Looking at a straight cut box for my track car and wondered if anyone had any experiences?

Car will be over 500bhp so Looking at what box, place to buy and best prices etc.

Also would be interested in buying a second hand one if there's any about.

Cheers.

 

I have a straight cut Bara Motorsport box in my 4x4 puma, I think it's great. Mine is used on the road. Be prepared for noise but I'm guessing you won't be too bothered about that in a track car. Long motorway journeys in it can be tiring but again I'm assuming you won't be doing that.

Picked mine up second hand and it's been faultless so far. I have a short shift fitted and hydraulic clutch, gear changes are fine but the clutch needs to be fully depressed to avoid crunching.

Hope that's of some help.

 

out of interest does a straight cut box change gear as quick?

 

I thought that wasn't the case with straight cut for the same reason you can change a bikes gears without the clutch? Are all straight cut box's the same?

 

Thanks for the info. I wouldn't want straight cut if it was a road car because of the noise but it's track only so don't mind. Funny enough I phoned bara today to pick the brains but gonna see if maybe I can get a second hand one first.

 

My oppliger is semi straight cut and makes some nice noises but I can still have the stereo on in the car, it's good for over 700bhp and close ratio. Bara built it for me 4x4 box. I think the close ratio would be great on track as would top put 150 / 160 but gets there very quickly.

 

You're thinking of a dog engagement box, like a seqential gear box.

A straight cut gear is exactly that, straight accross the mating surface. A helical gear kit is tapered to one edge to make it quieter as it has less surface area in contact than than a straight cut gear - hence a straight cut being stronger as there is more metal to metal contact.

A straight cut box will still have sycros, so wont change gear as fast as a dog box.

Pics

Helical top, straight cut bottom

https://www.google.co.uk/search?q=st...3n1brHnyeQjFM:

Syncro left, dog right

https://www.google.co.uk/search?biw=...MiN8jAPy2nDXM:

 

Well actually a straight cut gear is less strong than a helical cut gear as the straight gears have less area to be in contact with the other gear. The problem though with helical gears is that they put a side loading on the bearings of the gearshaft. So basically the gears try to push away from each other. If there is a bit of play on the shaft the contact area of the gears becomes less and the teeth can break.

 

Helical gears are quieter, more contact patch AND stronger than straight cut gears. It's also the helical profile that makes them quiet.

But typically straight cut gears tend to be sold as stronger because they're aftermarket, made for racing and made from stronger materials than OEM stuff.
But like for like, helical IS stronger. But helical also imparts side loadings onto the system which can affect case strength, bearings etc whereas straight cut doesnt do this quite the same.

And depending on geometry used for the gears, some SC gears can be bloody noisy, although mostly that's a thing of the past too. Most should be quite tolerable even in a road car as long as the gearbox isnt bolted solid to the car ( and then it can be feckin horrific lol )


And a straight cut box...will have straight gears. That has no baring on the shift mechanism. They can be made with both synchro engagement or dog engagement. Entirely up to the buyer to decide what they want.

 

just go with the tko 600 rich ,seems a good box

 

Is that not sequential the tko 600?

 

nope rich .its the same as mr tarry runs.i have one for the kaliber rep

 

Ah ok. I'm not up to scratch on my boxes. You just as well sell me that mate hadn't ya

 

With the car lol

 

no and no rich lol

 

No, it's a big old brutish synchro box.

The TKO range isnt renowned for smooth shifting, but probably no different than a T5 really.

 

i think its a little better with the pro quick shift stevie

 

I think I'm gonna see what's around before I make a decision but if I end up buying new I will need too do my homework.

 

The stick isnt going to magically change the internals.

I'm not saying they'll be terrible, but they are by no means a modern box. Old design, but definitely strong.

If you can fit one in the tunnel, and I dont really see why one wouldnt, a T56 Magnum would make a lot of sense.

Stronger than a TKO although more expensive, and far superior synchro internals for better shifting.

Either would be good options though

 

you could ask paul at north yorks to see what they are running in the 5oo race cars rich

 

it shouldnt matter though stevie as the engine will most likely break first

 

And there was me thinking i knew what i was talking about

Iv'e been schooled lol

 

Thanks fudgey, obviously getting my syncros mixed up, I understood the straight cut part, but miss information was that the straight cut meant they slid together easier I'm guessing what I know now I should of taken a more logical approach and realised my error

So the reason a dog leg works without the need of a clutch is due to the large spacing between teeth allowing the gears to mesh quickly without issue?

 

The tko with pro5 shifter is just fine on a 1989 Road going Sapphire . Would not be suitable for a race car I guess. Can I point out I don't use a tko600 . My tko box was built in the States by 'Dark Horse Performance' with gear ratios to suit the Cossie & take 700ft-lb. It cost more 16 years ago than a tko600 does now. Like my Diff it was fitted for strength not speed & its certainly been strong as neither have broken, gone wrong or until my latest build had its oil changed. THE ULTIMATE FIT & FORGET.

 

"Dog leg" refers to the H gate, as found on some old M BMW's, where 1st was a dog leg...ie not on the main H

Dog engagement is different.

And yes, a synchro box will only engage gear when all synchro teeth are in alignment, which requires the baulk rings to adequately slow the gears to match that of the slider/shaft.

With a dog setup because there is a large window of opportunity to engage it can happen more easily, far less smoothly but pretty much unhindered even if gears/shaft speeds are not matched

Great for racing....not always so nice on the road. A lot can depend on the driver for normal road use as to how tolerable it can be.

 

elite sequential strong reliable and a hoot ok its 5.5k but for that money its great

 

thanks Steve, never really delved into the wizardry of boxes much, and I didn't realise how Miss informed I was, I got my head round wet clutch autoboxes, and now this, the world has gone mad

Does dog engagement bring a small amount of shunt into the box then due to its nature?

 

Small....I'd say variable, rather than small.

Just depends on driving type at the time, type of clutch etc etc

Sometimes you might be able to make it pretty smooth, others not. But a lot depends on overall drivetrain to. If everything is fairly tight, box rubber mounted etc then any clunks would be less noticeable anyway.
But you can never expect it to be as smooth as a synchro box. But then a full manual synchro box will never shift like a dog box when racing.

 

what kind of power/torque can they do jay?

 

I ran a Glebe straight cut dog box in my old sapph and found that fine for a road car, much faster to change gear than a standard t5 box, either with or without the clutch, although around town I used to use the clutch because it wasn't really happy with slow clutchless changes, was noisy apart from 4th gear but I found it liveable with, you could still have a conversation without raising your too much etc

 

A dog box still requires the clutch to change gear, doing so without will be slowly damaging the dogs.

The only other option is some sort of power cut to enable safe shifting, ecu controlled or otherwise. But downshifts should always use the clutch unless you've some sort of throttle blipper

 

tried and really tested in 600 bhp and 500lb and never serviced just kicked in and no issues at all

 

What sort of prices are glebe or straight cut boxes? iv got a tremec tko to go in my car but would like an improvement over the gear change of the t5 if possible.

 

You could have your TKO faceplated...essentially turning it into a dog box.

 

Tidy il have to look into that any ideas who does this too a tko?

 

Liberty in the US would be the main place. Either buy already done from them, or if you had a TKO you could send your gears to them for the modifications. I did this with my T56.

http://libertysgears.com/our-products/tremec/

One good benefit of doing this as opposed to a full dog box...is you have the option of leaving 1st or 5th as synchro.

For a regularly driven vehicle, leaving 1st as synchro is a good thing, even more so one that might see a lot of traffic.

And if your racing never sees you shift hard into 5th, again, leaving this synchro can make driving the car much nicer.

Not a bad explanation here lol


Or a comparison with T5 and TKO.

 

And an old box which has had 1st left alone with the rest faceplated

 

Great thanks for that good info think that's the way to go fit and forget then and will handle more than my little 2.0 can ever throw at it!

 

Spot on.
Regardless of being straight cut, close ratio etc, it will still have synchros so will change gear the same as a normal box.

A twin/triple plate and hydraulic clutch may help with gearchange though, especially at high revs. That's the route I'll be going next year

Cheers Paul

 

I had a 5.0 shifter fitted too, was ok but because I felt the throw on the lever was still too far I removed it and fitted a b&m short shifter and to me drives much nicer

Cheers Paul