Dolly 1850 single rail gearbox in to mk3 GT6

[Clive]

1 hour ago, Peter Truman said:

Firstly Pete re using a resin adapter as the concentric slave is in compression, remember when the clutch is engaged the rotation of the clutch release bearing will put a frictional rotational force on the slave housing so it should be positively held, also the slave needs to be accurately positioned so the circumferential gap to the input shaft is equal all the way around. I think I'd prefer a positive restraint as per the fabricated adapter plate,

 

Oh I do wish I could find the earlier Dolly 1850 3 Rail J Type OD Gearbox, what an easy replacement for the Vitesse that would be, just the clutch, speedo pinion & gearbox mounting to sort, I have spare Bellhousings! Dream On!

Please tell me where you think I'm wrong or stuffed up, or what I've forgotten.

 

Peter T

 

Re the concentric slave cylinder (CSC) , it is ALWAYS in contact with the clutch cover, and most CSCs are preloaded, so when fitted is is compressed, the internal spring (not insignificant) keeps it all in contact. Not an issue in the slightest, most cars made in the last 20 years have a CSC. And they are reliable. So I would notwant to use anything other than metal for the mount, it will get hot, compressed hard many times every journey and suffer all sorts of vibration. Besides, it is made from a flat piece of ali, and if a machine shop is available, not tricky to get right. Hard to do so in your average home garage with a holesaw, as I discovered. But as per earlier comment, the hardest part is getting a "clearance" measurement to allow for clutch plate wear. There is a fine line between that and running out of movement and the CSC popping apart.

Re the early dolly 3 rail OD boxes, they use the same clutch as a vitesse, coarse spline. Speedo pinion set for 3.63 diff, though I can't recall if the speedo in a dolly is one of the  TPM100000 type, so that would throw things out. (I have a feeling the J type equipped cars were all the same speedo TPM? and calibrated via speedo pinion drive in the box. Info would be good to confirm)

[johny]

Peter, all the 3 rail cases I have seen are the same and perfectly interchangeable. Also if you go to an 1850 3 rail unit its quite possible there won't be a thick mainshaft tip which is one of the principal benefits of the single rail.

[thescrapman]

The 1850 3-rail has small mainshaft tip. Got one in bits at the moment

[Nick Jones]

41 minutes ago, thescrapman said:

The 1850 3-rail has small mainshaft tip

This is true.  Aftermarket versions with the large tip are also available but also require the input shaft to be modified to match.  They are often knackered and needing repair anyway.

Nick

 

[Nick Jones]

14 hours ago, GT6M said:

Why any body would want t,use a single rail is beyond me,

its bigger, heavier, totally numb t,work on, and no as good a shift

Bung yer bits into a 3 rail case

Having tried most variations...... the best change I have ever had from a Triumph box was form the ex Dolly 1500 single-rail with OD I had in my Herald.  Just carefully built and with the gear lever shortened to remove the insulating bush.  It stayed nice too.  No bushes in the remote to fall apart....  However, as noted, it did weigh as much as a small planet!

Nick

[johny]

2 hours ago, thescrapman said:

The 1850 3-rail has small mainshaft tip. Got one in bits at the moment

Out of interest has it got the larger synchro rings and quieter gear angle?

[Peter Truman]

Well that's a bummer re the Dolly 1850 having the small tip mainshaft, rather empirical considering there not available anyway.

I have a Dolly 1850 OD Single Rail Box that I will convert to a 3 rail for the Vitesse that will leave me with a new Mike P TKC899 small tip mainshaft and a D Type Adapter Plate 313085 that I'll sell as there NLReqd.

Now to see if I can pick up a 3 Rail case locally. & search for the selector reverse washer 158585, and 1st/2nd selector sleeve, UKC0706 and Spit MkIV 3 rail reverse shorter distance piece 137687, if I knew it's length I could modify the existing single rail 22G1435 to suit, can anyone advise?

Thanks for the info

Peter T

[Graham C]

Originally I was told by various people that the 1850/J type OD  single rail box was better than 3 rail D type OD, in addition, if retained as is, it was easier to fit. Attempting to convert this into a 3 rail box with J type seemed to be harder, though interesting I could see be going wrong as I have never rebuilt a gearbox.  Looking at Peter's shopping list and the various comments I still believe this for me a better route, however people have various comments, beliefs and thoughts which make life so interesting. At the end of the day no one is right or wrong.

Graham

[johny]

What we want Graham is your comments on driving the finished article👍

[thescrapman]

10 hours ago, johny said:

Out of interest has it got the larger synchro rings and quieter gear angle?

It has the same synchro rings as Vitesse / GT6 and gearset from Mk3 GT6, which seems to differ in the angle on 1 gear, possibly second, to a Vitesse

[thescrapman]

7 hours ago, Peter Truman said:

Well that's a bummer re the Dolly 1850 having the small tip mainshaft, rather empirical considering there not available anyway.

I have a Dolly 1850 OD Single Rail Box that I will convert to a 3 rail for the Vitesse that will leave me with a new Mike P TKC899 small tip mainshaft and a D Type Adapter Plate 313085 that I'll sell as there NLReqd.

Now to see if I can pick up a 3 Rail case locally. & search for the selector reverse washer 158585, and 1st/2nd selector sleeve, UKC0706 and Spit MkIV 3 rail reverse shorter distance piece 137687, if I knew it's length I could modify the existing single rail 22G1435 to suit, can anyone advise?

Thanks for the info

Peter T

I have 2 or maybe 3 single rail 1850 boxes to convert to 3 rail, so mods to bits is of interest to me.

keepmus updated as to what's you find

[johny]

11 hours ago, thescrapman said:

It has the same synchro rings as Vitesse / GT6 and gearset from Mk3 GT6, which seems to differ in the angle on 1 gear, possibly second, to a Vitesse

Im losing the plot here, as listed by Rimmers I thought the 3 rail boxes in 1850 (s/n WM) and Mk3 GT6 (s/n KE) all had the larger synchros and all other GT6 and Vitesse had the small ones. You can easily tell the synchros apart because the small ones had 4 channels cut through the cone grooves and the larger had 6....

[Graham C]

Johny -"What we want Graham is your comments on driving the finished article👍 "

I would like to feed back, but I have to sit at home with this gorgeous weather working, and having to wait until the weekend.

Basically I need to make the cover plate of the prop shaft, fit the gearbox cover and the interior. Service and then get an MOT at my local garae who I am attempting to keep going by getting varous modern family cars seriviced and MOTed. He has seen his MOT business drop and the folow on work.

I have booked off a holiday on Friday to get it done.

Easy enough work but the just need to get out there.

Hoping to get it MOT next week.

AND PETROL IS SO SO CHEAP!!!! no way to go

 

Graham

 

 

[johny]

54 minutes ago, Graham C said:

Johny -"What we want Graham is your comments on driving the finished article👍 "

I would like to feed back, but I have to sit at home with this gorgeous weather working, and having to wait until the weekend.

Basically I need to make the cover plate of the prop shaft, fit the gearbox cover and the interior. Service and then get an MOT at my local garae who I am attempting to keep going by getting varous modern family cars seriviced and MOTed. He has seen his MOT business drop and the folow on work.

I have booked off a holiday on Friday to get it done.

Easy enough work but the just need to get out there.

Hoping to get it MOT next week.

AND PETROL IS SO SO CHEAP!!!! no way to go

 

Graham

 

 

I can see the problem with work getting in the way but one thing you might be best off driving it before the cover and interior goes back. This will be noisy but could be useful for leaks etc

[thescrapman]

12 hours ago, johny said:

Im losing the plot here, as listed by Rimmers I thought the 3 rail boxes in 1850 (s/n WM) and Mk3 GT6 (s/n KE) all had the larger synchros and all other GT6 and Vitesse had the small ones. You can easily tell the synchros apart because the small ones had 4 channels cut through the cone grooves and the larger had 6....

I will have to have a look.

 Same synchro in a 1850 3-rail box as a Mk4 Spitfire box I think as I am sure I was testing some between 2 boxes

[johny]

Yes some normality has been restored! That'll be the bigger ring and they're worth having as the older type seem to wear out pretty quickly.....

[Graham C]

Latest update.

On Friday I fitted the gearbox tunnel and as expected it did not fit. I had to extend the shoulder at the rear of the tunnel, I cut down though the gear level hole and then across the top of the rear, where the prop shaft coupling would be covered. Then moved the cut section back by about 20mm and then made to plates to to fit either side to 're attach it. If you move back to far then the gear lever hole becomes to big for the rubber  gatter.

Lined the tunnel with sound/ heat proofing, and edged it with 20x10 foam.

Saturday took the car for a quick run down the road to everything, OD did not work, did last year now nothing. Spent 2 hrs sorting that out, believed the solenoid was sticking. Rest of the day spent fitting the tunnel, enlarging fixing holes so they would fit. Screwed it down.

Sunday finished off fitting the two screws that fix the tunnel to the bulk head from the inside, now remember these were fitted from the outside. Refitted the drivers side parcel shelf, seats.

Took the car for another test drive, guess what OD did not work.

However changing gear is smooth and the car is totally different to drive. I have suspected someone, PO had fitted an OD diff to the standard non OD gearbox and the car was rubbish, very disappointing. Now a lot move responsive and quicker.

I will visit minty lamb to get speeds and revs from his database to check, but I am confident this has sorted that problem.

So the previous gearbox sounded like an old Bedford lorry, now it's sounds really nice, smooth gear changes and car drives better.

I know I have an oil leak from the rear seal so I will need to work on that and will sort out the OD at the same time later on in the year.

My next move will get the car MOT and on the road and enjoy it for a while, I know the OD works so it has to be either the limiter switch or the solenoid.

Would I do it again, yes but hopefully quicker now I know the pitfalls.

Graham

 

 

[johny]

Sounds good Graham, only  I don't understand the diff bit. The two  gearbox ratios are identical and the OD just drops the cruising revs. The OD diff will give faster acceleration than the non OD one with either box. The idea was that with an OD model you had better acceleration but kept the relaxed cruising as well...

[Graham C]

Hello Johny

My understanding was that the gear ratios in an overdrive box were slightly different on the 3rd and top gear, to that of a standard box. I had checked the car at various speed and RPM against Minty Lambs calcultion and came to the conclusion I had to have higher revs than thoses caluclauted to achieve certain speeds, so put this down to an incorrect diff. I also jacked the car up and check the wheel rotation and thought the diff had an over drive diff ratio.

I noticed the new Minty Lamb only has one set of gearbox ratios, so may be my original thought about gear ratios is wrong.

I have done a quick check on various websites and it does not seem conclusive, some show Non OD 3rd as 1.25:1 and 4th as 1:1, and OD 3rd as 1:1 and 0.8: 1 and simarly the diff are show Non OD as 3.27:1 and OD 3.89:1. May be the OD ratios are after the OD has been activated?

Graham

 

[NonMember]

1 hour ago, Graham C said:

My understanding was that the gear ratios in an overdrive box were slightly different on the 3rd and top gear, to that of a standard box.

I do not believe this to be the case. I believe the same gear cluster was used with or without overdrive, certainly on the small car gearbox. There were differences between 3-synchro and 4-synchro gears, and I think between Spitfire and GT6, possibly between 3-rail and single-rail, but not for OD fitment.

The GT6 WSM gives the number of teeth on the input shaft as 19, and on the 3rd gear as 22, with corresponding countershaft gears as 26 and 24. This makes the 3rd gear ratio 26/19*22/24=1.2544 while the D-type O/D is quoted as 0.802 (I believe the J-type is 0.797). This means that 3rd-OD would be 1.006 (D-type) or 0.9997 (J-type) - both might as well be 1:1

The standard GT6 diff was 3.27:1 without OD and 3.89:1 with... on most models. There were exceptions both ways and special order options. If you plug those figures and the standard 155/13 tyres into MintyLamb, the OD-top figure is 21mph/1000RPM while the non-OD with longer diff gives a little over 20. So there's a small difference in overall gearing between 4th in a non-OD car and 4th-OD, the same difference for 3rd. The raio from 3rd to 4th is the same for both.

[johny]

The fairpoint.net site has a good table which shows all models of GT6, Vitesse 2L, Dolomite 1850 and Tr7 (4 speed) had the same ratio forward gears. However apparently not all are the same design as there were changes to teeth angles and synchro cones.

[Graham C]

Hello

Thank you, you learn something new everyday. I was told years ago the gearbox had different ratios and may be the way some ratios are presented give the impression that ratios are different.

Anyway I feel the car drives better and it has been an enjoyable journey.

Hopefully people will find the information useful and can improve on it. If you do than please add to this thread your improvements if you fit a1859 single rail gearbox with OD.

Graham

 

[ahebron]

I removed the gearbox from my Vitesse 6 today to release the clutch that had rusted to the flywheel. 
As I have commented and asked questions in this thread I decided not to start another thread.
Is this a 3 rail 1850 overdrive gearbox?
In picture of the reverse switch the adaptor plate between the overdrive and gearbox doesnt look right to me.
Gearbox housing number is DC94713 AAW 

Thanks
Adrian

[johny]

It's definitely a 3 rail box but has the later j type overdrive. I don't recognise the serial number but that's nothing unusual!

[NonMember]

It's not a standard Vitesse/GT6 box as it has a J-type overdrive. The gearbox number stamped on there with a "DC" prefix I don't recognise but there seems to be another number there with an MW prefix, or possibly AAW upside down? The adapter is odd. I suspect it's been built up out of a mix of parts from different vehicles.

Edit: On second look, that J-type has the extra fixings on top of the tail for a single-rail gearstick assembly fitment. The adapter oddness is probably because that, too, is for a single-rail box.