I'm a bit Stuck

[Carledo]

The Vitesse 2 ltr and GT6 3 rail boxes are identical, including all internals, the 1600 Vit box is different, being more closely related to the 3 synchro Herald box.
I would guess, to use a single rail box in a GT6 you would have to use a 1500 input shaft (the 1850 one is longer, I think) and the original bellhousing, which I'm pretty sure bolts up to either case. But I don't know why you, or anyone else, would want to, the 3 rail box is unique to the small chassis 6 cylinder cars and whilst it's not all that strong, I reckon it's still stronger than the single rail which was never meant to be in anything bigger than a 1500 ohv. I know the later 1850s got it, but that was more to do with the accountants than the engineers!

Steve

And BTW my prayers go with you too, get well soon mate!

[DazasDolly]

My understanding is that an 1850 single rail od box with a vitesse bell housing will fit a vitesse without modification, that's what I'm fitting to the vitesse when I get there

Cheers

Darren

[Jon Tilson]

Much as I dislike disagreeing with Steve I dont think there is a lot to choose between 3 rail and single rail for toughness...

The layshaft and need roller bearings are identical....most of the gears for the same application are too....

It was used in the TR7 4 speed with no issues, so is quite capable of dealing with the TR7 dolomite conversion. The TR7 version was supposed to have uprated bearings (extra roller), and I have used these on all boxes I have rebuilt.

Most box failures I have seen on either type are due to nutters bump starting in reverse and knocking teeth or shrapnel off the laygear
and the debris doing damage eslewhere.

Jonners

[Carledo]

Much as I dislike disagreeing with Steve I dont think there is a lot to choose between 3 rail and single rail for toughness...

The layshaft and need roller bearings are identical....most of the gears for the same application are too....

It was used in the TR7 4 speed with no issues, so is quite capable of dealing with the TR7 dolomite conversion. The TR7 version was supposed to have uprated bearings (extra roller), and I have used these on all boxes I have rebuilt.

Most box failures I have seen on either type are due to nutters bump starting in reverse and knocking teeth or shrapnel off the laygear
and the debris doing damage elsewhere.

Jonners

Maybe I'm just a bit old fashioned! Or out of date! I have to admit, that when I was regularly messing about with 3 rail boxes it was the mid 80s, when single rail o/d boxes were mostly still in the Dolomites they were in from new, not in the scrappies! Only the 1500 Spit single rail box was around in any numbers and it wouldn't have occurred to me or my contemporaries to put a Spit box in a GT6 when the GT6 box was already marginal.
Most terminal or near terminal 3 rail box failures (I don't count layshaft/bearing wear, that's normal) I have seen concern failure of the mainshaft circlip damaging the end of the mainshaft, though I have seen a couple of reverse idlers with rather less than the regulation number of teeth on them!
A lot of people, me included, tend to forget the 4 speed TR7. But it is not only a stronger box (if you can find one) but the diff bearings in it's 3.63 axle are better too. These are what Fitchetts use in their recon 3.63s for all models.

Steve

[DazasDolly]

Hello Steve

Plenty of 4 speeds about usually around the 70 quid mark. It's the 5 speed that seems to command good money. Is it worth me getting hold of a Tr7 diff and is it easy to convert it too the dolly.

Cheers

Darren

[Carledo]

Hello Steve

Plenty of 4 speeds about usually around the 70 quid mark. It's the 5 speed that seems to command good money. Is it worth me getting hold of a Tr7 diff and is it easy to convert it too the dolly.

Cheers

Darren

I'll bet a TR7 4 speed with O/D is more than £70! As far as I know, a diff from a 4 speed TR7 (front loading 3.63) should bolt into a (non Sprint) Dolomite axle case without any problems. someone else on here (one of the Mazda gang) has, on my advice, used a Spitfire 1500 3.63 diff in his car, needing only to lose the rear case and chop off the front mounting bracket. Of course the Spit diff won't have the uprated bearings unless previously rebuilt by Fitchetts, even so, it's stronger than the 3.89 your car will have now and will be a more suitable ratio for the TR7 motor as well.

Steve

[cliftyhanger]

My understanding is that an 1850 single rail od box with a vitesse bell housing will fit a vitesse without modification, that's what I'm fitting to the vitesse when I get there

Cheers

Darren

Darren, notquite as simple as that.....

The bell housing needs a hole drilling and capping IIRC, to accomodate a shaft.
late 1850 clutchplate (easy)
But it is slightly longer than the 3 rail od box, so needs a shortened prop.....but if you are getting a new one it won't be more expensive.
The 1850 OD boxes seem to be cheaper (or were!) than the GT6 type. I guess rather smaller market plus fear of how to convert.

If you want an indestructible setup, get a sprint box/prop/axle. Sadly the sprintboxes are no longer the cheap bargain they were,I think they are used to build TR and saloon boxes....

[Jon Tilson]

TR7 boxes have a longer bell housing and input shaft and have never seen one with o-d which looks like a missed trick somehow...

I'm sure you could do one and it would be IMHO superior to the LT77 5 speed abortion some 7's come with. Strong but horrible to rebuild
and cant be towed.

Heavier than a Sprint box too.

You can combine your 1850 input shaft and bell housing with a TR7 box no worries...but you have to drop the layshaft which is ok with
a dummy one...

But I would strip the TR7 box and use its innards with an o-d mainshaft myself. Done that on a few now but have used my last 7 box now.
The 7 diff bolts straight in the 1850 casing. The 7 diff just has longer half shafts and tubes and different brakes.

Jonners

[DazasDolly]

I'll keep an eye out for a diff, I don't thrash the car in low gears so hopefully it will be ok for now. Not that she is fit for the road yet.

I've got to make a pipe from clutch master to slave, but I'm unsure of the size of the union as the one from the 1500 slave is too small for the 1850/sprint slave.

Fit two brake pipes (I've already made them up) Bleed system and then find a prop as I cannot get mine to move on the splines. Not sure how far they're meant to move?


Clive, it was Colin that led me to believe the 1850 o/d with vitesse bell housing would fit straight in. Have you jumped into any bushes lately #essexwinterrally

Steve I was thinking the standard non o/d TR7 box

Many thanks

Darren

[cliftyhanger]

Ahyes, that was a Targa rally at woodbridge. And I got distracted in the carpark.....
It was Colin who convinced me a singlerail gearbox would last 30 minutes max in my hands! That was soon after the targa, so he remembered my driving "style"!

[DazasDolly]

Ahyes, that was a Targa rally at woodbridge. And I got distracted in the carpark.....
It was Colin who convinced me a singlerail gearbox would last 30 minutes max in my hands! That was soon after the targa, so he remembered my driving "style"!

Ahhh that's a new one, I didn't know that story...

I was referring to hedge and call of nature on the last Essex winter rally... I went passed thinking you may have broken down in the tolly, fifty shades of shi*e flying past Never did say cheerio to you and Gill as I went out for a cig and my mate had to get home as he had been on nights the night before so needed to get some shut eye

Cheers

Darren

[cliftyhanger]

Ah yes, the rally "comfort break", an essential skill to learn!

Of course a few years ago there was "the big one" n Scotland, but that resulted in a roll in the heather. Literally. And I didn't like it much!