TR2/3/3A TR3 Rear Sway Bar

[martx-5]

The Roadster Factory has rear sway bar kits on sale. Has anyone installed one of these, and does it help. I'm putting on a front sway, but I'm thinking that with a solid rear axle that a rear sway might not be much benefit. Set me straight on this way or the other. /ubbthreads/images/graemlins/driving.gif

 

[Alan_Myers]

I've not personally tried a rear sway bar on my TR4 (quite similar to your car) because every report I've heard from folks who have, has been very negative. The cars' handling doesn't improve by adding a rear bar, it gets worse (not to mention harsh).

However, a front anti-sway bar is beneficial and recommended by most. There are a wide variety of thicknesses available ranging from 5/8" up to 1". I'm using a 3/4" and will probably stick with it.

There are also various end link options, ranging from rubber mounts that are the cushiest riding, but reduce the bar's effeciveness, to urethane that are noisier/harsher but make the bar more effective, to rod ends (also called Heim or rose joints) that are race-only harsh.

It's possible to combine types of end link fittings, to do some fine-tuning. On my car I have rubber on one end and urethane on the other end of the links.

There are also different bar mounting possibilites. The bar can ride in rubber or urethane (and rarely, aluminum) bushings.

On the other hand, many think the later IRS cars benefit from a rear anti-sway bar. But, one should only be installed after a front bar has been installed (usually slightly larger, say 3/4" front & 5/8" rear for example).

For live (solid) axle cars, one of the British vendors - Revington TR I think - offers upgrade D-washers to be used on the front leaf spring mounts, to help keep the axle aligned. This and harder urethane spring shackle bushings are probably the best initial improvements for the rear suspension of live axle TRs, plus are relatively cheap .

There are even harder front eye and rear spring shackle bushings made of nylon and metal, but these are harsh/noisy and pretty much race-only.

Cars with a lot of engine modifications and acceleration might benefit from traction bars, but most cars don't need them. They reduce ground clearance, for one thing.

Mono-leaf springs are available in England, I'm looking for a source in the U.S. These eliminate the rubbing of multi-leaf springs and the spring action is more consistent and smooth.

There are improved links for the lever shocks, that seem especially useful if the cars are set up mono-leaf springs, along with some upgraded shocks. The links are fitted with rod ends (aka Heim or rose joints) that eliminate play in the rubber bushings of the stock mounts.

Tube shocks in place of the levers are another good setup with mono-leaf springs.

Someone (Racetorations?) also offers a panhard rod to help keep the diff centered, but I've heard mixed reports.

Finally, a limited slip differential can be a big help for all TRs (usually Quiafe or Salisbury, both of which are pricey).

Lot's of options, depending upon what you are hoping to accomplish.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[martx-5]

As usual, Alan comes through with a wealth of information. You have set me on a proper course for my wants and needs for this restoration. I didn't think that a rear sway would be of benefit to me, but I like the idea of the upgraded spring bushings and D-Washers.

Thank you.

Art /ubbthreads/images/graemlins/cheers.gif

 

[PeterK]

Alan,

I've read your response in a couple of instances where people are insterested in a rear bar on a TR3-4A. Both times, you say the results were negative and the card handled worse so you personally wouldn't recommend a rear bar.

What exactly do you mean by "results were negative" and "handled worse"? Did the car you heard about already handle poorly and now, even worse? Too much oversteer? Snap oversteer? Since you haven't tried this setup on your TR4, I wonder what the owners felt the change in handling was at the limits on a course and on the street.

I'm asking because I have a rear bar for my 4A (very different chassis rigidity than your TR4 and not as stiff at the front spring mounts as your 4) and am running a 7/8" front bar with poly bushings. I figure that the 7/8" bar would stiffen the front to the extent of pushing hard in a tight corner and think that the 5/8" rear could adjust the car to be fairly neutral with the right amount of pedal applied /ubbthreads/images/graemlins/grin.gif.

I've also got Morgan 7/8" rear brake cylinders, Alfin drums (240Z) and Kevlar shoes to balance out the Toyota 4-pot calipers ( also using a TR6 M/C and servo). I'm tuning for autocross but want my car streetable.

I hate the idea of drilling and reinforcing my chassis just to mount the rear bar that I take off a week later.

Anybody try a rear bar on 4A solid axle??? Experiences???

Thanks. Peter

 

[Alan_Myers]

Hi Peter,

Sorry, I haven't heard any tales good, bad or indifferent about rear bars on solid axle TR4A. I hope someone chimes in with some real-life experiences.

Yes, I can understand why you wouldn't want to modify your car, and then not like the results. It's *possible* a rear bar works better on solid axle TR4A than on a solid axle TR4, because of the additional flex in the 4A frame. But I can't really say one way or the other.

I think your best bet would be to try a modest size front bar, like the 3/4" you mention, without a rear bar and see how you like it. If it does the job and you feel understeer is about right, great. If there is too much understeer, then you can think about adding a small bar at the rear, or you can try many other things first. Raising and lowering tire pressures or ride height, front and rear, changing front/rear weight distribution, adding wheel spacers at either front or back, changing alignment, adjusting shocks or using harder or softer springs can all have an effect.

One reason for trying just the front bar first is that a little too much understeer is generally safer and more controllable than too much oversteer.

What I've heard numerous times firsthand from owners/drivers, plus read about in books and magazines, is that a rear bar on live axle TR4 (and earlier) usually induces too much oversteer. Worse, some said it was unpredictible because the car becomes unforgiving and sensitive to road surfaces, reacts differently on wet/dry, slick/cobbly roads. So most don't use a sway bar at the rear. Heck, even the Leyland Competition Prep manual makes no mention (that I can find) of a rear bar on TR2-4. It does detail front bars on TR4 and gives extensive info about making/installing both front and rear on IRS TR4.

The added harshness from heavy rate springs and sway bars might make for a pretty bumpy ride. But, someone planning to head out to autocross on the weekend might not notice or object to it!

Another consideration, a front bar in conunction with a limited slip diff might induce a lot of understeer. So, if a TR4 has both installed, a small rear bar (9/16-5/8") might be usd to counteract that. However, the TR4 in the Competition Prep manual was fitted with a 1-1/16" front bar, LSD, and, apparently, no rear bar.

These were mostly racing situations and vary to some degree by personal preference or driving style, are different in one type of driving or racing than in another, and even with different tire and wheel packages. The TR4 chassis is a little more flexible than TR2-3, too. But, I drove my car for years with no sway bars and close to stock rate springs and it's a pretty rigid ride.

In fact, I recall talking to someone or reading somewhere about successfully taking an entirely different approach to setting up a racing TR4, more like a Morgan would be, using no sway bars and allowing the chassis to flex quite a bit. Tuning was done with the springs and shocks.

Street cars might not need or want sway bars at all. A lot of handling improvement can be accomplished just by going to urethane bushings, different shocks or playing around with spring rates, etc., or maybe installing a LSD.

Like you, I'd like to go autocrossing in my car, but still want to be able to use it on the street. Let us know what you think of your brake setup. I've thought about doing something similar, probably using two Girling brake MC of different sizes to balance front and rear, or maybe dial it in with a just a balancing valve on the rear circuit.

Cheers!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[aeronca65t]

I don't have a big TR, but Spridgets have a generally similar layout (live axle rear).
I got a rear 5/8" sway bar for free and put it on my racer, just to see what it was like. It was terrible....made the car very twitchy. Took it off right away.
I've noticed among my race pals that no one seems to run a rear bar on smaller live axle cars. On the other hand, many of the fwd cars (like Golfs) do not run a front bar but do run a rear bar.
Bigger live axle cars (Mustangs) run a pretty small rear sway bar (and enormous front bars).

 

[PeterK]

hmmmmmmmmmmmmmm

 

[TRTEL]

Boy does this discussion bring back memories. For me it was no way for a rear sway for track use in a 3. Though I was always tempted to set one up for autocrossing because it would want to switch ends so easily you could on a very tight course 'two wheel drift' with minimal steering input by just modulating the throttle. 4's seemed to make better use of them, both 4's and 4a's. Was it the increased track, I don't know, but the quickest 4a(live axle) driver I knew at the time didn't use one. He just used stiffer springs and shocks and he always made the runoffs every year. If you're really serious about the autocrossing save up for the limited slip.
Tom Lains

 

[PeterK]

That's my goal, being able to kick out the rear end for close courses. But twitchy wouldn't be good so maybe I'll modify the ends with rose joints so I can adjust it.

I used to have a 911 that I could almost pass myself with - lots of fun as long as you don't get scared and back out of the throttle and swap ends toooo fast.

 

[TRMark]

I had a rear bar on my 63 tr4 for several years. The idea was to bring the tail end around a bit for autocross. The car has a 13/16 front bar that I found in a wrecking yard in the 70's, think it was off of a Buick Special or a Tempest. It worked ok except it still understeered, one could not get on the throttle while still in a corner. I got the bright idea of replacing the rubber mounts and end pieces with urethane, front and rear. That made a difference, the car would spin at the least provocation, thank goodness I found this out at an autocross and not on the road. I took the rear bar off and did what I wanted to do for years; I reworked the upper A arms (I did not cut and shorten them) to dial in some negative camber. Now we are haveing fun. I am running Kumho ECSTA 195-65-15 on TR6 rims. The D washers and rear suspension stuff Alan was mentioning is available from Ken Gillanders at British Frame and Engine.

Mark Richlen
Billings Montana

 

[Alan_Myers]

Hi Mark,

Interesting what you have to say. So, you found the rear sway bar a bit much *after* you eliminated the initial play in both sway bars by installing urethane bushings (I'm assuming that's what you meant). Makes sense, since both bars would then have immediate effect. Another method of tuning would be to use urethane on one end, rubber on the other, to eliminate half the play. Or, different rates of urethane might be used, softer or harder.

That was a monstrous front bar, do you recall what size the rear bar was?

How did you rework the upper a-arms? How much negative camber did you set up?

I'm curious because I've got the Revington adjustable upper fulcrums installed to dial in a bit of neg camber. However, it will be a while until the car gets back on the road, I have it aligned and make a final decision on the camber, then weld up the fulcrum brackets.

All in all, I think TR4 suspension "tricks" would generally apply to TR3, due to the similarity of the two suspensions and frames. For example, the I'd expect a rear sway bar to be "too much" for most folks on both cars. And, I'd think front bars of similar size would give similar results on both cars.

But, there are some differences too, between the models, that will effect handling: TR2/3/3A track is narrower, front and rear. TR4 has rack & pinion where TR2/3/3A does not. TR2/3/3A has O caster, which is only found on the first few thousand TR4s, the remainder have 3 degrees of caster. So, for example, making a change such as dialing in some negative camber will likely have a bit different effect on TR2/3/3A than on most TR4.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L

 

[TRMark]

Alan, I think I may have confused you on the front bar, it is thirteen sixteenths. It is still in place with the urethane bushings and end pieces. The rear bar was a 5/8, I think an Addco. I reworked the A arms by lengthening the pocket back toward the fulcrum and slotting the bolt holes for the upper ball joints. I had to grind a little metal off the outer arms so they did not interfere with the wheels. I set it at 1 1/2 degree neg. with 1/16 toe out. It was fine for autocross the front end really did stick but difficult to drive on the street. I reset it this spring to 3/4 degree negative with toe at zero. I haven't done any competition this year but it is much nicer to drive, the front still seems to stick pretty well. I am sure that gaining neg camber this way probably makes a mess out of roll center, but the car does feel and handle better. As most everyone knows these older TRs were not designed for radial tires therefore they used positive camber for use with bias tires.

 

[Alan_Myers]

Hi Mark,

Thanks! I was looking to dial in 1 degree or more of neg camber and might just try 3/4 degree instead, based upon your experience.

Actually it wouldn't be too hard to cut the weld and change, if I ever wanted to experiment with something else.

I'm using a 3/4" bar on the front (misread your post, I see now that yours is only slightly larger). Pretty sure this is one of the common Amco bars. It needed some serious bending to make it fit well. The end links were very poorly aligned, as it was supplied.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L