My Voigt 5-speed conversion

[steve lyle]

And if you ever wondered what was inside of a T9 tailshaft - here ya go:

[1owner69Elan]

I suppose you haven’t heard from Alan yet as to the possible origin of the chips.

I just locktited my plug in place. In the process I did tilt the whole gearbox upright to get the plug that Alan supplied out. That plug was too small and got pushed well into the shaft by mistake as I was checking the fit. To get it out I tilted the tailpiece up and then tapped the tailpiece shaft bore until the plug fell out under gravity. Presumably any chips in the bore would have also been expelled. Nothing else came out.

Now knowing what you found, I would reinspect the bore, but having loctited the plug in place it would be difficult to remove. I guess I’ll roll the dice and hope I don’t have the swarf blocking the rail movement that you had.

I just hope that you have found the root cause and can move on.

[1owner69Elan]

Another thought regarding the origin of the aluminum chips. Your shaft bore plug has a retention screw. I had (and have) no such provision. Nor did the other poster that had a Welch plug in place.

Perhaps in drilling and tapping for that screw the swarf from that process was allowed to tumble into the bore.

[alan.barker]

Well done Steve,
now at last you can go forward.
Good luck with the assembly.
Alan

[vxah]

Just a moment though, my understanding of the issue is some sort of debris in the shaft bore preventing full selection of 5th gear?
The result was a grinding of the dog teeth between 5th gear and the hub outer ring?
So what damage has been caused to either part? Hard to see in the photo but there looks to be some shiny flattened off teeth? I might well be wrong but please check carefully before re-assembly!

[steve lyle]

Just a moment though, my understanding of the issue is some sort of debris in the shaft bore preventing full selection of 5th gear?
The result was a grinding of the dog teeth between 5th gear and the hub outer ring?
So what damage has been caused to either part? Hard to see in the photo but there looks to be some shiny flattened off teeth? I might well be wrong but please check carefully before re-assembly!

Good point. I did check that out, but all I could see was shininess - no flattening. The shape of the teeth seems to be unchanged to my eye.

[steve lyle]

Well, maybe that wasn't the problem.

I talked to Alan and Mark this morning, and they had me look down into the shifter opening when the tranny was in 5th. I shouldn't have been able to see the 5th gear dog teeth, but I could just see the back edge of them, which was a concern. So I took the tailpiece off when it was in fifth, and took this picture. I measured it at about 1/16" of the teeth showing.

I sent them a couple of emails yesterday that they still haven't gotten. So we decided to post the pic here so that they could see them when they get home, since they have no computer at the shop.

So here it is, Alan & Mark - what do you think? (If you click on the picture, you'll see a larger version).

In this picture, "up" is to the top of the picture, so gravity is pulling the shift hub down. There's enough play in the shift mechanism so that I can lift the shift hub up to fully cover the teeth.

[steve lyle]

Alan/Mark just called. Their diagnosis is that they drilled the shift rod just slightly in the wrong place - the dog teeth should always be covered, and they clearly aren't. This isn't adjustable, so they're sending me parts from a tranny that they just built and know is good, and I'll swap them out and we should be good to go.

Meanwhile, I've ordered a BMW grommet, more Red LIne MT90, and an MGB gaiter. Alan's already sent me a replacement reverse switch. So I should be in a position to get everything fixed up early next week.

[1owner69Elan]

I just checked my Voigt box in fifth. Peering into the lever hole the dog teeth on fifth are completely covered. The collar completely covers them. You cannot see any portion. Not like what your picture shows with the dog teeth exposed.

I tried to take a picture:

voigt 5th.jpg (73.75 KiB) Viewed 1093 times

So, it looks like the your problem has been identified.

[steve lyle]

I just checked my Voigt box in fifth. Peering into the lever hole the dog teeth on fifth are completely covered. The collar completely covers them. You cannot see any portion. Not like what your picture shows with the dog teeth exposed.

I tried to take a picture:

voigt 5th.jpg

So, it looks like the your problem has been identified.

Then you're good. Mine is likely a one-off problem, since they haven't seen this issue before. I'm sure they'll be watching for it from here on out.

This has been quite the adventure! I prefer driving adventures, but you take what you can get, I guess.

[1owner69Elan]

My uprated clutch friction plate for the Voigt gearbox arrived from the UK: AP Racing CP5352-5

I could not find one of these in the US and many of the UK suppliers were sold out and not expecting any resupply soon from AP. Obtained one from:

Motorsport Tools UK Ltd,
Llithfaen,
Pwllheli,
Gwynedd,
N Wales,
LL53 6NH.

(no affiliation). Quick delivery, Competitive price.

The AP plate is much more substantial than the standard one provided by Voigt and I think necessary for my uprated engine.

Marginally larger, 1/4" in radius. Friction material surface area on the AP is 40% greater. But, a lot of that area (~75%) is due to the larger radius, and presumably able to transfer more torque. I cannot assess the friction characteristics of the different organic materials but the AP appears to have more metal to it.

The AP weighs 206 grams more. The springs are of larger gauge on the AP. The overall construction appears more robust.

I believe that the clutch cover on my car (yet to be removed) is also an AP with a ~170 lb-ft torque rating (supplied by Dave Bean). This new AP friction plate, compatible with the T9, should be an appropriate match.

[1owner69Elan]

One more piece of the Voigt kit that I am replacing is the shift saddle. I had posted before that it looked like in my testing of the gears that I might have damaged it. I now think that the saddle was just an old one retained during the building up of the gearbox. The amount of scoring and chewed up bits of plastic do not comport with the minimal amount of test shifting that I did with the uninstalled gearbox.

Here is a comparison of the new shift saddle (white) vs the existing one delivered with the Voigt gearbox.

I think this is a reminder that these 5-speed kits are not made from new materials. An existing, used Type 9 box is the starting point. In the process, presumably serviceable parts are retained in cases where the new Lotus conversion parts are not involved. For example, existing gears are normally retained (synchros, bearings, etc, as well?). That is partly why I opted for a completely new BGH gearset.

The existing shift saddle, I suppose is serviceable, but with a broken tab and the erosion evidenced, I would not have hesitated to replace it. Apparently, these are an expendable item and get replaced as the gear shift action becomes less precise over time.

I could be wrong about the shift saddle not being a new piece but the evidence seems to contradict that. In any event, I have a new one to now install. And one less excuse for not proceeding with installation.

[2cams70]

The AP weighs 206 grams more. The springs are of larger gauge on the AP. The overall construction appears more robust.I believe that the clutch cover on my car (yet to be removed) is also an AP with a ~170 lb-ft torque rating (supplied by Dave Bean). This new AP friction plate, compatible with the T9, should be an appropriate match.

You might want to ask Voight about their opinion of the AP clutch plate. With clutch plates bigger and heavier is not necessarily better. Best to only fit what you actually need.

The synchcronisers need to speed up and slow down all that clutch plate inertia during gear changes. A larger clutch plate will force the synchronisers to work harder and potentially therefore make the shift quality slower and baulkier than it otherwise might be.

[1owner69Elan]

The AP weighs 206 grams more. The springs are of larger gauge on the AP. The overall construction appears more robust.I believe that the clutch cover on my car (yet to be removed) is also an AP with a ~170 lb-ft torque rating (supplied by Dave Bean). This new AP friction plate, compatible with the T9, should be an appropriate match.

You might want to ask Voight about their opinion of the AP clutch plate. With clutch plates bigger and heavier is not necessarily better. Best to only fit what you actually need.

The synchcronisers need to speed up and slow down all that clutch plate inertia during gear changes. A larger clutch plate will force the synchronisers to work harder and potentially therefore make the shift quality slower and baulkier than it otherwise might be.

I guess we will have to see if the shift quality is degraded. But, with 181 bhp (vs Sprint 126) and 143 ft-lb (vs Sprint 113) I think I need the uprated clutch.

This AP clutch setup is often used with the T9 for higher outputs. I haven’t picked up on concerns about poor gearbox shift quality.

[JohnCh]

I wouldn't worry about that clutch creating any long term issues with the BGH gearbox. That's a common clutch/gearbox combination on Caterhams and Westfields. I have it in my car, and it's still going strong after 25k miles.

-John