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TR2 drum to TR6 disc brakes


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All,

I am working on a TR2 rebuild, and planning ahead.  The TR2 has drum brakes all round.  Original plan was to convert the front brakes to a disc set up from a TR3 front clip that came with the project.

Further reading on the subject seems to recommend going from the drum set up to the late TR4 / TR6 set up instead.  I am also hoping to keep under the bonnet original by retaining the combined brake / clutch master cylinder.

I have Googled, and read the hits, mostly from the TR Register, but I found the threads to be a bit confusing with mixed opinions on the way forward.

Has anyone else here made this leap?  Do we know that it is at least possible with minimal intervention?

i have read about changing the vertical links / trunnions etc to late TR4 to TR6, but i am not sure that i want to go that far from original.

I look forward to any input.

Thank you,

Graham

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When front discs were introduced to TR3 i believe that they changed to separate master cyl for brake and clutch using a common reservior at same time.

subsequent upgrades used separate masters with their own reservior.

Indicates to me that common master tr2 style not suitable for disc brake operation.

I converted a TR2 to front discs with toyota 4 pot calipers using TR4a master cylinders and  TR4a pedals as the tr2 are too close together. If you go to TR4a - 6 set up you get the advantage of 3 deg castor which improves straight line steering and the 4 pots bolt on without modification provided you use the later TR6 bolts (metric shoulder and unf thread)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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A friend with a TR2 put 3A discs on his car and used the original master cylinder. It works fine.

Having said that, I have drums on both my TR2s and have no problems with braking. It does require more attention to keep the front brakes balanced but in normal sometimes spirited driving the brakes work very well on both cars.

The only time I had brake fade was many years ago (before radars and risk taking was expected of young TR drivers) flying down a 5km long hill (Mt Ousley), there was not much left at the bottom. 

Edited by John McCormack
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Hi Graham,

As stated TR2 brakes are OK but scary if you are used to modern braked cars.  You car already has the big rear drums (10" x 2 1/4") same as the front brakes according to your TS no. so that is a benefit.

You change your driving technique and style to suit the limitations of the older car.  The car is so different to drive with its heavier steering and switch gear layout that you do quickly slip into sidescreen TR driving style.

Yes you can fit the front disc brake setup from TR3-6 on a TR2.  The only things you will be tripped by are the change in threads from the Lockheed (drum braked) to Girling (disc braked) for all the hydraulic lines. Plus how to mount the flexible hoses to the chassis.  Lots of solutions for both those tasks.  Otherwise the task to fit is simple hubs, discs, caliper mounts.  Post the photo of what you have and are thinking of fitting and we can talk you through it.

The 3 degree castor angle is achieved by a top wishbones and top ball joints and trunion change.  You would need TR4 trunions Not TR4A-6.  if you are doing this with TR2 vertical posts.

Cheers

Peter W

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The TR2 which I bought in 1964 had been fitted with TR3 disc front brakes - I would not have bought it otherwise as I had scared myself on numerous occasions with brake fade.

The car had retained its TR2 combined brake plus clutch master cylinder, and this did not give me any problems in the 5 years I had the car as my daily driver (none of us had 2 cars back then!).

I was fortunate to have the 9" rear brakes, whereas my brother's TR3 had 10" rears and would lock the rear under heavy braking.  My brother fitted smaller slave cylinders at the rear to alleviate the problem, but it was not a complete cure.

Peter has identified the problems to be overcome, but they are not major.

Ian Cornish

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I can agree with your brake fade comment Ian. I had terminal brake fade in a VW when approaching a roundabout on the A4 back in the 70s. Frightened the life out of me as I sailed onto the roundabout at pretty much undiminished speed in between two vehicles that were already on it. 

Frightened the life out of me. 

Rgds Ian

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thank you all for your input.

 

i have a full front clip from a TR3, "B" type calipers.

I have TR6 calipers with 16PB markings.

i also have a Girling TR3 rear axle available, if this adds to the conversation.

Graham

IMAG1319.jpg

IMAG1141.jpg

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The Lockheed rear axle is the weak link in the TR2's specification - it cost me quite a lot to have seals replaced repeatedly in my old TR2 when it kept wetting its rear brakes with oil from the differential.

However, a number of items need to be changed to effect the change to the Girling axle, and this has been covered in detail elsewhere on the Forum by the experts.

Ian Cornish

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Which of these caliper mounting plates do you have?

 

image.png.fa1a09fa0bee48cd3c2118059eca049a.png  TR3 - early 4 for the big 'B type calipers

 

image.png.0d1bc6f2794af929ec2f4672d07ce701.png  TR4-6  for the 16P type calipers

 

The use of the later caliper makes getting brake pads easier as they are common on a lot of other European cars and plus some rice burner truck that uses a similar sized and shaped pad.

You then need to decide which size disc you have/wish to use.

You need to bolts to fit the caliper to the bracket - they are a different, larger shank size on late TR6 (AKA the Metric caliper which has metric hydraulic connection threads)

I trust you have a second hub and all the attaching bolts for the disc.

Dust shields can be dispensed with if you are also doing the Revington steering lever mod - worth it in a lot of users views.  https://www.revingtontr.com/product/rtr3314k/name/steering-geometry-imp-kit-tr2-3b

Cheers

Peter W

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Graham,

I know you've already acquired the car, but did you consider getting a slightly later

TR3, already with disc brakes as standard, but retaining the good looks of the

TR2?.Just seems a shame to modify, what is a shrinking resource, into a clone of

a later model made in much greater  numbers.Most certainly disc brakes are superior,

but drums, unless you are going to be driving the car at it's limits all the time, are perfectly

adequate for all normal usage, and even the occasional competitive  event.

TR2s were much raced and rallied in period and were very successful.

Remember, there were around 4 times as many TR3/As with discs versus drum braked TR2s,

and that ratio has no doubt  increased over the years.

Your chance to buck the trend!

 

Roger M-E

 

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7 hours ago, BlueTR3A-5EKT said:

Which of these caliper mounting plates do you have?

 

image.png.fa1a09fa0bee48cd3c2118059eca049a.png  TR3 - early 4 for the big 'B type calipers

 

image.png.0d1bc6f2794af929ec2f4672d07ce701.png  TR4-6  for the 16P type calipers

 

The use of the later caliper makes getting brake pads easier as they are common on a lot of other European cars and plus some rice burner truck that uses a similar sized and shaped pad.

You then need to decide which size disc you have/wish to use.

You need to bolts to fit the caliper to the bracket - they are a different, larger shank size on late TR6 (AKA the Metric caliper which has metric hydraulic connection threads)

I trust you have a second hub and all the attaching bolts for the disc.

Dust shields can be dispensed with if you are also doing the Revington steering lever mod - worth it in a lot of users views.  https://www.revingtontr.com/product/rtr3314k/name/steering-geometry-imp-kit-tr2-3b

Cheers

Peter W

Peter,

I have the TR3 B type mounting plates currently.

i have a bunch of rotors, only two of the rotors are at original .500 spec, these are the smaller 10 13/16? size. i have 11" that are at .475.

Hubs etc, yes, i have the full front clip from the TR3.

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5 hours ago, roger murray-evans said:

Graham,

I know you've already acquired the car, but did you consider getting a slightly later

TR3, already with disc brakes as standard, but retaining the good looks of the

TR2?.Just seems a shame to modify, what is a shrinking resource, into a clone of

a later model made in much greater  numbers.Most certainly disc brakes are superior,

but drums, unless you are going to be driving the car at it's limits all the time, are perfectly

adequate for all normal usage, and even the occasional competitive  event.

TR2s were much raced and rallied in period and were very successful.

Remember, there were around 4 times as many TR3/As with discs versus drum braked TR2s,

and that ratio has no doubt  increased over the years.

Your chance to buck the trend!

 

Roger M-E

 

Roger,

To be honest, my absolute preference would be to rebuild to as original as possible.  This vehicle will be for pure local pleasure use.  

It is this forum, and others that have "worried" me into performing these changes / upgrades.

The tub is a replacement 58 or so (sloped rear floor), but i intend to convert it back to the TR2 spec as much as i can, including the wood dash support.  I will change or convert the rear valance and front bulkhead also.  I intend to put the aeroscreen mounts on also.

The car currently has the complete original drivetrain - condition to be determined, but everything spins freely.

I have a replacement TR3 front clip, O/D gearbox, and the Girling rear end as previously mentioned that could go in.

I would really like to build this as it left the factory, if possible, practical AND safe to use.

Sorry if the photo is upside down.

Graham

 

STANDARD REGISTER BUILD SHEET 1955 TR2 TS7831L.jpg

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Graham,

I would agree that some of the contributors to this and other forums do get

rather carried away with the 'safety' advice. This can lead one to make changes

to an historic piece of equipment which, if used in the manner for which it was

originally intended and is maintained to a reasonable standard and driven by a

reasonably intelligent driver, doesn't really justify any great changes to it's original

spec.I fully agree that fitting a roll over bar, 4 point racing harness, radial tyres, not

to mention vented disc brakes, will perhaps make you 'safer' in the event of an incident,

but having all the aforementioned upgrades (as they are labelled) will generally ensure

your arrival at the said incident at a greater pace than you might have intended, whilst

giving a degree of comfort that all will be well on impact.

It's all a matter of choice of course.What anyone does with their property is their own

business, but it does seem a shame to make changes for the sake of them in my personal opinion.

I wish you the best of luck with your project and very much look forward to seeing things as they

move forward!

Cheers

Roger M-E   

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17 minutes ago, roger murray-evans said:

Graham,

I would agree that some of the contributors to this and other forums do get

rather carried away with the 'safety' advice. This can lead one to make changes

to an historic piece of equipment which, if used in the manner for which it was

originally intended and is maintained to a reasonable standard and driven by a

reasonably intelligent driver, doesn't really justify any great changes to it's original

spec.I fully agree that fitting a roll over bar, 4 point racing harness, radial tyres, not

to mention vented disc brakes, will perhaps make you 'safer' in the event of an incident,

but having all the aforementioned upgrades (as they are labelled) will generally ensure

your arrival at the said incident at a greater pace than you might have intended, whilst

giving a degree of comfort that all will be well on impact.

It's all a matter of choice of course.What anyone does with their property is their own

business, but it does seem a shame to make changes for the sake of them in my personal opinion.

I wish you the best of luck with your project and very much look forward to seeing things as they

move forward!

Cheers

Roger M-E   

+1

Peter W

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it would be so much easier to put it back together the way it came apart!!:D

are all drum brake parts available? i do not have any of the insides.

is the O/D gearbox upgrade fair game?

should the Laycock diff be left?

Where is the cut off for originality vs best solution?

Graham

 

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42 minutes ago, roger murray-evans said:

Graham,

I would agree that some of the contributors to this and other forums do get

rather carried away with the 'safety' advice. This can lead one to make changes

to an historic piece of equipment which, if used in the manner for which it was

originally intended and is maintained to a reasonable standard and driven by a

reasonably intelligent driver, doesn't really justify any great changes to it's original

spec.I fully agree that fitting a roll over bar, 4 point racing harness, radial tyres, not

to mention vented disc brakes, will perhaps make you 'safer' in the event of an incident,

but having all the aforementioned upgrades (as they are labelled) will generally ensure

your arrival at the said incident at a greater pace than you might have intended, whilst

giving a degree of comfort that all will be well on impact.

It's all a matter of choice of course.What anyone does with their property is their own

business, but it does seem a shame to make changes for the sake of them in my personal opinion.

I wish you the best of luck with your project and very much look forward to seeing things as they

move forward!

Cheers

Roger M-E   

I would suggest that "using it in the manner it was intended DID include driving it with "brio" and the whole ethos of sports cars in the day was "race it Sunday, go to work in it on Monday", and as our much missed Alec posted,

1338465883_TRSafety.jpg.bfaae08fc637c62265ba09e6eea2aff0.jpg

The cars were imperfect (some would say downright dangerous) when they were originally designed and built, to want and drive around in a museum grade machine "purely for pleasure" with all it's faults and original shortcomings faithfully reproduced is a choice an owner can make, but maybe not if he or she discusses it with  their partner and considers that children or grandchildren will on occasion want to accompany you.  

Mick Richards

 

Edited by Motorsport Mickey
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Mick,

I'm thinking you're not a huge fan of 'museum grade cars'?

You come across as being a little contemptuous for those who want no more

from their old cars than to drive them around "purely for pleasure", fiddle

with them and try to keep them close to the original concept?

I'd like to take small issue with your comment " The whole ethos of sports cars

in the day was race it Sunday, go to work in it on Monday".

Such an observation may have had some relevance to the avid reader

of Motor Sport or other period motoring magazines, but a perusal of the

entry lists into the various motor sporting categories will elicit that the entries

were made up of the same tiny cohort of drivers, that did in fact own,

perhaps a TR2, for the purposes of Sunday racing/Monday work.But they

they would have made up a very small percentage of the total number of, say,  TR2 drivers.

UK sales 2800 odd.10 percent would seem an unlikely number.But a possibility.

The same would apply to MG, Jaguar, Austin Healey etc.The vast majority of sports

car drivers were just that. Sports car drivers!

I'm not really sure what to read into your inclusion of the TRAction letter from Alec Pringle,

which I didn't find particularly enlightening, but which appears to be his conjecture into the

circumstances of a rather horrible accident to a close friend in a TR4A, and which obviously and

understandably caused him some considerable anguish.

Not everyone buys an old car with the intention of entertaining his/her children or grandchildren.

Selfish I may be, but the last thing on my mind when contemplating the acquisition of yet another old

banger is, how long will the kids be kept riveted in awe of the prospect of an outing in Dad/Grandads

old car, before they disappear in the direction of an Ipad or a football.

Cheers

Roger M-E

 

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You are reading a lot into what you "think" I mean Roger, whereas I expressed exactly what I meant in what I said.

It was yourself who used the expression "purely for pleasure" in your original post as if an totally original car somehow pleases more rather than driving a car modified for safety incorporating safety features as any driver can choose to do, and intimating that having a car modified for safety encourages a driver to drive in an unsafe manner or at too great a speed " will generally ensure your arrival at the said incident at a greater pace than you might have intended, whilst giving a degree of comfort that all will be well on impact".

Your comments seemed straightforward to me.

Mick Richards

 

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7 hours ago, roger murray-evans said:

Graham,

I would agree that some of the contributors to this and other forums do get

rather carried away with the 'safety' advice. This can lead one to make changes

to an historic piece of equipment which, if used in the manner for which it was

originally intended and is maintained to a reasonable standard and driven by a

reasonably intelligent driver, doesn't really justify any great changes to it's original

spec.I fully agree that fitting a roll over bar, 4 point racing harness, radial tyres, not

to mention vented disc brakes, will perhaps make you 'safer' in the event of an incident,

but having all the aforementioned upgrades (as they are labelled) will generally ensure

your arrival at the said incident at a greater pace than you might have intended, whilst

giving a degree of comfort that all will be well on impact.

It's all a matter of choice of course.What anyone does with their property is their own

business, but it does seem a shame to make changes for the sake of them in my personal opinion.

I wish you the best of luck with your project and very much look forward to seeing things as they

move forward!

Cheers

Roger M-E   

Agree.

I have had a daily driver TR2 for 45 years. Original steering, brakes and suspension. Some engine mods before I bought it and a Girling rear axle. I have had no problems with brakes, handling or performance and have no trouble keeping up with the guys in much more modified cars.

When I got the chance to build a two owner long door car nearly four years ago I have made it as original as possible even down to bolts and screws. It has a Lockheed axle which, touch wood, hasn't been a problem yet in the 1650 miles I have covered since putting her back on the road.

Both are wonderful driving cars.

I appreciate the modified TRs as well, but I get dismayed when owners modify one of the few original examples. They are only original once and in my view the few remaining ones should be kept that way. Just my personal view.

 

 

IMG_0194.jpg

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TRs were sports cars for the masses, they aren’t custom built works of art. So how an individual chooses to rebuild his or her car is down to them. 

Personally, I rebuilt mine with modern electrics and R&P steering and am happy with the decisions I made. I originally had a brake servo as well but found it wasn’t needed so removed it. The car stops perfectly well on its original disc brake set up, it will lock all four wheels on a dry road and has never suffered from brake fade even on Alpine passes. 

Rgds Ian

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I thank you all for your input to this topic.

I have always liked "original", my TR6 is very much this way.  

This TR2 will be gently enjoyed as a pleasure vehicle for local use.

I have decided to rebuild this TR2 back "as close as practical" back to original specification, with the addition of the O/D gearbox.

Graham

 

 

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2 minutes ago, Graham J said:

I thank you all for your input to this topic.

I have always liked "original", my TR6 is very much this way.  

This TR2 will be gently enjoyed as a pleasure vehicle for local use.

I have decided to rebuild this TR2 back "as close as practical" back to original specification, with the addition of the O/D gearbox.

Graham

 

 

Wise move, for your chosen use.

Peter W

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8 hours ago, roger murray-evans said:

Good decision Graham. And I wholeheartedly agree with the overdrive inclusion.

I can remember when i engaged overdrive for the first time in my TR2 and 

couldn't believe what a difference it made!

Roger M-E

 

I wouldn't consider any TR without it. It is a long way between places downunder, overdrive is essential.

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on the topic of Overdrive....

the OD gearbox i have is TS3900.  i have not researched it yet, but I am guessing this will be an early non-synchro 1 st gear unit.

 

Graham.

 

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