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Midmount buggy
sinecure - August 1st, 2006 at 02:58 PM

I've almost aquired a farm basher VW based frame buggy with swing axle. I have read around this forum somewhere that you can achieve a correct midmounted config by turning the gearbow around and inverting the diff/transaxle centre.

Is this true? And if so, is it that easy? Does it work for an IRS?

I know the mounts, gear linkages and such will have to be custom made, but is that it really?

BTW, this will never be rego'd.

It hasn't arrived yet but when it does I'll post up some pics.

Thanks,

Mick.

[ Edited on 1-8-2006 by sinecure ]

[ Edited on 10-8-2006 by sinecure ]

[ Edited on 10-8-2006 by sinecure ]


Baja Wes - August 1st, 2006 at 04:14 PM

yes. pull the side plates off, pull the diff center complete with ring gear out of the left side of the gearbox, then put it back in the right side of the gearbox.

You basically "flip" the diff so the ring gear is on the right instead of the left of the pinion. Therefore it gets spun the other way.


shaihulud - August 1st, 2006 at 05:13 PM

I believe that you can also turn the whole gearbox upside down. I don't know if this can be done simply. Remember that there is a little air pressure vent at the top of the box, so you would need to block that and drill another hole to replace it.

Again I believe, that by inverting the ring gear you get the diff to run under power on the normal run on side of the crown wheel and pinion. So the crown wheel and pinion are running in the incorrect way. That limits the amount of power that can be put through the system. I think it also wears faster.

My 2 cents worth.


Baja Wes - August 1st, 2006 at 05:27 PM

It doesn't wear any faster with the diff flipped.

Reduction box kombi's all run with flipped diff's, to counter-act the reduction boxes.

What you are thinking of is probably running a reverse rotation engine like a corvair, which makes the whole gearbox run backwards. This is reported to have negative effects on gearbox life.


tassupervee - August 1st, 2006 at 05:29 PM

Quote:
Originally posted by shaihulud

Again I believe, that by inverting the ring gear you get the diff to run under power on the normal run on side of the crown wheel and pinion. So the crown wheel and pinion are running in the incorrect way. That limits the amount of power that can be put through the system. I think it also wears faster.




Nope, the gear drive in precisely the same fashion regardless of which way its oriented.
Exactly the same way as flipping the entire gearbox. Have a think about it. theres no difference.

Quote:

I know the mounts, gear linkages and such will have to be custom made, but is that it really?


have a look at the back of any Formula vee M8. The job is already done and it will show you how easy the gearlinkage setup will be.
no brainer.
If you cant get to one ill take some pix of my gearshift setup to point you to where you need to go K.
L8tr
E

L8tr
E


sinecure - August 1st, 2006 at 05:56 PM

Thanks heaps, guys.

Tas, I've been following your threads since I started on this forum, as I'm a big fan of small racing classes. The work you did on your suspension was brilliant, and truly artistic. Your thread is where I got the idea to reverse mount the engine in the shortened pan, one seater off roader I'm going to build. Nothing like the engineering quality of yours, just a toy - more like a big Honda Odyssey (spelling?). In fact, I'm using the cage from an old Odyssey as the driver protection.

I've been looking hard at your shift linkages in the pics, hoping to 'borrow' from your design. Thanks for the help offer, as soon as I've got the thing home, I'll post up a pic or two and bother you to distraction with questions.

Cheers,

Mick.


tassupervee - August 1st, 2006 at 06:40 PM

Mick
Thanks for your very kind words re: my suspension development. I really appreciat the positive feedback I have received and I hope some of my fun and games helps out someone else.

I was looking thru the "Progress" thread and having a look at some of the pix to point you to but youve beaten me to it.
This very simple setup preserves the stock "H" pattern shift.
However, one of them there has a pretty good closeup of the universal joint right at the gearbox.
There are 2 more of those UJ's up the line as well as the shifter shaft has to change directions twice.

The other consideration is the bearings/bushes you need to support the shifter tube itself.
The tube needs to smoothgly rotate and slide longitudinally thru the bush and too much radial play.
Cheap and nasty linkages ad bushes results in cheap and nasty shifts that you will learn to despise in very short time. In other words, you will "get what you pay for" and I reccommend spending extra time here for best results.
With that in mind, I have evn considered setting mine up again with small linear bearings! Overkill yes but hey!

Mine (bushes) are fashioned from some short lengths of steel tubing an some kind of nylon/plastic bush material pressed in to the tube and I keep them well lubed with moly grease.
The tolerance is quite close with the shifter tube and there is bugger all movement in there.

The UJ's are a commercially available item from various high end speed/race carcomponent shops. They are very nice quality but perhaps a bit exxie.
You can fashion some more affordable ones from lower priced 3/8" drive socket set universals welded to the end of the tubing.
An effective method of locking out reverse gear is vital tho.
My old Elfin had a locking mechanism that had to be physically unlatched to select reverse but it was a total pain in the arse.
The Kestrel has a very elegant and adjustable spring loaded bolt but its too difficult to describe and a picture here is worth a million words!
More on that later.

Newhoo, keep us posted with your toy M8.
L8tr
E

[ Edited on 1/8/06 by tassupervee ]


pete wood - August 1st, 2006 at 08:01 PM

hyundai excel steering column and unis. ;)


sinecure - August 10th, 2006 at 05:01 PM

Well, the bloke I contacted to buy the chassis never got back to me and then it dissapeared from ebay. Bit cranky, but he obviously didn't want to sell it too badly, or got a better offer. So I'm looking for another one. Really wanted this one though as it had been shortened already.

Back to looking, but have an in-law with me now so it should progress more quickly.

What's with the steering column and unis? Why the Excel?


pete wood - August 10th, 2006 at 05:10 PM

$15 bucks from pick and payless.

comes with two sealed unis. much better than a setup off a ratchet set.

http://www.geocities.com/peterwood732/buggyproject/gearshift2.JPG

Here's my setup. it allows me to run the shift rod (kombi box) along the top of the tunnel without fouling on the handbrake. ;)


tassupervee - August 10th, 2006 at 06:07 PM

Bwaaahahahahahahaha thats brutal stuff Pete.
How hard are you going to swing on that!!!!!!

Actually, i uses precisely the same steering shaft/unis in my Vee steering.
The gearshift unis we use are very compact and lightweight and weight is the controlling factor.
In yuor case, its obviously not a problem LOL!
L8tr
E


sinecure - September 3rd, 2006 at 08:56 PM

HOORAY!!!! :bounce

With MUCH thanks to Marc and Kath (midlife crisis) I now have a type3 chassis (when they finish with their other type3 body repair using it as a donor)

So is there anything fiercely different in mid-mounting an IRS as opposed to a swing? (I'm looking at you, tas! )

Can't wait to start this thing.

SO STOKED!!!!!!!!!!:tu::tu::tu:

[ Edited on 3-9-2006 by sinecure ]

[ Edited on 3-9-2006 by sinecure ]

[ Edited on 3-9-2006 by sinecure ]


tassupervee - September 3rd, 2006 at 09:44 PM

Umm I can see no reason why not.
At the end of the day, all the suspension stuff stays the same just the engine is at a different end of the car
What your going to find is that the gearbox front mount, which is now a rear mount might need some attention.

However, with a bit of chicanery here.
If you use an engine out of a Kombi or build an engine with some universal cases then you can utillise the engine mountingscast onto the front of the cases and simply mount your engine using the stock gearbox mounts and fabricate some front brackest to attach the front of the engine into the pan.

If your using a beetle case, then youll either have to fabricate a sufficient rear gearbox bracket so the engione hangs in the breeze like stock or utilise the lower crankcase bolts at the front of the engine and bracket up to them.
In this case youl have to either isolate the front mount with a rubber engine mount to prevent the mounts from pulling out of the engine cases, or solid mount the gearbox mounts.
This latter method is how my engine is mounted but the front bracketry has a fair degree of flexibility inherent in its design to allow the engine to twist a bit and the gearbox is rigidly bolted into the chassis so the only loads the front mount have to deal with is up and down and the cases can deal with that ok.

L8tr
E