Type 9 gearbox fitted to a 4.6 stage III v8

DaveEFI · Post by **DaveEFI** » Sun Feb 12, 2012 11:59 am

Unless your engine is terribly peaky, a RV8 is normally ok with a 4 speed box, performance wise. 5th is good as an 'overdrive' to reduce noise wear and fuel consumption when cruising.

stevieturbo · Post by **stevieturbo** » Sun Feb 12, 2012 12:25 pm

Obviously that box is a 6 speed, so will be comparable to other 6 speed Tremecs. 5speeds will of course be much shorter.

And you think that a 0.8 5th gear is fine....but with a big torquey V8, it's very easy to grab another gear when it's there.

My 6th gear is 0.5 which is mega tall. But still quite usable from around 45-50mph ( 40mph with the 3.55 diff )
5th is around 0.74, and when driving, it does always feel like you want another gear...which is handy when it's there lol

Opting for a mega tall 1st gear will be a mistake though. You may think it's what you need, but when stuck in stop start traffic, or long queues, you'll soon find it a pain.
When traffic is moving very slow, it's nice to be able to chug along at idle with foot off the clutch.
It's very annoying when you always have to slip the clutch in traffic, instead of trundling along in 1st gear at idle

sidecar · Post by **sidecar** » Sun Feb 12, 2012 1:24 pm

stevieturbo wrote:
Opting for a mega tall 1st gear will be a mistake though. You may think it's what you need, but when stuck in stop start traffic, or long queues, you'll soon find it a pain.
When traffic is moving very slow, it's nice to be able to chug along at idle with foot off the clutch.
It's very annoying when you always have to slip the clutch in traffic, instead of trundling along in 1st gear at idle

The thing is my second gear does what you can do in first, I can crawl along at idle in second gear with the clutch fully out!

I've bunged a load of ratios into a gear calculator, my current first gear is good for 38 MPH at 6k, second gear is good for 60 MPH. If I use first gear the revs will pick up so quickly that I could not get the box into second quick enough. (Plus it will just light the wheels up anyway, it will light them in second with very little effort but its more controllable).

I'm going to drop the box anyway because I want to get the flywheel lightened, I'll find out exactly what ratios I've got as there seems to be a lot of mis-information about the R380 ratios on the web!

I've also jacked the car up and run the engine at 2k in each gear, I think that the speedo is quite accurate because I set up using sat nav.

The speed per 1000 RPM worked out to be the following with the R380 box:-

1st.....6mph
2nd....9mph
3rd....15mph
4th....22.5mph
5th....27mph

taking fourth gear a a reference because it is the only gear ratio that I can be sure of I then tweaked the wheel size in the gear calculator, after the tweak it reckons that second gear is good for 54mph which seems about right as far a I can remember.(I don't drive the car in dodgy weather)

Cheers,

Pete

JSF55 · Post by **JSF55** » Sun Feb 12, 2012 2:00 pm

I might be talking through my a55 but i would have thought closer gears are what your after ? with 1st being unusble, surely making it lower, numerically, and moving second in the same direction will keep the power band in the right place ????
Edit :- possibly moving 3rd too ?

kiwicar · Post by **kiwicar** » Sun Feb 12, 2012 5:10 pm

Hi
personally in a Light car (under a tonne) I think 6 mph/thou is a bit low regardless of traffic, it just is too short. 7.5 to 8 is more like it. A tall 5th or 6th (over 30, 32/ thousand) is nice for when distance is to be covered but is easily sacrificed in favout of placing the rest of the gears where you want them.
With the termec 6 speeds there are basically 2 gear sets one with a high first and 2,3,4 close together and 5 and 6 far appart ending with 6 at .5:1 usually fitted to fords, the other version is a wide 1,2,3,4, with 5and 6 closer together with 6 at about .62:1 usually on chevys. . . . what I am getting around to is has anyone done the 1,2,3,4, from the ford with the 5 and 6 from the chevy, with the right rear end ratio and first about 7.5mph/k that would make a great box for a kit car. I still think they are a big heavy beast (they are quite a bit bigger than the 5 speed case) but a closr ratio 6 speed would be easy to live with, when not thrashing along all you do is go 1,3,5, 6 or 1,2,4,6 when pootling.
Best regards
Mike

stevieturbo · Post by **stevieturbo** » Sun Feb 12, 2012 5:32 pm

There are multiple ratios available for the T56 format.

They all fall within the 3 to 0.5 range though. And there are a few variants with the shorter 5th and 6th gear, Aston is one, and I think some of the Holden models might use them.

Again, how useful they actually are depends on the overall package. A friend with a Viper had his modified for a shorter 5th and 6th, but it doesnt really turn a lot of rpms, and as it's also supercharged makes a fair bit of torque.
That said, it does also use a 3.08 rear.

I considered the shorter 5th and 6th for myself, but all it would have done is given me a totally useless gearset for racing.
5th would be too short to achieve any decent speeds, and 6th would still be so tall that it was useless.

If I was to retain my 3.27 rear, I'd prefer the shorter 2.97 first. The 2.66 is too tall for traffic, regardless if whether the engine will actually pull off nicely or not ( it will drive off in 4th if I want, doesnt mean it's nice to do it )
But I'll prob go back to the 3.55. I doubt I'll be aiming for 200+ again in the near future, and if I do, it's a relatively easy swap back anyway.

Of course the other option is fit an automatic lol

kiwicar · Post by **kiwicar** » Sun Feb 12, 2012 7:39 pm

ah now you are talking. . .

auto that makes it easy

. . . powerglide . . .1st 1.82:1 top 1:1 . . reverse 1.82 again. Alternative ratios from 2.06 to about 1.5 ish can be built to weigh less than 100lbs and you can shove buckets of power through one, easy peasy, nice loose torque converter and you are away.
If you want to make it complicated you could look at one of those modern 7 or 8 speed twin lay shaft flappy paddle thingys, driven a couple on track, they are great for a track car, not sure how good they would be for town driving, it is a bit easy to get "lost" in one, unsure which gear you are in or how many changes you need to make to get there.
Best regards
Mike

sidecar · Post by **sidecar** » Mon Feb 13, 2012 1:57 pm

Hi Guys,

Thanks for your input on this one!

I've had an email back from RWD Motorsport with regards to their synco boxes. They reckon that they are only good for 230 BHP so that's no good to me! I might email them about their dog boxes but I'm not too sure whether I can live with one! (I'm getting old and syncro boxes are nice and easy to use!)

Just a bit more info on my car, I needed the 2:1 first gear because the car is light therefore does not need or want a short first gear but one thing it ain't is streamlined which is why fifth gear could not be too tall, 0.82:1 would give it a top speed of about 150 MPH at 5500 RPM without the revs being mega high at more 'normal' speeds!

Cheers,

Pete

SuperV8 · Post by **SuperV8** » Mon Feb 13, 2012 10:38 pm

How about the close ratio T5 box out a TVR tuscan s? 2.43 1st and 1.56 2nd. small, light and strong box.

Tom.

sidecar · Post by **sidecar** » Tue Feb 14, 2012 5:47 am

SuperV8 wrote:How about the close ratio T5 box out a TVR tuscan s? 2.43 1st and 1.56 2nd. small, light and strong box.

Tom.

Hi Tom,

Thanks for the reply, any idea where I could get a T5 Tuscan box from?

Cheers,

Pete

kiwicar · Post by **kiwicar** » Tue Feb 14, 2012 10:16 am

Hi
the bigger scrap yards have lots of Tuscans, especially the early ones before they tamed them a little. . . it rained, they got driven into the scenery!

I was at one stage (about 8 years ago) thinking of putting a TVR 6 and transmission into a SSC kit car. Would have made an "interesting" car, they were relitivly cheep and there were lots of engines and boxes about, very few body panals or chassis though.
Best regards
Mike

sidecar · Post by **sidecar** » Tue Feb 14, 2012 10:45 am

kiwicar wrote:Hi
the bigger scrap yards have lots of Tuscans, especially the early ones before they tamed them a little. . . it rained, they got driven into the scenery! I was at one stage (about 8 years ago) thinking of putting a TVR 6 and transmission into a SSC kit car. Would have made an "interesting" car, they were relitivly cheep and there were lots of engines and boxes about, very few body panals or chassis though.
Best regards
Mike

Hi Mike,

I've had a quick look on ebay, there are a couple for sale, I asked one guy if he knew what the ratios were but is reply was 'use google'....charming!
Anyway I like the idea of using a T5 box because I think it will be an eaiser conversion and they also seem quite cheap and strong but downside is that first gear is still a bit high (better than my 3.3:1 but is it enough difference to warrent the swap...).

The type 9 box is now back into the mix, Quaife can build me a box with the ratios that I want, they state that it is good for 250 BHP but when I emailed them they stated that this was very 'conservative' and that it would be OK in a light car. The downside is that it will cost about 3k by the time that I've finished fitting the thing. (Dunno how much the bellhousing will cost). My R380 and bellhousing must be worth a few quid though!

Here's a link that Quaife sent to me, it has straight cut gears which are noisy but I doubt that they are more noisy than my sidepipes...

http://www.quaife.co.uk/shop/products/qbe15z

Here are the ratios:-

1st 2nd 3rd 4th 5th
2.040 1.540 1.210 1:1 0.870.....I'd go for this option.
2.200 1.690 0.930
2.390

I think that I need to do some more research on the TVR boxes! I'll keep you guys posted! (If you haven't all got bored of my ramblings!)

Cheers,

Pete

kiwicar · Post by **kiwicar** » Tue Feb 14, 2012 12:29 pm

Hi
Not sure of the TVR straight 6 bolt pattern, but as it was an in house design I would see if it is Buick V8 anyway, might well be, if nit it isnt rocket science to make up an adaptor.
The Quaif box will be pretty strong, they have a reputation for making boxes that do not blow up and are pretty keen to keep it, what BHP is your engine, cant be much more unless you have merlin/TA (if they exist) or Buick 300 heads.
Best regards
Mike

DaveEFI · Post by **DaveEFI** » Tue Feb 14, 2012 12:45 pm

BHP is pretty irrelevant to a gearbox. It's peak torque which matters.

kiwicar · Post by **kiwicar** » Tue Feb 14, 2012 12:57 pm

DaveEFI wrote:BHP is pretty irrelevant to a gearbox. It's peak torque which matters.

Perfectly true however if it is a matter of say 50ftlb extra over box rating of a box rated for 300 ftlb, and it is a light car, don't full power short shift into third up a hill on a hot day with sticky tyres, use the revs and the gears in a way that doesn't shock load the second motion shaft!

By the way I bet Ians picture is the result of a high speed Yump in third on a tarmac rally again shock loading of the box (and probably a bit of a suprise to the driver.
Mmmmmmm straight cut gears good way to save weight, no point in fitting a radio, you will never hear it!

Best regards
Mike