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MG MGB Technical - 5 speed conversion with TR7

Hello,

I know that this subject is present once in a while. I read threads with conversions using Supra 5 sp or Ford type 9 kits avaliable from some companies, My questions is how easy to adapt a TR7 5 sp gearbox in a MGB. Does someone ever tried that?

Thanks,

JGC
Jean Guy Catford

Jean,

The 5 speed box in the TR7 is the LT77 box which was also used in a number of other vehicles.

It is generally used in the UK when people fit Rover V8 engines in the B as there were a number of vehicles that used that combination. It fits the B with a minor mod to the tunnel.

I do not think the LT77 was used with a B series petrol engine. IIRC the LT77 was introduced to the Sherpa van range when it changed from the B series petrol engine to the O series. However, the Sherpa continued to use the B series diesel engine. So I assume that the LT77 was used with the B series diesel although they may just have used the old gearbox.

However, I think that if there was a good supply of bell housings and back plates that enabled the LT77 to be used with the B series engine we would not have seen the Ford type 9 kits become so popular in the UK.

David
David Witham

Thanks David,

Yes indeed I found a lot of references for LT77 and V8 but nothing concerning B-engine...
Cheers,

JGC
Jean Guy Catford

I have been watching this post to see what kind of feedback you would get about the TR 7 5 speed gearbox. I'm posting this in an effort to draw on others knowledge and experience.

My only experience with the TR 7 5 speed was way back when they first came out. Someone had bought a car with one in it that had gone bad and they brought it to me even though my specialty was B's. In checking around I found that there was no good used units (they all seemed to go bad young and early), no repair pieces, and extreme prices if either could somehow be found.

Of course all the above applied to just about everything LBC in those days so I've been watching this post to see what the current state of the matter is.
Rick

Thanks Rick,

Usefull comment on that matter...

JGC
Jean Guy Catford

Rick,

The LT77 'box has a reasonably good reputation over here.

I know there was an upgrade to it at about the time it became available in the Jaguar XJ6 series 3. The story at the time was that the police had problems with it when reversing at high speed.

People I knew with TR7s when they were new had problems with them in general rether than the gearbox in particular.

The LT77 gearbox was replaced in the mid 1990s by the R380. The R380 was in effect an upgrade of the LT77. The R380 was mainly used in Land Rover products but was also used in the later MG RV8's. The early RV8's used the LT77.

Since my previous post I have asked a few people about the use of the LT77 with the B series diesel. However, I don't have any answers yet.
David Witham

Yes Dave, I agree about the TR 7 and "problems". The TR 7's didn't ring my bell so I never delved into them to see what they needed to keep them on the road, (although I will admit to using the steering wheel off a TR 7 on my 65 B for the last 20 years or so, just because the splines were compatable).

I remember now that the TR 7 that came in with the transmission problem was a convertible, and that was the source of it's interest to everyone, not it's 5 speed. Reading here about all the other combinations that used the 5 speed with apparent success has piqued my interest and I think I will see what I can learn about them.

The UK must be an amazing place... an XJ 6 with manual transmission... what joyful thoughts that conjures up in my mind. I had a few series 1 XJ6 and 12's but all with automatics. One 3.8 S with manual, that was truly a fun drive,... mufflers just right.. sounded so sporty yet looked so sophisticated.
Rick

Rick,

I tought of modifying my XJ6 to a 5 sp transmission as XK unlimited sells or many others. But with a north-american Jag with an axle ratio near 3.03, it means changing differential also. A costly pain in somewhere to do..

JGC
Jean Guy Catford

It was the oil pump gear that striped.
w c wolcott

In the US the Datsun 280z transmissions are plentiful, cheap, reliable, light and have good gearing. The late 280z (81-83)has closer ratio gears, except the 5 th gear which is a bigger jump. It goes nice with a mildly modified mgb engine.
Barry
Barry Parkinson

The pain would be in the rear end, Jean.
:)

Hi!
I fitted an LT77 from a Rover SD1 to my MGB (Mk1) in the early 80ies. When I started thinking about this I asked all the experts around. Ron Gammons told me on the phone that it would simply not fit at all and other specialists had the same opinion. That was enough motivation to have a try and it worked and still works!
Because there was just no bellhousing to use I sourced an old 3sync-case, had it gearbox cut off and an ali backplate welded on to the remaining bellhousing. Then it was just a case of making the holes to fit the box to the bellhousing at the right places (not an easy task!), design and weld a new clutch lever mechanism (used all original parts though), have a new, longer propshaft made and the crossmember modified.
A lot of work but the gearbox did fit in the car and, when fitted, the whole setup looks like it has been done by the works.
Today I just would fit a ford-conversion but back in these days there was none so I had to start thinking myself!.
Joern-M.

Well done Joern,

At the end this show me that it is feasible with some effort on this task.

Thanks all,

JGC
Jean Guy Catford

Joern-

Wouldn't it have been easier to fabricate a new rear engine plate for the conversion?

In general, I don't understand why the empahsis in Europe seems to be focused on generating bellhousings, when fabrication of the rear engine plate seems so much simpler. It is true, in cases like the MGC, where the flywheel diameter precludes the use of the bellhousing, a different plan is required, but for the MGB, I just don't get it.

greg fast

Greg
Some trans will fit with only a backplate change. Issues which the backplate can't change are location of starter on wrong side, depth of flywheel - pilot bearing issues, clutch mechanism location etc.

The after market backplates are alloy and save several pounds of weight from the stock steel plate.

Barry
Barry Parkinson

Understand what you're saying, Barry- but from my perspective, most of these are more easily addressed than casting a new bell.

I've cut away portions of the bell for starter clearance, seen extended pilot bushes and spacer plates for flywheels, exteneded splines on clutch plates, or steel strip installed between bells and rear eangine mounting faces to adjust depth.

Just seems to me there easier ways to to this than casting new bells, or in Joerns case, using an existing bell and welding/machining a new transmission mounting face.
greg fast

Greg,

good point, but two arguments against it:
1. I use all original engine components including the endplate from the early 3sync 18GA-engine with the old starter. Even the clutch and the complete actuating mechanism is standard. The crossmember is original and fitted in the original mounting points - so from underneath the setup looks like it has been done by the works.
2. In 1984 there simply were no 5-speed-conversions available, no modified endplates, no bellhousing to use. I had to construct it myself and for me it was much easier to use an existing gearbox (aka the bellhousing from it) as basis than designing a new endplate.

As I said: when I started thinking about this I asked all the experts: Ron Gammons from Brown & Gammons, all german parts dealers and specialists and even one or two MGb-racers. They all told me that a 5-speeder in an MGB would be just impossible.
Joern-M.

Forgive me, but I feel some corrections would be wise.

The LT77s went through 4 versions from 1976-1994 in an effort to address their weaknesses. It is an idiocynratic box with a chunky feel and an internal pump run with plastic gears. Use the wrong gear oil and the box is damaged in a few miles. Tow the vehicle with rear wheels on the ground..and the same damage will be caused in a mile. The right oil was/is an ATF. Alternatively, you can now use Castrol SMX, available only in some countries outside North America..UK, Australia.

It has NEVER been considered a good box..but it can be serviceable if its watchpoints are carefully respected. Parts are no longer made but fully reconditioned boxes can still be had in a few places in the UK at a reasonable price..but that price has doubled in the last 3 years.
Figure 600 GBP. It was used on many vehicles for a long time.

The R380 was its replacement box. I have had them apart and I cannot recall a single matching part. Totally different affair but they can be used on the same cars..with some home fiddling to create a new mounting bracket.

Substantial affair..more than double the load capacity of the LT77 and a much silkier shift...reverse is down to the right rather than up to the left.

SAd thing it was only made for a few vehciles and in different configurations, so that one is not necesatily changeable with a nother used on another model or marque. Very hard to find full units.though parts are still available.

The version fitted to the Sherpa Van was used in only one other car..the Morgan Plus 8...not a huge part of the R380 population.

This brings me the point..I am looking for a Sherpa version R3809. Any ideas?

Lorne
Mont Tremblant, Quebec, Canada
&
Abberley, Herefordshire, UK





Lorne Goldman

Forgive me, but I feel some corrections would be wise.

The LT77s went through 4 versions from 1976-1994 in an effort to address their weaknesses. It is an idiocynratic box with a chunky feel and an internal pump run with plastic gears. Use the wrong gear oil and the box is damaged in a few miles. Tow the vehicle with rear wheels on the ground..and the same damage will be caused in a mile. The right oil was/is an ATF. Alternatively, you can now use Castrol SMX, available only in some countries outside North America..UK, Australia.

It has NEVER been considered a good box..but it can be serviceable if its watchpoints are carefully respected. Parts are no longer made but fully reconditioned boxes can still be had in a few places in the UK at a reasonable price..but that price has doubled in the last 3 years.
Figure 600 GBP. It was used on many vehicles for a long time.

The R380 was its replacement box. I have had them apart and I cannot recall a single matching part. Totally different affair but they can be used on the same cars..with some home fiddling to create a new mounting bracket.

Substantial affair..more than double the load capacity of the LT77 and a much silkier shift...reverse is down to the right rather than up to the left.

SAd thing it was only made for a few vehciles and in different configurations, so that one is not necesatily changeable with a nother used on another model or marque. Very hard to find full units.though parts are still available.

The version fitted to the Sherpa Van was used in only one other car..the Morgan Plus 8...not a huge part of the R380 population.

This brings me the point..I am looking for a Sherpa version R3809. Any ideas?

Lorne
Mont Tremblant, Quebec, Canada
&
Abberley, Herefordshire, UK





Lorne Goldman

Thanks Lorne!

That is great info and I appreciate you posting it.
Rick

This thread was discussed between 14/11/2005 and 26/11/2005

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