Before you ask, the car would not go into gear(any gear) in the morning. I adjusted it, and it seems like the adjuster nut is at the end of its play. I almost have to force the shifter into gear. The clutch is original – 190 thousand miles. So I figure I may need a new clutch. For $300 more, I can get an Hf transmission to get better mpg… yeah, yeah, I know slower…blah… - I am old, I know….

Here are my questions –
- Is it a straight forward swap? (no other components needed – si transmission out – hf in?)
- When I get the hf transmission, should I change both the clutch and flywheel?
- What other parts / seals / bearings should I replace while I have the transmission out?
- How many splines is my transmission? (1989 si)

Thanks for looking! (and possible input)

 

The hf will go right on to the motor no problem. I know the axles are different from the si and hf along with the knuckles though.

 

1. If your car is a 1989, then the swap is straightforeward - just pull out the SI, and swap in the HF.

2. While it is BEST to replace the clutch, it is not necessary. This is a determination that you have to make based on such factors as the amount of funding that you have available, the condition of the clutch that is in there, and your need for the car. If you have plenty of cash, replace it. But if you don't have much cash at the time, the clutch still looks good, and you have another car to use should the clutch give you problems, don't bother replacing it. As for the flywheel, rsurface it if you get a new clutch. Otherwise, don't worry about it.

3. Besides the clutch, replace the pilot bearing and release bearing. Again, if you are short on cash, these can slide if they seem to be in good condition AND you have a backup car. Also, you probably want to replace the axle seals. But since these are easier to replace, you could just wait and see how they hold oil if you are short on cash. As for the transmission itself, you can open it and check it out if you wish and know how. But I would just try to throw it in and see if it works. However, when you pick up a transmission, at least make sure that it shifts into each gear AND that it makes no unusual noises when spinning the input shaft in EACH GEAR AND NEUTRAL.

4. I think the spline count is 20. But don't quote me. However, ALL 1989-1995 D-series transmissions have the same input spline.

One more thing. I don't know how much this is REALLY going to improve mileage. I actually threw an HF transmission on a DX that originally had an SI transmission, and noticed no improvement. This makes me wonder how helpful it really is on a motor that was not specifically designed for this gearing. But regardless, I feel than an HF transmission would probably reduce fuel economy during city driving (since there are fewer available gears in that kind of speed range), as well as make it MUCH more difficult to keep up with traffic. So if you drive alot in the city, DEFINITELY reconsider this transmission swap.

 

Great replies! Thank you!
So I would need the hf axles? And knuckles?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andrey320 &raquo;</TD></TR><TR><TD CLASS="quote">Great replies! Thank you!
So I would need the hf axles? And knuckles?</TD></TR></TABLE>

No and no. The SI stuff will work fine.

 

tyson told me that you can use si or dx axles on an hf tranny, he said the inner are the same and the one that inserts to the knuckles have to be an si or dx...is that true!!!

 

any interfacing part of the transmission is the same between HF and Si.

just make sure you get a clutch for an 89 year specifically. ebay has some great deals on exedy oem clutches.

you wont need a new flywheel. i just resurface my flywheels with some scotch brite and brake cleaner. no big deal. if its scored, then well, get a new flywheel or get it professioanlly resurfaced.

if youre going to get a new flywheel, then you need to make sure the clutch and flywheel years match.

just need 2 qts of honda MTL.

repalce the axle seals if you want. couldnt hurt, but not necessarily a must do.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by socalrex88 &raquo;</TD></TR><TR><TD CLASS="quote">tyson told me that you can use si or dx axles on an hf tranny, he said the inner are the same and the one that inserts to the knuckles have to be an si or dx...is that true!!! </TD></TR></TABLE>

Yes that's true. The inner join splines are the same.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andrey320 &raquo;</TD></TR><TR><TD CLASS="quote">For $300 more, I can get an Hf transmission to get better mpg.</TD></TR></TABLE>

$300 is SERIOUSLY expensive for an HF transmission. I would look elsewhere, as they can be had for next to nothing.

 

You mean craigslist or junk yard?
The problem with that, is that I want a non-California hf transmission. If I get a transmission from a local car, it is likely to be a California hf....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andrey320 &raquo;</TD></TR><TR><TD CLASS="quote">You mean craigslist or junk yard?
The problem with that, is that I want a non-California hf transmission. If I get a transmission from a local car, it is likely to be a California hf....</TD></TR></TABLE>

Are you concerned about having a 3.25:1 final drive vs a 2.95:1 final drive? If so, don't worry. The difference is EXTREMELY small, and probably will produce a difference in fuel economy that is not even noticeable. It might even DECREASE fuel economy, as the D16A6 is not designed to cruise at low RPMs. But if you are dead-set on getting a federal transmission, then all I can say is one thing: take a road trip to Oregon, Nevada, or Arizona to get one at a wrecking yard OR from someone on craigslist. This will save you CONSIDERABLE money, since you won't have to deal with expensive freight shipping OR with expensive full-service wrecking yards (which are generally the only places that will ship). The gas that you burn will be NOTHING compared to the cost difference. And taking a trip like this is always a nice thing to do.

If you are pretty patient, another possibility is to check the underside of the hood on HFs at local wreckers. The sticker should tell you whether the car complies with Federal or California regulations, which will tell you if it is a Federal or California car. It may take some time to find a Federal car. Bt I am sure you would eventually find one.

But honestly, I think that even a California HF transmission is probably TOO tall to improve fuel economy much, and could even DECREASE it. A DX transmission would probably be a better choice.

 

First off, DX/LX trannies can be found for $0-75, depending on the location and owner. They are everywhere, and almost nobody wants them. They have a little 'worse' ratio vs a HF, but if you can get an HF for "only" $300, the savings in gas with it is moot if you get a DX for less than a tank of gas.

As far as clutch, the 88 trannies had a different spline count, 89-91 was the same, but the 90-91 clutch has a bigger diameter. Incidentally, the 90-91 clutch/fw's are interchangable with the 92-00 d-series clutches.

The HF will drop you down a few hundred RPM, but you'll need to give it a little more throttle to keep the same speed. If you only do highway driving, it will benifit you. If you don't accellerate any faster than a fully-loaded semitruck, it may help in the city too.

IIRC, its the STD/HF <U>hubs</U> that were different sizes.

 

Here's how I see things. As I said in a previous post, an HF transmission did NOTHING for me when I swapped one into my 1989 DX (which previously had an SI transmission). Given the fact that the D16A6 is more performance oriented than the D15B2, I would expect the benefits to be even less. If you REALLY want to try the whole HF transmission thing, I recommend that you go to a local junkyard and get a transmission. This way, the amount of cash spent is relatively low. For instance, I got mine at a half price day at a local Pick-And-Pull - $40. For this small amount of cash, it is not going to hurt much if you find out that you are either not doing as good on gas as you hoped OR you cannot stand the sluggishness driving around town. And, like I said, 3.25 vs 2.95 is just not enough to worry about.

By the way, if you REALLY want better fuel economy, consider either a full HF drivetrain swap OR a D15Z1 with an HF transmission.

 

the tranny input shafts should be the same as all d16 so i wouldnt change the axles if your car is a si use the si one if it hf use the hf i know the hf are diff
but i never owned a hf before i did have a hf trans in my si and man does it feel diff feels like a whole diff car. Long gears

 

One local yard has an '89 hf transmission for... $300.
I can wait and look around for a while, but not too long.
And I think nippon-motors will deliver it for free....


Modified by andrey320 at 3:29 PM 1/19/2008

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by andrey320 &raquo;</TD></TR><TR><TD CLASS="quote">One local yard has an '89 hf transmission for... $300.
I can wait and look around for a while, but not too long.
And I think nippon-motors will deliver it for free...</TD></TR></TABLE>

That sounds like a full-service yard. You will always pay BIG TIME unless you go to a place where you pull the part yourself.

 

It works much better for me to get a transmission delivered to my house for $300 than to go look for one and pull it for $100.
Thank you for all the input. Everyones opinion is greately respected.