Swing axle or IRS..........

[Lee.C]

Right, First of all THANKYOU guys for all the info that has been supplied about IRS rear ends and 901 porsche boxes BUT I have been wondering.... Am I straying to far from what I originally intended for PROJECT 66 

You see I already knew MOST of the pros and cons of going with a Swing axle 4/5 speed ie Mods, Costs, etc etc and now I have a pretty good idea of whats involved with the IRS/porsche 5 speed and when you weigh it all up there really is not that much difference in COST and TIME.

OK a built swing axle 4/5 speed will be expensive BUT there is much less "modifying" to do, And yes a porsche 901/5speed will be cheaper to buy BUT once you have brought drive sharfts, mounts, A arms (and had them narrowed), Linkage (and modifyied that) Shifter (and modifyied the tunnel) it will probably work out cheaper and easyier to get a 5 speed type1 swing axle box "Built" 

And like I said guys I feel that I am drifting too far away from what I originally wanted from this project - A TRUE 70's CAL LOOKER


Anyway let me know what you think guys 

[kev d]

Depends what you want to use it for really, your `66 is a wide track car anyway is`nt it? whats the width difference between it and an irs car?
If the width difference is minimal why not use the better handling system?
If youre not planning to use it much its maybe not worth the hassle of changing what you have, but with the amount of miles you put on the buggy I don`t see it sitting in the garage much
A built motor & close ratio 4 speed is good fun but maybe not on a run to. say SCC?
A berg 5 makes sense, though I think theres some fabrication work to make it fit? KS is the man to ask.
A new berg is @£2500 is`nt it? How does that compare to the 901 costs?
Neither option is probably considered a `true` 70`s cal mod but plenty of cars had 356 `boxes fitted.
I`d bet not many 70`s cars did 1000mile round trips to shows though
Cheers,
Kev

[Lee.C]

Very Very good points Kev 

Firstly the 66 is a "short axle" car so the A arms would need to narrowed by around an inch to match the original rear track.

Secondly this Car will be used ALOT ie EBI, SCC, Camberg etc etc so thats the main reason for thinking about a 5 speed box,

A Berg 5 speed needs ALOT less fabrication and at £2500 would be abit cheaper too, when you consider a 901 box will be approx £1000 then you have to buy A arms (narrowed), brackets, drive sharfts (narrowed), shifter, shocks etc etc then make it all fit,

I thnk it just makes more "sence" to go with the Berg 5 speed - and there were a few cars from the 70's that had 5 speeds - Mike Billings Red 67 

Hmmm decissions decissions   

[71CALRIPPER]

4 speed type 1 IRS with a Tall 4th gear All the parts can be bought no problem 2nd hand all day long i rekon you could do the lot X the box for £300

[kev d]

4 speed type 1 IRS with a Tall 4th gear All the parts can be bought no problem 2nd hand all day long i rekon you could do the lot X the box for £300

Fair point, spec the box with the radius of the tyres your using & it`ll work well

[Bruce]

..... when you consider a 901 box will be approx £1000 .....

The newest 901 gearbox is 36 years old.  Factor in a rebuild.

[Lee.C]

..... when you consider a 901 box will be approx £1000 .....

The newest 901 gearbox is 36 years old.  Factor in a rebuild.

Yes I forgot to mention that too - to many things to think about 

[Zach Gomulka]

I honestly don't think a 901 box with IRS fits the theme of the car A properly set up swingaxle will still handle pretty damn good, it will never be an IRS, but it will still be fun to drive. As for 4 vs 5 speed... I think that depends a lot on your engine, and how you plan on driving the car (high speeds for long distances, or short jaunts around town). It's no secret you are thinking about building a small CC high RPM screamer So if you want an engine like that, with a narrow powerband, and you want to be able to drive the car to the mainland... I think a 5 speed will be pretty mandatory. And even then, I wouldn't gear it any lower than a 4.12 with a .89 final drive. Also, IRS is going to weigh about 40lbs more, your engine will appreciate all the weight breaks that you can give it. I'm thinking a Berg 5 swingaxle with a 4.12 r&p, 3.78, 2.25, 1.58, 1.125, .89 is your best bet (BTW, I am a fan of spread out "factory" gear splits, not racey 1-4 with a big drop when you slip it into 5th, makes a better driver, IMO).

[Lee.C]

Cool Thanks for the input Zach - But there have been a few changes since I spent the week with Richie Webb and Dave Rhoads 

As for the 1679cc mouse motor we kinda came to the decission that this "point" has more than been proved by Johannes with the 1603cc screaming mouse. So if I want an engine that can been driven hard around the streets AND driven to EBI, SCC,Camberg etc then I am better of going for a 2110cc stroker motor (more on this later)

Also as you can see from this thread I am leaning more towards the original Swing axle rear end - after all it is more "Cal Look" 

My plan is to get the engine built and dyno'd  ASAP and then I will design my ratios around that 

one thing that Richie did suggest that sounds like a cool idea - I could weld in the IRS brackets even if I don't use them straight away, I will have the body off so it will be pretty easy and they won't be in the way of any of the swing axle parts then in the future if I change my mind then IRS will be an easy swap

[71CALRIPPER]

wise words from Zach !!

i agree with doing the brackets anyway , no harm in it even if you never use it.

Now get on with the car as EBI is only round the corner

[Mike Lawless]

I'm wishing I would have installed the IRS brackets when I was doing my pan.

[j-f]

I have ask the same questions some months ago here  

I will go for IRS, even if it is not perfectly cal look. I think I will more appreciate to have a car that handle well and go straight than feel that I have built something period correct 

[flatfire]

Fabrication for a berg 5 type1 box isn't that bad. There are some great pictures on the Cal Look forum.
I gained from other peoples pain.
Installed the box and drove to the Bug In on the first ever road trip the car had seen in Europe
Driving the bug is a great pleasure drove on our local dual carriageway tonight at a few miles an hour over the limit at 4500rpm. 

The major problem with the berg 5 is the expense and the availabilty.

Getting the box ready before haircut


Attaching the shifter up the skinheads

[Bruce]

I honestly don't think a 901 box with IRS fits the theme of the car ....

.....a Berg 5 swingaxle with a 4.12 r&p, 3.78, 2.25, 1.58, 1.125, .89

Who cares about a silly "theme".  Build the car the way you want it.

Having that 4th gear in my B5, I recommend a taller 4th.  1.04 is better for a 100% street car. 
Then, that 4th would warrant a taller 3rd.

[Zach Gomulka]

I honestly don't think a 901 box with IRS fits the theme of the car ....

.....a Berg 5 swingaxle with a 4.12 r&p, 3.78, 2.25, 1.58, 1.125, .89

Who cares about a silly "theme".  Build the car the way you want it.

Having that 4th gear in my B5, I recommend a taller 4th.  1.04 is better for a 100% street car. 
Then, that 4th would warrant a taller 3rd.

We've talked about ratio's, and you know what I'm after I'm guessing monkiboy's car will see more strip miles than my car will, so that is why I suggested a slightly closer stack.
BTW, the Berg5 I have planned for my car will carry a 4.12 r&p, 3.78, 2.25, 1.48, 1.04, .82. If the factory ever used a 5 speed, I believe that these would be the ratios that they would use.

[Bruce]

... I'm guessing monkiboy's car will see more strip miles than my car will, .....

I thought we were talking about a pure street car??  I see no mention of track use above.

BTW, the Berg5 I have planned for my car will carry a 4.12 r&p, 3.78, 2.25, 1.48, 1.04, .82.

That is perfection in gearing for a pure street car, IMO.  Next time mine's out, that is what it will be changed to.