Jump to content

Unsprung Weight TR Disc Brakes


Recommended Posts

On Tuesday I received a complete set of TR disc brakes including discs, callipers and pads. I was surprise at how heavy the parcel was.

 

One disc, calliper, pads, calliper fixing plate and bolts etc. weighed nearly 20kg and that was just one side.

On the other hand with the 10" drum brakes the drum, back plate, shoes, wheel cylinder and adjuster etc. weigh about 10.5kg for one side.

This seems to be a massive difference and not what I expected.

How much will this change things after I have converted my TR2 front drum brakes to discs?

 

Regards, Colin

 

Link to post
Share on other sites

Colin,

 

I raced TRs for 10 years and it's amazing how many owners insist upon fitting alloy hubs, magnesium wheels and other corner "lightening" items convinced it will make a difference...it doesn't, not on a TR.

The lightening of unsprung weight is a worthwhile exercise and allows the suspension to explore and allow the very zenith of road behaviour and grip, will you drive your car to the extremes necessary to exploit it ?

The TRs were/are very robust mid range sports cars built to a price...a cheap price, their OE equipment is of surprisingly high quality whilst achieving this but the car has a chassis and a single skin (in the main) shell on top of it, it's never going to be light, and when racing by chopping and replacing with alloy etc etc the weight can be pared down to maybe 900 kg area. So that's maybe another 300 kg to go then before lopping off 9 kg from the unsprung weight on a single corner will give you any payback when driven to the limit.

On the other hand although the drum brake equipment as per original works at least as well as other similarly equipped marques of cars and often better than most, the disc brakes increase in braking capacity and continued high speed stopping capability even for the Triumph original equipment far...far outweighs ANY possible gain in handling from a reduction in unsprung weight.

Fit and forget and enjoy the increase in safety and confidence that the disc brakes will bring

 

Mick Richards

Link to post
Share on other sites

My first TR2 (bought about 1963) was standard, and its drum brakes scared me on many occasions as the fade from high speeds was very considerable.

My second TR2, bought a year later, had been converted to disc brakes (I wouldn't have bought it otherwise) and was a revelation - even when smoking, they still stopped the car.

As Mick says, fit and forget - and don't worry any longer about stopping!

Ian Cornish

Link to post
Share on other sites

Thanks Andrew, Mick and Ian.

 

I will not be racing the car, just normal road use in todays traffic. I have always felt that for drum brakes the TR2 10" x 2 1/4" were very good and better than any other drum braked car that I have had and much better than the Triumph Roadster. I suspect that the TR2 having two leading shoes at the front has something to do with it.

Mick, you make some interesting points.

 

Regards, Colin

Link to post
Share on other sites

Another feature of early TR2s was that the Lockheed axle pithed oil on to the rear brake shoes so you were really only using the front brakes with their characteristic fade. At the time we didn't really seem to care!

 

James

I can recall several occasions when I cared very much :o

 

Bob

Edited by Lebro
Link to post
Share on other sites

Me, too, Bob.

I recall approaching a roundabout at about 90 mph and having to go round it at about 25-30 mph because I couldn't reduce speed any further.

On another occasion, heading west on the A40 in the days when there were roundabouts at every intersection, I had reduced speed for a roundabout, then accelerated to about 70 mph when a Beetle moved to the righthand lane in front of me - he was very fortunate that, with hot brakes, I managed to reduce speed sufficiently because, with foot hard on the pedal, I came within about 5 feet of his bumper.

These experiences convinced me that my next TR HAD to HAVE disc brakes (and overdrive, as the first one hadn't).

Ian Cornish

Link to post
Share on other sites

You could consider an alloy caliper conversion using either the AP calipers or the American stuff available through the various tuning specialists. I've got a set to fit on my 6 and they are way lighter, plus they are four pot calipers and the disks are vented. I'm hoping it will brake like a modern (except for the ABS of course).

 

Even if you stay with CI it's definitely very much worth going from drums to disks on the front for any performance application, as once you've experienced drum brake fade in an emergency braking situation, you never want to repeat it...

 

 

Andrew

Link to post
Share on other sites

You could consider an alloy caliper conversion using either the AP calipers or the American stuff available through the various tuning specialists. I've got a set to fit on my 6 and they are way lighter, plus they are four pot calipers and the disks are vented. I'm hoping it will brake like a modern (except for the ABS of course).

 

Even if you stay with CI it's definitely very much worth going from drums to disks on the front for any performance application, as once you've experienced drum brake fade in an emergency braking situation, you never want to repeat it...

 

 

Andrew

Dont forget to do something with the rears when you fit those calipers as you will upset the F/R balance.

Stuart.

Link to post
Share on other sites

Thanks Stuart.

I am fitting a later "Girling" axle which came with 9" brake back-plates. I have fitted new bearings and seals to the hubs and the diff. and have purchased new 9" drums, shoes (1 3/4"wide), Wheel cylinders, springs etc.

Regarding front to rear brake balance, whilst googling I came across an American article written by someone who seemed to know what he was talking about. He was saying that (these are my words) fitting a brake servo would have the affect of reducing the foot pressure required for the brakes but would not increase the efficiency of the rear drum brakes but on the other hand would, because of the design, increase the efficiency of the disc brakes at the front. This would help to maintain the balance even with 10" rear drums.

I thought it was food for thought and I would be interested in what others might think.

 

Regards, Colin

Link to post
Share on other sites

Thanks Stuart.

I am fitting a later "Girling" axle which came with 9" brake back-plates. I have fitted new bearings and seals to the hubs and the diff. and have purchased new 9" drums, shoes (1 3/4"wide), Wheel cylinders, springs etc.

Regarding front to rear brake balance, whilst googling I came across an American article written by someone who seemed to know what he was talking about. He was saying that (these are my words) fitting a brake servo would have the affect of reducing the foot pressure required for the brakes but would not increase the efficiency of the rear drum brakes but on the other hand would, because of the design, increase the efficiency of the disc brakes at the front. This would help to maintain the balance even with 10" rear drums.

I thought it was food for thought and I would be interested in what others might think.

 

Regards, Colin

Thats cobblers, all a servo will do is reduce the pedal effort, it doesnt make the brakes better.

Stuart.

Link to post
Share on other sites

Dont forget to do something with the rears when you fit those calipers as you will upset the F/R balance.

Stuart.

 

Yes, I have a set of the larger diam. Morgan brake cylinders to fit and I also got a set of Bastuck finned drums to help with fade at the back, so I'm hoping that will do the trick. Otherwise, it's disks for the rear as well. Have to see how the new set up performs in the real world first.

 

 

Andrew

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.