ZF alternative

Thanks to Brian Wolff for the following information on tranaxles:

The first one is called an R25 or UN1 transmission and they were originally put into the 1987-1989 series Eagle Medallions (AMC/Chrysler/Jeep)! Although a little smaller than the ZF they can take up to 400 hp. The Brits and Aussies have been using them for years both for street and racing.

The other transmission that you might consider is the Hewland racing transmission. They go for about $2000 and as far as I can tell they do every the ZF does but at a fraction of the cost.

And, last but not least, there is also a transmission from a lesser known Audi that is also a match but I still have to get some more info on it. However, my feeling on this one is that it won't be as available as the R25 in North America.

Model	Part No.	1st	2nd	3rd	4th	5th	Rev	Diff
20	369.00	3.36	2.06	1.38	1.06	0.82	3.55	4.11
	369.05	3.36	2.06	1.38	1.06	0.82	3.55	4.11
20TX	369	3.36	2.06	1.38	1.06	0.87	3.55	3.778
20LS/TS	369	3.82	2.18	1.41	1.03	0.86	3.55	3.778
21Turbo	UN1-013	3.36	2.05	1.38	1.03	0.82	3.54	3.44
25GTX	UN 1-03	3.36	2.05	1.38	1.04	0.82	3.55	3.89
25V6	UN 1-04	3.36	2.05	1.38	0.96	0.76	3.55	3.89
Alpine GTA	UN1-05	3.36	2.05	1.38	1.04	0.82	3.55	3.44
25 Blindee	UN 1-06	3.36	2.05	1.38	0.96	0.76	3.55	4.11
Alpine Turbo	UN1-07	3.36	2.05	1.38	0.96	0.76	3.55	3.44
25V6 Turbo	UN1-08	3.36	2.05	1.38	0.96	0.76	3.55	3.778
30TX	369-01/06/017	3.36	2.05	1.38	1.06	0.82	3.55	3.89
30TS	369-01/06/014	3.36	2.05	1.38	1.06	0.82	3.55	3.89

The type UN1-013 Renault 21 Turbo is the preferred transaxle for use in the GT40 replicas although the 25 Turbo and GTA boxes are also often used. Also note that if the GTA box is used it either has to be inverted or the differential reversed unless five reverse gears are required. On all boxes the selector shaft has to be modified to extend out of the right hand side of the gearbox so as to link up with the right hand gear change linkage. The preferred CV joints are from the Ford Granada and adaptors have to be fitted to the Renault transaxle output shafts to couple to these. These adaptors are commercially available items.

The transaxle type can be found on a small aluminum disk around 1-1/4" diameter which is held onto the box by one of the fixing bolts on the rear end cover of the gearbox. Unfortunately if this cover has ever been removed the disk is rarely replaced and the only way to identify the box is by checking the gear ratios.

Type	1st	2nd	3rd	4th	5th	Rev	Diff	Speedo drive
013 Serial Number prefix 3T	3.46	1.79	1.07	0.78	0.60	3.17	4.11	0.52
013 Serial Number prefix HE	3.46	1.79	1.13	0.83	0.68	3.17	4.11	0.52
013 Serial Number prefix HF	3.46	1.79	1.13	0.83	0.68	3.17	4.11	0.52
093 Serial Number prefix 3Q	2.84	1.52	0.90	0.64	0.48	3.16	5.22	0.52
016 Serial Number prefix AAZ	3.60	2.13	1.46	1.07	0.86	3.50	3.89	0.52
016 Serial Number prefix 3V	3.60	2.13	1.46	1.07	0.83	3.50	3.89	0.52
016 Serial Number prefix 3K	3.60	2.13	1.36	0.97	0.78	3.50	3.89	0.52
016 Serial Number prefix 5N	3.60	2.13	1.36	0.97	0.73	3.50	4.11	0.52
016 Serial Number prefix 3U	3.60	1.88	1.19	0.84	0.64	3.50	3.89	0.52
016 Serial Number prefix BMO	3.60	1.94	1.23	0.903	0.684	3.50	3.89	0.52

The Audi suffix 016 transaxle is the preferred transaxle for use in the GT40 replicas. The 016 boxes have the selector shaft on the left hand side, all other boxes have the shaft in line out of the back of the box. The 016 selector shaft has to be modified to extend out of the right hand side of the gearbox so as to link up with the right hand gear change linkage. The CV joints used on most (UK) GT40 replicas are from the Ford Granada and the output shafts on the Audi type 013 transaxle have mountings to suit. The Audi type 016 has output flanges to suit similar but slightly larger diameter CV joints which could be adapted for use with the smaller CV's if necessary or better still to use as standard with larger diameter drive shafts. Note that Audi 200 were later versions of this car and the 9000 range were again the same but the American version of the car.

The standard Ford V6 flywheel commonly used on GT40 replicas will not fit into the bell housing on this transaxle. A special flywheel or extra thick adaptor plate will have to be used. The standard Audi flywheel would have too many fixing holes making the mounting unsafe if modified for use with the Ford V8.