T5 or T56?

[BB-Q]

I'm getting to the stage in my project (1968 Volvo 142, 2.3l turbo 16v, lots of boost) where I need to be considering which gearbox to use.

The obvious choice to me initially was the T5 from a TVR (strongest T5 made, apparently). But talking to some American guys has got me thinking about a T56. I'm told that the prices you see on Ebay USA are ridiculously high and that most people don't pay much more than $500 for a gearbox. Obviously, in that situation I also have to consider shipping and duties.

I was thinking of the T56 for two reasons- torque handling and the 0.5:1 6th, which would let me run a lower ratio rear to help with launches at the strip. Stock diff in the 8.8" axle is 3.73:1 and I was thinking that the 6 speed would allow me to run a 4.10:1 and still have the car cruise nicely on the motorway.

Obviously the 6 speed box would have to be pretty cheap to justify it, but T5 boxes aren't exactly economy purchases either.

Ideas? Opinions?

Edited by BB-Q on Wednesday 28th November 23:47

[stevieturbo]

Im not sure you'd get a good T56 for $500.

I recently seen someone ask on LS1Tech how much a damaged T56 was worth, and they said $500.

But they are strong....but also very big.

T5's arent strong by any means. If you can find one, what about a Toyota Supra R-154 5speed from a 88-94 Supra Turbo.

Very strong boxes.

Although if you have the room for a T56...no reason why not. A Monaro/GTO version has slightly shorter ratios, ending up with circa 0.63 6th gear ( although oddly someone recently suggested 0.57 over in the HSV section )
The Mustang version uses similar ratios.

[GavinPearson]

If you go to www.tremec.com you can see details of every T5 or T56 made. This also shows the torque capacity and ratios.

The T56 is a serious duty transmission designed for high output V8s and it is not exactly going to provide the crisp feel and knife through butter change of say a Getrag 220 5 speed.

Let me know what you intend the output of your engine to be, both in torque and HP terms and I will try to point you in the right direction.

[chuntington101]

alright BB-Q hows the build coming on??

like the other two have said, the T56 will be alot stronger but much bigger. the supra might be worth a look. as would the box used in the Nissan 300zx (think its shorter than the supra one)

thanks Chris.

[Boosted LS1]

The 56 is also incredibly heavy and comes with different front end arrangements. This effects price by quite a lot. Camaro items tend to be the cheapest and oldest. Ls1 boses are the most expensive. I'd steer you towards a WC mustang T5 as found on the v8's. Strong, plentiful and cheep. Or go for the supra item as Stevie suggested.

[BB-Q]

Projected hp is about 550ish. Torque I haven't troubled to calculate. We're talking about a 2.3l 4 pot turbo lump. I'm being steered towards the T5 as it's available in this country for "reasonable" money and word is that they will take a lot more torque than they are rated for.
I've been told by the guys from TVR (I live in Blackpool) that they uprated the T5's as they came into the factory with stronger components.

I can make a T56 fit if needs be by cutting out the tunnel and making a new one, but the idea of something smaller definitely appeals.

My budget is severely limited as always, which is why the idea of a cheap T56 sounded so good.

The problem with the Getrag and Supra boxes is that they all have crap ratios compared to the 2.95:1, 1.94:1, 1.34:1, 1.00:1 and 0.83:1 of the T5 in Cosworth, V6 Camaro or TVR form.

[Boosted LS1]

Your cheapest option will be a yank World Class Mustang t5 from the States and they're quite strong as well.

[stevieturbo]

Supra R-154 transmission

RATIOS
1st 3.30:1
2nd 1.95:1
3rd 1.34:1
4th 1.00:1
5th 0.75:1
Rev 3.20:1

I thought the Supra ratios to be very good actually.

The lesser T56's, although still damn strong. GTO/Mustang etc

1th 2.97
2th 2.07
3th 1.43
4th 1.00
5th 0.80
6th 0.62
Reverse 2.90

Stronger T56, as per LS1, Viper etc.

1st......2.66
2nd......1.78
3rd......1.3
4th......1.0
5th......0.74
6th......0.5

[BB-Q]

Boosted LS1 said:

Your cheapest option will be a yank World Class Mustang t5 from the States and they're quite strong as well.

Yes, but they have a nasty 3.35:1 1st gear. Well ok, not nasty, but nowhere near as tasty as the Ford based TVR T5 @ 2.95:1. Plus, there's plenty of TVRs in the breakers yards due to oh so many of their owners confusing their intentions with their abilities.

[GavinPearson]

Boosted LS1 said:

Your cheapest option will be a yank World Class Mustang t5 from the States and they're quite strong as well.

I would avoid like the plague. They are not man enough for the job, which is why Ford fit a Tremec TR3650 to V8 Mustangs nowadays.

I'd probably fit a T56 or a TR3650, provided the ratios were right.

[Boosted LS1]

Two points spring to mind here. The t5 mustang box has served ford well for years so it can't be that bad even if they have finally moved to a newer box for newermore powerful engines. It's tq ratings are available on the net. Also, don't forget that a t56 weighs in at a hefty 9 stone or thereabouts. As for the 'special' tvr box, well maybe look at chrysler offerings if there are any. I was told the tvr box is from a chrysler. Not sure how true that is but it's plausible.

Edited by Boosted LS1 on Friday 30th November 00:32

[BB-Q]

My comments about the TVR box came from the guy who used to build them at the factory, so I'll take it as genuine.

Having spoken to guys who've run them behind stuff as big as BB Chevys I'm inclined to believe these boxes will take a hellava lot more torque than they are rated for. Also, some of the Cossie guys are putting bonkers power through them reliably.

[teamHOLDENracing]

BB-Q said:

My comments about the TVR box came from the guy who used to build them at the factory, so I'll take it as genuine.

Having spoken to guys who've run them behind stuff as big as BB Chevys I'm inclined to believe these boxes will take a hellava lot more torque than they are rated for. Also, some of the Cossie guys are putting bonkers power through them reliably.

On the TVR Tuscan racers the T5 wasn't bad but 3rd gear commonly broke, particularly on bumby circuits where the rear wheels would spin up over crests. The race boxes have striaght cut 5th gear. Several of us switched to the big gear kits offered by Glebe and CTS to combat this, and these big gear kit T5s will take a lot of punishment. The gear kits are not cheap though.

If you are interested I have a Glebe T5 dog box, a standard race T5 with straight cut 5th and a big gear kit T5 all available at the moment, due to a change to sequential transmission for next year. You can contact me via my profile

[Boosted LS1]

BB-Q said:

My comments about the TVR box came from the guy who used to build them at the factory, so I'll take it as genuine.

Was there one bloke or was there a gearbox department? If they were buying in boxes, opening them up and doing really good stuff to them they'd need more then one guy, surely? I could be wrong but for the stock cars it's more economical to use a warrantied box and fit it as it comes, keeping the warranty intact. To open up a production box, modify it and reassemble it seems like a costly excercise. Maybe they just modified some of them for certain tvr models. In much the same was as some engines were virtually stock apart from improved heads.

Anybody here actually work in the gearbox dept? I'd like to know what boxes were used along with the mods. Would be interesting to clarify this.

[BB-Q]

It was a random meeting when I was doing a breakdown, but the next time I come across anyone from the factory I'll ask them.

[Boosted LS1]

BB-Q said:

It was a random meeting when I was doing a breakdown, but the next time I come across anyone from the factory I'll ask them.

Could be interesting as lots of people have paid a premium price for a tvr box. Just like some people pay a price for a 24v ford with a cosworth badge on the plenum. The badge rocks if you get my drift.

[spend]

Boosted LS1 said:

Could be interesting as lots of people have paid a premium price for a tvr box.

I keep telling the girls that, but they still keep slapping my face

Dave

[Boosted LS1]

spend said:

Boosted LS1 said:

Could be interesting as lots of people have paid a premium price for a tvr box.

I keep telling the girls that, but they still keep slapping my face

Dave

Ah, so you'r the guy from the spitting thread?

[BB-Q]

Boosted LS1 said:

BB-Q said:

It was a random meeting when I was doing a breakdown, but the next time I come across anyone from the factory I'll ask them.

Could be interesting as lots of people have paid a premium price for a tvr box. Just like some people pay a price for a 24v ford with a cosworth badge on the plenum. The badge rocks if you get my drift.

Well, I've already checked and ALL TVR T5 boxes are the same. You don't get special ones in Tuscans, etc. and the Cerbera one has the same torque rating as a Chimera one.

I found a place doing them for £350, but I've yet to call Douglas Valley Breakers and see how much they want. I'll do that in a minute but suspect they're going to be stupid money due to their "specialist" status.

I'm set on a T5 now (have you seen the gorgeous shifter kits you can get with the very weak dollar?!?!?!) unless a ridiculously cheap T56 comes along. Once I've got one (waiting for a small lump of cash that's coming my way) I'll measure it and report the differnces. There's a wealth of knowledge over on Turbobricks about the T5 ('cos they're all yanks) so the (external) differences can be noted. I think it uses the Ford input shaft and a different output shaft, but I'm not sure yet.

Edited by BB-Q on Saturday 1st December 09:14

[GavinPearson]

I think you need to be aware that the TVR transmissions have always been built in Tremec's factory in Queretaro, Mexico. How do I know? I asked the factory Manager when I went there.