LT77 to T5 question
Discussion
My winter project for the Griff (4.3 p-c) is to change the LT77 box for a T5. I have a T5 complete with bell housing and prop shaft from a Chim and am confident with everything required except swapping over the speed sensor on the LT77 that is used to control the idle speed by the ECU. My initial plan is to retain the sensor from the LT77 and make a toothed disc for the prop shaft or drive shaft. Before I reinvent the wheel however has anyone done this before or is there an easier way?
Toma500 said:
I have a 93 pre serp 500 with a rover box and was always led to believe that the conversion to a T5 was not an easy one as the chassis has to be modifyed . Let us know how you get on maybe i was misinformed. Tom . 
The gearbox mounting brackets used on the cars fitted with a T5 box have to be replicated and welded to the central spine tubes, fiddly but not too difficult. Apart from that I cant see what the fuss is about but there again I haven't done it yet. Incidentally, I think the T5 cars still have the LT77 gearbox mount holes through the gearbox tunnel tubes so a conversion the other way would be mechanically simple. The Steve Heath book advises against the LT77 to T5 conversion on the grounds of complexity/cost but it also advises that the Griff/Chim should be taken to a specialist to realign the doors and I found no problem. Maybe I'm sticking my cock on the block but I'll let you know.Chad speed said:
trackcar said:
It seems a lot of hassle for no benefit ..
Clearly I wouldn't have gone this far unless I thought there was a benefit, anyone out there got a more constructive response?Edited by Chad speed on Wednesday 24th September 19:23
No idea about the speedo sensor bit, but to get the T5 remote link rod in to the rose joint on the bellhousing I'm pretty sure you're going to have to flatten the top chassis rail above the gearbox in the transmission tunnel .. shouldnt be too much hassle once youve chopped the fibreglass away a few swift smacks with a really big hammer ought to do it.
trackcar said:
Chad speed said:
trackcar said:
It seems a lot of hassle for no benefit ..
Clearly I wouldn't have gone this far unless I thought there was a benefit, anyone out there got a more constructive response?Edited by Chad speed on Wednesday 24th September 19:23
No idea about the speedo sensor bit, but to get the T5 remote link rod in to the rose joint on the bellhousing I'm pretty sure you're going to have to flatten the top chassis rail above the gearbox in the transmission tunnel .. shouldnt be too much hassle once youve chopped the fibreglass away a few swift smacks with a really big hammer ought to do it.
Quinny said:
I did this conversion years ago. I never bothered re-connecting the speedo, so can't help there.
But regarding the conversion itself, I can think of no benefit other than the percieved use of a more modern box.
I actually ended up putting the old box back in to sell the car, so that it kept its originallity.
Its not as straightforward a swap as it could be so be prepared for a bit of messing about.
If you'ed like a bit of honest advice from someone who'es done it. It's not worth the bother unless you have a problem with your original box
Thanks for the advice, my LT77 is on it's way out, if it was in good nick I'd stay with it. I thought the speed sensor from the LT77 box was for the ECU idle speed, how did you get around that if you didn't re-connect it?But regarding the conversion itself, I can think of no benefit other than the percieved use of a more modern box.
I actually ended up putting the old box back in to sell the car, so that it kept its originallity.
Its not as straightforward a swap as it could be so be prepared for a bit of messing about.
If you'ed like a bit of honest advice from someone who'es done it. It's not worth the bother unless you have a problem with your original box
depending what dash gauges you have you should be able to drive the speedo from a toothed wheel / inductive pickup. The ecu only needs a signal if you want to take advantage of the stepper motor use off idle as far as I know (to stop the engine stalling when you come to a junction, and to reduce emissions on overrun) .. you can get around this by adjusting the base idle airflow though as many people have blocked off their troublesome stepper motors and do without the idle control anyway.
I assume you've discounted having your gearbox rebuilt by ken tomlinson (one of the original designers of the box) who does uprated packages as well as straight forward rebuilds. A good few people on PH have had their boxes done by Ken to good effect.
I assume you've discounted having your gearbox rebuilt by ken tomlinson (one of the original designers of the box) who does uprated packages as well as straight forward rebuilds. A good few people on PH have had their boxes done by Ken to good effect.
Well as I said 'I may be putting my cock on the block' but the last posts by trackcar and Quinny have got me looking for my old cricket box. Removing the dash, modifying the hand break and cutting chassis tubes is not something I relish but a rebuilt LT77 is going to have to be a damn sight better than the one I've got. How good are the uprated ones by Ken Tomlinson? I don't intend to increase the standard 4.3 power by much, I'm just looking for a nice action as they say. I know I'm not going to get the super slick change of my old S2000 (surely the best box ever)but I'd like to have an indication of what to expect before I choke down that humble pie.
As someone who has abused LT77s and only switched to a T5 when I started breaking shafts and then the T5 broke and needed upgrading ...
www.gearboxman.com (CTS) rebuilt my LT77 with stronger bearings and that was taking close to 400 bhp. Cost was around £350. The T5 conversion is not straightforward and considering in real terms the overall cost and the fact that these cars don't tend to do a lot of mileage, getting an LT77 rebuilt every 10 years or so is a lot more cost effective way of going forward.
It's a lot of work for no real advantage. It's your car and your call but I would sell the bits you have and that should pay for a couple of rebuilds I would have thought.
PS I said in the bible that realigning doors is a bit of a tricky job because in practice, it is either easy or takes a couple of hours and ends up with a worse alignment than you started with. It is very easy to damage the bodywork etc as a result which is why in most cases, the sensible approach is to leave it to someone who knows what they are doing.
The fact that you found it straightforward is great but shouldn't be interpreted as meaning that all the jobs and tasks that I described as tricky are straight forward.
The T5 change is not a drop in replacement.
www.gearboxman.com (CTS) rebuilt my LT77 with stronger bearings and that was taking close to 400 bhp. Cost was around £350. The T5 conversion is not straightforward and considering in real terms the overall cost and the fact that these cars don't tend to do a lot of mileage, getting an LT77 rebuilt every 10 years or so is a lot more cost effective way of going forward.
It's a lot of work for no real advantage. It's your car and your call but I would sell the bits you have and that should pay for a couple of rebuilds I would have thought.
PS I said in the bible that realigning doors is a bit of a tricky job because in practice, it is either easy or takes a couple of hours and ends up with a worse alignment than you started with. It is very easy to damage the bodywork etc as a result which is why in most cases, the sensible approach is to leave it to someone who knows what they are doing.
The fact that you found it straightforward is great but shouldn't be interpreted as meaning that all the jobs and tasks that I described as tricky are straight forward.
The T5 change is not a drop in replacement.
Chad speed said:
Toma500 said:
Didnt think it was easy 
Ok smug one, this pie may be humble but hey I opted for a pork pie.Thanks to all Phers who posted, I will let you all know how I get on with assessing a good uprated LT77.
The T5 box isn't for sale yet though.
Maybe you could do a swap.
Edited by Toma500 on Thursday 25th September 12:11
Edited by Toma500 on Thursday 25th September 12:13
Toma500 said:
Chad speed said:
Toma500 said:
Didnt think it was easy
Ok smug one, this pie may be humble but hey I opted for a pork pie.Thanks to all Phers who posted, I will let you all know how I get on with assessing a good uprated LT77.
The T5 box isn't for sale yet though.
Maybe you could do a swap.
Edited by Toma500 on Thursday 25th September 12:11
Edited by Toma500 on Thursday 25th September 12:13
shpub said:
As someone who has abused LT77s and only switched to a T5 when I started breaking shafts and then the T5 broke and needed upgrading ...
www.gearboxman.com (CTS) rebuilt my LT77 with stronger bearings and that was taking close to 400 bhp. Cost was around £350. The T5 conversion is not straightforward and considering in real terms the overall cost and the fact that these cars don't tend to do a lot of mileage, getting an LT77 rebuilt every 10 years or so is a lot more cost effective way of going forward.
It's a lot of work for no real advantage. It's your car and your call but I would sell the bits you have and that should pay for a couple of rebuilds I would have thought.
PS I said in the bible that realigning doors is a bit of a tricky job because in practice, it is either easy or takes a couple of hours and ends up with a worse alignment than you started with. It is very easy to damage the bodywork etc as a result which is why in most cases, the sensible approach is to leave it to someone who knows what they are doing.
The fact that you found it straightforward is great but shouldn't be interpreted as meaning that all the jobs and tasks that I described as tricky are straight forward.
The T5 change is not a drop in replacement.
Sh I took your advice re the lt77 and going the rebuild route best advice I have taken in along time and the Lt77 when in good serviceable condition has a wonderful gearchange. saved a lot of agro. thankyou for steering me away from a T5. Not saying as a project it shouldn't be undertaken for the hell of it , I have speant my life doing conversions of one kind or another but don't underestimate what might be involved.www.gearboxman.com (CTS) rebuilt my LT77 with stronger bearings and that was taking close to 400 bhp. Cost was around £350. The T5 conversion is not straightforward and considering in real terms the overall cost and the fact that these cars don't tend to do a lot of mileage, getting an LT77 rebuilt every 10 years or so is a lot more cost effective way of going forward.
It's a lot of work for no real advantage. It's your car and your call but I would sell the bits you have and that should pay for a couple of rebuilds I would have thought.
PS I said in the bible that realigning doors is a bit of a tricky job because in practice, it is either easy or takes a couple of hours and ends up with a worse alignment than you started with. It is very easy to damage the bodywork etc as a result which is why in most cases, the sensible approach is to leave it to someone who knows what they are doing.
The fact that you found it straightforward is great but shouldn't be interpreted as meaning that all the jobs and tasks that I described as tricky are straight forward.
The T5 change is not a drop in replacement.
tvralfagtv6 said:
shpub said:
As someone who has abused LT77s and only switched to a T5 when I started breaking shafts and then the T5 broke and needed upgrading ...
www.gearboxman.com (CTS) rebuilt my LT77 with stronger bearings and that was taking close to 400 bhp. Cost was around £350. The T5 conversion is not straightforward and considering in real terms the overall cost and the fact that these cars don't tend to do a lot of mileage, getting an LT77 rebuilt every 10 years or so is a lot more cost effective way of going forward.
It's a lot of work for no real advantage. It's your car and your call but I would sell the bits you have and that should pay for a couple of rebuilds I would have thought.
PS I said in the bible that realigning doors is a bit of a tricky job because in practice, it is either easy or takes a couple of hours and ends up with a worse alignment than you started with. It is very easy to damage the bodywork etc as a result which is why in most cases, the sensible approach is to leave it to someone who knows what they are doing.
The fact that you found it straightforward is great but shouldn't be interpreted as meaning that all the jobs and tasks that I described as tricky are straight forward.
The T5 change is not a drop in replacement.
Sh I took your advice re the lt77 and going the rebuild route best advice I have taken in along time and the Lt77 when in good serviceable condition has a wonderful gearchange. saved a lot of agro. thankyou for steering me away from a T5. Not saying as a project it shouldn't be undertaken for the hell of it , I have speant my life doing conversions of one kind or another but don't underestimate what might be involved.www.gearboxman.com (CTS) rebuilt my LT77 with stronger bearings and that was taking close to 400 bhp. Cost was around £350. The T5 conversion is not straightforward and considering in real terms the overall cost and the fact that these cars don't tend to do a lot of mileage, getting an LT77 rebuilt every 10 years or so is a lot more cost effective way of going forward.
It's a lot of work for no real advantage. It's your car and your call but I would sell the bits you have and that should pay for a couple of rebuilds I would have thought.
PS I said in the bible that realigning doors is a bit of a tricky job because in practice, it is either easy or takes a couple of hours and ends up with a worse alignment than you started with. It is very easy to damage the bodywork etc as a result which is why in most cases, the sensible approach is to leave it to someone who knows what they are doing.
The fact that you found it straightforward is great but shouldn't be interpreted as meaning that all the jobs and tasks that I described as tricky are straight forward.
The T5 change is not a drop in replacement.
Thats who sh recomended, the rebuild came to 420 with the vat at competion transmissions (GBM?), mind you the change was good before,I took it to them for the rebuild with the linkage so they can set it up with the linkage and renew any bushes etc a worn linkage on a new box is daft.I then loctited the screws that hold the linkage housing in place and for good measure rtv siliconed the heads in place, i am in traffic everyday with the car so reliabilty is paramount. Mind you that LT77 is as strong as an ox speak to any white van man sherpa driver with an axle tramping rear end.
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