Griffith - LT77 question

Griffith - LT77 question

Author
Discussion

davemac250

Original Poster:

4,499 posts

204 months

Wednesday 17th December 2014
quotequote all
Guys.

How much power can this gearbox handle before becoming a ticking time bomb?

Going FI and want to tie up all the variables.

Thanks.

D.

TV8

3,118 posts

174 months

Wednesday 17th December 2014
quotequote all
I had this thought on my last car. TVR Power didnt recommend lots of power with the existing LT gearbox.

Engineer1949 who supercharged the 4lt Chimaera runs the LT77 box with no problems but he had this rebuilt before increasing the power. There is also the 380 version of the gearbox, not sure what it is from but it is meant to be stronger.

Not sure what oil you use? If you dont already use it, I would try Difflock. Made a huge improvement on the smoothness and syncro noise of mine on track days.

gmw9666

2,734 posts

199 months

Wednesday 17th December 2014
quotequote all
Running 287bhp through my LT77, have a watch :-) = http://s1354.photobucket.com/user/gmw9666/media/IM...

davemac250

Original Poster:

4,499 posts

204 months

Wednesday 17th December 2014
quotequote all
That vid isn't working.

I'm not far off 287 already - and the gearbox was off for a refurb recently.

The question is what to aim for without needing gearbox work.

At the wheels options are 300-320, 350-370 or 400+ depending on the set up.

The head part of me is leaning to the middle option - SC with intercooler.

The heart part of me says bigger it big blower, new injectors, AFM etc and go for the big power.


gmw9666

2,734 posts

199 months

Wednesday 17th December 2014
quotequote all
davemac250 said:
That vid isn't working.

I'm not far off 287 already - and the gearbox was off for a refurb recently.

The question is what to aim for without needing gearbox work.

At the wheels options are 300-320, 350-370 or 400+ depending on the set up.

The head part of me is leaning to the middle option - SC with intercooler.

The heart part of me says bigger it big blower, new injectors, AFM etc and go for the big power.
Try clicking this

Ant.

5,254 posts

280 months

Wednesday 17th December 2014
quotequote all
My old Griff had/has around 327bhp and 345ft/lb through an LT77.....

From memory between me and the current owner Doc Toad its done around 7k with no issues...

griffdude

1,819 posts

247 months

Wednesday 17th December 2014
quotequote all
These guys seem to specialise in LT77 gearbox rebuilds

http://www.ashcroft-transmissions.co.uk/manual-gea...

I'd ask them.

davemac250

Original Poster:

4,499 posts

204 months

Wednesday 17th December 2014
quotequote all
Awesome info. Thanks.

gifdy

2,065 posts

240 months

Wednesday 17th December 2014
quotequote all
Killed mine with about 300ish bhp. Needs return but ashcroft suggested going to R380.

TVRVixenV8

81 posts

228 months

Thursday 18th December 2014
quotequote all
It's not the power that kills a gearbox, it's always the driver and his way of driving cars

davemac250

Original Poster:

4,499 posts

204 months

Thursday 18th December 2014
quotequote all
Pretty sure it's screwed then.

spitfire4v8

3,990 posts

180 months

Thursday 18th December 2014
quotequote all
TVRVixenV8 said:
It's not the power that kills a gearbox, it's always the driver and his way of driving cars
To a large extent it's this smile
I ran an LT77 behind a tuned 5 litre in my V8S, never had any problems at all.

LordGrover

33,532 posts

211 months

Thursday 18th December 2014
quotequote all
davemac250 said:
Pretty sure it's screwed then.
rofl

griffdude

1,819 posts

247 months

Thursday 18th December 2014
quotequote all
spitfire4v8 said:
To a large extent it's this smile
I ran an LT77 behind a tuned 5 litre in my V8S, never had any problems at all.
That's because you've got a modicum of mechanical sympathy.

TBH, I've expected mine to give me more trouble having done 80+ standing starts in the past few years, but touch wood its been ok after changing the nylon selector bushes & several oil changes. The weak point I've found seems to be the CV joints.

Hoover.

5,988 posts

241 months

Thursday 18th December 2014
quotequote all
Pretty sure Steve Heath used the LT77 in some of race cars, as remember a thread where he preferred the gearing of LT77 compared to the T5, due to the longer 2nd gear

davemac250

Original Poster:

4,499 posts

204 months

Thursday 18th December 2014
quotequote all
I remember reading that, he didn't like the reposition of the lever if memory serves.

Buggerit - I'll see what happens.