Jump to content
SAU Community

1998 ER34 GT into GTT details

JC71
 Share

Recommended Posts

JC71 Community Regular

JC71

Posted
Posted (edited)

I have a 1998 ER34 25GT 5 speed 2 door skyline. I have swapped engine for a R34 GTT RB25DET, along with GTT brakes and suspension,

and triple dash gauge. plus other things like seats, steering wheel, shifter and a bunch of other items that are no mechanical related.

 

my question for the SAUskyline community is what else is different between the 25GT and 25GTT R34 models

I know about turbo engine, HICAS ,Traction control, LSD rear diff, and the other things I already changed like brakes etc. but

what else is different?

 

thanks

 

 

 

 

please intelligent replies only

Edited by JC71
Link to comment
https://www.sau.com.au/forums/topic/480492-1998-er34-gt-into-gtt-details/
Share on other sites
Unzipped Composites Rising Star

Unzipped Composites

Posted
Posted

When you say suspension, which parts of the suspension have you changed? The R34 GT uses an eyelet type mount on the bottom of the rear strut, same as R33 GTST's. The GTT uses a forklet on the bottom of the rear strut. 

 

Gearbox is different as mentioned. Because the gearbox is smaller, the driveshaft is shorter. So if you fit a GTT gearbox, you also need the driveshaft and diff. 

 

Off the top of my head, the rest is mechanically the same. 

GTSBoy Grand Master

GTSBoy

Posted
Posted

The chassis number will always be for a GT.

There is no sense in converting a GT into a GTT for almost any reason at all. But doing it for drift is the worst reason of all. If making a drift car, just drop an LS3 into it and be done with it. It will be 20x the drift car with a suitable engine in it.

Kinkstaah Grand Master

Kinkstaah

Posted
Posted

The GTT has various under body braces that the GT does not. I can't be too more detailed (I swapped chassis about 5 years ago now) but I recall everything just looking more 'heavy duty' under the GTT. It was suprising.

Technically the gt also has no rear sway bar
The GT also has the ABS system from a S15
The diff by default is an open type diff with the same configuration and half shafts as a S15.

The gearbox is a weak piece of shit which is generally weaker. This theme is also apparent on a lot of different things you wouldn't ordinarily realise (or even notice unless you had the cars side by side on two different hoists).

GTSBoy Grand Master

GTSBoy

Posted
Posted
9 hours ago, JC71 said:

so what are the differences in the transmission and rear diff?

As Kinkstaah said above. The turbo box is about double the weight of the NA box.

You do know that you can google these things, right?  Google up the RB25DE gearbox and look at the images. Then same for the turbo box. There are even photos of them side by side.

About 4000000000 words have been written about these things on this forum in the last 25 years and that when you google you will get an endless stream of hits right here.

JC71 Community Regular

JC71

Posted
  • Author
Posted

yes, drive shaft, trans mount, etc.  any other things not previously mentioned?

I found a brand new neo GTT RB25DET 5 speed trans but it doesn't come with anything...(wiring, shifter ,etc.)  will these items taken off of my current  FS5W71C  trans fit onto a FS5R30A ?

GTSBoy Grand Master

GTSBoy

Posted
Posted

The shifter certainly won't They are completely different gearboxes.

As to the wiring plugs....the wiring is part of the car. All you need to do is make the connections. If the plugs are different, get the right plugs.

My car has has an auto, an 20DET manual (and a 25DE manual) and a 25DET manual in it. I think I had to change the plugs on at least one of the switches on at least one of those conversions. It's not rocket science.

Unzipped Composites Rising Star

Unzipped Composites

Posted
Posted

The shifter does fit actually, as long as it is an R34 gearbox. The R34 pull-type gearbox and the RB20 gearbox use the same shorter nylon bush. If you get an RB25 gearbox from an R33 and try to use the shifter from an RB20 or R34 then it will actually fit, but it won't work nicely. The R33 push type gearbox needs a longer nylon bush on the shifter, so it will pop out of gear.

JC71 Community Regular

JC71

Posted
  • Author
Posted (edited)

ok, so best to not try to "make" mine work. I will plan to get this then:

https://www.ebay.com/itm/CUBE-Speed-Premium-short-shifter-for-Skyline-R32-R33-R34-5-speed/223279617684?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D1%26asc%3D225073%26meid%3Deaba7acfdd5e45e3bb22a4e1af95dc1e%26pid%3D100167%26rk%3D6%26rkt%3D15%26mehot%3Dpp%26sd%3D221840569882%26itm%3D223279617684%26pmt%3D0%26noa%3D1%26pg%3D5411&_trksid=p5411.c100167.m2940

 

question: would this give me everything needed, to replace entire shifter assembly or would I have to use some parts from my current shifter assembly to mount and make work?

Edited by JC71
Unzipped Composites Rising Star

Unzipped Composites

Posted
Posted

Looks like it will work fine, it seems to come with both size bushes so you use the one that suits the gearbox you are using. Shouldn't need to use anything from your current shifter, it looks like it's all there.

Unzipped Composites Rising Star

Unzipped Composites

Posted
Posted

Feels off topic, but I really don't understand how a short shifter could increase synchro wear. All it does is change the throw at the top of the lever, the bottom of the lever stays exactly the same. 

 

Surely the only thing that effects synchro wear is engine speed vs gearbox shaft speed, ie. Not rev matching. So if your driving style smashing through gears, it doesn't matter what lever you've got, you'll wear the synchros with a stock shifter just the same.

GTSBoy Grand Master

GTSBoy

Posted
Posted
5 hours ago, Unzipped Composites said:

but I really don't understand how a short shifter could increase synchro wear. All it does is change the throw at the top of the lever, the bottom of the lever stays exactly the same.

 

5 hours ago, Unzipped Composites said:

So if your driving style smashing through gears

The latter quote happens more with short shifters. it is a proven fact. More synchros have died at the hands of clowns slamming gears with their hella epic short shifter (TM) than almost any other driving style.

Unzipped Composites Rising Star

Unzipped Composites

Posted
Posted

Ok sure, but that's not the fault of the short shifter. I've had mine in the car for the last 10 years, and it was in the old NA gearbox when I bought the car 2 years before that. Wouldn't have any idea how worn my synchros are, but they're still going. Get the odd crunch going from 4th into 5th after 5 or 6 laps, but that'll learn me for trying to use 5th gear on a race track. 

I think if you're the sort of person that drives like that then you're going to end up breaking things anyway, stock shifter vs short shifter is the least of your worries.

JC71 Community Regular

JC71

Posted
  • Author
Posted (edited)

I will be trying to find a stock shifter setup for my new FS5R30A 5 speed gear box (GTT RB25DET) other wise I may have to go aftermarket, if I cant find a stock one, I do find the brand "Cube" shifter for a R34 RB25det , any one have any comments regarding that shifter? or recommend a different shifter setup?

 

Edited by JC71

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
    • perry_r33
      R34 GTR Vspec Garage Sale - All must go!

      By perry_r33 · Posted

      Pm sent 
    • Robot
      Skyline v36 350GT sedan hunting on idle

      By Robot · Posted

      Hi,  Just joined the forum so I could share my "fix" of this problem. Might be of use to someone. Had the same hunting at idle issue on my V36 with VQ35HR engine after swapping the engine because the original one got overheated.  While changing the engine I made the mistake of cleaning the throttle bodies and tried all the tricks i could find to do a throttle relearn with no luck. Gave in and took it to a shop and they couldn't sort it. Then took it to my local Nissan dealership and they couldn't get it to idle properly. They said I'd need to replace the throttle bodies and the ecu probably costing more than the car is worth. So I had the idea of replacing the carbon I cleaned out with a thin layer of super glue and it's back to normal idle now. Bit rough but saved the car from the wreckers 🤣
    • GabsReDeal
      R32 GTS (RB20DE) Injectors Replacement

      By GabsReDeal · Posted

      After my last update, I went ahead with cleaning and restoring the entire fuel system. This included removing the tank and cleaning it with the Beyond Balistics solution, power washing it multiple times, drying it thoroughly, rinsing with IPA, drying again with heat gun and compressed air. Also, cleaning out the lines, fuel rail, and replacing the fuel pump with an OEM-style one. During the cleaning process, I replaced several hoses - including the breather hose on the fuel tank, which turned out to be the cause of the earlier fuel leak. This is what the old fuel filter looked like: Fuel tank before cleaning: Dirty Fuel Tank.mp4   Fuel tank after cleaning (some staining remains): Clean Fuel Tank.mp4 Both the OEM 270cc and new DeatschWerks 550cc injectors were cleaned professionally by a shop. Before reassembling everything, I tested the fuel flow by running the pump output into a container at the fuel filter location - flow looked good. I then fitted the new fuel filter and reassembled the rest of the system. Fuel Flow Test.mp4 Test 1 - 550cc injectors Ran the new fuel pump with its supplied diagonal strainer (different from OEM’s flat strainer) and my 550cc injectors using the same resized-injector map I had successfully used before. At first, it idled roughly and stalled when I applied throttle. Checked the spark plugs and found that they were fouled with carbon (likely from the earlier overly rich running when the injectors were clogged). After cleaning the plugs, the car started fine. However, it would only idle for 30–60 seconds before stalling, and while driving it would feel like a “fuel cut” after a few seconds - though it wouldn’t fully stall. Test 2 – Strainer swap Suspecting the diagonal strainer might not be reaching the tank bottom, I swapped it for the original flat strainer and filled the tank with ~45L of fuel. The issue persisted exactly the same. Test 3 – OEM injectors To eliminate tuning variables, I reinstalled the OEM 270cc injectors and reverted to the original map. Cleaned the spark plugs again just in-case. The stalling and “fuel cut” still remained.   At this stage, I suspect an intermittent power or connection fault at the fuel pump hanger, caused during the cleaning process. This has led me to look into getting Frenchy’s fuel hanger and replacing the unit entirely. TL;DR: Cleaned and restored the fuel system (tank, lines, rail, pump). Tested 550cc injectors with the same resized-injector map as before, but the car stalls at idle and experiences what feels like “fuel cut” after a few seconds of driving. Swapped back to OEM injectors with original map to rule out tuning, but the issue persists. Now suspecting an intermittent power or connection fault at the fuel pump hanger, possibly cause by the cleaning process.  
×
×
  • Create New...