Hi all,
I am not sure that this is the correct place to post this question, but, all help is appreciated.
I am putting the finishing touches on a 914-6 conversion. I purchased the car already converted. It had been exclusively a track/race car for many years. The car arrived with a 2.2L S engine and a 901 with short track gears and an LSD. The car is running on 16" Fuchs.
I have since removed the 2.2 and installed a stock 3.0L.
Here is the issue; driving down thew highway at 75 miles per hour the engine is turning at 4500 RPM. Way to high for comfort. The engine is screaming.
Any suggestions as to what would be the simplest way to improve the situation?
Thanks.
Bill.

Buy a good used trans and swap or rebuild your current box. You may be able to use your current 5th as 4th gear and get a new, taller gear for 5th.

I'm on stock gearing on my 2.7 & am around 2500 at 60 or so & its fine on the tracks...well, I did hit the rev limiter at Daytona out of turn 4 downhill to the trioval, almost 155 on the gps...praying for nothing to break...

Bill, what are you going to use the car for?. Track, gearing may be fine...Autocross, as mepstein said, just put a higher 5th gear in for highway. Street, stock or maybe taller gear stack. Best, Mark

The 3.0L is a lower revving engine than the 2.2S was. In addition to intended usage as noted above, the lower rev range needs to be taken into account.

Do you know what gears are in there now? Possibly A-F-M-S-X. Nice gear stack for a track car that revs to 7000+ RPM. Not so much for highway cruising.

Scott

I second AFMSX as likely, or shorter, in that box. If you plan to use on street and in any other application as well then you will have to sacrifice a little in both or more in one. I like stock gearing, but I don't AX much and have a 2.7 CIS with SC cams. You could do what the factory did for the 914/6 and go A, Ga, O, S, ZA. You can do 5th as a Z as well if you want to go even slightly shorter on the 5th. Some of those gears get pricey, and can be hard to come by when you want them. I have all of those if you are interested.

Hi guys,
Thanks for the responses and ideas.
I like to autocross once in a while, but the car's purpose is mostly to be enjoyed on the street/highway/pleasure cruising.
Would it be better to just sell the present trans to someone looking for a track unit and install a stock unit in the car?
I have access to a stock side shift trans from a parts car. However, I don't know its history or condition. Is there a way to bench test it before installing it? How about the LSD from the present trans? Worthwhile transferring to the new trans?
Thanks,
Bill.

Forgot to mention in my previous post. I have no idea as to which gears are in the trans.
Bill.

Bill, to transfer the LSD you have to have ring and pinion set up, that takes special expensive tools and knowledge. If you want to retain the LSD, you would be better to just swap gears. Not hard. My DVD actually gives all info you need and with a parts transmission, you would be ahead of the game and have a known unit.

I have stacks of good stock gears if you want to discuss. Good Dr's. DVD are very nice. Someone local might have the tools, and could also offer an extra set of eyes. Extra eyes always good.

For street stock gearing is very good, even a taller 5th is nice, but remember final gearing is based on your tire rolling diameter also.

Wish I booked marked the gearing calculator, I did not. it will let you figure out how the gear ratios should work for your intended usage. So if your highway driving is 80 MPH, and you want to be at 3000RPM, you can play with the factors to figure it all out, and hopefully purchase gears once to make it happen for you.

http://www.914world.com/bbs2/index.php?sho...79893&st=20

http://www.914world.com/specs/regearing_901.php


pull the gear stack change gears accordingly..easy button

I had an M-S 3rd - 4th with a stock 5th gear. Which would have been fine if I didn’t have a CHT gauge. In 4th gear on the highway it was annoyingly loud and winding pretty hard. I don’t recall the RPM. If I put it in 5th the CHT would rise because the type IV loves fan speed. Ignorance is bliss in this case. Without the CHT I wouldn’t have known the temps were edging toward 400*.
I’ll bet it works pretty well for what it is built for. Just not very well for driving on the road.

Guys,
Thanks for all the good information.
I have a question for Dr.Evil regarding the spare trans that I have access to.
Is there a way to bench test it to determine that it is OK to put in the car without disassembling it?
It is now time to make a decision on what to do. I am thinking about going with the stock gearing in the spare trans. Is it worth while transferring the LSD to a trans using the stock gears?
Thanks again for all the information.
Have a safe and enjoyable holiday and a prosperous New Year.
Bill.

Perfect opportunity to get the Dr video and dig into this project. He makes it easy to go through and it's fun too.

If I had a limited slip, I would want to keep it and have it on the car.

As Dr mentioned, use that box (LS) as a foundation. I would open both of them and retrieve all the best synchro bands, dog teeth, and sliders and build yourself a nice unit with the gears of your choice.

Good luck,

There is no way to bench test. You will either install it and get lucky, or it will need some work.

For the LSD, you are going about it backwards. You take the gears from the core and place them into the case that already has the LSD and ring/pinion set up. If you move the LSD, you have to install the othe transmissions ring and set it, or transfer the current ring with its pinion and set it. Way more work that you can’t do. Just gut the LSD box and swap the gears in from the core. Far less work.

Thank you again Dr.
I will do as you suggested.
Bill.

I think I have some of the stock gears that you're looking for, Daytona. I have N (stock 914 third) and V (stock 914 fourth) in case you are interested. Not sure if I have any tall fifths left, but can check if you're interested. Shoot me a PM in case I forget to look at this thread in case you'd like to take me up on that.

Scott

The thing about the stock /4 gears is that many of us have them lying around. I have bins of N, V, ZD, as well as M, S, X, plus a bunch of others in less aupply. Stock gears are cheap, but core box should have them without issue.