4.3 Pre-cat 2nd gear problems.

[gateeast]

Can anyone offer help please.

Synchro has gone on 2nd gear and I am unsure whether to replace with a recon or rebuild the gearbox?

Also, does a LT77 (SD1) gearbox fit straight in?

Or is there a way around the problem, at slow speeds all is fine but changing down from higher revs from third causes it to crunch?

Thank you.

[L1OFF]

The LT is not a straight swap, different prop etc. Normally it's 5th that is the weak link in the T5, a rebuild is pretty straight forward.
Alan

[5.0ltr]

gateeast said:

Or is there a way around the problem, at slow speeds all is fine but changing down from higher revs from third causes it to crunch?

Perhaps it is the changing down from higher revs from third? Might I suggest that a Griff should not be driven this way and risk partial lock up of the rears and the potential problem with weight balance transfer this will cause. Unless you can sustain revs to a gnats crotchet that is.

[350Matt]

L1OFF said:

The LT is not a straight swap, different prop etc. Normally it's 5th that is the weak link in the T5, a rebuild is pretty straight forward.
Alan

Au contraie, the pre-cats use the LT77 with TVR's own shift mech

So yes an SD1 box will go striaght in, make sure its a Vitesse box as these are stronger than the 6 cylinder ones

If teh gear is just starting to crunch might be worth trying a an oil change for some castrol SMX-S

[Barreti]

Doesn't sound like syncro is going from what I know of how they work - which I admit isn't exactly encyclopaedic.

Two things come to mind.
The nylon bush at the bottom of the gearlever - search for my old thread "sloppy back and forth" for all the detail. The crunching of 2nd was the first indication I had that something was amis. 3rd came next - or the lack of it.

Try to master Heel/Toe. It helps hugely when dropping down the gearbox and goes a long way to save you worrying about locking up the rears when you should be concentrating on that roundabout thats rapidly approaching.

[sunwharf]

Got the same with my precat, the "heel and toe" method does the trick for me. Mine tends to graunch a little when cold if I forget to "heel and toe" but a slightly slower grear change also works.

Had a gander but couldn't find the thread "sloppy back and forth"?

Nick

[Barreti]

sloppy back and forth LT77 thread

Google is your friend, even if PH Advanced Search isn't

I still have the pictures if you need any refreshing. If you search TINYPIC.COM for LT77 you will find my photos though (or most of them I think)

Edited by Barreti on Tuesday 15th September 19:49

[LordGrover]

If you do end up swapping the gearbox, as I have, you may run into problems with the speedometer. It may be down to the 'standard' vs vitesse mentioned above but my speedo is reading light - satnav confirmed 70 reads just under 60 on the speedo.

[gateeast]

Thank you all.

I'll try the heel and toe. Failing this any ideas where to get the gearbox from, I assume it is an engine out job.

Edited by gateeast on Tuesday 15th September 20:19

[sunwharf]

Thanks for the link. Cor blimey, I'm going to leave well along or get someone else to do it if mine gets any worse. If I tried to do that it would look like a massacre!

[LordGrover]

gateeast said:

... Failing this any ideas where to get the gearbox from, I assume it is an engine out job.

I'll have a 'spare' LT77 available in January/February but it occasionally jumps out of third - it'll need sorting.

[Hoover.]

Ran mine with same probs for a year... totally spoiled the driving experience..

don't do what I did and change for a T5, yes there is a diffence is not worth the cost IMHO... in fact I think the LT77 has a better gear ratio for of the line running

[350Matt]

gateeast said:

Thank you all.

I'll try the heel and toe. Failing this any ideas where to get the gearbox from, I assume it is an engine out job.

Edited by gateeast on Tuesday 15th September 20:19

No you can remove the box from underneath and leave the engine in place.

That LT77 is bloody heavy on your own tho!

[gateeast]

Where is the best place to get a recon one any ideas?

Thank you.