GT6 GT6 early vs later model differences / upgrades

[Scotsman]

Is the suspension of the later model GT6 compatible / bolt in with the earlier models.

Are there any other improvements that should be considered, and anything that cant easily be changed that would compromise the earlier models vs the later ones.

Is this and expensive endeavour (relative to improvements you might do on other model cars) with parts relatively easily found, and would it require tools beyond what you might find in a tool chest.

My understanding is that a number of improvements were made to later models to improve handling and performance. I like the look of the earlier models and there is one local to me for sale, but everything I have read is to stay away from them.

Richard

 

[tomgt6]

When you say earlier what year do you mean. There is the mk 1 that is 68 and mk 2 that is 69-70 and mk 3 that has a different body.

The mk 2 has a different suspension that wouldn't be easy to change out on any of the models

 

[Tybalt]

The first ones had swing axles. This changed with the MK II which went to double jointed axles with the inner joint being a Rotoflex unit. This double jointed axle set up carried on in the MK III through 1972. The 1973 Mk III GT6 went back to swing axles but this was the newer, somewhat improved swing axle set up of the later Spitfires. If you like the earlier body but want the improved suspension, then what you want is a Mk II series which was marketed in the US as the GT6+.

 

[3798j]

It's not difficult to tame the Mk.1's swing axles. Addco makes a 5/8" rear sway bar that will limit wheel travel just enough to eliminate that unwanted tucking. To re-balance the front and rear roll resistance, it's necessary to install the larger front sway bar that was fitted to the Mk.3.
In this photo you can just pick out the rear sway bar.

 

[trrdster2000]

I believe you will find the axle size is larger on the later ones. 1" on later and 7/8" early?? The shock mounting is different, but a kit from Rimmer takes care of it for then rotoflex system.
Our Spit6 project was a choice between the two rear suspensions and when the frame off the GT6 turned out good and on the forum members advise, we went for the Full Monty GT6 underneath the Spitfire body, rotoflex and all.

The conversion from swing axle to rotoflex would not be a easy swop, just saying.

Wayne

 

[Andrew Mace]

Another and arguably better alternative to a sway bar on the early swing-axle GT6 is a camber compensator. Still another alternative is to fit the late Mk3 GT6 (NOT the lighter-duty Spitfire version) swing spring, along with the corresponding fatter front sway bar. Then there's de-arching of the original spring and/or using a lowering block. Lots of possibilities to "tame" a problem that isn't necessary as bad as years of tall tales might lead one to believe.

Oh, and the primary difference between the very early and the very late swing axles is 1" in length.

 

[Scotsman]

I have been told that the addition of the mk3 front sway bar onto a mk1 can add significant weight to to an already nose heavy car. Comments....

 

[3798j]

https://www.sportscars.tv/Newfiles/GT6.html
A road test review from back in the day (that I'm pretty much in agreement with).

"Significant Weight"...no...unless one regards a 1lb. to maybe 2lb. additional weight between the Mk.1's and Mk.3's sway bars as significant.

 

[Andrew Mace]

"Significant Weight"...no...unless one regards a 1lb. to maybe 2lb. additional weight between the Mk.1's and Mk.3's sway bars as significant.

I have to agree. Once you've taken a Spitfire and thrown an extra 225 lb. (two more cylinders) worth of weight up front and ahead of the front axle line, another pound or two isn't going to make a lot of difference, at least not in terms of how additional weight affects handling!

 

[Scotsman]

I have heard that the mk3 has slightly more headroom. Is this a result of a change in seat design (or did they make additional changes to accomplish this). If so will mk3 seats easily bolt into a mk1 car.
I am 6' and some friends have cautioned me against buying a GT6 for this reason.

 

[3798j]

At your height I think you'll be fine when seated. The bigger question is how agile are you? The GT6 is 47" tall (about 41" at door opening). When I bought mine I was 33....sliding in and out was no big deal. Now at 65 it's more of a challenge looking graceful. I still say I'm 5'7".

 

[Andrew Mace]

Other than suspension I have heard that the mk3 has slightly more head room. Is this a result of a change in seat design (or did they make additional changes to acomlish this) and if so will mk3 seats easily bolt into a mk1 car.
I am 6' and some friends have cautioned me against buying a gr6. I have yet to sit in one.

Any changes would've been in the seats themselves, and setas likely are interchangeable.

 

[3798j]

Mk.1's & +'s used the same windshield as the TR4 - TR6. The Mk3 uses the larger windshield of the Spitfire 1500. Someone long in the torso would probably like the view out the Mk 3.

 

[tomshobby]

https://www.sportscars.tv/Newfiles/GT6.html
A road test review from back in the day (that I'm pretty much in agreement with).

"Significant Weight"...no...unless one regards a 1lb. to maybe 2lb. additional weight between the Mk.1's and Mk.3's sway bars as significant.

I found the review interesting. The '67 I had (photo) was a little different than the test car in the report. One of the interesting differences is that mine had a 7,000rpm redline and it was no stranger to it. It could easily reach 55mph in 1st gear. The only real complaint I had was that the clutch would slip badly if it was dumped under power. It was bad enough that the car could just sit unless the throttle was backed off so it could hook up. But, if it did hook up the tires could raise a considerable cloud of smoke. The article remarked that the mileage was 22 - 28. Mine was 33+/-a couple using premium. It was hard on tires. Even worse than the '65 Pontiac GTO I had at the same time. I had a set of 4 Goodyear radials wear out in 3,000 miles. What can I say, I drove it hard and loved every minute of it.