Re-siding the suspension towers on a GT6

[Ian Smith]

Yet another question for the collective, if I may....

I'm building a special, based on the GT6. Assessing the chassis, I'd like to move the engine back (rearwards).  To accomplish this, I notice that the front towers are 'handed'. By re-orienteering the towers, the original engine mounts allow the engine assembly to move back by 6-8 inches (150-200mm ).

Now, here's the question.... has it been done before? Please bear in mind that the modification requires a new firewall/bulkhead, new seating/driving position, and a shorter driveshaft. I don't anticipate making any structural changes to the chassis whatsoever. It will need  lengthening of the steering column. 

In all respects, the wheelbase, and the basic chassis, remains the same. The centre of gravity might change, but the new design loses a lot of bodywork weight from the original set-up. 

Cheers,

Ian.

[dougbgt6]

Ian,

Yes it has been done, one of ours at East Berks, Richard, has a Spitfire with a straight 6 and no power bulge in the bonnet. The engine is moved back into the cabin. Richard posts on here as rlubikey he has posted pictures of his car, but I can't find them at present. He may be along later to explain it all!

Doug

[Clive]

5 minutes ago, dougbgt6 said:

Ian,

Yes it has been done, one of ours at East Berks, Richard, has a Spitfire with a straight 6 and no power bulge in the bonnet. The engine is moved back into the cabin. Richard posts on here as rlubikey he has posted pictures of his car, but I can't find them at present. He may be along later to explain it all!

Doug

I think Richards was done using a spitfire engine front plate (Picton sportscars did a few like that) and does not need the chassis modifying in shape (though a few tweeks may have been required, especially with an OD box)

But yes, swapping turrets should be fine. 

I am guessing you wish to stay within the 8 point rule and avoid IVA?

[dougbgt6]

A picture of Richard's power steering (yes!) showing the engine pushed back into the cabin. On my GT6 you wouldn't be able to see the clutch slave cylinder.

Can't find any other pics but they're on here somewhere!

 

Doug

[Ian Smith]

33 minutes ago, Mathew said:

Good luck with what i understand you are going to do! The doors? I have installed a puma engine in a spitfire and rx8 gearbox. This involved cutting into the bulkhead about 125mm back to fit the engine and making a custom metal tunel cover. It did not need the seats or controls moved . It sounds like alot of work for not alot of gain . But anything is possible if you put time and money to it. Have a look around there maybe some one elsewhere who has done something similar. 

Hi Matthew. No, no doors. Although it's low-slung, the distance from A to B posts is somewhat truncated, so leaving out the doors allows additional strength without weight gain. 

[Ian Smith]

10 minutes ago, clive said:

I think Richards was done using a spitfire engine front plate (Picton sportscars did a few like that) and does not need the chassis modifying in shape (though a few tweeks may have been required, especially with an OD box)

But yes, swapping turrets should be fine. 

I am guessing you wish to stay within the 8 point rule and avoid IVA?

Hello Clive. Two reasons here. Moving the engine rearwards allows me to make changes to the bodywork only. The original mechanical parts won't be touched, other than refurbishment, and upgraded where needed. Secondly, the Chassis & mechanics can be changed back to GT6 spec, should it be needed in the future. If I can't get  the steering column through the front O/S tower, then I'll commission a new tower to allow the column to pass.  Then, keep the original tower so a future owner can move it all back, if they wish. 

The proposed gearbox is a Type 9 conversion, courtesy of Canley.  losing the overdrive here isn't a biggish problem, as the original car didn't have one.... However, any original part(s) recovered will stay with the accumulated parts.

Cheers,

Ian.  

[Clive]

Type 9 is probably a bit slimmer than an overdrive box, I have one in my spitfire (zetec engine) which sits a bit back in the chassis. You may need to trial fit to see what can be done.

Re steering, if the column needs to be longer, you could do what the kitcar chaps do and use a UJ or 2 in order to avoid things.

[Ian Smith]

6 minutes ago, Mathew said:

This in my muddled head has got me more confused! No doors! Or leave where they are? As shown already alot have pushed the engine back but this has only involved the central part modified. There is even someone on who has a rear/mid engined car with mods. So its all do-able just your imagination and careful measurement!

Measure twice, and cut once! Indeed, measure as many times as  needed.  If you imagine an up-scaled Lotus 7, with that lovely straight six. 1930's style bodywork, with everything get at-able; useable, and (hopefully), recognisable to the average Triumph enthusiast.

I used to mess about with a mates Dutton Phaeton: 1600 Mexico engine, Lotus trailing arms. A very, very nice car. I've got a bit older in the ensuing 30+ years, so I want a bit more 'width' and a lot more comfort. A touch more finesse for my old bones....

[Ian Smith]

2 hours ago, Mathew said:

It becomes clearer, will be interesting to see your build progress. You could start a thread on the restoration section. Would be very interesting and bouncing ideas as you come to problems should prove usefull.

Thank you, I will start a rebuild/ restoration thread on here. If the weather is better, I'll take some photos.

[Reg Smeeton]

Swapping the suspension turrets to move the engine back in the chassis is a well tried technique as used in all Burlington Arrows for example.

Reg

[Ian Smith]

3 hours ago, Ian Smith said:

Thank you, I will start a rebuild/ restoration thread on here. If the weather is better, I'll take some photos.

 

3 hours ago, Reg Smeeton said:

Swapping the suspension turrets to move the engine back in the chassis is a well tried technique as used in all Burlington Arrows for example.

Reg

Funny that Reg; that's where I'm also headed....

[mark powell]

Towers swapped round on my Midge. And extra 'brackets' to lift engine front by 2".

[Ian Smith]

Nice, very nice! A picture paints a thousand words indeed. Am I correct in thinking Spitfire with overdrive? I can see your modifications on the engine mounts. Is this to accommodate the new starter motor & bellhousing position? 

Nice work,

Ian. 

[mark powell]

1 hour ago, Ian Smith said:

Nice, very nice! A picture paints a thousand words indeed. Am I correct in thinking Spitfire with overdrive? I can see your modifications on the engine mounts. Is this to accommodate the new starter motor & bellhousing position? 

Nice work,

Ian. 

Yes, basically to stop the bellhousing fouling the chassis where it narrows. It also has the effect of tilting the whole engine / gearbox assembly to improve the propshaft angle.

All these modifications were suggested in the original build manual for the Midge in 1985.

The chassis is modified Herald, the power train is Spitfire 1500 / Mk4 3 rail overdrive box / GT6 prop / 3.89 diff.  15" wheels. 

[JohnD]

There was a successful race GT6, in the ?60s, ?70s? that had the engine shifted back nine inches to achieve near 'mid-engine' balance, I think by using a saloon front engine plate to mount it.    Sorry, I can't recall names, but I think it had a one piece rear body, like a Le Mans Spitfire.

It was featured in retrospect in the Courier, so maybe a search of the Index?

A more moderate move back can be done by putting the rubber mount plate flanges behind the turrets, rather than as standard, in front.  This achieves less than an inch, but that is valuable with the Vitesse where there is almost zero clearance from the radiator.

John

[Ian Smith]

Hello John. The rationale behind the move is both aesthetic and possibly, mechanical improvement. The Spitfire is realistically 2+2, as is the GT6. The frontal aspect of the project will be radically changed, without loss of performance & ability. If you look at Marks photo (2 posts up ) then you'll see what he's doing, which is very similar to my own work. I'm not copying him, honest! Well, only a little bit... 

Moving back the engine allows the introduction of an electric-controlled radiator, so I'm hoping for a win-win situation. I can keep my sarnies in there as well (joke ).

Back to Marks photo. From here, it looks like the movement rearwards  is in order of 6-8 inches. Theoretically, that rearward move can be as much as you need. However, there is a  downside I can foresee, any rearward move is liable to impinge on the cockpit length, and the ergonomics of things like gearchanges, etc. That said, this will be a pure 2-seater. On that basis, the Midge addition/ conversion has great merit. 

Enough for a Roots blower....

 

Have a great weekend,

Ian.

 

 

[DrKai]

On 28/09/2021 at 15:17, dougbgt6 said:

A picture of Richard's power steering (yes!) showing the engine pushed back into the cabin. On my GT6 you wouldn't be able to see the clutch slave cylinder.

Can't find any other pics but they're on here somewhere!

 

Doug

I'm very interested in the cutout of the starter motor bulge. I have also relocated the engine and was looking at removing some of the floorpan to allow the body to be lifted off with gearbox in situ. However this is a much neater solution. I assume it's allowed by the replacement of the original Lucas unit with a HT starter? Is there any more info/ pictures around? 

Thanks

Kai

 

 

 

[dougbgt6]

Kai,

Here is the thread I got the picture from. rlubickey is Richard who comes to East Berks. He post on the forum, but not daily, more like weekly. Best contact with him might be a Personal Message. The second page of the thread shows Peter.H's PS. I had a quick re-read but nobody mentions starter motors.

 

Doug

[DrKai]

Thank you

I've sent a PM. Merry Christmas