A balance between road and hillclimb/sprints

[Si Y]

Hi

I’m a relatively new TR4 owner.  I bought a 1963 TR4 about 3 years ago.  It has historically had a lot of money spent on it by a previous owner in preparation as a fast road/ sprint car.  Revington TR fitted rally suspension front and rear, some chassis strengthening at the front end, a roll over bar, a rear bulkhead in front of the fuel tank, modified the electrics, facet fuel pump, alu radiator etc. The engine was rebuilt by Sigma Engineering and recently I have fitted twin 45 Webers.  The engine produces about 160 bhp on the rolling road.  Despite the money spent on the cars preparation I don’t believe from the file of work done that there have been any modifications to the rears axle/half shafts/differential or to the steering set up.

I still want to use the car on sunny weekends and the odd long trip to France etc so I don’t want to turn it into an all out sprint/racing car but rather a fast road car first and foremost that I can drive to hillclimbs and sprints.  

My questions are as follows:

1.  Should I be strengthening the rear axle components - halfshafts etc?

2. Would a LSD make much difference?

3. The steering seems ok but not that precise - are there mods that can be done to improve that.

4.  The car is on its original chassis which was strengthened at the front end by Revington TR in about 2003.  The body was not removed completely to do this so I’m not sure how extensive the strengthening could have been. When driving slowly along a bumpy road surface if I put my finger on the gap between door and rear wing I can feel slight movement between the two.  Is that normal as I don’t know how stiff a chassis on a TR4 should be?

Apologies if this is basic stuff but I thought it best to draw on the experience and wisdom of you guys before continuing the evolution of my car.

Regards

Simon

 

[Hamish]

Simon welcome. 
 

first of all let me point you to your championship 

https://www.tr-register.co.uk/motorsport
 If you have all steel body panels I guess you’d be in class 2b or c ( depends on power/weight)

if fibreglass panel class 3

get signed up and start entering the individual events.

the back axle ( non irs) should be fine. If you tour as far as France I would stick with the stock 3.7:1 ratio. Your 160bhp ( is that flywheel or wheels ?) should cope with the 3.7 in competition. If you have an overdrive it may already be 4.1:1 good for acceleration less good for touring. 
 

fitting LSD means your are moving more from touring bias to competition and depending on the type more noise.

half shaft would be a consideration strength wise if you used very sticky tyres  I would guess.

You will need tow points front and rear. 
 

talk to revington about steering. Ackerman arms may be a consideration. ? Any anti roll bars fitted front and or rear ? If rally suspension fitted (uprated fitted !) I would imagine it has at least the front anti roll bar  

 

I shouldn’t be telling you this as with 160bhp you’ll be beating me in my 3a but that’s what the classes are for.

Enjoy the forum

H

 

 

[Si Y]

Many thanks Hamish.  Very useful.

Is my concern about chassis stiffness I’ll founded?

KR

Simon

[Motorsport Mickey]

Posted 13 hours ago

Hi

I’m a relatively new TR4 owner.  I bought a 1963 TR4 about 3 years ago.  It has historically had a lot of money spent on it by a previous owner in preparation as a fast road/ sprint car.  Revington TR fitted rally suspension front and rear, some chassis strengthening at the front end, a roll over bar, a rear bulkhead in front of the fuel tank, modified the electrics, facet fuel pump, alu radiator etc. The engine was rebuilt by Sigma Engineering and recently I have fitted twin 45 Webers.  The engine produces about 160 bhp on the rolling road.  Despite the money spent on the cars preparation I don’t believe from the file of work done that there have been any modifications to the rears axle/half shafts/differential or to the steering set up.

I still want to use the car on sunny weekends and the odd long trip to France etc so I don’t want to turn it into an all out sprint/racing car but rather a fast road car first and foremost that I can drive to hillclimbs and sprints.  

My questions are as follows:

1.  Should I be strengthening the rear axle components - halfshafts etc? 

Answer ...... Not unless you are a driving God and able to utilise "trail braking and balanced throttle inputs to stress the units...see below.

2. Would a LSD make much difference?

Answer.....Yes it would stress those rear axle components we were talking about on item 1. The front anti roll bar you have now fitted will change the Triumph standard understeer (manufacturers like understeer) into UNDERSTEER and fitting an LSD will mean the rear tyres will grip better under power meaning more grip which will give you UNDERSTEER in spades. To balance the handling it needs a rear anti roll bar of suitable size hopefully able to be varied which will stop the car rolling at the rear allowing the rear tyres to slip (not skid) changing the rear grip so the car be balanced between the front and rear.

3. The steering seems ok but not that precise - are there mods that can be done to improve that.

Answer...Yes assuming all the suspension and steering units are correct and working correctly if the "bump steer" has not yet been corrected a large benefit can be gained in handling by altering it to the best advantage. Good news it will cost you about £1 and maybe 2-3 hours to carry out. If you wish to supply me your e mail address (PM a message to me) I'll send a little article I've written on a "how to" correct a cars bump steer which has been sent to over 140 TR owners who wanted it (if anybody else wants it send me your e mail address).

Just a mention...if your car is handling like it's it's on rails...you're not driving fast enough. Race cars are miserable when driven on public roads, you can't drive them in the manner they need to utilise the handling and power requirements of the engine, a fast road car is far more difficult to build and utilise than a race car.

Mick Richards

 

 

Edited March 14, 2021 by Motorsport Mickey

[MadMarx]

I broke two axles and damage and repair was pricy.

I moved to the Southwick Conversion and I'm happy since.

As LSD I use a Bastuck unit which was designed by ZF Germany. Open LSD with up to 90% locking rate.

for more precision steering....two cardanic TR6 joins instead of rubber.

Edited March 16, 2021 by MadMarx

[Si Y]

Thank you both.  I do have a rear anti roll bar fitted as well and the car feels like it handles well although I have not driven it in anger on a track yet.  Mick, I’ll message you about the bump stop issue.  MadMarx - the TR6 joints instead of rubber look a sensible upgrade.

Can anyone comment in relation to the chassis stiffness in my original post please? “When driving slowly along a bumpy road surface if I put my finger on the gap between door and rear wing I can feel slight movement between the two.  Is that normal as I don’t know how stiff a chassis on a TR4 should be?”

Many thanks for the helpful comments so far.

KR

S

 

[Motorsport Mickey]

Even when brand new a seperate chassis car with only a single skin bodywork on top (all these TR roadsters) will have a degree of movement. After a few years this will increase as the joints wear aginst one another and the fastenings flex, from your description it sounds fine.

Mick Richards

[Hamish]

Simon

i think that there is some flexibility in these chassis and I think the stiffer you go on suspension anti roll bars the more potential for chassis flex.

if  I were you I would do this seasons club championship and see how you go. 
perfectly standard road going cars take part and have fun. 
it’s what I did with my 3a in 2017. I also bought photos from the track side photographers ( professionals) that allowed me to see the attitude of my car through the bends. A lot of the courses are small tight ones where handling outweigh power. But you have power so the circuit courses like good wood and castle Combe will stretch your cars legs. 
 

vidoes help. In learning your own mistakes. 
You’ll find mine here 

https://youtube.com/channel/UCrXjQt8CiQNaGDrjhmPLqMA

 

Edited March 17, 2021 by Hamish
Video link

[stuart]

But if your getting movement in the door then I would check to see if you have the door restraint fittings attached and adjusted properly Item 54 here Door fittings

Stuart.

[ianc]

Is your steering rack mounted solidly, or is it held by squidgy rubber?   With a 1963 TR4, might well be the latter.

If the latter, and the rubber is knackered, the steering will be affected detrimentally as the rack will be able to move from left to right, depending on the forces applied.

The two rubber doughnuts on the steering column can also get squidgy - can be replaced with universal joints, at one or both ends of the shaft.

See "How to Improve Triumph TR2-4A" by Roger Williams, where the problem of rubber mountings on the rack is discussed.

Ian Cornish

Edited March 17, 2021 by ianc

[Si Y]

Thanks very much all.  Useful comments and tips.  I’m going to try and get to some club sprints/hillclimbs and see how it goes!

[Motorsport Mickey]

Si,

You have an e mail.

Mick Richards

[kevin bryant]

As well as the sprint and hillclimb championship where you'll get lots of advice and encouragement, you may also find it helpful to book a couple of track days.  Because of the 2 hours or so of track time over the course of the day, It'll help you get to know your car, build your speed during the course of the day and even play with some of the settings. Book in the TR Register shop Track Day (tr-registershop.co.uk)

 Kev