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jfg

4 to 5 speed gearbox change

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the car i bought has a 4 speed box in it and i have now been offered an LT77 5 speed from a land rover.

 

will this fit? does it need a different bell housing, prop shaft, diff upgrade?

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No idea regards the bell housing that is used to mate the box to a Landrover. Others may help here.

From memory when I changed to 5 speed box I think I changed the rear axle, prop shaft and gearbox complete with bell housing to the 5 speed items.

The gearbox mounting probably needed a couple of parts changed also.

I could probably help you out with a gearbox with bell housing and propshaft.

Sadly I no longer have any axles.

Regards

David

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jfg,

 

Whatever you decide do not discard the TR gearbox and ancillaries. When you come to sell the car buyers will not be keen on a hybrid.

.

 

Alan

Edited by barkerwilliams

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Try the TRDC forum.

Why not THIS forum? Sad to see a forum member on one forum recommending another.

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You'll definitely need a 5 speed prop shaft, very likely a bellhousing too.

In my opinion you're making the right decision on converting to a five speed. It drives so much better and is a more robust box.

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i have a little more information on these. there are a few types of this box. called long and short shaft, depending on their serial numbers and there is a later lt77s box but i don't know dimensions on that as yet.

 

looks like i have a bit of a shopping list on this already.

 

as far as devaluation goes, well that depends on condition & viability to keep it standard and what someone is willing to pay.

 

my car was advertised as a "training vehicle" but i don't know what that means yet. the certificate with manufacture details hasn't arrived yet either.

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Back axle needs replacing too!!

Can I ask why? As a TR7 newbie I haven't got as far as my back axle yet, still working on the engine and front suspension.... but I know from years of other Triumphs that the diff ratios differ between cars; is this the same with the TR7, or is it more of a physical / mechanical reason?

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Why not THIS forum? Sad to see a forum member on one forum recommending another.

Hi There,

we have a good number of TR7's in the TRR but posts on the forum tend to be on the lower side.

 

The TRDC predominantly cater for the wedge cars and thus may have more information and quicker response.

 

having said that there are some clever folk here that will help if they can.

 

Is your car on the road. They are getting fewer and fewer. Keep them alive.

 

Roger

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I'm not aware of anyone who has successfully fitted a 4x4 derived LT77 into a TR7 before, I would certainly be interested to learn of one because the 4x4 variants have a much more readily available supply of spares and rebuild support. Remember the input shafts, gear ratios and quite a few other details I'm told are different on a Land Rover box to those found on a 2wd car, not least because they were engineered for use in conjunction with a transfer box of course. I understood that it is far from simple to replace a 5 -speed TR7 LT77 with an LT77 from a 4x4 - let alone all the necessaries mentioned above to convert from a 4-speed.

 

Bell - housing , clutch, prop shaft, rear axle and diff ratio (3.45:1 - I think... in 5-speed compared to 3.63:1 in 4-speed) are all different. Gearbox mount, bushings, remote, selector stick, speedo, speedo drive will also need changing as well. There might be other little details, that's off the top of my head.

 

Keep us posted on how you get on!

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The Sherpa van had an LT77 gearbox, as did the Rover SD1 Vitesse which I believe had uprated shafts and bearings to take the extra. power.

 

5 speed TR7 gearboxes and appropriate conversion parts are not that rare so why bother with all that extra work?

 

As Wayne says, the 4wd LT77s are a different animal to the 2wd versions.

 

Ian

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looks like the landy box is out.

 

is there an option to improve gearing in a 4 speed instead of doing the 5th switch?

 

is there even anything wrong with the 4 speed.

 

i can't drive ityet as it's a full resto car.

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Is your car on the road. They are getting fewer and fewer. Keep them alive.

 

Roger

It will be once I have the thermostat housing helicoiled, front suspension replaced and a few other tweaks for MOT.

It was the same with my GT6 - a lot of them about, nobody wanted them so they were broken or scrapped, then they started to be pushed as a value classic, people wanted them again, and the prices went through the roof (mine is valued at £18000, bought for £1900...) so the TR7 will go the same way. Possibly surprisingly quickly, too.

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Personally I would stick with the 4 - speed unless you are doing long European autobahns or track days. Its a rare car in that form now and you will find it perfectly capable. I did the Round Britain Run in a 4spd TR7 and it did very nicely indeed.

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Wow, lot of misinformation about this.

 

The conversion is very straightforward and is all just bolt on.

 

Parts needed are:-

 

gearbox with remote, bellhsg, gearlever assy and associated bolts etc

clutch

box mtg is the same apart from an additional spacer and plate along with the longer bolt

handbrake cable

rear lwr links are different

rear axle which is a 3.9:1 final drive ratio and not the 3.45:1 as stated in another post along with the 5 speed rear brakes

prop

gearlever gaiter along with the transmission tunnel plates and gaiter insulator

 

think that is about it

Edited by stevew2

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will a 5 speed axle mate up to a 4 speed box?

 

 

is it worth just doing that? will the different diff ratios make any worthwhile benefits?

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Wow, lot of misinformation about this.

 

The conversion is very straightforward and is all just bolt on.

 

Provided you have all the necessary bits, which looks to be absolutely everything apart from the engine and front suspension.... :)

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Provided you have all the necessary bits, which looks to be absolutely everything apart from the engine and front suspension.... :)

not really, only parts required on the rear suspension are the lwr trailing arms

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Wow, lot of misinformation about this.

 

The conversion is very straightforward and is all just bolt on.

 

 

Hi ya Steve, great to see you posting unrivalled expertise on here! Are you suggesting above that you are able to fit Land Rover 4x4 LT77s into our 5-speed TRs at S&S as a simple bolt in conversion as well? If so, this is exciting news surely, as we don't need to bother with these more scarce 17A and 19A boxes anymore?

 

I stand corrected on the 5 -speed diff ratio. My spare CWP is 3.45:1 and came out of a 2 litre originally - hence the confusion in my brain, silly boy. :rolleyes:

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not really, only parts required on the rear suspension are the lwr trailing arms

"Parts needed are:-

gearbox with remote, bellhsg, gearlever assy and associated bolts etc

clutch

box mtg is the same apart from an additional spacer and plate along with the longer bolt

handbrake cable

rear lwr links are different

rear axle which is a 3.9:1 final drive ratio and not the 3.45:1 as stated in another post along with the 5 speed rear brakes

prop

 

gearlever gaiter along with the transmission tunnel plates and gaiter insulator"

I was being humorous, but it seems like almost everything from the engine on back is required and not interchangeable - I'm just too used to the early Triumphs, where things are more flexible and forgiving for upgrades.

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i've been away from this project for a while but while looking again today i found this thread, input appreciated on this method.

 

http://tr7triumph.com/forum/viewtopic.php?t=8060

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You can put a LT77 gearbox in and retain original 4-speed axle, with a suitable prop shaft, but why would you want to?

You can also put in a diff from an automatic to give slightly better motorway driving.

You can also put in a single-rail Dolomite overdrive gearbox as well instead of an LT77.

If you want an even stronger gearbox you can use a R380 gearbox from a 2-wheel drive MGRV8 or TVR  

The original 4-speed axle is weaker than the 5-speed axle but much heavier (didn’t BL use the 4-speed axle on the first 16V rally cars though?)

E&OE !

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