TR4/4A Questions: new tires on old wire wheels

[RJS]

Hey

I am finally going to replace the 14 year old tires on my TR4A this spring but, I have two quick questions:

1. The wire wheels on the car are in excellent shape but, are probably the same age as the car. The tires on there now were mounted by the PO and have inner tubes. Do I need to go with inner tubes again? I have no problem with tubes other than I wouldn't want to use them if not necessary. What's the downside to using them? What's the upside? If the tubes provide added assurance of no leaks with little downside, I'll probably use them again.
2. With the new tires in the new size, I estimate I'll lose about 6lb of unsprung weight at each corner. Curious - do you think that will have a big difference in how the car handles and takes bumps?

Thanks guys, Spring is near!

Bob

 

[glemon]

1. Most wire wheels require tubes, the ones installed on the cars new did, so if yours are original they need tubes. Think about all the spokes, they go into the rim, leaks like a sieve unless sealed up some way. Dayton sells wheels that don't require a tube, and you can seal up your wheels with some kind of sealant and probably end up with a tubeless wire wheel, but I have never done it, so don't know much about it. If your wheels are that old probably wouldn't work to well to seal them as some spokes may be a little loose.

As to advantages, I think tubeless is better, I have had tubed wire wheels spring a leak, and they almost always go flat very fast, had it happen one time on the highway on my old 4A, was a little disconcerting to say the least. I think they are more likely to have flats as well from chafing, although if the wire wheels are in good shape and the tubes the right size and installed properly this should be minimal. But when I drove the cars as daily drivers in the late 70s and early 80s I have a couple cars where this wasn't the case and I got flats all the time, kind of left a bad taste for me regarding wires.

2. If you are saving six pounds per tire I assume the new ones are smaller, don't know if you will feel a seat of the pants difference in ride/handling from the weight loss, but if you get narrower tires IMHO the car will feel lighter and more agile and be more enjoyable to drive.

 

[MarshgrassA]

Not that often I can chime in with something of value (maybe) other than I have fun with my cars!

My TR4A has tubeless but on new wire wheels. I would recommend (as was recommended to me when I replaced tires on my A) not only tubes but a wheel liner if your wires are old or original equipment. At the time I replaced tires on the MGA you could order the liners from some of our LBC catalogs. The older gentleman who did my tires said that duck tape would work as well. He knew what he was doing since the only problem I have had in 5 years is waking up to a flat on the A after the TR4A joined the garage! Hope I did not jinx my luck!

Cheers,
Irene

 

[TR3driver]

As noted, most wire wheels require the tubes. If you do use tubes, some sort of liner is required (otherwise the ends of the spokes will rub holes in the tube). Some sources say not to use duct tape, but it seemed to work OK for me, with the caveat that it has to be replaced every time the tire is removed. The adhesive seems to get hard and stop sticking the very first time the tire gets hot.

If they have not been serviced regularly, now would be a good time to have the wire wheels checked for trueness and spoke tension. The nipples and/or spokes sometimes break when they are adjusted, especially if it has been a long time.

Another downside of using tubes is that the vast majority of tires are not rated for use with tubes. The tubes cause additional friction, which causes more heat, which is basically the limiting factor for both maximum speed and load rating. So the tires need to be derated slightly when using tubes. Not normally an issue with Triumphs, but some tire shops may refuse to install tubeless tires with tubes (for liability reasons).

I doubt the reduction in weight will make much of a difference, but new tires probably will.

 

[RJS]

Thanks, you convinced me to go with inner tubes and rim bands. That was my first thought but, glad to have it confirmed. I'll take a visual inspection of the rims. They balance perfectly now with no shakes or issues so, I hope that means they are in good shape.

The tires will drop in weight from 24 lbs each to 18 lbs each. I know sports cars go to great lengths to reduce unsprung weight with lighter wheels. So, I am interested to see if this improves handling at all. My one main handling issue is if I hit a bump in the course of a curve, the car "hops" to the outside of the turn. So, I'm pretty sure the tires are not staying connected with the road.

In fairness, I suspect the springs and shocks are original! That job may be on my list this summer. Just not sure if stock replacement springs and shocks will bring the handling back or, if I go more spring, more shock or both.

Bob

 

[Geo Hahn]

FWIW, this is what I use to wrap the rims on my wires with tubes:

https://goo.gl/NZ0PcI

And this is what I use to seal the spokes on my wires w/o tubes:

Both methods seem to work well.

 

[sail]

Do a better job sealing the inside of the hub than I did and the spline grease won't weep out on the spokes.

 

[Keoke]

A better choice for use on the splines is Coppa Slip it will not flow out.

 

[glemon]

The tires will drop in weight from 24 lbs each to 18 lbs each. I know sports cars go to great lengths to reduce unsprung weight with lighter wheels. So, I am interested to see if this improves handling at all. My one main handling issue is if I hit a bump in the course of a curve, the car "hops" to the outside of the turn. So, I'm pretty sure the tires are not staying connected with the road.


Bob

The rear axles of TR4s and 4As with rigid axles are prone to that sort of hop, I don't think reduction in unsprung weight will make much difference, the cars have very limited suspension travel in the rear, and very stiff springs to keep the car from bottoming and provide the car with what was considered a sporting ride back in the day. Better shocks might help, but it is somewhat the nature of the beast, I have even read some vintage racing guides that talk about taking a leaf out of the rear springs on some old rigid axle british sports cars (don't remember if it is TR4s or later Sprites) to make the suspension work better, opposite of what you would usually think, but race courses are usually pretty smooth, race cars don't get loaded down with passengers and luggage, and lowering the ride height does not create the problems on a race course it does on the street, so the spring rates can be less of a compromise than they are on a street car

 

[TR3driver]

The rear axles of TR4s and 4As with rigid axles are prone to that sort of hop, I don't think reduction in unsprung weight will make much difference, the cars have very limited suspension travel in the rear, and very stiff springs to keep the car from bottoming and provide the car with what was considered a sporting ride back in the day. Better shocks might help, but it is somewhat the nature of the beast,

With a solid axle car, I believe the cause of the "hop" is the inner side rear suspension topping out. The axle hits the frame and then the tire lifts from the road, suddenly putting more load on the outside tire. Then when the outside tire develops more of a slip angle (starts to slide sideways), the suspension unloads and plants the inner tire, causing the slip angle to go back down.

At any rate, that was my theory when I added a rear sway bar to my previous TR3A, and it solved the "hop" problem completely.

However, I don't think the same analysis would apply to an IRS car. They can still lift the inside rear wheel, but at least on my Stags, I did't see any tendency to hop sideways because of that. However, they do both exhibit what others have called the "Stag twitch", where the rear end seems to hop sideways once after making a hard corner under power (like at the top of a freeway on-ramp). That effect appears to be from the splines in the halfshafts binding and then moving suddenly.

 

[glemon]

Randall, good points, I haven't had a sway bar in a solid rear axle car since a Sprite I had in college (which was wickedly quick in the corners), but your explanation makes sense. I always thought that the TRs rear suspensions were so rigid that a rear sway bar wouldn't be needed, but maybe I though wrong.

But I will add that fitting a rear sway bar to my TR250 (with a matched front bar of course) transformed the handling, and since car corners much flatter I never get the dreaded axle bind and release either.