GT 4.11 rear gears

[jeff denton]

There once was a mention of the 1.1 liter GT coming with 4.11 rear ratio. The discussion included a warning that they are too weak to use in a 1.9 liter car. Nevertheless, I want to try some in Speedway GT, if for nothing other than a test to see if that ratio works in third gear better than 3.44 in second. (7.41 ratio vs. 5.61)
Anybody got some laying around?
Then again, maybe a test of Kadett 3.18 gears in second (6.85) is in order.
Anybody got some laying around?
Ultimately what I need is some Risse 4.75 gears but they are kinda spendy...
For testing purposes we need to keep it within budget, ya know.
Thanks!

[Gary]

A little off topic but... Jeff, do you have any action shots of the Speedway GT?

[jeff denton]

Do we ever! But they are still in the camera, hope to get 'em out soon. Last night we went to the Wednesday evening practice session at Raceway Park and put some more laps on Speedway GT. It was sporting all new tires, a bunch more cross weight, and the valve cover modifications that were needed to stop spewing oil out the right side. This time I was able to run it at 7000 rpm and the car was absolutely glued to the track. However it was too slow so I went to third gear but couldn't get the rpm needed to power out of the corners. So I put a very experienced (Limited Late Model) driver in it and told him to go for it. In third gear he could drive it in to the corner real hard, hit the brake to set the car at the apex, but couldn't power out hard either at 4200 rpm. He did say the car will go wherever he wants it to, and on our track that is good!
We need more gear. 4.11 or 4.75, I'm thinking. Also a plug check later tells me we're running rich, so a jet change will happen next, too. And a visit to another track sixty miles away is in the works, too, it is a bigger, flatter tri-oval that our present gearing may work at.
Tire temps say we need more camber on the left and less on the right...

[davegt27]

I don't think 1.1 4.11's will work

impulse 3.90's would be a Good idea

how tall a tire you running


Davegt27

[jeff denton]

Here's our situation. Car #5 (Toyota, points leader this year) tells us he's running 3rd gear (1.4) and 4.11 rear at 6200 RPM. Car #71 (Mustang, 3rd in points) runs 2nd gear (2.05) and 3.08 rear at 6400 RPM. Doing the math we see #5 has overall ratio of 5.754 although he claims it is 5.90. #71's numbers come out to 6.3 overall. See there's quite a difference there, and you never know how accurate the competion's advice may be...
I estimated my overall ratio should be 6.05 overall. Impulse 3.89 in 4 speed's third gear equals 5.31, right? 4.11 rear gear in third comes out 5.61, sounds close enough to give it a try, huh? Now the Risse Motorsport 4.75 gear in third would be 6.48, but in third gear of a 5 speed we see 6.25!!This sounds like it would be do-able, but to try this we'd be spending thousands of dollars. Kind of a spendy experiment compared to slamming in some stock GT 4.11s... So if the 4.11 fit the 1.9liter GT rear carrier we're in like Flynn, if not, what would it take to make it fit? We could certainly build a ring gear carrier housing (called a "spool" in stock car racing), but would the pinion go in the housing?
Questions Questions Questions. See why I love gt.com? One of you guys will know all this!!!
We all run the same tires, Goodyear Eagle measuring about 71" circumference on the right side and Hoosiers measuring about 69" on the left, giving us 1-1/2 to 2 inches stagger. Rear diffs are locked, so there is no differential activity, so to speak.
Thanks for the interest and any possible advice! Since people are requesting pictures, here's another. Notice the spring buckets. That's how I like to "slam" the GT, and it does not alter ANY stock geometry if you move the panhard link on the chassis, this one is ajustable up and down.

[RallyBob]

Originally Posted by jeff denton So if the 4.11 fit the 1.9liter GT rear carrier we're in like Flynn, if not, what would it take to make it fit? We could certainly build a ring gear carrier housing (called a "spool" in stock car racing), but would the pinion go in the housing?

Not even close to fitting Jeff. The 1.1 rear axle assembly is far smaller than the 1.9's, they're not even remotely related. It won't take the power either, with a spool, you'll break those tiny axles (should you try to find a complete 1.1 rear axle).

BTW, don't worry about what 'the other guys' are doing, worry about your own car. We learned long ago that the Mustang/Pinto/Celica/Monza/Vega tricks and setups mostly don't apply to the Opel. You've got a short-stroke engine there, capable of decent rpms, but short on torque. You'll want to come off the turns spinning at least 5500 rpms, preferably higher.

We used to run big McCrearys at our track, 74-75" in circumference. We ran a 3.44 rear axle, and 2nd gear with a stock 4-speed. Worked for our particular engine and track.

Sounds like you could use a 4.22 (hard to find these days) or a 4.30 final drive (kinda rare in this country). But occasionally the 4.22's pop up from old autocross cars or hillclimb cars.

I could make a phone call to a friend of mine in Sweden, he builds Opel rally cars and they mostly run 4.75, 5.13, and 5.28 rear axles. Once in a while a good used set comes up, and sometimes a set of 4.22's gets dumped for a set of 4.75's or a numerically higher gearset.

Bob

[jeff denton]

That would be super awesome if you were to locate what I need, Bob!
I was afraid that my 4.11 plan was unsound, as a message from Dietrich Risse indicated his gears would not fit the 1.1 liter GT. There must be a big difference...
Yeah I know it's hard to trust a competitors word, but you got to investigate every possibility! Really all I know for sure is we are over-revving in second and lugging in third...
Thank You!!

[RallyBob]

Jeff, I got a call in to my friend in Sweden, he thinks he may know where there are some 4.75's, so I'll give him a few days to check and will get back in touch with him and let you know if they're for sale or not, and for how much...

Bob

[jeff denton]

Thanks a kazillion, Bob. IOU big time!!

[davegt27]

you have a rear sway bar i cant tell from your Pic

Davegt27

[RallyBob]

Originally Posted by davegt27 you have a rear sway bar i cant tell from your Pic Davegt27

Dave, usually for circle-track use, a rear sway bar is not run at all. On our old Ascona we used 715 lb front springs, a 1" front bar, 180 lb rear springs, and no rear sway bar. Sounds odd I admit, but it works. Totally different setup than for road-racing.

Bob

[montana]

Jeff if you just buy my car you get 4.11 welded rear end and a 3.something . Come on... Glad to hear your running speedway... SOMEBODY PLEASE BUY MY CAR i need the $

[davegt27]

I thought you sold your car a friend said he saw a red race GT going down the highway


Bob i was just thinking about the rear sway bar for axle location

to save the barrel spline

i know mine bit the dust autocrossing with out a rear sway bar

Davegt27

[jeff denton]

Hi Dave, no rear sway bar, like Bob says it's just unheard of in circle track racing. I was gonna try one, 'cause you just never know what might work. But the one I had (off the Kadett parts car) I let go when Darin (manta 73) traded me a parts GT for the Kadett... I guess you're wondering what my spring bucket mod does to the sway bar. I imagine it would still go in OK.

Here's a snapshot of step one to my way of lowering a GT

Hi Pete, I wish I could buy your car, it's certainly the only other GT race car around here, and only 90 miles away. I wish you would just bring it up and race with us. Wouldn't it be a hoot if a couple funny little German cars suddenly took over the track? It could happen!
Just for fun, advertise it for sale in the Kalispell paper, and in the Mountain Trader. I don't know if you'll get any calls, but I'm sure I will. I could certainly push it for you!! Did you ever set a price on it?