My Voigt 5-speed conversion

[rgh0]

I know nothing about the T9 box but I would be asking myself 2 questions

1. What is the function of the tab in the first place? It must be there for a reason in the original change mechanism?

2. Does that reason still apply in the modified Voigt mechanism ?

Once you can answer those questions you can tell if its safe to just remove the tab or whether you need to modify the Voigt mechanism so the tabs function can be achieved in some way.

cheers
Rohan

[1owner69Elan]

I know nothing about the T9 box but I would be asking myself 2 questions

1. What is the function of the tab in the first place? It must be there for a reason in the original change mechanism?

2. Does that reason still apply in the modified Voigt mechanism ?

Once you can answer those questions you can tell if its safe to just remove the tab or whether you need to modify the Voigt mechanism so the tabs function can be achieved in some way.

cheers
Rohan

I am just getting acquainted with the T9 myself but I am pretty sure that the answers to the questions you raised are:

1. The tab keeps the saddle from rotating out of position as you insert the shift lever fork.

2. This also is of importance with the Voigt box, but the custom tailpiece casting of the Voigt box interferes with the saddle tab, unlike a standard T9. However, with the saddle properly snapped onto the shaft and rotated into position and then carefully inserting the lever, you can still ensure alignment. Once inserted the fork keeps the saddle in position without reliance on the tab. It can no longer rotate but provides a sliding interface mechanism between the fork and the shaft, and is held captive by the fork.

Thus, I think the tab can be removed, so long as you ensure that you guide the lever fork into the saddle. After all, if this tab was important I would hope that Voigts would not have delivered the gearbox with the missing tab on the saddle.

I don’t think grinding the Voigt casting down to accommodate the tab makes sense. The tab only plays a role when installing the lever not for the functioning of the mechanism under operating conditions. This is further evidenced by how flimsy the tab is, easily snapped off in the standard plastic version.

A saving grace is that the saddle can presumably be replaced in situ after gearbox installation. The plastic part is a maintenance item, eventually wearing down and leading to a loose lever and poor gear change quality. The metal version potentially obviates this, not wearing out. But, it may need to be greased periodically to reduce noise.

[rgh0]

That makes sense. If the tab was only there to aid production line assembly and has no real function once assembled, then with careful assembly to ensure the saddle and lever are correctly positioned it can be safely removed.

cheers
Rohan

[pharriso]

It appears that a saddle with any tab basically does not fit the Voigt box. ...........

In both non-Voigt cases the saddle tab sits on top without restricting the full seating of the saddle onto the shaft, unlike the Voigt T9 conversion.

At this point, I suppose I need to use one of the plastic ones (broken tab or deformable tab) or grind the tab off of the metal one. .....................

As I posted earlier, my saddle (removed from a fully fuctional & just serviced by Voght T9) has no tab, Reading both your analyses it looks like it is not needed.

[1owner69Elan]

I checked the gear ratios on my gearbox again as I had not carefully verified the fifth gear ratio previously, figuring it was either 0.82 or 0.84, the two options offered.

What I had thought I had ordered was the BGH "Sporting Close" gear set:

2.66 / 1.75 / 1.26 / 1. 0 / 0.82

While gears 1-4 align with this specification, the fifth gear measurement is closer to 0.75 (perhaps a little less). I was surprised by this and didn't know such an option might exist. I had asked Alan for a tall fifth so maybe he used this alternative. I didn't find much on the net regarding such a ratio for the type 9, except for a Caterham specification that included a 0.75 fifth:

"Caterham 7 Sigma engine Ford Type 9 gearbox taller ratio gear set"
https://www.type9gearbox.co.uk/store/p3 ... r_set.html

So, apparently such a tall fifth gear ratio (0.75) for the Type 9 does exist. I have reached out to Alan for a clarification.

I would note that if this tall fifth is indeed installed in my box, I am quite fine with it as I was looking for an overdrive type gear for relaxed cruising. The first four gears give me the acceleration and performance up to 120 mph already. My engine with a broad (and elevated) torque curve should allow moderate acceleration in fifth and also not having to downshift into fourth for climbing (at speed). This O/D fifth with my tires/diff will yield around 3000 rpm at 70 mph and ~3400 at 80.

It is interesting that with this tall 5th the theoretical maximum speed at a 7K redline would be 160 mph. I know some on the forum have reached 140+ mph in a racing situation. With 277 bhp/ton my car perhaps might approach this theoretical 160 mph maximum but I will never know.

Puzzled by the apparent long 0.75 fifth gear in my Voigt gearbox (expected 0.82) I have been trying to reverse engineer the number of teeth in my gearbox from the observed ratios.

The overall ratios that I thought I ordered were:
2.66 / 1.75 / 1.26 / 1.0 / 0.82
This is the close ratio BGH gearset (Heavy Duty 2.8 Sporting Close).

I did not find a lot of information on main and layshaft tooth counts. Referring to the following two articles:

1. https://www.classicfordmag.co.uk/wp-con ... -guide.pdf. This gives the main shaft gear tooth counts for the BGH gearset.

2.http://www.middlebridge-scimitar.co.uk/ ... /type9.pdf . This gives the tooth counts for the 2 Liter Standard T9 (18/34 input shaft ratio) and the 2.8 Liter Standard T9 (19/34 rato) .

From this data and my empirical measurements of the input vs output revolutions (I did not disassemble the box to count the teeth) I get the following for my gearbox which indicates a combination of both the 2.0 and 2.8 gear sets:

Main input: 19 Layshaft: 33 (33/19) .(This corresponds to the 2.8 liter T9 version)

First gear: Main: 30 (from BGH article ) Lay: 20 (assumed) (30/20)
Overall ratio : 2.61 (calculated) - vs 2.66 spec. Observed ~2.66
I have not been able to resolve this yet. The standard T9's have 30/19 or 29/15 or 31/19 or 29/15. None of those pairs yield 2.66

Second gear:Main: 25 (from BGH article) Lay:25 (assumed) (25/25)
Ratio: 1.74 (calculated) vs 1.75 spec Observed: ~1.75
The standard 2.0 and 2.8 T9 both have a 25/24 pairing

Third:Main: 21 (from BGH article) Lay: 29 (assumed) (21/29)
Ratio: 1.26 (calc) vs 1.26 spec Observed: ~1.26
The 21/29 pair is the same as both standard T9's

Fourth: Direct

Fifth:Main: 19 (BGH article) Lay: 44 (assumed) (19/44)
Ratio: 0.75 (calc) vs 0.82 spec. Observed: ~0.75
The 19/44 pair is the same as the fifth on the standard 2 Liter T9 




Thus, I conclude:
1. The 0.75 fifth does in fact exist, confirming my observations. It is achieved by using the standard 2 Liter T9 fifth pair in conjunction with a 19/33 tooth main input from the 2.8 Liter vs 18/34 from the 2 Liter. A bit of each box.

2. It makes sense that I have the 19/33 input of the 2.8 liter because I supposedly have the more robust, heavy duty layshaft bearing of the 2.8.

3. To achieve the specified 0.82 Voigt would have had to swap out the standard 2.0 fifth ratios of 19/44 for 19/40 (standard for the 2. but he didn't do that. I would note that I have found this 0.75 fifth ratio offered by some T9 suppliers, further confirming that it does exist as an option.

4. Can't explain the 1st gear ratio discrepancy of 2.61. Given that the other gears match up, I think I have surmised the correct input ratio (main to layshaft) given that gears 2-5 all seem to match up with observables and spec.

5. I'm OK with the apparent ratios of my box as delivered. But, I might have expected to be informed about the change in the fifth gear ratio from what was offered and thereafter chosen by me (0.82). Others with a less powerful engine presumably might not be happy with such a long fifth (0.75). Also, probably less likely to be desirable for racing applications.

[steve lyle]

Alan's parts arrived today, along with instructions on fitting them.

Here's the before and after pics of the 5th gear dog teeth.

[1owner69Elan]

I think it looks good but let the Voigts give their final blessing.

Looks like you’re back on track!

[steve lyle]

I just got off the phone with Alan - he says it looks good, go ahead and put it in the car. Woohoo!

[1owner69Elan]

Congrats. Great that you could fix this yourself with help from Alan.

[steve lyle]

I just got off the phone with Alan - he says it looks good, go ahead and put it in the car. Woohoo!

Hold the phone. I fit everything back on to the transmission, and verified that I have a speedometer gear issue. I had mentioned this to Alan, and he had assured me that the problem wasn't in the transmission. Stupid me, I dropped the issue, until now.

I uploaded a video to show the issue - here's the link: https://youtu.be/w1FHDZ8XPEY

I thought maybe I had switched his pinion with my old one. My old one is green, and definitely a larger diameter, but it doesn't mesh with the worm gear, so I don't think that's the issue. My pinion is just too small of a diameter, methinks.

And no, you can't get to the thing once it's in the car, so this is a showstopper for now. Kicking myself for not following up on this sooner.

[pharriso]

Steve, this is the Speedo Gear in my Voigt box:

Looks to be 24 teeth

Obviously black, the Root Diameter is 0.84" & the OD 1.025"

Your gear is just too small.....

[steve lyle]

Steve, this is the Speedo Gear in my Voigt box:

Obviously black, the Root Diameter is 0.84" & the OD 1.025"

Your gear is just too small.....

But my gear is the same size as yours. Does yours work?

[alanr]

Just a thought...
If the size and diameter of the speedo gear is the same for both of you, is it the depth placement of the gear in relation to the gear on the mainshaft that is perhaps the problem?...either the gear is too long or too short?

Alan.

[pharriso]

Steve, this is the Speedo Gear in my Voigt box:

Obviously black, the Root Diameter is 0.84" & the OD 1.025"

Your gear is just too small.....

But my gear is the same size as yours. Does yours work?

Gearbox is on basement floor, but the Gear seems positely engaged, let's see if I can find a meaningful measurement with what it meshes with...

[steve lyle]

Just a thought...
If the size and diameter of the speedo gear is the same for both of you, is it the depth placement of the gear in relation to the gear on the mainshaft that is perhaps the problem?...either the gear is too long or too short?

Alan.

The pinion is bottomed out in the hole of the tail piece. The worm gear seems to be contacting the pinion (to the very limited extent it does) in the middle of the pinion cogs, so I don't think that's the problem.

i think the vertical hole that the Voigts drill in the tail piece is just a bit (the depth of the pinion teeth) too far outboard.

I talked to Alan, he's going to check the diameter of a known good pinion. If it matches mine, then he'll be sending me a new pinion carrier in which the pinion shaft hole is offset inboard. Might make the right angle drive a tight fit, but I guess we'll cross that bridge if need be. Anyway, sounds like they've seen this problem before...

BTW - Mr. Oneowner - I asked Alan about your 5th gear ratio - he confirmed that it's .75. He thought that he might have told you differently earlier, confusing you with another customer from Holland.