GT6 tubular manifold - flexible joint

[Adrian Saunders]

I’ve noticed a comment regarding tubular manifolds, that the 3to1 collector is actually a slip joint and the perils of this. I introduced my own flexi joint (axial and radial flex capable) under the gearbox of my GT6 as it did indeed all look a bit too rigid. Has anyone else tried one of these on the road? My car’s still work-in-progress. 

[Nick Jones]

I think that's a really good idea.  Assume you have the front of the main exhaust section supported just behind the flexi?  Have you also got a steady bracket for the  forward section - off the bell housing bolts perhaps?  Would probably be the final touch if not.

Have  contemplated similar on mine but the fat Toyota 5 speed I have fitted means the exhaust takes a slightly different line and there is less space available.

Nick

[Adrian Saunders]

Thanks Nick. The pipe is supported just after the joint, at the original position off the chassis, adjacent to the rear of the gearbox. I haven’t added a support forward of the joint but I could, it’ll  be clamped to the tube rather than welded,initially, and then welded once proven. I used an ILOC 15050 joint which I welded the clamp extensions onto. If I remember correctly, you can’t get the 150 long x 50 bore joint with extensions. The ends of the joint are swaged-on/aluminised mild steel, but I  cleaned off the Al coating and used Argoshield to MIG weld the mild to the stainless tube with stainless wire. I’ll get you the O/D of the joint tomorrow, don’t think my wife would be too happy if I get it tonight. 

[dougbgt6]

Adrian,

I put a new stainless exhaust on last year, this summer the exhaust started banging on the centre chassis rails. The centre box has about 1/4" clearance on either side.  Slackening off and resetting sorted it, but for how long?  A flexible piece in the down pipe might be the answer or will it make it worse? I'm monitoring your progress with interest!

Doug

[dave.vitesse]

The factory originally fitted a bracket from the exhaust down pipe to the bell-housing on most of their cars. This is often left off.

Leaving it off a 1500 Spit with a standard exhaust meant a blowing down pipe gasket in a few hundred miles! Lovely design. 

Dave

[NonMember]

49 minutes ago, dave.vitesse said:

Leaving it off a 1500 Spit with a standard exhaust meant a blowing down pipe gasket in a few hundred miles! Lovely design.

And the reason I went with tubular.

[dougbgt6]

Would have thought the bracket a little cheaper than a tubular manifold. 

db

[Adrian Saunders]

1 hour ago, dougbgt6 said:

Adrian,

I put a new stainless exhaust on last year, this summer the exhaust started banging on the centre chassis rails. The centre box has about 1/4" clearance on either side.  Slackening off and resetting sorted it, but for how long?  A flexible piece in the down pipe might be the answer or will it make it worse? I'm monitoring your progress with interest!

Doug

Doug, I have (car came with) a rear box only but, the pipe is close to the chassis. Rather than have several clamped joints I welded as much as possible but allowed for disassembly and maint. Also, it is a bit loud so I’ve introduced an easily removable baffle into the tailpipe. Theory is: fire up, don’t annoy my wife and neighbours, drive about a mile to the rear of the NEC, remove one screw and the baffle, make a splendid noise all the way to Kings Norton. 

[dougbgt6]

Adrian,

My old exhaust was stainless in standard configuration, rear box and centre box. The stainless was still OK but the welds had failed and the baffles, no longer baffling. They don't last forever despite what's claimed! I suppose if I could remember who I bought it from 40 years ago I could've demanded a replacement. 

I listened to a lot of club cars before deciding what to replace it with, full sport,  just TOO LOUD! Semi sport, nice, but got a headache after only a short journey. So back to standard, nice burble and still a head turner. Quite a few told me they had initially gone for something sporty, but finally in the long term got it replaced, full to sport to semi, or semi to standard. So, be careful what you wish for. 

Doug

[NonMember]

56 minutes ago, dougbgt6 said:

Would have thought the bracket a little cheaper than a tubular manifold. 

Well, yes, but since I didn't have a serviceable cast manifold either... ?

[dougbgt6]

Rob,

OK I'll let you off. 

My bracket goes to the gearbox, or should there be another one? 

Doug

[rlubikey]

One to gearbox (or is it bellhousing?) and one to diff front crossmember.

Cheers, Richard

[Adrian Saunders]

2 hours ago, dougbgt6 said:

Rob,

OK I'll let you off. 

My bracket goes to the gearbox, or should there be another one? 

Doug

I’ve got one to the tiny x-member under the rear of the ‘box. 

[dave.vitesse]

A hard mount bracket on the bell housing, the gearbox will do. A flexible mounting on the diff carrier and a flexible mounting on the rear.

Dave  

 

[Adrian Saunders]

Scope for bell housing mount? 

[Adrian Saunders]

My small x member mount. Is this an original position? One side of the U bolt goes through an angle which bolts to the chassis x member and there’s a rubber between the angle / x member. 

[Clive]

Is the last one fixed to the chassis or the gearbox?

I ask as if the chassis the engine/box will be wiggling about a bit, and all the movement to fixed will be within a small distance, even with a flexi it is a lot to ask. Maybe worth comparing to a modern flexi-equipped car, see what sort of mounts/distances they use?

The cars have an essential flexible support on the diff, which shouldn't move much, and pretty fixed at the rear, although again rubbers allow some movement.

[NonMember]

12 hours ago, Adrian Saunders said:

My small x member mount. Is this an original position? One side of the U bolt goes through an angle which bolts to the chassis x member and there’s a rubber between the angle / x member. 

I believe that is an original mounting position but I'm not sure what cars used it - might have only been early Spitfires. The WSM shows a hanger there on the GT6 Mk1/2 exhaust but makes no mention of what it attaches to. It's so close to the back end of the gearbox that it's not clear.

[Adrian Saunders]

I’m going to change mine to: bell housing, off diff front mount and  off rear valance. 

[Adrian Saunders]

On 9/6/2018 at 10:10 PM, Nick Jones said:

I think that's a really good idea.  Assume you have the front of the main exhaust section supported just behind the flexi?  Have you also got a steady bracket for the  forward section - off the bell housing bolts perhaps?  Would probably be the final touch if not.

Have  contemplated similar on mine but the fat Toyota 5 speed I have fitted means the exhaust takes a slightly different line and there is less space available.

Nick

Hi Nick, ILOC 15050 is 71 mm o/d. 

[Nick Jones]

Yeah...... thanks for the info........ but mine looks like this.  There's also an O2 sensor you can't see.

I do have a MTP 6-3-1 to fit (once I get around to having it blasted and aluminium sprayed), so maybe then.

Nick

[Don Cook]

I have a Phoenix 6-3-1 and it has/had a push fit collector. I cut a slot and welded nuts so it can be clamped up tight. No problems since.

I too had the centre silencer banging on the chassis rails and as its a TSSC stainless system I got Bell silencers to make me a straight-through pipe. Bit noisy though.

[Adrian Saunders]

On 07/09/2018 at 20:48, Adrian Saunders said:

Scope for bell housing mount? 

After a few of rounds of 3D printing and adjusting of holes etc, a stainless steel bracket was bolted in tonight. Yes, there’s too much material but that’s intentional, I’ll trim off any excess. I think I’ll do a 20 mm wide strap (akin to a U-bolt), 2 mm thick, to keep the pipe in place. All suggestions will be greatly received. PS: I had two brackets made. 

[Adrian Saunders]

Right, after several months, I’m just about there. The bracket in the picture is mk 4! The plain nuts on the clamps will be changed for K nuts. Few changes en route to mk 4: hole centres, bend angle, thickness, clearance cut outs. 

[Adrian Saunders]

Now with K nuts.