Steering, Suspension, & Brakes

Does anyone have experience with TR3 ackerman settings. I've done some reading but nothing conclusive, only that switching the steering arms improves it or putting on the Revington arms. There is also a lot of info on suspension geometry changes, caster,camber and bump steer.but ackerman isn't discussed much other than stock is negative and that it makes the car hard to turn into a corner. I also read somewhere that after changing to rack and pinion and then driving a worm and peg steering car with the Revington arms they wouldn't have changed to rack and pinion. Mine's torn down for the winter and am trying to get some direction.

Merry Christmas and Happy New Year to all here

Greg

I'd raise this on the TR Register forum.
[www.tr-register.co.uk]

There are people there who eat and drink this stuff.

Ivor

Thanks Ivor, spent some time on this sight and it really cleared up or verified the data I have.

Greg

Hello Greg. Thought I would answer your PM on the forum so more people could follow it and possibly help out. I.v got to sets of TR4 steering arms . One set is completely separated from the up rights and one set is attached to the whole upright assembly so it is easy to see which is pass and driver. They are massive compared to TR3s. The TR3 arms are 7 1/2 inchesroughly in length and 4As are 8 3/4 roughly . .I'll see if I can get my ever helpful nephew to take some pictures and send them to you. I will measure distances from TR3 arms from calipers vs same for TR4 and let you know. Have been busy with work last week and now Christmas but will be in touch Tim

Hello again . I just went out to the garage to do some measuring. . On the TR3 the distance from the disc to the outside edge of the steering arm is 680 thou and 1 inch and 20 thou to the center of the hole in the steering arm. When I got under the 4A which was already jack up I was very surprised to see the longer steering arm is forward of the disc and curved round in front of it kind of,,possibly making the hole in the arm right on or outside of the Ackerman line!. I'm going to have to see if one of the spare arms will fit on the TR3 project . How's that for interesting news.? Tim

Tim, this is interesting. I have done some scale work off the TR3 manual. Bending the 3 arms to just clear the rotor with the tie rod ends it looks like it falls in the Ackerman line. It also looks as if swapping the 3 arms side for side gets it about halfway there. Bending the 3 arms would shorten them a slight bit making the steering heaver. Using the 4 arms would probably lighten up the steering.
Looking forward to seeing your photos after the holidays

Greg

I measured distance from tie rod to rotor and got 1.20". Could your arms have been changed side for side? The center of the tie rod end on mine looks to be 3/4" inside center of the upright piviot. I'm going to get serious about this and take photos.
Greg

The TR3 I took measurements from, is the one I'm restoring and has the shortened rack on it. Yes the steering arms have been swapped side to side. But I'm going to try putting the TR4 arms on it instead and will try them stock position and swapped also. This should be easy as the body is off the frame. Seems to me we will get better Ackerman ans easier steering.Makes me wonder how TR2s and 3s did so well rallying?I guess it wasn;t considered a problem back then.PS The shortened rack is a TR4

The geometry was designed around bias ply tires. I have found if the tie rods are different lengths by even a small amount interesting things happen in less than a snooth corner.

Still getting used to a I phone

Ya Greg The 4A steering arm ,referring to the last picture is way over by the rotor and slightly ahead of it. I can just stick my forefinger between the rotor and tie rod balljoint . Like I said will try 4A arm on TR3 project car and let you know. Will take pictures and get my Nephew to post them

Hi Greg. I just put a 4A steering arm on the TR3 on the drivers side and the arm is 620 thou from the rotor to the edge of the arm and 970 thou to the centre of the hole . I think the spacers could be shortened to move the another 1/8 inch aprox closer to the vertical link. But you would know better since your a machinist. Hope you find that interesting and pictures to follow maybe tomorrow. Tim

Thanks for the update Tim. Looking forward to the photos

Greg

Hi Greg. Got some photos posted but forgot to tell my nephew where to post them so he put them in the Triumph cars slot. They are a little backwards but you can figure it out. Things look promising but give me your opinion from a machinist point of view. I have two sets of tr4/4a steering arms so if you can;t find any i've got you covered Tim

Forgot to mention ,,,picture number two where the arm is very close the clearances are200 thou from rotor to steering arm and545 thou from rotor to center of arm. The tie rod end still has lots of clearance.

Tim, the 4a arm looks good. It would lighten the steering up a bit. My concern is with the angle of the tie rod. It would have to angle forward to the arm. Perhaps not a problem but I would like to see a line more parallel or on line with the drag link-rack and pinion. We all know there is little room to move forward to maximize the leverage of the 4a arms so now I understand why the switch side for side and or bending to get the tie rod end as close to the rotor as possible. I will probably bend the 3 arms. I want to try to minimize the the drag on the 3 linkage by replacing the silent bloc bushings and using thrust washers. I rebushed my steering sector last spring and looked at the spring pin concept. I decided that a thrust washer on the bushing side of the lever shaft would be more effective in controlling the back lash which I believe it has as the worm now can't draw the peg into or push it out of the helix. Of course the thickness of the thrust washer is critical but after about 12,000 miles it hasn't changed. I have 205-60s on the car now and am going to change back to 165R15s. I don't race but if I did then the tire to use is a 165 Hosier. I really think if I wanted lighter steering I'd buy a light servo and attach a cylinder to the 3 drag link. Price would be about the same and if it was stock you could still use the fan and turn signals with the way the servo is driven of the sector. I'm not ready to go there yet. Vintage car vintage handling but without the surprises. Bump steer can be eliminated and Ackerman can be improved but for a price.
Sorry but I've lost my train of thought. The reversed 3 arms and modified r&p works if the piviot points of the rack are the same location and distance center to center of the drag link. It is easy enough to check by checking the bump steer in the suspension. You just have to correct by moving the rack up or down to fine tune it.
Tim, thanks for all the switching and photos, they really cleared up questions as to what stock parts look like. I'll update the post as I go along.

Greg



Edited 1 time(s). Last edit at 12/31/2016 01:41PM by ghornbostel.

Greg Glad that helped you. I was thinking the same thing about my r&p being too far rearward for the 4A steering arms but I had decided to re vamp my rack mounting bracket any way since now I know more about the whole situation thanks to you.The rack height above the frame is the same as the tr4 rack so that should be ok. How does one check bump steer> Is that where you move the whole A arm unit up and down minus the shock and spring and measure toe in deflection? I saw that on the Binky Project . Are you familiar with that series? Tim

Not with that series but they all do the same thing. You will have to set your chassis at ride height and remove the springs, then move the suspension through its range and observe any change in front to back of tire or gage. There are many ways to do this depending on how close you want to get and how much money you want to spend. Also the tie rod wants to be somewhat parallel with the lower control arm for up and down angle. I guess the angles want to look like a stock 3 setup. The race setups I've seen use heim ends so they can be changed with spacers on the pivot points. It's been done but cheap guys like us are always trying to find a way around buying the conversion. LOL. Bump steer or rather lack of it is the most critical part of the conversion.
Once again, thanks for the help, I'll keep in touch.

Greg

Compromise. Swapping outer arms side for side and fabricating new idle and sector arms to get zero bump steer

Hi Greg . Those new arms look well made . What did you change from stock to make the bump steer disappear? What about the Ackerman ? Tim