choosing gear ratios for full weight bug

[Rocket Ron]

Hi

I'm looking to put together a gearbox for my full weight car. The engine will be putting out close to 200 hp and rev to late 7000 rpm

my question is how do you go about choosing gear ratios etc to get the best from the car on the strip

the car will be more of a weekend warrior ( i hate that expression ) more than a comfortable street car so I can live with a more extreme set up. The car will be trailered to the strip as I live 120 plus miles away and for some local fun

I'll be running 205 70 15 rear tires or 26 " slicks when I get to grips with the car

I have a zf diff to use and would like to stay with a type 1 swing axle box

any suggestions would be useful

[markvo]

You need to weigh the VW with you in it and helmet, fuel, wheelie bars etc. How much do you want to spend?

[Rocket Ron]

have a budget of £1500 to £2000

stock weight '59 / 60 rag top say 862 kg with 80kg fat bloke in it and add another 12kg for fuel and safety gear  950kg all in ??

[dannyboy]

there was abloke on here with a medeola tranny for sale try him 

[SteveW]

You call up Peter at Cogbox and tell him all your specs and what you want to do with it, then not long after that you hand over some cash, install the 'box and then don't worry about it again

[hector]

You call up Peter at Cogbox and tell him all your specs and what you want to do with it, then not long after that you hand over some cash, install the 'box and then don't worry about it again

yup what he said

[Jason Foster]

  We have a Bloke like that over here too but his name is Jim Kaforski.

[gyles]

Hi Ron.  I am in the process of getting Mr Englezos to price me up a type 1 swing axle box for just this application.  His first opinion was something along the lines of 'you can't fucking do that!'.  In short he thought 200bhp on the road on a type 1 box was doable, but start spanking it on the strip with slicks regularly and you need to look at a bus box and IRS set up for reliability, with an obvious increase in price.  Pete is, I think, currently in the process of looking at what he can do for me in the way of a type 1 box, but obviously the risk is mine.

If I find out more I will let you know, and hopefully you can do the same for me 

[Rocket Ron]

Maybe we could get a group discount  

[gyles]

Maybe we could get a group discount  

 

[Bill Schwimmer]

Going by by the info you provided. It would probably work w/ 3:88 rp 4:11 1st 2:47 2nd 1:72 3rd  1:31 4th.   An aftermarket mainshaft w/ the 3:88 is about as strong as you can make the t1.  How long it lives will be dependent on the suspension, clutch & driver.

[Rocket Ron]

I 've been forwarded a link to John Maher web site with the gear ratio calculator which seams like fun 

suspension wise I'll be running a engine support bar, gear box mid mount , type 2 snubbers and spax shocks. Also thinking of an up grade on the torsion bars and a kennedy stage two pressure plate but unsure on the friction plate 

I run a similar set up on my other bug without the upgraded torsion bars and a kennedy stage one , It always seams to launch fairly square but the hp is more like 140 rather than 200

Bill the 4.11 first is very short is that something you have used

Also thinking about a ali front beam but not sure how much weight that would save , dont want to start cutting the car up to save wieght as its only done 68 k klms and is in original condition . I am only willing to do things that are reversible

there was abloke on here with a medeola tranny for sale try him 

yep but they are 100mm longer than a normal trans and the one I had, had pro rings spool etc and was over kill for what i wanted 

Hector / steve / gyles

Pete 's name comes up a lot and probably for good reason. maybe its time to give him a call 

[Zach Gomulka]

Bill the 4.11 first is very short is that something you have used

It's not so short when used with the 3.875 r+p. Compare the difference between it and a 4.125 r+p with a 3.78 1st

3.875 x 4.11= 15.93

4.125 x 3.78= 15.59

Slightly more aggresive, but I'd imagine hardly noticeable. Being full weight you could probably use the extra gearing off the line anyway.

[Bill Schwimmer]

I have not personally used the 4:11  3:88 but I know a few people that have with great results. I do have experience with the 3:78 3:88 with a 26" tire, it is too tall. Once in a while it will get a good launch but it mostly blows the tire off or bogs, no inbetween. The shorter 1st gear will lower the 60 fts & make it much easier on the trans.  Try putting your bicycle in high gear & try to take off fast & then put it in a lower gear & see which is easier to accellerate. As for the bigger torsions  I would  think twice. I know some people have good results ,but whenever you stiffen up the back trying to make it launch harder, you shorten the trans life. The launch energy has to go somewhere. Let it squat a bit in the back & make sure the front can rise easily & things will live & work much better. Just my 2cts  Bill

[Bruce]

The launch energy has to go somewhere.

I didn't know you knew Newtonian physics!

I completely agree with this.  The hit on the line has to be absorbed by the transmission and the suspension.  If you have softer bars, the hit is absorbed more gradually.  This should translate to longer gearbox life.

[nicolas]

yep, stiffer torsionb bars are not always the 'cure' but in my case the problem. the car hasn't got enough power to keep the car pinned and therefore it bounces when you accelerate. big wheelhop. the reason is the shocks and engine can't keep the car down and the torsions are not a 'fixed/ constant' force so what you get is not that good. i broke my stock box like that. before i was running orginal torsion bars (22 mm from a type3 on a type3) and it squatted more but worked out better.
i think for me the setup with stock bars and koni's or spax would work out best. but again i play with 115hp and not 200.

hope it helps anyway

[Rocket Ron]

thanks for the explanation `Bill

I have noticed that my car seems to "sit down " quite deep when I'm launching probably as a result of using the stock bars. I did have one go soft on me last year but after changing that it seemed fine.

Even with conservative launches it runs decent times for a full weight car with extra stuff , dyno mat etc and not a lot of power.

Looks like I'll be trying out the same setup without the upgraded bars

thanks Bruce and Nicholas

[kepajake]

Next winter I´m going to change my gear ratios too.

This is what I have now (driven 14.8./Alastaro, Finland):
1st 3,78 feels allmost perfect, shift @ 7200 rpm
2nd 2,06 rpm drop under 4000, shift @ 7200 rpm
3rd 1,32 rpm drop to 4500, time 12,2 / 175 kmh @ 7400 rpm
4th 1,04 no use
R+p 4,12

I think this is what I should have:
1st 3,78 shift at 7500 rpm
2nd 2,25 rpm drop to 4500, shift @ 7500 rpm
3rd 1,58 rpm drop to 5300, shift @ 7500 rpm
4th 1,18 rpm drop to 5600,  time ??,? / 185 kmh @ 7000 rpm
R+p 4,12

Car is full weight and cam is XR328.

[SuperBeetle73]

It can be done with a type 1 box and a heavy car if its got a gusseted case and built correctly
Rancho Pro Drag
3.89
2.56
1.58
1.12

with a 3.88

Shift light set at 7200

Full weight 1303 with bumpers etc