Gearbox modifications

[amalgamated users from prior forum]

Message originally posted by: Tony Wylde
I am about to take delivery of a Roadster LWB which has a Marina 1800 engine and box in situ.
My question is: Is there an alternative box that will bring the gear stick out of the tunnel further back, as the one in the car is tucked way up under the dash and has had to be bent at a severe angle to bring it to hand. I seem to remember (from my youth) that the Marina shared its box with certain triumph models, is this so?
If it is which one is bestfor the job. Please note that this engine has been bored to 1950 and has a big valve head as well (or so i am told anyway) I dont want to go to daft as it is my intention to swop the drive train to Fiat 1800 twin cam when I have sourced a decent RWD gearbox. The one I had had to go into my Sylva.

Regards

PS Great web site by the way.

[amalgamated users from prior forum]

Re: Gearbox modifications

Message originally posted by: Stefan Carlton
Jez Cox had an interesting article a few months back in PitStop magazine where he drafted on a Ford Type 9 'box onto the Marina engine (it's the Sierra box), but that ran into considerable exspense due to having to convert the Marina B Series to MGB version and then get the adaptor plates etc. He did say it was the best thing he did mind. There is also an article in Technical Tips IIRC regarding which gearboxes to use (and more importantly which will fit into the tunnel), email me and I'll dig them out for you...

On a slightly different note, take it easy with that engine. I've been researching how to get more power from my beastie (same engine) and was told to be careful trying to pushing too much power out due to the poor crank design (forged instead of cast) and the use of 3 bottom end bearings (as opposed to later B designs using 5). I was told that revving past 5k5 was a bad idea & that standard power was pretty much on the acceptable limit. The other thing to consider is that the bore's will now be quite thin and you might start to get a bit trouble (1860 is the preferred over-bore which keeps the walls thick enough).

I'm quitely musing over changing the whole drive train over to a Alfa Twin Cam as well, problem is I know nothing about the engines (and available parts).

[amalgamated users from prior forum]

Re: Gearbox modifications

Message originally posted by: Tony Wylde
Yeah, I know that the engine is weak!! but I only have the word of the chap I am buying it from with regard to capacity and state of tune. With regard to gearbox choice that would be great if you could do me the article.
My E-mail is tonywylde(at)blueyonder.co.uk

[lil_red_roadster]

Re: Gearbox modifications

C'mon guys, the B Series has oodles of charm and character, if a little short of horses..! Seriously if money is not an object the B can be pushed to around 150-160bhp, although 120 would be about right for the car IMHO, and with a 1950 overbore is quite within reach I'd have thought.

Just to correct things, the Marina 1.8 was always an 18V type engine, which came with a cast crank and 5 main bearings. 18G engines, as fitted to early MGB's (later versions having the 18V), were 3 bearing affairs. In all cases MGB's were fitted with forged cranks, which are the preferred item for serious power applications.

As for gearboxes the Marina 'box was a derivative of the Triumph single-rail box fitted to the Dolomite (exc Sprint), 4-speed TR7, Midget and Spitfire...

If you can find a 1.8 diesel B series Sherpa from the early 80's you'll find it has a 5-speed box fitted...this is the LT77 SD1 box (with different ratios) - so by stealing the backplate and other sundry bits you could fit a decent SD1 5-speed unit to the petrol B...

My local gearbox chap will happily mate a Marina box with a Spitfire overdrive for about ?200...doesn't help much on gearstick positioning but makes for a much better drive... It's also somewhat cheaper than the 5-speed route I took..!

Another option would be to pop in an MGB unit - big and heavy but the gearstick is further back. You might run into problems with the size of the spigot bearing though.

Or just hold on until you can get a complete Alfa power-train installed...

Cheers

[amalgamated users from prior forum]

Re: Gearbox modifications

Message originally posted by: Stefan Carlton
Hmm, if what you say is true Jez (the Marina having a 5 bearing engine) where on earth did my unit come from?

I agree with you on the charm and what-have-ya, I'm personally looking into rebuilding an MGB lump (with 5 bearings), porting and flowing the head etc, should realise a comfy 100bhp, not be massively difficult to fit into the car (marries up to scoop I'm getting done) & can have a 5 speed / od box fitted easier.

Still, this one works so will keep it like this until it's not my everyday car.

[AndrewKB]

Re: Gearbox modifications

I have a refurbished Marina box with overdrive fitted available for sale if anyone's interested. It'll be in the next Pitstop magazine but I can't recall how much I was asking - ?250 if I recall correctly. I can be reached directly at andrew.k-brown(at)virgin.net.

[beergutdave]

Re: Gearbox modifications

Hi im looking for a triumph overdrive box if anyone knows of one lurking around.

[jon_cox]

Re: Gearbox modifications

Tony,
I have a fiat 1800 TC in my roadster and love it! Good choice. All parts still easily available as well.
Word of advice on the gearbox - make sure you buy one from the sport / Arbarth which has the longer remote gearstick. This will bring the lever about 200mm (8in) further back. If not you will have the same problem as you do now.
Try Avanti motorsport for gearbox. www.avanti-motorsport.co.uk.
You can see from the picture where my lever is now positioned.

[amalgamated users from prior forum]

Re: Gearbox modifications

Message originally posted by: Tony Wylde
Thanks for all the help guys.