Cimbria SS

[ydeardorff]

I just thought I'd mention this so when your screaming that pour engine down the road*yipes* you'll know why*laugh*
Brett

I ran some calcs on your setup using the 091 6 rib transmission info, and my WRX transmission info to compare the difference.
Bus 091 6 rib transmission 4.56 final drive:
First gear - ratio 3.80 idle to 3500 RPMs = 0-15mph
Second gear - ratio 2.06 1900-3500 RPM = 15-27 mph
Third gear - ratio 1.26 2100-3500 RPM = 27-45 mph
Fourth gear - ratio 0.89 2400-3500 RPM = 45-63 mph
3311 RPM's @ 60 MPH
3863 RPM's @ 70 MPH

TY75 turbo transmission with 3.9 final drive:
First gear - ratio (3.45) idle to 3500 RPM's = 0-24MPH
Second gear ratio (2.06) 2000-3500 RPM's = 24-40 MPH
Third gear ratio (1.45) 2400-3500 RPM's = 40-57 MPH
Fourth gear ratio (1.09) 2600-3500 RPM's = 57-76 MPH
Fifth gear ratio (0.83) 2600-3500 RPM's = 76-100 MPH

2100 RPM's @ 60MPH
2400 RPM's @ 70MPH

This is just to show you the difference in your RPM range.
Using this final drive ratio in your 091 transmission will run your engine at 68% of your RPM range
while cruising at 70mph. This constant high rpm will cause excessive wear, and a lot of heat build up
in your engine.

This info isnt to convince you to ditch your transmission. The 6 rib is a very strong transmission capable of handling up to 300hp..
It is commonly used in sand rails. But sand rails need low gearing, and don't cruize at 60 or 70mph.
So when you get to the point of installing the cooling system, ensure you have a big enough radiator,
and its in a very good position for fresh air. Also, You may also need an oil cooler as well. That engine
will really cook the oil at those freeway/highway RPM's.
Just points to consider as you move forward.

 

[sector]

So I just measured my gear ratios and it doesn't make much sense.
Here is what I have,
Gear = Input Shaft Rotations = Tire Rotations
Neutral = 23 = 10
1st = 86 = 10
2nd = 47 = 10
3rd = 29 = 10
4th = 20 = 10

Measured twice so the numbers should be correct. Now what does that mean?

 

[ydeardorff]

ok your terminology is off I think.

You mean input shaft?


You should have no rotations on the output shafts while in neutral.

In first, your measure says you turned the axle 86 times but the wheel which are connected directly to the axles only turned 10 times?? Then something is broken...

Turn the input shaft of the transmission. Then in first your output shafts should turn 1 full revolution per 3.8 turns of the input shaft as an example...

 

[sector]

you are correct, I meant to say input shaft.

My car was driving fine before I took it apart last year.

 

[ydeardorff]

So I just measured my gear ratios and it doesn't make much sense.
Here is what I have,
Gear = Input Shaft Rotations = Tire Rotations
Neutral = 23 = 10
1st = 86 = 10
2nd = 47 = 10
3rd = 29 = 10
4th = 20 = 10

Measured twice so the numbers should be correct. Now what does that mean?

Per this result, something is wrong, as all of your results have the same output with differing inputs.

Try it again. How did you do this procedure?

If you have the wheels on the car, put one wheel on the ground, and lift the other so it can spin freely.
Then try it again. If you have 8.6 rotations of your input shaft to 1 tire rotation, you have the gearing of a farm tractor. *laugh*

If you had both wheels in the air, one can spin backwards, while the other is spinning forward. This would mess up your results.

Currently according to this your gearing is:

1st 8.6
2nd 4.7
3rd 2.9
4th 2.0
and nuetral??? 2.3

With a final drive of 4.56 and a 4th gear ratio of 2.0 youll hit 28 mph at 3500 rpms in 4th.

 

[sector]

You are correct about neutral, it was simply rotating due to friction, most likely because of low viscosity of oil due to cold temperature. I've checked gearing again and came up with the same results. It doesn't make any sense. Driving it around town was just like any other car with manual transmission.

 

[ydeardorff]

Im not sure what is going on. Can you describe exactly how you are doing this?

Per the information I gathered, your 1st gear ratio should be 3.8:1 with a final drive of 4.56:1.

So if Im remembering how to do this correctly, you turn the input shaft 3.8 turns, then the final drive pinion should turn 1 time.
If the final is 4.56:1 then you should have to turn the input shaft 17.3 times to get one full rotation at the wheel.
So your formula should be as follows:
Gear ratio multiplied by the final drive ratio = number of turns of input shaft to get one wheel rotation.
This is what you should be getting as results:
1st) 3.8 (4.56) = 17.3 full rotations of input shaft to one full rotation of wheel
2nd) 2.06 (4.56) = 9.3 turns full rotations of input shaft to one full rotation of wheel
3rd) 1.26 (4.56) = 5.7 turns full rotations of input shaft to one full rotation of wheel
4th) .89 (4.56) = 4.0 turns full rotations of input shaft to one full rotation of wheel

091 6 rib vw bus transmission info:
VW Transaxle

 

[sector]

This is what I did.
1) Jacked up right rear wheel.
2) Marked input shaft and Tire with permanent marker (relative to each other).
3) Engaged 1st gear.
4) Rotated tire 10 revolutions and counted number of revolutions on the input shaft.
5) Repeated Steps 3 & 4 for the other gears.

 

[ydeardorff]

This is what I did.
1) Jacked up right rear wheel.
2) Marked input shaft and Tire with permanent marker (relative to each other).
3) Engaged 1st gear.
4) Rotated tire 10 revolutions and counted number of revolutions on the input shaft.
5) Repeated Steps 3 & 4 for the other gears.

Ok, then your working backwards. Usually people turn the transmission input shaft, not the wheel. But what ever works for you.

If you are doing this via the tire, you only need one revolution of the wheel.

The numbers I posted above still apply.
One wheel rotation should give you 17 rotations of the input shaft in first gear.
So on and so on.
Its easier to count the turns from the input shaft than the wheel.

Slide on your clutch pressure plate onto the input shaft. Then use a phillips screw driver and insert it into one of the guide/bolt holes and then rotate the input shaft. Its easier to count smaller numbers of rotations.

 

[sector]

It seem that my measured numbers are off from your calculated values by a factor of 2x. Is there any other gear reduction happening from trans input shaft to engine?

1st) 8.6x2=17.2
2nd) 4.7x2=9.4
3rd) 2.9x2=5.8
4th) 2.0x2=4.0

 

[ydeardorff]

hmm,
I'm not sure.

if 1st is 3.8:1 then 3.8 turns of the input shaft would turn the pinion shaft one full rotation.

From there if your final drive is 4.56:1 then you would need 4.56 turns of the pinion to make one rotation of the wheel.
3.8 x 4.56 = 17.328

So 17.328 rotations of the input shaft should rotate the wheel once.

If your getting a very reduced version of this, then your final drive may be something else, or the gears were modified to be much lower than stock.
Your saying you were driving with this tranny before, so Im not sure where the error is.
Here are the final drive ratios that came with your transmission.

5.375 5.375 5.375 4.857 4.571


How to Determine Gear Ratio: 6 Steps (with Pictures) - wikiHow

Since your errors are consistent, to the ratios of the gearing and final drive ratio then I would surmise the ratios are correct despite the error in results.

End point, if you are not going to be spending any time on the highway or at speeds above 40 mph then this transmission will be fine for you.

With this gearing setup, of which you have no options that will fix it, you will not enjoy the screaming engine that will result. And wear out the parts youve spend probably a lot of money on.

This 6 rib would be great for a dune buggy or sand rail, that's all about power at lower speeds. But is not a good choice for a road car.
It would be if there were a kit or something to reduce the final drive as that is the main culprit here. Changing any of the 1st-4th gears wont make any real difference. Its the 4.57 final drive that is the problem. Everything else sounds fine.
The figure above with my TY75 WRX transmission show where this engine should be sitting at freeway speeds. About 2200 to 2400 RPM's or less @ 60-70mph.

 

[sector]

I did a quick test fit of Subaru dashboard. Looks good but I am not sure about the legroom. Need to investigate some more before I make a decision.

 

[sector]

Finally had some time today to spend with the car. Installed roof frame. Used 1"×1" 11 GA tubing, welded and bent to shape. Next I will fiberglass over it.

 

[letterman7]

That looks good! Now's the time to run any wiring you think you want to the roof for dome lights or whatever. Might even be wise to put a chase to the center and a pull wire, just in case.

 

[sector]

Wires will be done after fiberglass.

 

[Peter]

Compared to the Eagle that is about right if a but nearer the openings. I would think about tying it into the A post too before glassing it to avoid any screen cracking problems, don't rely just on glass to hold the joints, weld them.
You might want to think about extending the glass on the door openings to allow a rain channel and rubber trim.
The most common cause of screen cracking on the SS is people hanging onto the top corner of the screen when getting in and out, fit folding car 'over door' handles in the roof as aids to getting in and out.

 

[sector]

My windshield frame already has 1" round steel tubing welded together and glassed in around entire perimeter. It's visible in the previous photo where I test fit subaru dashboard. Drip channels will be incorporated during gassing process.

 

[Peter]

Great, good to see it coming on, I would still weld the A frames to the roof, surprising how much stronger it makes the whole thing, if you haven't already of course. Be interesting to see the whole thing done. what hinges are you going for? The main differnce I can see is the SS bars are further in and has a couple of 3" strips across for the hinges.


I like the Subaru dash, seems fit right in there, what are the overall dimensions, w,h,d (to screen) is there sufficient curvature at the front or would it need significant infill?

 

[sector]

What is the deepest floor pan that can be intalled that would not cause issues with ground clearance?

 

[Peter]

As a rule 3" is OK without grounding issues but i have seen 5" but I guess he lives in a no speed bump area and doesn't use an underground car park.

It also depends on your ride height of course.

I prefer the sloping floor rather than the 'skip' type so there is also a progressive rise to seat height as well as forward travel and it presents a better frontal area underneath.