evlgsr

As per the titles i am hoping that a transmission guru can help me out.

basically its a B18B integra LS stock engine and trans unsure of what clutch is in it, at the local drag meet on the saturday i started having problems with 4th gear, 1st 2nd and 3rd shift ok through the runs but going from 3rd to 4th i get locked out. As well as being locked out of the gear like there is a wall that wont allow the gear shifter to go past it also grinds real bad as soon as the gear gets to the 4th gate.

Normal driving is not affected so i can shift between all gears at low load and rpm and it shift perfectly fine no crunch no grind, this only happens at the top of 3rd going to 4th, basically at the strip this happens just before the 1000 foot mark. I did manage to try double clutching it one run and it did go into 4th but i had dropped some speed by that time.

i thought maybe it was the fluid so i went ahead and remove the fill plug with drain plug left in and got oil coming out of the fill plug (car was jacked up from front only at the time), so added some oil once we got the rear jacked up too and put in enough to get to the bottom of the filler plug. this made no difference. The other though was the engine rear engine mount could be affecting the shifting as its fucked and the engine torques a bit with throttle but i did strap the engine with ratchet strap and made no difference.

This only started to happen at this event, just to **** me off even more on my last run i was locked out of second gear so had to go from 1st to 4th back to 3rd and then 4th again this time 4th gear was fine.

sorry about the long thread but hopefully someone can tell me what it could be or if youve experienced something similar, also what kind of tests can i do to rule out some stuff.

ratchetEDsedan

I would guess shift forks might be a little askew, bent or something. I believe that b series used steel forks, as opposed to aluminum D series forks, so they wouldn't be snapped. I think if you've done a lot of hard shifting you may have done something. That lockout situation sounds a LOT like burnt synchros, with it being really hard to shift, and grinding. But I'll have to let someone else say whether or not the situation may "move" to different gears. I'm not at all claiming trans expertise, that's just what occurs to me.

ratchetEDsedan

Your motor mounts are fine right? I feel like I've heard that excessive engine movement can cause strange shift behavior under hard driving, because of the solid linkage.

evlgsr

Rear mount is fucked but as a test i did strap the motor to a mounting point so it wouldnt be torquing as bad but made no difference to 4th problem only difference was the car was so much less jerky than before. in terms of syncros why would the problem only show up when shifting at high speed. i can drive the car all day long happily shifting into 4th without going WOT and no cruch or grind or lock out. the only time i can simulate the problem is if going WOT throuch the gears.

It could be syncro ring gear not able to slow down the 4th gear enough at very high rotations.

could it be caused by clutch.

the car is a 97 i believe these had hydros not cable.

Thanks Gents

ratchetEDsedan

Maybe if both rear and front were toast it'd give you some issues but I've driven a car with some nasty nasty mounts and I didn't really see any problems like that, not that I was ragging on it. I could be wrong but maybe if they were worn but not completely shredded, then they would have problems under really heavy load, but not necessarily in regular driving. I don't see the clutch being an issue, as I'd think slipping would be prevalent. Maybe a throwout bearing on its way out would have some effect like that? I've never driven a car with a shitty throwout bearing so I can't say for sure. Does the bearing whine at all? You might try bleeding the clutch, if there's just a small bit of air in the line, you might be getting full clutch travel, but engagement might be just a little slow, you know? Like when brakes need to be bled, and you can stop, but it takes a second for the fluid to compress the air, and then engage the calipers.

evlgsr

I dont really think the mount is whats causing the issue but just thought i would throw it out there, i did think it could be clutch pressure or something clutch related due to double clutching that one time after grinding it did go into 4th. there is no bearing noise or trans noise what so ever the only noise i get is grinding when i try to go from 3rd to 4th at WOT otherwise gearbox is pretty quiet. It could well be the throwout but you would think it would present itself in few more scenarios not just going from 3rd to 4th at high loads.

I did also put the car on jack stands and go through the gears up to 4k rpm and all good no issues but then again on jack stands the engine doesnt see much load.

I have seen lockouts of 2nd and 3rd on other cars but this is the first time i have seen this kind of problem with 4th just strange. The first round early on in the year shifting was fine that was NA, then 2nd round hooked up the nitrous and at the end of that round the last run i had issues with 4th then this event nitrous still on and issues with 4th all day.

ratchetEDsedan

Yeah, what I would do, is bleed the clutch first, and if that didn't seem to change anything I'd drop the trans and check out the clutch, pressure plate and throwout. If those looked alright I'd split the trans and start looking around. Cause if bleeding the clutch doesn't help at all, then the problem has to be clutch or trans itself, regardless of knowing exactly what the problem is, you'll have to pull the trans to fix it, so you might as well. I dunno what kind of times you're pulling but that trans can't be happy with the nitrous haha.

evlgsr

ultimately i will have to pull the trans, just wondering if there is any tests i can perform to eliminate potential problems and pin point to an area which is causing the problem.

times wise with 50 shot it ran a 15.0 with shitty street tyres so no launching first just taking off normal, but that was round 2. round 3 which is the one that just passed it ran 15.8 with no 4th gear. usually the problem comes up just before the 1000 mark so fair way out. best MPH so far with 50 shot was 94mph.

ratchetEDsedan

Not that I know of, but like I said earlier, I'm definitely not the trans guru. And I know a lot more LS trannies have taken a lot more abuse then that, and lived to tell. I'm not sure what would have caused the issue, directly anyway. How's the shifter itself? Is there any slop in it? Cause when you're slamming gears something might be binding at a halfway point.

Spiff671

Sounds like your tranny will need to be opened up and inspected.
Read this thread: https://honda-tech.com/forums/transm...-gear-3146460/
The O.P. had a similar issue to yours. Check out my replies to him, I stated the likely causes.

Good luck!

evlgsr

Thanks Spiff671, i read through that thread but i dont think its related. the only time i experience the lock out and grinding is changing at 6.5k rpm from 3rd to 4th. other than that i can shift into 4th with no issues at all. so it seems its load\speed related.

Spiff671

Ahhh ok. Man, it sucks that all signs point to the transmission (being that it only happens with 4th gear). If you get to the point where you have the trans opened up, just be sure to inspect all the components with your 4th gear synchro set, not just the synchro ring itself. Heck, I would even verify the specs on every single component since it's already torn apart. Synchros, springs, sleeves, hubs, shift change holder and all. Bounce all measurements off the factory service manual and you should (hopefully) find the problem. Good luck bro!