Modified Stags - Jonathan Finnis Point of View

I read the article, "The Founder Member's Point Of View" with great interest. Before you read my response, you may like to read it again. Whilst most of the article makes a lot of sense, naturally I do not concur with everything he writes.

BRAKES

The Stag's brakes may have been adequate for the 70's, but on today's roads more powerful brakes with no fade and less pedal pressure must be desirable and even essential for those of you with enhanced performance. The article says that "when they design any car a great deal of R&D goes into providing systems that are more than adequate for the job in hand." True, a great deal of R&D should go into providing systems that should be more than adequate for the job in hand....but in the case of the Stag?...I have my doubts about this. I think it is likely that to save money, Triumph used some parts from other (sometimes obsolete) models that they had in stock in order to come in with a price well under the Mercedes SL sports car which was the market Triumph were after.

It is accepted by most people that the demise of the Stag was as a result of inadequate development. Some of the things Triumph did and did not do beggar belief. One small example, the use of UNF (fine) threads in aluminium instead of UNC. This causes so much inconvenience with stripped threads, especially on the rear hub fixing studs on the trailing arms and diff cover plate which pull out even if the very low torque figure is adhered to. And how Triumph could supply the car with drive shafts which have to be thrown away as they cannot have new U/J bearings fitted? I guess they reconsidered this as they put it right on the MK2. Was it to save money? Surely it would have cost only a couple of pence more to have studs made with a different thread each end and recess machined into the drive shaft yokes so that circlips could be fitted. Or was it that they had bins full of surplus incorrect parts and didn't care if they were not fit for the purpose so long as they were cheap enough? There are countless other examples...no drain plug on the diff etc etc... more on this later.

Back to brakes...

Tony Hart's racing Stag is 1000lbs lighter than the standard car which weighs in at approx 3000lbs kerb weight (including petrol, extras etc). This means that his brakes have much less work to do and he in effect with his standard brakes (except for the racing pads) has a 30% uprate which is the only reason he can get away with the standard set-up. Even so, with solid discs I am surprised that he doesn't suffer fade while racing, even with cooling ducts.

For those of us with standard weight cars it is a different story. Front/rear brake balance also is most important and can be adjusted to suit weight distribution which is affected by engine weight. On the Monarch Stag, because of the all-aluminium Rover engine saving 100lbs weight and the battery being relocated into the hood recess behind the rear seat, this is 53/47 which is much closer to the 50/50 ideal and a huge improvement over Stag-engined cars with cast iron engines and the battery overhanging the right front wheel.

Only a fool would leave the front of the car sticking up in the air like Concorde taking-off at Heathrow after fitting a Rover engine. Shorter tailor-made progressive-rate springs take care of the lighter engine on the front so that the correct height and body rake can easily and cheaply be set. I can also supply adjustable-height struts, not so much for setting corner weights (although if you can improve this as I have on the Monarch Stag it makes a huge difference to grip) but more for setting the correct height due to chassis tolerances differing from car to car. By the way, since the Stag has the battery, driver and petrol tank all on the right-hand side of the car, there is NO chance of getting corner weights equal without moving the battery and petrol tank as I was forced to on the Monarch Stag.

What makes you think the Stag was made for the American market? It annoys me that home market customers counted for nothing in the 60's and 70's, although I guess it was export or die in those days.

It is a matter of opinion whether the rear brakes should lock up first. As this is more likely to precipitate a spin, I think it is not a good idea. In fact, my performance car tyre specialist recommends that when fitting only 2 new tyres these should go on the back wheels to give more grip and reduce the likelihood of the rear wheels locking first. Incidentally this is also the view of the Police. If deemed necessary, the power of the rear discs on my kits can easily and cheaply be adjusted by fitting my pressure proportioning valve in the circuit when the rear kit is installed. It is important to have the balance right on the Stag, which, with its heavy cast-iron Stag engine, is prone to be tail happy anyway.

SUSPENSION

Further to my statement earlier about bits being used from the parts bins of older models, take the front hub bearings and spindles for example. Unless I am mistaken, I believe I have seen front hubs and spindles identical to the Stag's on a Standard Vanguard Phase 3. I'm sure somebody will correct me if I am wrong, but I would bet my bottom dollar that they are the same. These may have been OK for the Vanguard in the 50's with drum brakes, but not for a modern high performance touring car with four times the performance and disc brakes. What I think happens is that the hub spindle bends under load causing the hub, and hence disc, to move out of true and knock the pads back. If you have ever driven fast enough through an S-bend you must have noticed a long brake pedal the next time you use the brakes. Also that very small outer wheel bearing doesn't help matters either. Most Stags suffer from this bearing working loose on the spindle due to the load on it being excessive as there is too little surface area in contact with the spindle.... "More than adequate for the job in hand"...?...Hmmm! I don't think so. Here's a tip. Assemble the inner race on the spindle with LOCTITE STUD'N BEARING FIT. Marvelous stuff. Only snag is they are harder to get off!

However, for those of you who are serious about improving your Stag's handling and do not believe that two wrongs make a right, I can supply you with aluminium hubs (reduce unsprung weight) and bigger spindles made from EN24T high tensile steel that take a larger outer bearing (the same bearing as the inner one), all of which helps to reduce bending under load. This is the same steel as is used to make high-performance crankshafts (See price list).

LOW-PROFILE TYRES

Yes, wheels and tyres are an extremely important part of the set-up. I agree with Tony that the camber change of the Stag's rear suspension is a problem when considering "Inching up" to 15" wheels with wider rims. Slightly lower profile tyres can be fitted to the standard suspension, say 185/65 (621mm o/d) or even 195/60 (615mm o/d, which is the same as the standard car). These wheels and tyres are certainly a temptation as they look great and I believe the Stag's rear suspension can tolerate them. They increase the contact patch area and therefore offer a huge improvement in grip under braking without altering the rolling radius and hence gearing. I am not a fan of tyres that look like balloons on the Stag as they date it so. They have a place on 4 wheel drive vehicles, not on high performance touring cars! If your car suffers from the extreme wheel movement and hence camber change on the road then maybe some modifications to your suspension should be considered. I can help here. On the road there is normally very little suspension movement and the advantage that such tyres give in improved braking and appearance in my opinion far outway any disadvantage. As in most things, there are pros as well as cons. Originally I had very good results by lowering the suspension on the Monarch Stag (and hence c of g which in turn reduces roll), fitting 15" wheels and 205/55 tyres using standard suspension. Of course this was using adjustable camber inner trailing arm brackets to keep the camber correct when lowering the car, Koni Classic shocks, progressive-rate springs, adjustable Track Control Arms and up-rated front anti-roll bar to keep roll under control. (All available from Monarch). The standard Stag McPherson struts are ideally suited to the use of lower profile tyres. But for optimum grip the Stag's rear semi-trailing arms need to be modified to trailing arms (thus reducing unwanted excessive camber change as the wheel goes up and down) by fitting my new BMW rear suspension transplant which would enable you to fit 15" or 16" wheels and sticky wider Bridgestone Protenza 50 section tyres. A truly amazing increase in grip and traction for more powerful engines can be achieved by this modification.

ROVER ENGINE CONVERSIONS

The complete opposite to what Tony wrote about the lower weight of the Rover engine is true!!! Tony's words should be corrected as follows: "The biggest advantage of a Rover conversion is that it's 100 lbs lighter than the Stag lump. (Appropriate term for it? Well, let's be honest, it is pretty heavy, isn't it? But at least the heads are aluminium). With the lighter all-aluminium Rover engine the weight distribution is better and brake bias, car height etc. can all be dealt with as already described. Car designers strive endlessly to reduce vehicle weight to improve performance, handling and economy, which is why even diesels are now being made out of aluminium. Like all modern engines, the all-aluminium Rover V8 is heaven sent to reduce unwanted performance-inhibiting weight.

I agree that there were some pretty dishonourable cowboys who did a disgraceful job in the past of putting Rover engines into Stags, but that's water under the bridge now. There are some really outstanding examples of installations that are better than the Triumph factory would have done, of which may I be conceited enough to say that the Monarch Stag is one. We have had over 30 years of technology advance in cars since the Stag designed, so lets benefit from this wealth of knowledge to increase the enjoyment to be gained from driving our Stags by transforming the performance, handling and economy.

I would also rewrite Tony's last paragraph as follows:
"To summarise regarding engine conversions, a 'Triumph' Stag can be vastly improved by using a 'Rover' engine." (Same manufacturer now in fact). Whilst the Stag engine is undoubtedly a superb engine and with its twin O/H cams is in many respects far more advanced than the Rover (apart from its weight) it nevertheless is not as robust as the Rover and cannot produce anything like the same power output reliably. The weight factor is a serious disadvantage. Triumph did indeed contemplate using the Rover engine and built a prototype Stag with one in but scrapped the idea for political reasons.

In my opinion our modern-day conversions which encompass appropriate re-engineering to compensate for less engine weight and altered weight distribution most definitely enhance the original safety margins designed in by Triumph engineers thirty years ago.

Jonathan Finnis
March 2003


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