4-Speed vs Overdrive vs 5-Speed Gear boxes

[Tom Fremont]

I share Alec's sense about the rarity of O/D when the cars were new. I reckon a lot of buyers could barely afford them or when optioned out could lead to wandering eyes toward other marques. In the '70s I seldom saw one so equipped ( though AH 3000s all seemed to have it ). As he noted, the percentage with it fitted new would be interesting to know, and to compare to today's percentage especially - way, way higher now I bet. Rather like Surrey hardtops are now.

 

Coming across a 5-speed conversion is a heartbreaker for me. What's amazing is that those conversions save precious little over fitting a rebuilt A-type. I'd pay $3-4K less for a car with one than I would for an original 4-speed, and its " correction " would be my 1st order of business - with an A-type box of course.

 

I've never had a failure of an O/D in over 100K miles. ( I have had layshafts let go and then get the whole box overhauled, O/D and all. ) I once read that they generally outlast the gearbox and I have no reason to doubt it.

 

John's advice to try one on for size is the best suggestion. I'd never again be happy without one in mine ( got two in cars plus a rebuilt spare ).

 

Cheers,

Tom

[stuart]

OK not "A" type but Volvo fitted overdrive to their cars up till mid 90`s and they will do starship mileage with minimal attention.

Stuart.

[North London Mike]

Wow, in late, sorry guys

 

Has to be O/D, LNK was originally a 4 speed car and the O/D was the first thing I fitted, The Big Healey comment is well made and I treated myself to the Works Healey type switch mounted on the gear lever.

 

Use it hard as well, 5000 in O/D 2nd etc

 

45,000 miles later I can't imagine TR'ing without it ......

[TriumphV8]

The good thing is that this thread made me thinking about making a 5-speed gearbox.

I got an old TR gearbox with strange parts in it, and an old LT77 5-speed gearbox from

a Rover SD1 I bought 40 Years ago for my first V8 conversion and recently bought a

central clutch operator from a Ford that unfortunately did nor fit into TR6 gearbox.

 

But all that fits seems to fit nicely to form a 5-speed box for TR6:

First will mill the gearbox housing of the old TR gearbox off and only keep the bellhousing,

the LT77 has a removeable beel housing and will fit on the new surface the bought clutch

operator fits fot LT 77 like being made for it.

Just a little work over winter and hopefully will end with a cheap and reliable gearbox..........

[The_Doc]

I agree with you Andreas, this has given me a huge amount to think about. I've got lots of time to really decide what I want as The only things that I've actually got working are the starter motor and dynamo.

 

@ Chilliman, I'm in Buckinghamshire but I work quite near Didcot so I'm hoping there might be things going on near TR-Register HQ...

 

Adam

[stargazergs]

Hi Adam

 

I've pondered this one as well Adam, I purchased a Toyota Supra W58 gearbox a while back and have looked into the 5 speed conversions available. If I decide to go with the 5 speed box I'll go with the HDVA kit and as it's a tried and tested DIY kit it's pretty straight forward to do and as mentioned before the Toyota boxes are bullet proof and the HDVA kit retains the original gear stick location and appearance unless you look under the car.

The things I've to consider are my locaton to any mechanical assistance if I were to have problems with an Overdrive box and I couldn't fix it myself, I'd put good money on it if I took an overdrive box problem to a local garage they would not have a clue what one was let alone know what it looked like or what to do with it. So reliability is a biggy for me, what ever I fit it's got to work and it's got to last.

I understand the arguments for originality and selling value but it really boils down to the fact that it's your car and you do what you want to it and enjoy the challenge of modifying or upgrading it to suit what you wish it to do, don't get to hung up on resale or originality as the key is to enjoy what you have as you could walk out the door tomorrow and get knocked down by a passing HIPPOPOTAMUS and you cant take it with you! the car or the monetary value.

The financial side of things is pretty much the same for buying the kit as it is for buying a refurbed overdrive box.

Modifying the triumph gearbox bell housing on a DIY job is not impossible but I'd be worried about alignments causing problems and if any alloy welding is done will it be done correctly or will I be driving the car one day and when I put my foot down the gearbox falls on the floor and causes no end of damage to the car. So measure twice,three,four times cross your fingers that your right before you cut and make sure the welding if required is up to standard.

So the question is to go 5 speed or overdrive and for me the jury's still out, I've never driven and overdrive car so I won't know what I'm missing if I don't, I have driven plenty of four speeds and on little short runs or on country roads they are fine, but if your on the dual carriage ways and motorways today I'd definitely upgrade to one or the other as after a few hours of the engine screaming and droneing at you you'd wish you'd taken your modern instead. And lets face it we don't live in the 40's to 60's so we're all going to take our cars on a motorway unless you wan't to spend a liftime avoiding them.

 

I'm still trying to make up my mind to go with the overdrive box or the HDVA kit but as I have a W58 box my options are open and time will tell what I end up with but what ever I do go with I'll enjoy doing it and at the end of the day it's a personal choice as long as you enjoy the project and the end result.

 

Gavin

[TriumphV8]

After reading this post i decided to try to make a 5-speed gearbox

to fit into TR 4-6.

My old LT77 gearbox from Rover is ready to fit

 

Next step was to sacrifice a Triumph gearbox and mill it down

to receive a suitable bellhousing:

 

[TR4Geoff]

Hi Adam,

 

My comment is slightly off beam, but if you do decide to go the 5 speed box route (and particularly if it is a Japanese Box), do make sure you know precisely what age and model it came from, together with the relevant production numbers etc of the donor vehicle.

 

You virtually need to know the date it was made and the name of the bloke who built it, otherwise you might be in troubl IF you need to buy spares at any time in the future!

 

Cheers

 

Geoff

[TriumphV8]

Fully agree to that.

Having a bellhousing that is bolted to the gearbox and not casted

and being cheap and widely availiable is as necessary as the donnor

car having a bit more power.

 

The Rover LT77 or R380 gearbox has all that and also many British cars

had them in use and spares are easy to get at Landrover shops or Rimmers.

[Tony]

Fully agree to that.

Having a bellhousing that is bolted to the gearbox and not casted

and being cheap and widely availiable is as necessary as the donnor

car having a bit more power.

 

The Rover LT77 or R380 gearbox has all that and also many British cars

had them in use and spares are easy to get at Landrover shops or Rimmers.

Hi Andreas, i am in the same situation, just restoring a 4 which came with a ford type 9 5 speed box, the previous owner had cut the front of the TR box off just behind the cross shaft and welded

4 sleeves into the rear of the TR box to fit the type 9, . As the 4 will have the Moss supercharger kit fitted along with a rebuilt low compresion engine with larger exhaust vavles and a special cam, i have decided to stay

with the Ford box, it is being rebuilt by BGH Geartech with a higher first and fith gear and will handle up to 240bhp ( i wish!!) the bell houseing will come from Uk Gearbox conversions. The total cost is less than a rebuilt TR overdrive box

and i am not sure the the overdrive could cope with the added torque the engine will hopefully produce.

[Don H.]

...Ultimately, I don't find any NEED for an overdrive...

 

I'm also in the minority here, but I'm with Tim. A friend gifted me an A-type overdrive a couple of years ago and it's now in my car, added to the original gearbox. So I have experience with/without overdrive in the same car. I use it often because it's fun, but to be completely honest it really doesn't change my driving experience that much. In no way do I consider it transformative or essential.

 

If I had your car, I'd for sure keep the original 'box and OD. Tom's right in thinking a several thousand $/£ hit to value over here for fitting some modern gearbox into an otherwise well-sorted car. And as Alec says, all rules are off where hot rods are concerned.

[TriumphV8]

the previous owner had cut the front of the TR box off just behind the cross shaft and welded

4 sleeves into the rear of the TR box to fit the type 9, . A

 

i have decided to stay with the Ford box, it is being rebuilt by BGH Geartech with a higher first and fith gear and will handle up to 240bhp ( i wish!!) the bell houseing will come from Uk Gearbox conversions.

 

Did I catch it right: You have already a bellhousing made from an old TR gearbox

and now get another bellhousing from Uk Gerabox conversion?

 

What was the reason to buy another?

[Tony]

 

Did I catch it right: You have already a bellhousing made from an old TR gearbox

and now get another bellhousing from Uk Gerabox conversion?

 

What was the reason to buy another?

The one that i have i am not 100% sure it lines up correctly with the spigot bush in the crank, the clutch worked Ok but the home made spigot bush

looked a bit oval, meaning the main shaft was probable not inline .I do not want to risk the new type 9 box being damaged, with mis alignment.

if i had the time i could probable make the old bellhouse usable, but not now, to much more to do on the car.

[TriumphV8]

Agree, that is difficult. I will make a gauge that precisely gives the depth

that the input shaft will protrude over the bellhousing and centers the shaft.

I will pick up these points from a TR6 gearbox employing the bellhousings bolt circle

and than bolt this gauge to the new bellhousing and put gearbox with the bolted mounting plate

into position on the bellhousing and than weld the plate to the bellhousing.

Than strip the gearbox and weld plate and bellhousing completely.

 

Thats the theory, quickly explained, tricky to do and takes its time as you said

because it must be precise.

 

So if you can get a suitable bellhousing at a fair price it is not the worst idea to take it.

 

Do you have a picture of your old bellhousing?

[Tony]

On 10/27/2015 at 6:31 PM, TriumphV8 said:

Agree, that is difficult. I will make a gauge that precisely gives the depth

that the input shaft will protrude over the bellhousing and centers the shaft.

I will pick up these points from a TR6 gearbox employing the bellhousings bolt circle

and than bolt this gauge to the new bellhousing and put gearbox with the bolted mounting plate

into position on the bellhousing and than weld the plate to the bellhousing.

Than strip the gearbox and weld plate and bellhousing completely.

 

Thats the theory, quickly explained, tricky to do and takes its time as you said

because it must be precise.

 

So if you can get a suitable bellhousing at a fair price it is not the worst idea to take it.

 

Do you have a picture of your old bellhousing?

Pictures attached

Edited May 21, 2019 by Tony
old

[TriumphV8]

Many thanks, does help!