Did I mess up on gearing?

My calcs say when you used to be doing a certain speed in fourth at 3,500 rpm you should be now doing that speed at 3,036 rpm. You're down about 13.3%.

I should have asked questions while replying above. I'm trying to learn more about gearing as I could use taller gears with my Soob. Could you elaborate on the rebuild of your tranny? What's the purpose of the bus third gear ? I've heard of hardened keys, gears and welded third and fourth gears. Did you get that done too? For my purpose I'm thinking of keeping stock gear ratios and just changing the 4.125 r&p out for a 3.44 getting a 65 mph cruise at 2,800 rpm.

Replacing the .89 with the .82 makes the 3-4th spacing wider than stock. With a 24 1/2" tire and 3.88 r&p, the stock 1.31 3rd gear hits 3500 at 50mph and 4000 at 57. With the .89 4th the motor is running at 2500 at 53mph and at 2800 rpm speed is 58mph; there's a fairly large "shifting window" to work with. With the .82, 2500 rpm doesn't happen until 57mph, so you're either revving high in 3rd (3800rpm) or lugging it a little in 4th (2382) to lope along at, for example 55mph. Unless you almost never cruise at 52-58mph, I think you've made a mistake. Stock 1st through 4th gears with a 3.44 r&p would be a better way of achieving higher cruise speeds, and your bigger motor will have the torque to do it. I know this isn't what you want to hear...  

The 3.88/.89 combo (24 1/2" tire) will give highway speeds of 74mph (3500) and 85 (4000rpm). With the 3.44, the speeds are 80 and 92mph. Maybe just put the .89 back in the gearbox and see if it's enough?

David- I'm of the understanding that the VW gearing is a little short (compared to the Subie gears) as the subie can cruise at a lower rpm. Maybe the 3.44 with stock gears is right for you? Have you compared final drive #'s?

Hope this helps. Al

Not trying to hijack the thread...just gaining info. Not trying to split hairs either but I just checked my tire size again and measured from the concrete floor to the center of the hubcap and got 11.5". Therefore my 155/80/15 tires are only 23" effective inches in diameter. The gear calculator I'm looking at says at 2,800 rpm I'll do 65 mph and at 3,000 I'll do 69 with stock type 1 gearing of 3.80  2.06  1.26 and .89 with r&p at 3.44. For the Soob, I think this will do well.

I have the 3:88 R&P with stock 1,2,3, and a .82 4th gear with a 2110 engine. I think that if I were in hot areas or did a lot of hill cruising I would go with the .89 4th gear. The drop between 3rd and 4th is pretty big with the .82 4th gear. My motor pulls it fine on the freeway but if I had it to do over I would get the .89 4th.

Badspd, I originally had a .82 4th and 4.12 R&P and wasn't happy.  I seemed to be either reving high in 3rd or lugging it in 4th.  When passing I would have to rev it to near redline so the engine wouldn't fall flat on its face when I shifted into 4th (note that my engine at the time was a 2110).

Now I have a .89 4th with a 3.88 R&P. (185/65-15 tire-24.5").  I wish I'd gone with the 3.44 R&P, but I'm really glad I dumped my .82 4th gear.

Ron

Thank you for all your replies.  I was looking to get input from those that have had/have this gear and I did.  I am thinking I might have gone too tall, really wish we could have machined in the bus 3rd gear.  What I did reallize is that average driving speed here in Reno is 70mph on the freeway.  Highway is 80mph.  Around town it is 45mph.  I know thath is a hole in this gearing from the 50-57mph mark.  I am running 185/65/15 on it, forgot to mention that and I used the Gear-up calculator on another post to run through my options and this was the best I could think of, but was hoping that the split between 3rd and 4th was not too much.  I will get my car back together by Thursday so I guess I will know for sure then.

Again,  Thank you for all your input.  Dave, I hope you get your sorted.

Trans is back in and out for a test drive.  Right now I am happy with the outcome.  There is a stretch between 3rd and 4th but I know I can work with it.  Feels much nicer on the car to not be hammering on it trying to keep up with traffic.

Cheers and thank you all again.

BADSPD

Quick update.  I am loving the gears.....  Car is light enough and engine has the power for the switch between 3rd and 4th.  Ran up to Tahoe and was not over revving and was not over heating....  Any less power in engine, I am not sure it would work.  I found out I do have a Super Beetle 1st gear. 

I do miss blowing the BMW's off the line, but I will deal.

So Happy.....

BADSPD

BADSPD- What's in your motor? Glad to hear it's workable.

Al,

94X78.4 crank

120 Cam

17lb Flywheel

40x35.5 ported heads

SS Tubes with Chromoly Rods and Dual Springs

Compufire

Dual Weber 40mm IDF

BADSPD

Al,  It is a really fun combo.  So 3rd....  with the 3.88 r&p, 185/65/15 tires and 1.31 gear it will stop pulling at about 4300 - 4400 and kind of go flat.  that is getting me to just over 60mph. 

The car pulls really well, not like it did with the 4.12 r&p, but still goes.  My biggest thing was to be able to keep up with traffic, not live up the the "objects in mirror are losing" sticker.

BADSPD

With what you have it should go to 6000 rpm with power, so something isn't right. Where did the heads come from? What size venturis are in the carbs? Exhaust size tubing? Was any porting done?

Lied to you.  Driving the car today and thought I would test what you said.  I really have on revved to 4500 so beyond that I was not sure.  Yes, it is still pulling up to 5000 when I figured I should shift.  It has Made in Mexico heads.......  not sure on the rockers, but I am thinking 1.1 but maybe 1.25 as there is a light hitting on stock valve covers.  Not sure on the carbs, they are right out of the box weber 40's IDF (so much better then the solexes that were on there). 

I am sure it will rev higher, I just haven't and don't think I will.  All I can say is it puts a smile on my face every time I drive it.

Stephen

Not a good sign.

Ron