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Steering adjustments and alignment

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bluemiata90

bluemiata90

Jedi Trainee
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I just replaced most of the front end parts on my TR4a and took it out on the road for the first time in many years. It ran great and steered straight, but at about 60-65 mph, the steering wheel developed a vibration. I brought it to a local alignment shop, but needless to say they really didn't know what they could or could not adjust.
What kind of adjustments can be made on the front or rear of my TR4. I honestly think it's the tires that need balancing, but if adjustments can be made, I'll have the shop do them. I just have to tell them what to adjust.
 
Nearly 100% of the time, vibrations are not caused by alignment (or lack thereof). I would get your wheels/tires balanced and possibly trued if the balance doesn't fix the problem.

As for an alignment shop, I ended up driving 70 miles to a place that actually knew how to work on my 6. I would think that Chicago would have someone that knows how to align a triumph.
 
I agree it is most likely the tires &/or rims that are at fault here. As for alignment... the basic adjustment is toe-in which is pretty easy to do yourself. Several home-brew methods using everything from tape measures to spirit levels to string and push-pins have been discussed here... a search should turn up a few.
 
Hi,

The toe on your TR4 is easy to set by adjusting the tie-rod ends and, assuming modern radials, should be set to 0 to 1/16" toe-in.

The caster is not adjustable, but should be 3 degrees.

The camber is adjustable by placing or removing shims at the inboard (frame) mounts of the lower control arms. It was originally around 3 degrees positive, but should be close to 0 with modern tires. This will make steering a little heavier.

You might want to order some of the shims from one of the TR vendors to take with you to an alignment shop. It's possible they won't have anything to fit. If the shop is looking up data, be sure to say TR4"A". TR4 are different and do not have the same adjustments.

I believe there is also some adjustment available on the rear of TR4A IRS, if you car has independent rear suspension. I'm not really familiar with it.

However, I agree that the sort of vibration you describe is not likely to be related to the suspension work or alignment. Most likely it is tire balance. It's also possible that a steel or alloy wheel is bent or a wire wheel is out of true. Another thing you should check is the tires themselves. I've chased vibrations problems in brand new tires that couldn't be resolved, had to install another tire. But, that's rare.

Even tire pressure can make a big difference, depending upon the car and the tires. I had a car that was really sensitive to incorrect pressure in the rear tires, would steer very strangely and vibrate if a rear tire's pressure was too high or too low.

Finally, I doubt it's related to the engine, gearbox or driveshaft imbalance or harmonics, since you feel it in the steering wheel. Those tend to show up in the shift lever and the seat of your pants.

You know, this problem might have been present before, but went unnoticed due to bushing wear and the softer, rubber suspension bushings. Harder bushings such as urethane will make any balance, steering or alignment problems more obvious.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
 
You didn't say if you had wire or disk wheels. Disks are much easier to balance and any tire shop should be able to do it. If you have wire wheels take them to someone who knows enough to use a cone on the inner mounting point. Wheels should be balanced the same way they are mounted on the car. Usually, if it is a balance problem, the viration will start at one speed and go away 10-15 MPH later.
 
Thanks for all the advise. I do have solid wheels and I'm going to try and get the car in this weekend to have the wheels balanced. I have a feeling it is a wheel balance problem, but I just needed some reassurance. Thanks again for all the info.
 
When you guys use a measuring stick or rod, with or without a gauge (depending upon your equipment), doesn't it bother you that the slightest differences in tire width or air pressure on the front tires could easily upset the accuracy of the toe-in??? After all, 1/16 of in inch is nothing, so how accurate is anything that works off of the tires?
 
Marc - The method I prefer uses the same spot on each of the front tires, i.e. you take your 'rear' measurement then push the car backwards 1/2 a wheel rotation and take the front measurement at the same point on the tire.

There can be variations in tire width, run-out, etc. but I think they don't enter into the calculation so long as you use the same point on each tire.

There is also a method that scribes a center line on the tire as you spin it (off the ground)... this also gives a true reference regardless of tire variations. It doesn't even need to be an exact center line as it is the *difference* between a front and rear measurement that matters... not the measurement itself.

In all cases, air pressure should be identical side to side -- I use a digital gauge for this.
 
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