I currently have a stock 1991 Si tranny sitting in my garage waiting to be built for my soon to be boosted D16A6.

I have a Std. four-speed tranny in the car now, and also a stock HF tranny sitting in the garage. My plan was to use the HF fifth gear and an OBX LSD and install them into the Si tranny.

I have a few questions before I start undergoing this project. The Si tranny as it sits now is in perfect shape except for one thing: if I redline shift, it will grind going from 1st->2nd. I was told this could be the countershaft bearing backing out. It doesn't have any other grinds or noises, so I assume other than that it's fine. What bearings should I replace when I'm in there? Input shaft, counter shaft, and main shaft bearing? Is it normal to replace synchro rings while I'm in there?

Now, as for the actual 5th gear swap, what does that entail? Do I need some gear pullers, slide hammer, press? The OBX install I'm fairly confident I can handle no problem, considering the amount of info available for it.

I was wondering what kind of special tools / supplies will I need to pull this off?

I've also posted this on TD16 if anyone cares... http://turbod16.com/viewtopic.php?f=19&t=43155

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">: if I redline shift, it will grind going from 1st-&gt;2nd. I was told this could be the countershaft bearing backing out.</TD></TR></TABLE>

its most likely the syncros. Once you have it apart, make sure that syncro fits snugly on the gear cone.

btw if you need syncro's call up GearSpeed, they have carbon coated syncros for 2nd, 3rd and 4th

 

also make sure to get new diff bearings. I would change the input shaft bearing while in there as well. for the 5th gear you will have to get a puller and pull it off of both shafts, its at the top so its the easiest, you might also need a press to press it back on though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote"> What bearings should I replace when I'm in there? Input shaft, counter shaft, and main shaft bearing?</TD></TR></TABLE>

replace every bearing. the ones you mentioned plus needle bearings on the main/counter shafts and differential bearings.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Tippyman &raquo;</TD></TR><TR><TD CLASS="quote">
I was wondering what kind of special tools / supplies will I need to pull this off?</TD></TR></TABLE>

you should have gear pullers, slide hammer, and a press. i didn't have a press or slide hammer so i used **** lying around and made "special" tools .

degreasing solvent "ef type" to clean parts. the cat litter bucket is the parts washer. the vise on the left holds the main/countershafts during disassembly and reassembly. the 10" wood working vise holds the diff for ring gear swaps. feeler gages for blueprinting. the rubber hammer and pvc is my press. this is all i need to rebuild a tranny.


this 2 jaw puller is modified. this end is modded to pull the needle bearing out of the clutch housing. does the slidehammers job.


This end is modded to fit between the speedo gear and diff bearing and it pulls diff bearings with ease.


for the synchros and 5th gear swap...get a helms. it will explain how to swap 5th gear and inspect your synchros. you may also want to read up on scuffing gear cones too.