Guest hybrid_eg Posted October 5, 2006 Share Posted October 5, 2006 here is the deal.. i'm running an RB25DET trans on the 26 as its in a 240sx from an R33 GTST push type.. i inspected the trans prior to install, outside and inside the bell housing looks as clean as it can get.. obviously i wouldnt know aobut the gears until driven.. to make long story short.. driving the car around normally all gears check out great.. baby smooth.. problem is going into 5th from 4th when underload or simply moving at higher speeds.. say 90mph+ it just grinds 5th.. so if you were trying to go into that gear as you normally would it will not go in unless you force it in.. i'm assuming the syncro is bad.. whats suprising is that it doesnt have any indicating of it being bad bellow those speeds.. absolutely none. From what i've researched 5th gear is not really common to go out anyways unlike 3-4th gears.. but then again transmission did not come from this motor and it was from another car and god knows who and how they drove it overseas.. i plan to pull it off in a little while and change out the 5th from another 26trans as the internals should be interchangable.. and if i find anything else out of the ordinary. Going through some UK forums i found the following info where some guys were debating RB20 vs. 25 trans difference, and i'm not quite sure if this could be realted to the problem i'm having : Same as before, The MX7 is has single ring syncros, and the R33 box' has twin ring units. Only this time the R33 has twin ring units on everything! these boxes are built like a brick s**thouse (aussie term) and take a heap of abuse.And yes you can use a ceramic clutch on these puppies...happy? Also as before 5th gear dies due to the output shaft and layshaft nuts, do 'em up! something in a sense of taking the back cover off the trans and tightening the output shaft bolts that prevents it from going in smoothly? any any advice would be greatly appreicate! tons of tks in advance!! i'm sure this doesnt help but here is the trans used.. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted October 6, 2006 Share Posted October 6, 2006 What gear oil are you using? I hear nothing but high praises about the Redline Heavy shock proof curing the dreaded gear crunch in the rb trans.... I have two rb25det trans, and thats what I have to use in them (until I gernade them...) then I'll try a auto.... I'd give the Redline a shot at curing it..... Quote Link to comment Share on other sites More sharing options...
Guest hybrid_eg Posted October 6, 2006 Share Posted October 6, 2006 cool! i can definitely give that a shot.. i've only crunched it twice very very lightly.. as soon as i realizied that it was happening in 5th at higher speeds i made sure i'm in 5th earlier.. other then at higher speeds.. 5th is like butter, as all others gears are.. not even a hairline feel of crunch.. i'm using Valvoline 75-90 gear oil i believe.. not 100% sure.. regular gear oil.. do you have anymore details on the redline stuff?? exact weight of that oil.. label and etc.. i'll go look for it asap and give that a shot as it doesnt hurt.. btw i'm running 2.8lt of it.. let me know.. many tks again for info! i just found it at local parts store, gonna give it a try asap see if it will take care of the prob.. next time i pull the trans to replace the clutch to twinplate i'll fix that 5th syncro and whatever else.. as long as she holds for the time being! btw, do you know anyone that may have some base PFC maps for 91 octane? for BPU, DP,filters, exhaust, fuel pump etc..pretty much bone stock.. Quote Link to comment Share on other sites More sharing options...
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