Internal gearbox upgrades

That could be very interesting, I had these on my long range radar to have a look into as well.

Might be worth looking into an ally bronze to, Pretty sure thats what we used to use on the reverse boxes at my old place.

Ryaneg6freak wrote:

GTI-R US wrote:Sorry i havent checked this thread for months.

Well just to update everyone........im afraid its a no go as far as the forks are concerned which is a real shame

I attempted to fit the fork in a customers race car as a perfect test base for them but..............the forks are way off fitting correctly, infact i spent over 2 hrs just boring out the centre so it fitted correctly over the selector rod, but then we had a further problem with the side arms of the selector being to deep so out come the angle grinder and narrowed those down until thry were correct depth.

Went to install the selector into the guys box only to find that the angles of the selector arms were also wrong, that was the killer blow as nothing i could do regarding that.

So outcome was a complete waste of time as the cad drawings must have been way out for that to have happened.
Also Adam no longer works there and think the guy that made them is no longer there either. 
So in a nutshell its a no go with them 

When I get home I'm going to take a stock fork to my good friend Tim who can do 3D scans into solid works, and then replicate the part with billet steel via a 5 axis CNC.  He said i should be able to replicate it for around $200 based on size.  Bob, what type of steel were you having yours made from?

I was thinking about maybe 8620 Billet or a type 410 stainless.

I was thinking exactly the same thing using a laser scanner at work.
8620 & 410 are case hardening steels and easily strong enough even in soft state. I would use 817M40 (EN24T). It's easily available in bar stock (cheaper?) and has good combination of tensile strength (850-1000N/mm^2) v machine-ability.
Either, if way, i reckon you'll have a Que of buyers.

Par 3/4 selector fork costs quite few dollars 490 AUD to be exact not cheap at all...


Zia

Zia wrote:Par 3/4 selector fork costs quite few dollars 490 AUD to be exact not cheap at all...


Zia

That's bloody ridiculous

If anyone is going to attempt to get these made up (copying the stock 3-4th selector) you need to be careful if making out of billet steel.

Reason i say that is 'the weight of it' i can tell you that its way way heavier than the cast alloy one.
This could possibly cause a whole heap of other issues with gear selection in a synchro box.
The gear could be over engaged which puts a lot of extra stresses on the synchro's, baulk rings, and gears in general. Synchro clips may need upgrading as well as detent springs as it may not hold in a neutral position with the weight of selector.

All this above was the reason they needed to be tested in a harsh enviorement (race use) as your not going to pussyfoot around in changing gear as fast as possible with little mechanical sympathy.


Personally i think the weight WILL be a problematic factor unless you are running a non synchro dog engagement gearset such as i am using.

Maybe thats why the par and ppg ones available are very narrow in design and have shorter selector arms in order to cut down the extra weight but in so doing they have created another issue!

GTI-R US wrote:If anyone is going to attempt to get these made up (copying the stock 3-4th selector) you need to be careful if making out of billet steel.

Reason i say that is 'the weight of it' i can tell you that its way way heavier than the cast alloy one.
This could possibly cause a whole heap of other issues with gear selection in a synchro box.
The gear could be over engaged which puts a lot of extra stresses on the synchro's, baulk rings, and gears in general. Synchro clips may need upgrading as well as detent springs as it may not hold in a neutral position with the weight of selector.

All this above was the reason they needed to be tested in a harsh enviorement (race use) as your not going to pussyfoot around in changing gear as fast as possible with little mechanical sympathy.


Personally i think the weight WILL be a problematic factor unless you are running a non synchro dog engagement gearset such as i am using.

Maybe thats why the par and ppg ones available are very narrow in design and have shorter selector arms in order to cut down the extra weight but in so doing they have created another issue!

That's a good point Bob, the billet part would have to be thinned in non-critical area to try and get the weight the same,

GTI-R US wrote:If anyone is going to attempt to get these made up (copying the stock 3-4th selector) you need to be careful if making out of billet steel.

Reason i say that is 'the weight of it' i can tell you that its way way heavier than the cast alloy one.
This could possibly cause a whole heap of other issues with gear selection in a synchro box.
The gear could be over engaged which puts a lot of extra stresses on the synchro's, baulk rings, and gears in general. Synchro clips may need upgrading as well as detent springs as it may not hold in a neutral position with the weight of selector.

All this above was the reason they needed to be tested in a harsh enviorement (race use) as your not going to pussyfoot around in changing gear as fast as possible with little mechanical sympathy.


Personally i think the weight WILL be a problematic factor unless you are running a non synchro dog engagement gearset such as i am using.

Maybe thats why the par and ppg ones available are very narrow in design and have shorter selector arms in order to cut down the extra weight but in so doing they have created another issue!

Bob, a lot of the aftermarket performance EVO shift forks are actually made of 7075 T6 aluminum, it's quite strong. A lot of what I suspect is the main issue with us breaking the 3/4 fork might be something else altogether, such as synchro/hub misalignment or broken/worn loss energizer springs. The company who make these aluminum shift forks also offers a Synchro blueprinting service, and they are really good at what they do. Take a look at their technical articles.

https://www.jackstransmissions.com/collections/3s-parts/products/billet-cnc-machined-transmission-shift-forks-6-speed

https://www.jackstransmissions.com/pages/synchro-blueprinting

Just looked at their site and the parts look to be very well made.

I totally agree with you regarding fork breakages...........if there is a selection issue which as you rightly say could be down to any number of things such as you said above or even down to a dodgy clutch, user abuse, shit ebay quick shifts, worn linkage bushes etc etc

So when you remove the box to inspect the first thing you see is a busted selector fork and that gets the blame.....but who's to say that has'nt broken due to one or more of the reasons above!

I personally would Not fit an inferior aftermarket fork it simply has to be a perfect fit or it will cause you issues. It could end up costing you a damned sight more in the longrun rectifying the issues that the aftermarket one has caused if not a perfect fit.

The only gearboxes i would say that need upgraded gear selectors is if you are using a straight cut dogbox where your likely to flat shift up and down the box which puts a lot of stresses on the selectors so they need to be up to the job in hand.
And lets face it........How many people are using a box like that on the road............

i thought 3rd gear synchro misalignment was the reason why Nissan revised the synchro spring design? Rickys springs were the old design and may explain why shift forces were higher due to synchro tilt.
Rickys fork failure was a clean break (eg the broken fork didn't get smashed up go through meshes) and the break indicates the failure was on overload, not fatigue, eg the surface is very rough with no beach marks.

Indeed, and that's why all my loss energizer springs have been replaced with the updated design.

Cosmic, get your metal laser 3d printer thing on the case lol I would deffo buy a fork off you!

Im no expert, but I doubt the extra weight could make that much of a difference???

I had look at this years ago when par was almost half current cost .

Surprised one made that much of a mess as thought those guys do aerospace stuff :-S and to fair a guy with a lathe bridgeport could could knock up a solution in his garage.

You can make 3rd-4th in steel in 3 or 4 parts which basically the shaft bored section the C section and a gusset piece, I seen this in a malaysian built tranny.
The shaft section can loose mass and so can gusset section, C section best kept same t profile for rigidity but can be slimmer so weight kept sensible, Keep C forks same length original important and ppg not good on that .
Only reason I didn't get steel one done was par at time cost effective solution, now it twice the price for what should be £150 part really .
* Not sure the current par selector same as was and they also may of copied ppg current design !
Any half decent engineering machine shop can make a fork and no need for laser scanning or cnc lathes although that long term better solution if doing bigger production numbers .

Mr B, you make everything sound so simple! Hope some one manages to sort some thing out soon.

[quote="Mr B"]
Any half decent engineering machine shop can make a fork and no need for laser scanning or cnc lathes although that long term better solution if doing bigger production numbers .[/quote


Exactly what i was going to do for myself as im not happy with the par selector fitted in my dogbox

The hardest part will be getting the bore correct over the selector rod as it needs to be perfect, too loose and will cause misalignment but too tight and with heat it could partially seize on the rod causing shift prob's. Iwill make one then dummy fit it on a selector rod and heat it up with a blowtorch just to make sure before installing it.

Basing bore off oem and aftermarket selectors should be perfect, easy enough keep it tighter and ream as required, even in my climate box temps not that high and shift forks/rod will be around same oil temp really. Is fair bit of time for one off low tech fabrication .

Mr B wrote:I had look at this years ago when par was almost half current cost .

Surprised one made that much of a mess as thought those guys do aerospace stuff :-S and to fair a guy with a lathe bridgeport could could knock up a solution in his garage.

You can make 3rd-4th in steel in 3 or 4 parts which basically the shaft bored section the C section and a gusset piece, I seen this in a malaysian built tranny.
The shaft section can loose mass and so can gusset section, C section best kept same t profile for rigidity but can be slimmer so weight kept sensible, Keep C forks same length original important and ppg not good on that .
Only reason I didn't get steel one done was par at time cost effective solution, now it twice the price for what should be £150 part really .
* Not sure the current par selector same as was and they also may of copied ppg current design !
Any half decent engineering machine shop can make a fork and no need for laser scanning or cnc lathes although that long term better solution if doing bigger production numbers .

3D scanning is a relatively quick process.  My old room mate is about to graduate Utah state University with a degree in mechanical engineering and has asked me if I have something he could design as part of a final project he has due.  I said "as a matter of fact there is".

His plan is to take a 3d scan of the factory fork. upload to Solidworks (which will highlight any perceived weaknesses), redesign it without losing strength and original shape, and use the school's 5 axis CNC to machine it from a solid block of 7075-T6.  He said all I need to pay for is the materials.  I guess he will be writing the program for the CNC as well.  Give me about 6 months time or so and I just may have a working prototype.  
What about the brass wear pads on the tip of the fork?  How would  you approach that? You think maybe since the fork would be entirely made of aluminum that it would no longer be necessary?

Using wear pads makes selector serviceable and adjustable to some extent by offsetting depth of pads either side of c fork face .
I do prefer smaller friction area of pads over ppg design and if not doing pads I would be inclined machine in contact areas rather than whole surface of the c fork being in contact in the hub groove.

Machined pads should have a small amount of crowning to reduce contact area and isolate tilting hub from tilting the fork,

Great read and great dedication from a lot of people. interesting to read so many different point of views with the gtirs gearbox weakness's.

Still no updates yet, haven't been home long enough to set this up. I haven't forgot about y'all!