T5WC - Frankenstein Box Lifespan?

[ukkid35]

I have two broken T5WC, one with blown 5th gear, and one with a broken input shaft.

According to some YT videos input shaft failure is not uncommon



However the really sad part is the damage to the countershaft



I have a perfectly usable input shaft from my 5th gear failure box, and what I'd like to know is how long a Frankenstein box like this would last, if I just swapped input shafts.

I'm not asking simply because I'm too lazy to rebuild the box properly (in part but not really), it's because I have DN15 booked in a few days time and I'd really like to be there if possible. I will be wasting several hundred pounds on the track day and accommodation if I don't go.

The input shaft is only about £100, so that is all I would be sacrificing, apart from the real pain of having to pull the gearbox again.

If it could survive 1000 miles, 800 highway and 200 on track that be wonderful, but is that too much to ask?

Assuming it fails, now I've had more time to think about the failure mode, I reckon as long as I can select 4th, I should be able to drive an unlimited distance. Or at least far enough to be able to get home.

Any thoughts?

[350Matt]

they aren't matched pairs you can swap input shafts between boxes with no issues - just have to adjust the preload shims between shafts
or do you want to run the good input shaft against the damaged lay / counter shaft?
this would work for a while
typically once a tooth is chipped you get a lot of gear noise and the possibility of more pieces breaking away and shredding the rest of the box

can you not make a completly sound box out of the two?

[ukkid35]

350Matt said:

they aren't matched pairs you can swap input shafts between boxes with no issues - just have to adjust the preload shims between shafts
or do you want to run the good input shaft against the damaged lay / counter shaft?
this would work for a while
typically once a tooth is chipped you get a lot of gear noise and the possibility of more pieces breaking away and shredding the rest of the box

can you not make a completly sound box out of the two?

Yes, just use the good input shaft, and try to set the preload. Not even sure where I can get shims, ideally the peelable sort that Paul Cangialosi supplies with his billet retainer.

The other option would be to swap 5th, but that is impossible to shift without a press. That would be my preferred fix, but definitely can't get that done in the time available.

[ukkid35]

I admit I guessed the cost of a replacement input shaft based on eBay searches, without factoring in the rarity of the TVR variety (24 tooth 23 spline 9.25 inch). In fact they cost £200 plus vat, with the only supplier I've found been Gearboxman (or Readman Racing - can't remember which).

I can't find anywhere in the UK that can supply a set of shims, but there are US suppliers.

The main thing you want to avoid with T5WC issues is any sort of deadline...

[Andy_mr2sc]

Have you tried removing 5th on your old box? When rebuilt mine I removed the circlips, selector etc and 5th came away with a light tap on the end of the shaft.

[ukkid35]

Andy_mr2sc said:

Have you tried removing 5th on your old box? When rebuilt mine I removed the circlips, selector etc and 5th came away with a light tap on the end of the shaft.

The damaged 5th gear has moved enough to cover the circlip indent, but now won't budge. Rather than cut the race, I'm considering grinding the last remaining bits of damaged teeth, but maybe the metal will be too hard for me to do that.

Will need to buy a replacement 5th gearset too, and the US seems like the right place to get that.

[ukkid35]

I've been shopping




One of the cheapest items was the 070 cluster gear (as they call it in the US) just $100 new, made in India but I'm not concerned by that.




I'd previously ordered the wrong countershaft from somewhere else, but fortunately they let me change the order to a new(?) T5WC case. It's not new obviously, but it looks OK, and since it's so easy to strip threads in these I thought it was worth having, again for $100.




The rest I bought from Paul Cangialosi, he did me a great deal on the 24T 23S TVR input shaft, and they are very difficult to find. This one is used, but in very good condition.




Rather more expensive was the new fifth gear set




Plus the rebuild kit 'This kit includes all main bearings, synchro rings, all seals, cup plugs, peelable upper and lower shims, thrust washers, snap rings, caged needles,needle rollers, plastic pads, shifter bushing, dowel pins, clips, springs, strut keys, counter gear rear bearing retainer plate, oil funnel and 5th strut key retainer plate.'

And a fifth gear stabiliser just for good measure.

I found a card from airport security in my case saying they'd inspected it, and the only box they'd opened was the one containing the T5 case, presumably because it's only open on one side it must look interesting in the scanner.

[Andy_mr2sc]

Did you use his Sebring heavy duty 5th gear set? That doesn't look expensive for what appears to be considerably stronger.

[ukkid35]

Andy_mr2sc said:

Did you use his Sebring heavy duty 5th gear set? That doesn't look expensive for what appears to be considerably stronger.

It's not an option with our 27 spline output shaft.

[QBee]

Have you considered hiring or borrowing a trailer, and towing the car there and back? Granted they will charge you more on the ferry, but it also covers the risk of mechanical breakdown or accident recovery.

[ukkid35]

QBee said:

Have you considered hiring or borrowing a trailer, and towing the car there and back? Granted they will charge you more on the ferry, but it also covers the risk of mechanical breakdown or accident recovery.

In July I brought it back from Adenau when the gearbox failed on a hired truck, it cost a fortune even as a DIY job. I did consider a trailer, but couldn't borrow one or find a car with a tow hook.

The additional ferry cost was one of the biggest considerations, bizarrely the truck used less fuel with the Cerb on the back than the Cerb does by itself.

Getting it on and off the truck was far from simple.

[77racing]

Some of the TVR Rover engine racers using T5WC box's got so fed up with replacing third lay and 5th gear that we have gone down the TKO 600 route. I have had no problems with the TKO in three years racing with it and the last year with T5 had three failures. Just saying like

[ukkid35]

77racing said:

Some of the TVR Rover engine racers using T5WC box's got so fed up with replacing third lay and 5th gear that we have gone down the TKO 600 route. I have had no problems with the TKO in three years racing with it and the last year with T5 had three failures. Just saying like

In this instance the failure was entirely my fault for not replacing the pilot bearing, which grenaded and then caused the incorrectly shimmed input shaft to go unstable.

[350Matt]

Don't forget to use 75W80 gear oil too, this helps box life a lot

[ukkid35]

350Matt said:

Don't forget to use 75W80 gear oil too, this helps box life a lot

I'm using the most expensive fully synthetic AFT that I can find.

DN16 day one over, and all good so far. However I didn't that many laps because I had to fix a suspension issue, and there were more track closures than usual.

[fredd1e]

350Matt said:

Don't forget to use 75W80 gear oil too, this helps box life a lot

Is that ok in the T5 box? Thought it was atf only? Though I have no idea on what the difference is between atf and the "normal" xxWxx gear oils

[ukkid35]

DN16 finished, with only one rain shower over the two days. I admit I haven't done a huge number of laps, but I've driven as much and as hard as I wanted. The box has lasted, and only now has to get me home, but I doubt that will pose a problem after the punishing it's had over the last couple of days. Very pleased indeed.

[ukkid35]

I have my answer now - nine months.

The box has failed on the way to the Burghley House TVR Meet.

But, not the damaged countershaft, instead fifth gear has blown.

I did not see this coming, but I was concerned that I might have put too much preload on the input shaft so that the disc shaped needle bearing between input and output shafts might suffer. It seems I did that part fine.

However when I fitted the 5Speeds.com 'Counter Gear Stabilizer' I have to admit that I was not able to set preload on the countershaft accurately because you need to remove the output shaft to do so.

It will be interesting to seem what the preload is when I strip down the gearbox later in the year.

My aim now is to get the spare box repaired, and to do that I need to find a way to get the remains of the 5th gear off the output shaft, and more importantly fit the new 5th gear without damaging it.

Sadly there's no way I'll be at DN17 in the Cerb, but I absolutely must have the car ready for DN18 in July.

[ukkid35]

The Frankenstein box has another chance to prove itself, as it's now been rebuilt with the damaged countershaft (because I can't find the intact countershaft that I've stored safely somewhere)

I'm hoping it will survive the CircuitDays event at Easter

I'm also hoping to build a box with a Quaife Gearset, but the lead times for the parts are very vague indeed

Edited by ukkid35 on Monday 14th February 09:34

[Andy_mr2sc]

ukkid35 said:

The Frankenstein box has another chance to prove itself, as it's now been rebuilt with the damaged countershaft (because I can't find the intact countershaft that I've stored safely somewhere)

I'm hoping it will survive the Easter CircuitDays event at Easter

I'm also hoping to build a box with a Quaife Gearset, but the lead times for the parts are very vague indeed

Is your box standard or close ratio?