New Replica Manufacturer?

Paul Thompson 'Hooligan' · 12-31-01, 04:19 PM

Hi Geoff
The site you mention I believe is in fact run by Mark Sibley who used to work at GTD many moon's ago.

If you want to contact him directly - mail me your number or email address and I will pass it on to him.

regards

Paul Thompson

12-31-01, 10:13 PM

The site says that delivery will begin in August 2000...anybody actually own one of these?

TT

Geoff Deakin · 01-01-02, 01:36 AM

Have just found following site: www.gt40replica.co.uk
Is this a new manufacturer? I have tried to e-mail and phone, but cannot contact them.
Anybody know anything about them?
Also, searching for the ideal GT40 replica. One thing that concerns me is the ride height of the body at the rear. Some replicas appear to have considerable clearance between the top of the rear tyres and the bodywork. Ray Mallock Racing always emphasised that the reason they used a ZF 'box was that the engine sat lower in the car, as on the original.
Anybody got any ideas?

Julian West · 01-01-02, 02:08 PM

Yes, I've also seen several ads in Motorsport & C&SC mags. Tried the number but got no reply...

Paul Thompson 'Hooligan' · 01-01-02, 05:42 PM

Hi Julian and all,
Mark Sibley can be reached on either of the following email address's.

masibley@supanet.com

or

marksibleymdagt40@virgin.net

Hope this helps

regards

Paul Thompson

01-02-02, 05:23 AM

Geoff,

""One thing that concerns me is the ride height of the body at the rear. Some replicas appear to have considerable clearance between the top of the rear tyres and the bodywork.""

Couple of reasons for this that I've seen. When the original cars are set up to race they have less ground clearance than when their on the road. This lowers the whole car body and all, with the same size tire it's closer to the body. But a road car with clearance for speed bumps etc sits higher so with the same size tire you going to have a gap.

Shock travel and spring rate could be a factor also typically a race shock has less travel and stiffer springs than a road one hence not as much clearance is needed with the race unit. Tire size could be a factor also. Some of the kit manufactures may be giving a little more clearance compared to
a race setting were performance is enhanced by getting the clearance as close as possible.

I have a friend that races a GT40 MarkV, (quiz, which one is this?) at the historic races his shocks have about 3/4" bump travel and 450lbs springs on the front as opposed to a road car with 1-1/2" 300lbs. This car also has about 1-1/2" less ground clearance than a road unit. And I do note that the edge of the fender lip is actually below the top of the tire as compared to the car I'm building which has about 1" clearance.

""Ray Mallock Racing always emphasised that the reason they used a ZF 'box was that the engine sat lower in the car, as on the original.""

Here's the way I figured this. The original pan depth is 6", and the bottom of the pan is flush with the bottom of the car. That puts the crankshaft center line at 6" from the bottom of the car. (The 302 crank center line is flush with the pan gasket surface) So now your criteria for choosing your transaxle is
that it can be no more than 6" from the input shaft centerline to the bottom of the bellhousing or trans case. Otherwise you have to raise the engine to maintain ground clearance of the Taxle.

I lucked totally on this because I bought the G50 Taxle knowing only that others had used it sucessfully. I didn't really measure the G50 but it just so happens that when it's inverted as is necessary the bell housing is the lowest point and the diameter of the bell housing is 12", so 6" radius. This is the lowest you're going to get it as this is probably the smallest bellhousing your going to see due to flywheel/clutch size constraints.

The only problem I see with the G50 is that the axle flanges sit a little high so there's going to be some droop angle to the CV shafts at ride height (robs power). Not sure how much yet but I do note that a real GT40 with a ZF box has 3 deg droop and that's with 3.5" ground clearance.

This raises another factor. Due to transaxle design the centerline of the axle flanges is either above or below the input shaft centerline (they have to cross each other in the box) so this decides whether your axles droop a little or your engine is higher than you'd like.

Sorry this got a little long but it does show that things are not always as simple as they seem, and also demonstrates how much time and effort went into the design of the original and the current replicas.

[ January 02, 2002: Message edited by: Kalun D ]

01-03-02, 01:48 AM

A thought on drive shaft angles. You need some angle on them as otherwise you get excessive wear on a single part of your CV joint which can then fail. I have heard that you need anywhere up to 10 degrees of angle. Haven't measured mine but seems to be about 5 degrees.
MAlcolm

01-03-02, 01:49 AM

A thought on drive shaft angles. You need some angle on them as otherwise you get excessive wear on a single part of your CV joint which can then fail. I have heard that you need anywhere up to 10 degrees of angle. Haven't measured mine but seems to be about 5 degrees.
MAlcolm

Robert Lawrence · 01-03-02, 02:59 AM

Hi,
has anybody got the relative weights of the gearboxes: suck as Renault, ZF, Audi, etc??

jimbo · 01-03-02, 09:20 AM

Regarding the relative weights of transaxles; these are in a chart on the Kennedy Engineered Products website, which you can find by doing a web search with the keyword 'transaxles'. He also rates them for strength, although this pertains mostly to hot VW engines. (While they put out a lot of power for their size, it is not close to what we are getting out of built-up small block Fords. The weight data is useful, though.) He also has a rebuilt vintage ZF box, with a ZF bellhousing, suitable for a GT40 project, at what I think is a reasonable price ($5500, I think it was).
Jim R

jimbo · 01-03-02, 06:28 PM

Kalun:
I found this by putting "transaxles" into Google, it comes up on the first page of search citations. It seems to be www.kitcar.com/kennedy/transaxles.html, that is what it looks like in my Favorites column when I saved it. Most of this chart, again, pertains to hot VWs because most of this interest has todo with VWs and sand buggies, but the table is in there and it includes a lot of Porsche/Audi weights as well. And, I think, some adapter info.
Jim

01-04-02, 01:31 AM

Malcolm, thanks I didn't know that, makes me feel better about the G50 now.

Robert, the only ones I know are
Porsche 915- weight 115lbs, capacity 237ft/lbs torque
Porsche G50- weight 135lbs, 300ft/lbs torque

these are factory torque ratings, the 915 is good for 350 to 400hp and the G50 to 500hp

Jim, just searched the KEP site, can't find the charts you refer to?

[ January 03, 2002: Message edited by: Kalun D ]