Sprint overdrive 'box in an 1850?

[xvivalve]

Is there anyone still out there who has fitted a Sprint overdrive gearbox to an 1850 than can describe any pitfalls in doing so?

[Carledo]

I've not done it, but i've spoken to someone sometime who has. Obviouslythe block and bits and gearbox are compatible since the 1850 and Sprint blocks are effectively the same.

The problem, if it is one, is that the Sprint and 1850 block sits at a slightly different angle in the subframe and this puts the gearbox at a less than perfect angle. The solution would be, I guess, to use a Sprint subframe and engine mounts. Youd probably need a Sprint tunnel and prop as well.

But I have to ask, why go to all the trouble when the best way is just to drop in an entire Sprint drivetrain. or if, for whatever reason, you need to keep the 1850 motor, the 1850 box is good enough for an 1850's power output. Don't fix what aint broke!

Steve

[cliftyhanger]

I drove Bill Goodwins 1850 on an RBRR. That had an 1850 engine in at the time (I think, it had a TR7 at some point too)
The gearstick was at an odd angle. I believe it had a sprint axle and prop too. I believe Carl did the mechanical work on the car.

When I converted my Toledo to TR7 power, I used a sprint gearbox (on the basis the 1850 type would not last with some of the events I was doing) along with teh matching prop and axle. On that car I dodn't vhange teh subframe, but made engine mounts etc to get the engine in the correct position. I had to use a sprint tunnel. But otherwise it was painless.

[xvivalve]

I've not done it, but i've spoken to someone sometime who has. Obviouslythe block and bits and gearbox are compatible since the 1850 and Sprint blocks are effectively the same.

The problem, if it is one, is that the Sprint and 1850 block sits at a slightly different angle in the subframe and this puts the gearbox at a less than perfect angle. The solution would be, I guess, to use a Sprint subframe and engine mounts. Youd probably need a Sprint tunnel and prop as well.

But I have to ask, why go to all the trouble when the best way is just to drop in an entire Sprint drivetrain. or if, for whatever reason, you need to keep the 1850 motor, the 1850 box is good enough for an 1850's power output. Don't fix what aint broke!

Steve

It’s not broke, just non-overdrive and they’re looking at economic ways of getting overdrive.

[xvivalve]

I recall there is an issue with the front flange of an 1850 diff being in a different relative location fore/aft to a Sprint one, so I thought from memory a non-sprint prop with a sliding joint was used?

Sprint tunnel is a given necessity, as is the adaptor plate and rear overdrive 'box cross member. It's an early 1850 so the 9 spline clutch should be compatible...

[Carledo]

I recall there is an issue with the front flange of an 1850 diff being in a different relative location fore/aft to a Sprint one, so I thought from memory a non-sprint prop with a sliding joint was used?

Sprint tunnel is a given necessity, as is the adaptor plate and rear overdrive 'box cross member. It's an early 1850 so the 9 spline clutch should be compatible...

I did mention the possible need for a prop! The difference in nose length on the diff is only just over an inch (the Sprint diff is longer so the prop is shorter) How this works out in your configuration is unknown to me as i've only worked in the other direction with a Sprint axle in a non Sprint body with a non Sprint prop. At worst, my guy in Hartlebury will lengthen your Sprint prop by any amount you need for a reasonable sum. A non Sprint prop with a sliding joint is a better bet than the Sprint prop with the CV as the CV'd joint has less sliding movement and is therfore what I use. It's also worth noting that the 1500 auto and Toledo props have their sliders at the rear which is a real advantage if you need a different length at the front. Most 1500 and 1850 (single rail) cars i've seen have the slider at the front which is an awful idea, it's beyond me why they even thought of it!

Steve

[Bitsa]

I put that Sprint OD box into my TR7 powered Toledo which previously had an 1850 OD box.

It’s was relatively straight forward - I think these were the main snags:

- Sprint and 1850 OD crossmembers look identical but aren’t. It won’t fit with an 1850 one.
- Needing a full set of engine > adaptor > gearbox bolts
- Not dropping the subframe - you can get the box in with the subframe in place, but it’s a nightmare!
- Sprint clutch wouldn’t fit the flywheel, so we reused the old one
- We needed 8x wheel nuts as the sprint axle had different threads
- No LSV = possibly ending up in a ditch unless you fit a pressure limiter off some kind.

My thread may have some more info, swap started bottom of page 1:
https://forum.triumphdolomite.co.uk/vie ... hp?t=37703

I still have an 1850 single rail OD box and associated bits up here in Scotland, I think the OD is fine but box needs rebuilt, if that is of any interest!