TR4/4A Steering Stop Lock on trunnion

[Scotsman]

Is the steering stop lock on the trunnion necessary, and if so where can I get them, OR even better is there a simple do it yourself? Moss does not carry them, and the picture in its catalogue suggests it is like a thick washer with an offset centre. Both of the trunnions on my car are missing the bolt and the stop, and I have heard it is not uncommon for the bolts to shear off.

Thanks

Richard

 

[TR3driver]

TRF has em. 101407

Can't say how necessary they are, I've always used them. Can't imagine how you'd break a bolt, unless maybe if you hit something really hard with the steering already turned up against the stop. We are talking about a 5/16 steel bolt threaded into a brass casting, so I'd think the casting more likely to break even then.

Not too hard to make your own, if you've got the dimensions and a lathe handy.

 

[Scotsman]

Randall,
What I'm referring to is not the bolt but rather the "lock stop collar", #21 in the attached graphic from the service manual. Moss just refers to it as a STOP. Thanks

 

[TR3driver]

Right, #21 on your diagram is the stop, P/N 101407.

The bolt is just an ordinary 5/16NF, 3/4" long, available from any hardware store.

BTW, you might find this PDF file helpful. Among other things, it has much larger parts diagrams.
https://drive.google.com/open?id=0B2H2NJt34OffMWQ4N2EzZGQtNjc0Ny00YmE2LWFiN2UtZWYzMjNjNGFiYzY4

Sorry it's so big, I'm working on ways to get the size down as well as ongoing improvements in other areas. I suggest you download to your hard drive for faster access (plus bookmarks and so on), but check back in a few months for any improvements.

 

[Scotsman]

Continuing this thread. No one has actually said if the Lock Stop is really necessary on the tr4A - 6

On my TR3 the vertical links screw right down into the trunnion so they engage the lock stop on the trunnion very close to the bolt head and onto the OEM stop washer (1/4 " thick).

I have just finished rebuilding the front suspension on my 4A and have discovered the links don't screw in as far as on the TR3 with the surface on the link that engages the Lock Stop being a good 3/4"+ (vs 1/4" on the TR3) above the trunnion surface requiring me to stack 7 washers under the bolt head (have no OEM stop washers). This would appear to risk shearing off the bolt. In fact one of the trunnions I had to switched out for this reason (I was not able to use a tap as someone had already tried this and broken the tap in the trunnion).

I am guessing without the stop the tyres might touch the body in full lock, and the trunnion bolts come in touch with the break disk. On the other hand the only time the steering would be in full lock would be at very low speed when parking or when doing a 3 point turn.

Any feedback would be helpful

 

[titanic]

Richard-The stop does prevent the the trunnion nut&bolt from contacting the brake disc. Contact with the disc results in a mysterious groove. I don't know if the stops on the TR4A are drilled off center to provide adjustment or drilled on center. as on the TR6. Either way, they serve an important function.
Berry

 

[Scotsman]

Thanks Berry,
I was guessing this was the case, but surprised that the links dont screw down as far as on my TR3. On using the Stop Washers from the TR3 on the TR4A the link surface that should engage the stop rides above the stop washer, which is why I have to stack additional flat washers. I have read that they redesigned the links in the TR4A's making them "handed" which they weren't on the TT3A's. This appears to have resulted in other unexpected changes as described above?
Richard

 

[PeterK]

You've confused me. Why can't you just use the correct length bolt for your 4A instead of ones from your TR3? Anytime you have to add a stack of washers is time to rethink the reason.

Also, on my 66 4A the stop lock collars are concentric, not offset. So there is not way to "set" it's offset like the early cars.

Hope this helps. btw, one of my bolts was also sheared off at some point before I got it and I had to drill it out because the threads were seized.

 

[Popeye]

I'm not sure if the stops are necessary; I installed them just because that's the way I am .

Originally they had offset holes, so that rotating them would adjust the steering stops. However TRF (not sure about others) only stock the non-offset stops found on the TR6 (I don't know what the TR250 used). I installed the non-offset ones, but I'm not driving yet so I can't give further feedback.

 

[Scotsman]

Dear confused,
It is not the bolt that is the issue, it is how high above the trunnion the flat surface on the vertical link is in relation to the top of the trunnion. The vertical link screws down into the trunnion, and there is a flat horizontal surface on the link that engages with the stop washer (hopefully you are following along here).
On my TR3A the link screws down into the trunnion to where this flat surface is approx 1/8 - 1/4" inch above the trunnion top so it will engage with the stop washer which is 1/4 thick. On my TR4A both links bottom out with the flat surface riding about 1/2"+ above the trunnion. (note I am screwing it in without any other parts attached which could interfere with the assembly).This results in it riding over the top of the stop. To solve this I have to stack multiple washers in order to raise the height of the stop so that it will engage with the surface on the link. I have had the whole assembly apart cleaned and switched out one link and trunnion. All three of them do the same thing. The rubber seal is not the issue. They say a picture is worth 1000 words so I am attaching two. The dirty assembly is that of the TR3A.