be as good as it is going to get and that will be okay as long as I recognize that. I'm going to try the additional toe in and see what that does. Seems excessive but it's worth a try.
Mark

[stephen stierman]

Mark, the tire wear was not excessive, now I did tend to rotate my tires with some regularity. When you are driving a couple thousand miles a year, well it isn't a particular problem. I restored my TC and the steering box was not worn with a lot of free play, the TC just sort of had a mind of its own and I really wasn't happy with it. I drove a friend's car that had been converted to a VW box and it really was much improved even though it was slower in response. It had less free play so was easier to provide correction as needed. Even so I thought about doing the same conversion. One evening I was looking through my Bentley manual and noticed toe in settings at 1/2" for prewar cars, why is this, same chassis basically? Nobody has ever answered that question. As an experiment, I increased the toe on TC2911 and it was transformational. Give it a try and report back please, see what you find.
By the way I have had Morgans for many years and these cars used a later version of the BC box with a bit of similar free play on center but they do go down the road in a straight line. Maybe the steering box when in reasonable shape is not the problem, perhaps it is the front end geometry?

[Mark Strang]

Stephen, I increased the toe in from 1/4 to 3/8" this morning and took it for a drive. It seemed to make a difference that was noticeable. I'm going to increase it to 1/2'" and try that. Please bear in mind that I only have 58 miles on the car since a total 1,800 hour rebuild and other things could be affecting the steering although from day one I was extremely careful to get the front end repair as good as I could. It seemed today that the faster I drove the better the steering felt..
I too have a couple of Morgans with the same setup so I was surprised that the TC wasn't better. I rebuild old Jeeps at my summer place and they also have the same setup. The steering when rebuilt is poor. Same arrangement with the spring loaded ends etc. Perhaps I should put more toe in on those and see what happens.
I'm not worried about tire wear. I have three MG's, the Morgan driver and a little old Porsche. I can only drive one at a time and it's tough to get a lot of miles on them except for a 1,000 mile trip through the mountains of Virginia and West Virginia each fall with my '53 TD driver. It's a great hobby and keeps me out of the taverns. I'll let you know how the 1/2: toe in responds. If that works, I'll suggest it to my other TC friends.

[Steve Simmons]

Keep in mind that one downside (or design feature depending on how you look at it) of the original ends is that the toe decreases with speed. So setting the toe a bit aggressive can give the desired toe at higher speeds.

[stephen stierman]

Mark, I have been suggesting increasing the toe to 1/2" for years after I read it in the manual and tried it myself. A couple people have done it, Norman Verona (Frenchblatter for one) and had good results also, yet the same complaints about poor TC directional stability are still mentioned regularly. This allows me to assume that most people have not read the suggestion or simply ignore it and continue to blame the steering box. Along with much better directional stability at speed, the turn in became smoother much more like a modern car than the rather notchy feel it had previously.
As I have said, I do not necessarily believe the directional stability is a function of the BC steering box, it is more a function of front-end geometry on an old car. Yes, if your BC box is really sloppy with lots of free play, keeping the car in a straight line is much more work, but if the chassis is set up so that it goes straight instead of pattering right or left, the free play in the steering is not so much of an issue. If you choose to install a VW box, which has very little free play the task of keeping the car becomes much easier, but the chassis issue is still there. There is no reason why the Cam Gear steering box in my old Morgan with some free play also should be any better than the BC box that was in my TC as they are the same design and even use the same bearings. Yet the Morgan goes in a straight line (for the most part) given the chassis set up.
And Steve is also probably correct in that directional stability was not an issue so much at low speeds, but rather as speed crept up it became increasingly evident.

[Mark Strang]

Stephen, after reading all of the posts, I'm pretty much sure that my steering box is good. I took great pains to assemble it correctly and even took steel dye to check the contact surfaces on the worm as the peg moved in the worm. I assembled the box with the high point correctly. End play on the column is satisfactory. I replaced ball ends where necessary. The springs are good. The preload on the springs appears to be satisfactory. With the drag link disconnected from any other parts any slight movement either direction in the steering wheel is reflected accordingly.. The axle is installed correctly but there are no shims which I don't care for at this point. I'm going to go the "Full Monty" and increase the toe in to 1/2". I Can't think of anything else to do and have decided that since it rolls straight as an arrow at 50MPH with hands off the wheel, It probably won't get better so I can tolerate the quirky steering at low speeds. I guess that's just the way it is based on the design. I'll let you know what the final correction does to the whole thing.
As as little aside, my TC friend who checked mine out a couple of days ago has started to take his front end apart to figure out what is wrong with his steering! He has the VW box and it wanders at speed among other things and realizes it could be better.

[Will]

Mark,
Will be interesting to hear how the 1/2" tow-in comparison goes. But also wondering with all the work that you have done to the steering and suspension that you may be reaching the limits imposed by your brand of cross-ply tyres which in their day could wander somewhat.
Bty, I installed lowering blocks and a panhard rod. Did I notice improved handling? No clue as having installed those I discovered my RH spring mounting dimple location was 3/4" to rear! That certainly must have affected the handling.
I do think the panhard rod helps counter undulations and potholes at the side of the road negating the fear of heading into the ditch.

[stephen stierman]

Mark, I have to tell you that my TC prior to increasing the toe to 1/2" did NOT go straight as an arrow. Now I didn't expect it be like my Miata but hoped it to be at least as drivable as my Morgan. That changed when I increased the toe and it was quite Miata like after that.
Not at all surprised that your friend with the VW box is having some issues also, I still think it is not so much the steering box but suspension geometry, in particular toe in.
Will, my tires were nothing special, the typical Excelsior brand that many people use on these cars.

I wonder if there are any pre war TA TB owners whose cars were supposed to be set at 1/2" who care to comment on how their cars handle in a straight line as a comparison?

[JayF]

What method are you using to set the toe in? string? homemade kit? something store bought?

[Will]

Jay,
For me, two lengths of schluter aluminium tile edging profile from home despot. Or any straight profile of your choice.
Four magnets with spacers to reach the rim. Some folk wire or zip tie the straight edge to the spokes but the straight edge then rests on the tyres, Probably near enough.

[Mark Strang]

Stephen, I finally got around to setting the toe in to 1/2 inch. It continues to roll straight down the road with hands off of the wheel. There is no difference between 1/4" and 1/2" on my TC. It still is wonky when trying to follow slight curves which means when the peg is off of the high spot on the worm. I don't know how to solve that problem. There is apparently some excess clearance in the worm when the peg moves from the neutral/straight ahead position. I can't at this point figure out what to do although I'm told that my car is fine. There aren't too many variables to play with assuming the parts are proper. I'm usually pretty good at solving mechanical issues but this steering thing has me stumped. It's not fun to drive. Does the VW alteration make much of a difference?

[Steve Simmons]

One thought... there are aftermarket worm gears out there that were machined with an incorrect angle in the grooves. I'm not sure if they would cause this type of problem, but it may be worth looking into. The have a more gold color than the originals, which were a darker bronze finish.

[stephen stierman]

Mark, I'm not sure what to tell you regarding the situation you have. My TC improved greatly by increasing the toe with better straight-line stability and also turn in. I did not spend enough time driving a TC equipped with a VW box to notice a lot of change other than decreased on center lost motion. Steve may be on to something with his comments.

[Mark Strang]

Well, I have two other old steering boxes that I could examine to see how they look. The worms didn't look as good on these but maybe they are better. I think there is clearly too much slop in the grooves to maintain a constant contact with the peg and as a result there is too much free play and the car oversteers in either direction. Perhaps I might have set up the whole box with improper shims etc.. At this point everything is in question. I'm out of pocket for the next five months so I guess the project will just have to sit until this fall. Thanks for the input.

[Duncan M]

Mark-
Another problem to consider from your description is worn out front hubs. They wear where the bearings fit in. Jack up the front axle and do like you are checking for worn out wheel bearings or a loose nut. They will all feel about the same. Bearings press in with normal resistance, but once they are pressed in they are loose. No way to fix when worn, but people do try.

[Mark Strang]

Duncan,

I'll try that, Thanks.

[jabawok1]

I would be interested to hear from any member in UK who has put Bridgestone Ecopia EP500 radials on standard TC wire wheels and what radial tubes they are using. Although 155/70/19R tyres are available for the likes of the BMW i3 I have yet to source suitable radial tubes. I would like to give this a go!