Drag Racing Gearbox

[Fitzpatrick Speed Works]

the probelm with an auto in a gtr is the transfere case. Have a look at an american auto something that is good and can be built to take the power, say turbo 400, c4, powerglide... Then have a look at the extension housing on the thing its around 2 inches round and the transfere case has to be bolted to that- its a nightmare... It can be done by you basically re-inventing the gearbox case to do it which equals alot of time and developement. Sure you could use a gts4 auto but they simply wont take the power and people dont make any parts for them, and custom one off parts are going to land you in holinger terratory, read mortgage the house!!!! Also with the jatco style jap boxes they melt even with all the good stuff, thus we are left with no other option than a jap manual box...

[NXTIME]

get me one with a GTR transfer case fitted to it and im there!

Tell me about it! Surely there must be an answer other than the 15K + Holingers, HKS and Trust boxes?

[Sydneykid]

Tell me about it! Surely there must be an answer other than the 15K + Holingers, HKS and Trust boxes?

How about an $8K PPG?

you could use a gts4 auto but they simply wont take the power and people dont make any parts for them, and custom one off parts are going to land you in holinger terratory, read mortgage the house!!!! Also with the jatco style jap boxes they melt even with all the good stuff, thus we are left with no other option than a jap manual box...

You should have a talk to Mike Vine at MV Automatics, you might be surpised how much power a $2500 upgrade on a GTS4 or Stagea gearbox will handle.

[NXTIME]

I have always liked the idea of a strengthened gts4 or Stagea box, but the have been told that they won't handle a drag application. Since my car isn't ready yet I haven't needed to look further into this option. Thanks for the tip, SK, will give MV a call when its time.

How could I forget the PPG gearsets? What is your feedback on them?

[4door_Sleeper]

Just a thought, could you rebuild a box from a Stagea or GTS4. I heard that the internals from a Nissan Patrol auto (also a 4x4 and has a transfer case) fit into the same case (but different bell-housing) and are almost identical to the GTSt's but are built to handle a lot more torque.

You could get in contact with Mike at MV Automatics for more information.

.

[Sydneykid]

How could I forget the PPG gearsets? What is your feedback on them?

The race GTR's use Hollingers, as the PPG's weren't available at the time. We do use PPG's in other race cars and they have been great. Just a regular service after 20 or so race meetings, we life them at around 1,000 laps or ~2,200 k's. Which is great for a dog box ,where we do 50 or so gearshifts per lap on some circuits.

That's equivalent to about 8,000 runs down the 1/4.

When I get around to upgrading the gearbox in the GTST, I will be using a PPG.

[2rismo]

That's equivalent to about 8,000 runs down the 1/4.

In distance only!!! No-one here believes the same stress and wear occurs on a box in the applications you listed especially how you said it would.

What a crock. Please qualify this tripe - every reasonable person would agree that a violently abused, flat-changed, shock-loaded and generally smashed about drag racing gearbox suffers more and much sooner than a box in a similar vehicle used for circuit racing.

Come on?!!?

Adrian

[Sydneykid]

In distance only!!!  No-one here believes the same stress and wear occurs on a box in the applications you listed especially how you said it would.

What a crock.  Please qualify this tripe - every reasonable person would agree that a violently abused, flat-changed, shock-loaded and generally smashed about drag racing gearbox suffers more and much sooner than a box in a similar vehicle used for circuit racing.

Come on?!!?

Adrian

Hi Adrian, let me start off by saying that I am not claiming that circuit racing is better than drag racing, or harder, or more difficult, or tougher. That can be the topic for another discussion. This one is about gearboxes.

So, let's look at the facts;

1. In circuit racing the gearbox changes both UP and DOWN with load and speed

2. In drag racing the gearbox only changes UP with load and speed

3. I have heaps of data logs for the circuit cars that show the speed of the gearshift. In the 30 or so gearchanges per lap, even 1/100th of second delay in changing costs 6 seconds over the race distance. Last week we lost a race by 4/100ths. How important do you think that 1/100th of second saved in each gearchange is?

4. I also have a few data logs that show the speed of the gearshift in a drag racing event. Obviously 1/100th of second delay in changing gear cost 4/100ths of second over the 1/4. But the speed of the upchange is no different to that used in the circuit race.

5. In a circuit race, the driver often has to change gears in a sub-optimal situation, baulked by another car, accident avoidance, mid corner etc etc. This means the quality of the change is sometimes compromised by other events happening at the same time and G forces other than the straight acceleration experienced in a drag racing environment. Hence the chance of a bad/missed change is much higher in a circuit race than a drag race given equal driver skill.

6. In a drag racing environment I have not seen gearbox oil temperatures over 70 degrees, in circuit racing I see gearbox oil temps over 150 degrees. And for long periods of time, 10/15 minutes continuously. The driver still demands the same speed of gearchange at the end of the race as they did at the beginning.

In the same 650 bhp race car, weighing the same 1400 kgs (inc the same driver), with the same tyres, I am going to see the same loads on the gearbox, the same speed of change, the same torque and rpm loadings whether it is used for circuit racing or drag racing. But the gearbox is going to do a lot more work in a season of circuit racing than it is in a season of drag racing.

The difference occurs when you have an 1,100 bhp drag car, with 30" slicks on a properly prepared track. Now that's a totally different ball game, not because of the speed or violence of the gearchange, but due to the torque loadings on the gearbox exacerbated by the amount of traction available.

PS; if I had a driver that "violently abused, flat-changed, shock-loaded and generally smashed about drag racing gearbox"........I would find a new driver. Because they are most definitely slow.

[r33_racer]

You cant argue with that mate. I believe someone else in this thread stated something about how if gear changes were made that little bit softer and smoother during the course of the drag they could improve reliability and limit the gear wear considerably. But then again who in drag racing would even think of doing that if its gonna slow them down by a fraction of a second? But then again how can you race if you keep stripping gears and spend your race weekend removing gearboxes instead of doing what you came to do!

[4door_Sleeper]

I dont want to take sides on this one, but do have a question/comment about the differences between drag and circuit work.

I would have thought most of the load on the trans (including the gear box) occurs when you accelerate from a standing start (which both circuit and drag racing cars will do), but a drag car will do this 8000 times over 2200km (to use the example above), whilst the curcuit car will do this only a few (perhaps 50?)

I guess gear changes on the move are probably equally hard on the car in both drag and circuit work for equally powered and weighted cars.

(Not having looked in some of the boxes listed above, but other than the ratio is there much of a difference in gear size (strength) between 1st and 3rd (if 3rd is the one that often breaks), or is the failure a result on the shifting gear on a pre loaded trans)

I would have thought an auto was the best option for a drag car, add a suitable torque converter to match the engines power delivery and away you go. Someone above mentioned a Trans Brake for the auto (used by the big boys of drag racing) but I was advised that it would be too harsh on the driveline of a skyline ("rip the ass end out" were the exact words) without a lot of work to strengthen the rear end.

[benm]

I would have thought most of the load on the trans (including the gear box) occurs when you accelerate from a standing start (which both circuit and drag racing cars will do), but a drag car will do this 8000 times over 2200km (to use the example above), whilst the curcuit car will do this only a few (perhaps 50?)

I too thought that is where most damage would occurr, the initial load from the launch.

Surely their would be less load on a gearbox that is already moving 'at speed' than a gearbox that has just recieved 650bhp all at once (even if the tyres/diff let go)?

[Fitzpatrick Speed Works]

I have had extensive talks with the two authorities on jatco style gearboxes (one was MV) and they both agree yes they can modify a gts4 gearbox for around 4g and get a pretty good item but thats all they can do, and they really arent going to take a serious drag application with 400rwkw+.. its just the design of the box and nothing can be done about it... For a serious drag car you need a transbrake and the jatcos fall to pieces with transbrakes they literally smash apart the governers and melt the the maze inside the auto!!!!

I have seen a powerglide adapted to the gtr 4wd drive and it was a nice job but in no way was it an easy or small job, plus powerglides are 2 speed I am a strong believer that on a turbo application with step power curves, narrow torque spread, and ridiculously high rpms and hp figures in high rpms, a 2 speed is a waste of time. The spread for gearing means on a huge turboed car you need to launch them at massive rpm and they are really hard to get right.. Too high rpm launch equals wheels spin too low equals the turbo off boost. Then when you change gear mid track you are way back down your rev range which on a small capacity engine with high peak torque isnt a good thing for building speed....So while you can beef up you gts4 or stagea gearbox you are never going to be able to get anything substantially benificial for full on drag cars making good power(read over 500kw), without basically rebuilding everything inside from scratch then you into holinger terratory.....

On another note it is really hard to compare different motorsports to each other, for example in trusty old datto 1600s alot of my mates run around with r180 lockers on the street and circuit with around 200rwkw from fj20's, the diffs themselves never break they last and last, however at the circut you usually see them break the planterys (the constant torque on off out of varying corners). Now the same diff in a rally car with 120rwkw goes through a r180 nearly every meet, it smashes the absoulte crap out of everything they are throw aways. On another 1600 with around 180rwkw we have been through 4 sets of half shafts (the diffs stay beautifull but the break the shaft in half) on the same diff (r180) from taking it to the drags. So although this doesnt have much to do with skylines it shows the varience of effects the car is under from different motorsports.

Hope this adds to the discussion.

[Sydneykid]

I too thought that is where most damage would occurr, the initial load from the launch.

Surely their would be less load on a gearbox that is already moving 'at speed' than a gearbox that has just recieved 650bhp all at once (even if the tyres/diff let go)?

I have seen around 20 damaged GTR gearboxes, leave out the poorly maintained ones (no oil changes or low oil levels) and the busted synchro ones. What is left have stripped 3rd or 4th gears, all the teeth on the input and output gears ripped completely off. Maybe ask the guys with lots of GTR drag racing experience, but that has been my observations.

I have never seen one with a stripped 1st gear, in fact I don't think I have seen even one with a chipped tooth on first. That is because of the torque transfer though the low ratio (between the engine and the tyres). This evens out as the ratios (input versus output) become closer together, with 4th being 1 to 1 in a road ratio box.

[Sydneykid]

I have had extensive talks with the two authorities on jatco style gearboxes (one was MV) and they both agree yes they can modify a gts4 gearbox for around 4g and get a pretty good item but thats all they can do, and they really arent going to take a serious drag application with 400rwkw+.. its just the design of the box and nothing can be done about it... For a serious drag car you need a transbrake and the jatcos fall to pieces with transbrakes they literally smash apart the governers and melt the the maze inside the auto!!!!

Looking at it another way, what if a 400 rwkw 4 speed auto was faster than a 500 rwkw manual? I guess it depends on what the target is, a faster time or more power? Personally, I would much rather brag about having doing a faster time with 400 rwkw.

[underground]

Guys,

I really hope you will share some advice.

I have a 700 whp RB26DETT 240SX with a GT4088R and nitrous setup.

At the moment, I am planning on running a RB25DET Stock Gearbox with a Unsprung Exedy Triple Disc Clutch.

I have been told that the gearbox will not last very long at this powerlevel, and that I need to rethink my game plan.

I feel very torn, as this is a street car for me, with the occasional stint at the drag strip.

I have been speaking with Dane @Desynz in Australia, and he has mentioned the Holden Trimatic Auto Setup.

Any feedback on this suggestion?

I have also been looking at the PPG Gearsets, but I am leary of whether they will holdup to the abuse this car will be put through.

Thanks!

Chris

[T04GTR]

if your going to smash it thru the gears either a dog engagment or an auto. doesnt matter what gearset you have. if it crunches it WILL break. ie..synchro engagment

[turboedsloth]

the trimatic is a piece of shit and will not ever handle any of these power levels you guys are putting out. these things hardly hang together behind the stock 6s or v8s that there bolted to. we build the jatco 4N71Bs that are behind the vls an there handling 10sec passes an still hang together but we modify them a sort of trade secret way. C4s are a good upgrade as are turbo 400s and turbo 700s behind the commodores. the things you have to worry about is the bellhousing which atm the powerglides have the opportunity of having. the standard skyline gearboxes are the same as whats behind partols an terranos, atm people are looking into modifying these to handle extreme power levels an abuse. i havent had experience with the straight cut gear sets so i'll leave that to the other guys

[2rismo]

the trimatic is a piece of shit and will not ever handle any of these power levels you guys are putting out.

agreed

we build the jatco 4N71Bs that are behind the vls an there handling 10sec passes an still hang together but we modify them a sort of trade secret way.

who is "we" ?

C4s are a good upgrade as are turbo 400s and turbo 700s behind the commodores. the things you have to worry about is the bellhousing which atm the powerglides have the opportunity of having.

RB bell housings are no problem for any of the boxes you mention.

[turboedsloth]

we is my boss and i. i work for a automatic transmission shop in western australia

[Desynz Motorsport]

we is my boss and i. i work for a automatic transmission shop in western australia

Well i is a Performance shop that build custom cars... and i as well as heaps of other shops have seen really good results from the trimatic. Hugos has done tons of 9 second VLs with a trimatic behind them with very few issues so i wouldn't go mouthing off just because it's not something you do yourself.