Welcome to our resource for MG Car Information.
Triumph TR3 - Rack Steering for TR3A
|I have heard that there are kits available to convert the steering in a TR3 to rack and pinion, but nobody seems to remember where to get the kits or plans. Does anybody know?|
P.S. I have a spare MGB rack, but it looks like it will be difficult fit.
|Jerry, I think that the main source of steering racks for the TR2-3's are from TR4's. I stand corrected on this but have thought of doing the same conversion myself. Would appreciate if u kept me or the BBS informed.When I power up the PC the two first things I do is check the MGA bbs and this one . There isnt so much activity on this one and thats a shame. Best wishes John.......|
|John Strange email@example.com|
|I'm glad someone else is tired of the original Rope&Pulley steering. I've got some experience with TR3's and Rack and Pinion- here goes.|
My 59 3A had the usual steering box failure about 20 years ago. My brother owned the car at that time, and he decided to install a Spitfire rack to solve the problem. He removed the existing steering and built a robust mounting platform, upon which the Spit's rack was mounted. Of course the steering shaft angle was wrong, so we cut up an MGB steering shaft, and installed the universal joint at the correct location. ( exact details a bit fuzzy...) a bit of welding and that was resolved nicely. I stabilized the shaft with a fabricated bracket that attached to the body/chassis mounting bolts on the left side wheel well.
Next, we did some similar customization to the old Spit steering rods, slicing off the inner side rack-end joints and grafting the old TR3 steering toe-in/out adjusters and outside tie rod ends to the Spit bits. Sounds difficult, but it wasn't. So, we reassembled the car and did a crude alignment. The test ride was a significant improvement over the Rope and Pulley ( OK, worm and roller- ) but the steering ratio was pretty slow. There was little if any play, but here is the bad part. The rack was designed to fit a car with a wider track, so we compensated by making the tie rod assemblies shorter. ( Anybody see the problem yet?) As the suspension travels up and down, the wheel traverses an arc defined by the lengths of the upper and lower control arms. However, the tie rod links are now shorter, and they travel in a different arc, which is much smaller. So as the suspension travelled up and down, the toe in/toe out changed significantly, w
hich resulted in terrifying 'bump steer', so the car was now especially unstable on bumpy corners and, frankly, any road condition that caused the suspension to move very much. The car went into storage and my brother went to Florida. He gave it to me, ( transport would've been $$$$) and I proceeded to restore the rest of the car, rebuilding almost everything and respraying, etc. It looked great, but still drove poorly. So, I started measuring up every other rack I could find, looking for a more narrow one, with hopefully a tighter steering ratio. The MGB rack seemed the most likely to suceed, so I removed the Spit rack and installed the MGB part. Once again, not really a lot of work. The rack was a little more narrow, and certainly more robust than the Spit's. I expected to see modest improvement, at least. Well, the steering ratio was a little better, but the bump steer was still problematic. I also became familiar with
what is called Ackerman geometry, which defines the fact that the front wheels are positioned at different steering angles when you make a sharp turn. If you think about it, the car ideally goes into a "toe out" condition, as the outer wheel travels a larger radius path. THere isn't too much written about this topic, so I decided to build a scale model steering assembly out of stiff cardboard, push pins and a couple of protractors and rulers. I tried to determine the factors which would improve the Ackerman, which was not correct as evidenced by lots of tire scrub on tight turns. It seemed that the positon, fore/aft of the rack would influence the turning rates of the L & R wheels. The data confirmed it, but it was not the most conclusive of exercises. In the meantime, I bought a great big milling machine that had been obsoleted by my company, and decided to improve the steering ratio to my satisfaction, by manufacturing a new set of steering arms. ( the
ones that bolt onto the back of the wheel spindles) The new ones I made were about 5/8 inch shorter, and I built new mounts for the steering rack, in hopes of Optimizing my Ackerman data with the shorter arms. I thought I had this project well under control until I drove it this past June. Everything looked really good, and the car drove terribly. The bump steer was outrageous, the car cannot be driven safely at all!!! Wow, was I pissed! I am now taking two different tracks to solve this. I am convinced that the tie rod assembly length is simply too short, and there is no hope unless you can make them approximately equal to the length of the lower control arms. They need to travel like a parallelogram, so that the suspension's natural tendency to move the actual wheel position in/out as the suspension travels is in concert with the swinging arc traversed by the tie rod assembly as it moves. Investigation has shown several racks are avaliable that drive
the tie rod assemblies from a center point, instead of the familiar 'end of rack' connection points. With this approach, one could fit a inner ball joint connection bracket to the center of the rack, and you could decide precisely how long your tie rod assemblies would be. ( I certainly Hope!) The Alternative plan is one facilitated by the Internet- I actually found a small company in the UK that has apparently found a rack that will fit. I have not been able to reach this guy yet, Maybe he is on vacation? I have no idea of whether he knows what is going on, but there was a small note found in a Triumph forum at www.cam.net/~jacad/triumph/interest/htm The guy is at Protek Classics, Unit 13, Bushells Business Estate, Wallingford, Oxford,UK, @ 44 1491832372
If anyone has any experience with this guy, please give me a call (USA) 201 529 6186 or RSVP thru this site.
Desperately Seeking Steering,
|bob westerdale firstname.lastname@example.org|
|Hi Bob, Jerry and I have been communicating on this conversion. I was under the impression that a TR4 rack would go in but I was mistaken. I am going to a TR social function in Sept and the guy who is hosting the function has a conversion that is Ford Cortina orientated. I will find out more and let u both know, apparantly he has a converted chassie with eng and transmition in his workshop. So I'll take the digital camera and send some pix when I have the info. I enjoyed your comments on all the mods u have tried. We will see what we can come up with. Regards John.......|
|I spoke briefly with a gentleman at Protek Classics in the UK, who indicated they could supply rack and pinion steering solutions for left and right hand steering TR3's |
Protek has no website, but are available at 44 1491 832372.
The Boss should be back in the office later this week, Aug. 24/25? and more info should be available. regards, Bob Westerdale
|bob westerdale email@example.com|
|Bob,thanks for your very well detailed progress report. I have sat for many evenings in front of the open chassis of my TR3A looking for the correct geometry or at least some inspiration. Your research is clearly miles ahead of mine and I have decided to reinstall the "Rope&Pulley" to complete my restoration. In the meantime, I have asked the mechanical designers in our engineering group see if we can create a "working model" of the front end suspension and steering in software. I let you know if we can do the modeling and I will probably ask for more specific details of your research, if you don't mind. I hope the boys at Protek Classics have a reasonable solution. One question that I do have is...do you think that adding some form of power assistance the original steering would be any real benefit. I have an electrical/electronic concept for power assistance that I will pursue if your responses are favourable. Jerry.|
|Hi Jerry- One of the problems I have found in pursuit of replacement steering is that no reasonable documentation of the TR3 suspension geometry is available. I found some reasonble data for the TR4, which details the dimensions of various components, probably for damage asessment. But I suspect there are some differences in the TR3 that make me hesitant to make too many assumptions TR3=TR4 . I don't think my car has any serious accident history which could affect the suspension mounting points, and I have already done a complete F suspension rebuild and the components looked fine. I have a pretty good frame/dimension drawing, but no useful suspension geometry is included. I may have to make measurments the old fashioned way- tape measure, straight edge, plumb-bob, etc.... A friend here at work is really good with Algor ( not the politician) and has volunteered to do some simulations if I can get some good dimesional data |
Concerning the development of a power assisted steering system- this might be interesting if you can maintain some of the road feel at the steering wheel. I think a major problem would be that you might lose the road feel and end up with a "Servo Steering" system that makes the car hard to drive rapidly. The feedback you get from the steering wheel is especially crucial when you are pushing the car hard, and doubly so becasue of the 3's propensity for trading ends after terminal oversteer! Would this be a hydraulic system ( belt driven pump- where?) or some electrically assisted device? sounds interesting! I will try to contact Proteck today and see what they have to offer. Thanks! Bob Westerdale
|bob westerdale firstname.lastname@example.org|
|Hi Jerry- A bit more information on the steering project- I spoke with "British Auto Restorations" in Roanoke, Virginia, ( 540 989 5121 ) who are the US agents for Protek's rack and pinion kit. They gave me a few details, which sounded pretty encouraging. The kit is comprised of a modified mini-Cooper rack, mounted upside down ( I've gotta see this....) on the original mounts that held the steeing box. It includes the needed U-joints for the steering shaft, and the tie-rod assemblies. Apparently there is no room for the standard fan, so they provide an electric one, and some hardware to eliminate the old fan mounting post. ( a little unclear here,) The kit is best fitted to TR3's with the split steering shaft, as identified by a clamp on the shaft near the distributor. My car, a 59, had the one piece shaft originally, (long gone) but I have since modified mine in a mannner which seems to be agreeable to the upgrade k|
it. The fellow in Virginia says he has done about 45 of these installations, and the results are terrific. The steering ratio is a bit quicker, and the degree of control is said to be significantly better that even a perfect original worm and roller. Of course this guy was in salesman mode, so time will tell. I have no idea what the price is, but I suspect I'll learn more about that when the literature arrives.... I will let you know how it looks.
Regards, Bob Westerdale
|bob westerdale email@example.com|
|Further discussions with "British Auto Restorations" in Virginia-- The Mini-Cooper rack they offer, with accessories, costs $ 895 ( choking sounds...) but it does seem to be a well thought out solution. I added up the prices to completely replace the original steering setup, and it came to well over $ 1000 USD, per Roadster Factory in Pennsylvania, so I suppose it is not way out of line. The rack is alleged to have a distance of 19" center to center, for the inner tie rod joints. The MGB rack is about 24.5", which is too long for the TR3's narrow track. I am going to do some calculations tonite to see if 19" is optimum or just a fair compromise... One interesting note- you must remove and reverse the steering arms ( L-R ) to accomodate the new rack position, presumabley now higher because it is actually a right hand drive rack, mounted upside down for left handed cars. The rack would now 'hang ' from some brackets %|
28supplied) affixed to the same bolt holes that held the original steering box and idler ass'y . A little difficult to visualize, but I'm pretty sure this is a winner..... Bob Westerdale
|Have you guys been to the "Racestorations" site? They have lots of pictures of race prepared TR-3's, seems like they'd know how to make your car work right. Just an idea, but I was imressed with what they had to offer. I just bought my 3rd TR, an early 4, just starting to get it sorted out. I can't say I like the steering better than the 3's yet. It seems to have this bump steer thing, too. Hope it goes away with some tinkering.|
|Hello Guy's, hope you don't mind me jumping in on your conversation but I thought I'd tell you what I've been working on. I've fitted a rack from an early Spitfire. It's mounted on two brackets each bolted to the inside of the "H" frame and uses the original rear hole that holds on the bumper bracket. Each mounting bracket has a 1/2" diameter grade8 support bars joining it to the original frame mount used for the idler bracket, (Moss667-030) and its counter part on the other side. The actual mounting surface for the rack sits at an angle of 45 degrees on the top of a 1"sq tube about 5" above the frame. Now the part that may help you! The rack has been shortened! I removed the actual rack and cut off 2" from the opposite end to the pinion when positioned in the tube. I re-machined the threads and put the thing back together. This removed the excess length from the rack and not the control arms. I then cut the threads off the control rods on each sid|
e and welded up the diameter of the rods to enable me to put the threads back on, thus, shortened, but not by much, about 2" each side. (I know how that sounds, but I had a professional welder and machine shop do this, and you can't tell) I have used the original Tie Rod Levers in their original position together with (I think) TR6 Tie rod ends. The universal joint is from a TR6 and lines up very well. I've used the top half of the original TR3 split steering assy the Coupler and the bottom half with the worm gear from the original steering box removed. Welded and pinned in the end of this tube is a splinned shaft which fits the universal joint. This can be cut off the TR6 shaft that is meant to do the job on the TR6. I have 2.3 turns lock to lock and I can turn the wheel with two fingers. I can't comment on this steering bump thing you mention because I haven't driven it yet. If you want me to Email pictures to you let me know.
|John Burton firstname.lastname@example.org|
|Hi John, I assume you have read the other posts regarding R & P steering- Sounds like you are definitely on the right track (no pun...) A few ideas you may want to consider- With the car at rest, supported under the hubs, view the car from the front: Make sure the tie rod assemblies are parallel to the lower control arms. you can eyeball this pretty easily, the reason is to ensure that the lower control arm and the tie rod assembly are at the same ' swing ' position. ideally, this motion should be a parallelogram, which will minimize any toe-in/out transitions as the suspension travels up / down. |
The R & P idea for this car is a terrific inprovement, as the original steering box is simply not robust enough for the job. Folks got tired of the steering wheel play, and removed a couple of shims from the end plate on the box- usually too many, which tightened the steering up nicely, but wrecked the bearings and surfaces in short order. I'm sure you'll agree this was one of the best upgrades possible for these great cars! Mine is vastly improved. I'd enjoy any pictures you can send....
Thanks! Bob Westerdale
This thread was discussed between 15/07/1999 and 29/11/1999
Triumph TR3 index
This thread is from the archive. The Live Triumph TR3 BBS is active now.