Can anyone have, or put in a SADEV SL90-20 trans for a GT40 car just for track? I believe some GT40's have the SADEV SL90-20. The ZFQ/RBT ZF has had too many failures on my car and like many other's, who have experienced the same fate from using the ZFQ/RBT ZF. My car has a 302 Windsor, Webers, with 495bhp, 420ft/lb. I did two laps before it broke, gearbox engineers have told me a ZF will last only two laps, it's a common story. And always breaks on the upshift NOT the downshift. The car will go on the stands until I can find a decent trans.
GT40 Transaxle.
- Thread starter Wirruna
- Start date
Question Warren... The first time it broke was any research done to check the housing in the areas that have now failed looking for an issue that might have been inherent in the castings & if so the problem was always there. I work on a lot of stuff here in NZ and some of it is Pfitzner, Jerico, G-Force etc. In the Pfitzner gears you could 'see' the tooth markings 'straight cut' with taper wear caused by the housing deflection, Jerico mag housings that distorted the size of the layshaft that could have there life extended by fitting O/S bushings to restore their alignment and center distances. Now most people would regard these trans to be up top strength wise, but these guys were able to break them and in-car footage shows how tough the shifts, up or down, really were. HP/Torque were about 50 down on your numbers. One car has run the same Jericco for nearly 20 years, No failures and been down for a cautionary check twice with only bearing replacement, The guy that drives it has put in many miles in dog box cars and has shifts down to an art. Have you looked at the ALBINS 6 speed transaxle?
The Quaife ZFQ box has had numerous refurbs over the past 10 years, the recent refurb was done for the gears, mostly synchros and 4th gear. After having that done that at the next track day, the diff blew, when apparently a carrier bearing for the CV fell apart so the diff was completely rebuilt by a Quaife tech. So the ZFQ was pretty new on the insides, I only had a few laps at Eastern Creek to test it before I took it to Bathurst. Two laps in the case broke in half. I'm still waiting for an analysis of what happened. In the mean time I am looking for a better option.
Yes I looked at Albins and discussed the ABG but it's too long.
Could the case have been damaged when the diff blew previously? I feel your anguish over repeated failures. I gave up track days after twice breaking 4th gear on my RBT. I'm not familiar with SADEV, but going to a non synchro box with straight cut gears should be more reliable.
Rune
Supporter
Go for a Porsche G50 it is strong.
If the G50 was to survive where the ZFQ failed it would sugest that the latter's case/housings have some design/strength issues.
Howard Jones
Supporter
I am right at the point of putting together a new motor for my SLC. I am going up 100hp from 435hp/350sbc to a 535hp/406SBC. I called up California motorsports who built my G50. It is upgraded with all the good parts available for a G50 to make it stronger, side plate, steel synchro, and better gears when I changed ratios. I asked Rodger how much power I could put through my GRBX and he looked at my build sheet and told me he was comfortable with 500 ft/lbs. The car weighs 2500ish, runs Hoosiers, and has a Quaife TBD in the GRBX I will tune my motor on the engine dyno to that number. The smaller diameter 7.5-inch R&P in the g50-01-03s is the limiting factor whereas the 9-inch G50-52 is quite a bit stronger.
So that is what I can tell you about a well-built G50 run as a track car GRBX. If I was doing your car with a Porsche I think I would be looking at a G50-52 or a 930 which also uses a 9-inch R&P.
What about the offroad Porsche-derived GRBX's like the Fortin, Albins etc,
www.fortinracing.com
Then there are the $$$$$$ race stuff
www.xtrac.com
So that is what I can tell you about a well-built G50 run as a track car GRBX. If I was doing your car with a Porsche I think I would be looking at a G50-52 or a 930 which also uses a 9-inch R&P.
What about the offroad Porsche-derived GRBX's like the Fortin, Albins etc,
FRS5L SEQUENTIAL | Fortin Racing
www.fortinracing.com
Then there are the $$$$$$ race stuff
Xtrac - P1529 TRANSVERSE GT CAR GEARBOX
This rear transverse transaxle gearbox is designed and manufactured for the latest GT car applications where the vehicle package requires the cluster to be behind the differential. This gearbox is...
www.xtrac.com
Homepage - Hewland Transmissions
Hewland delivers extraordinary race-bred transmission products and racing gearboxes to our racing, specialist and OEM customers.
www.hewland.com
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Neil
Supporter
I am right at the point of putting together a new motor for my SLC. I am going up 100hp from 435hp/350sbc to a 535hp/406SBC. I called up California motorsports who built my G50. It is upgraded with all the good parts available for a G50 to make it stronger, side plate, steel synchro, and better gears when I changed ratios. I asked Rodger how much power I could put through my GRBX and he looked at my build sheet and told me he was comfortable with 525 ft/lbs. The car weighs 2500ish, runs Hoosiers, and has a Quaife TBD in the GRBX I will tune my motor on the engine dyno to that number. The smaller diameter 7.5-inch R&P in the g50-01-03s is the limiting factor whereas the 9-inch G50-52 is quite a bit stronger.
So that is what I can tell you about a well-built G50 run as a track car GRBX. If I was doing your car with a Porsche I think I would be looking at a G50-52 or a 930 which also uses a 9-inch R&P.
What about the offroad Porsche-derived GRBX's like the Fortin, Albins etc,
FRS5L SEQUENTIAL | Fortin Racing
Then there are the $$$$$$ race stuff
Xtrac - P1529 TRANSVERSE GT CAR GEARBOX
This rear transverse transaxle gearbox is designed and manufactured for the latest GT car applications where the vehicle package requires the cluster to be behind the differential. This gearbox is...
Homepage - Hewland Transmissions
Hewland delivers extraordinary race-bred transmission products and racing gearboxes to our racing, specialist and OEM customers.www.hewland.com
It also helps to keep the car as lightweight as possible.
Thanks for the info, I’m leaning towards a MFT Holinger sequential, it’ll fit in my SPF. The MXT is a bit too long.I am right at the point of putting together a new motor for my SLC. I am going up 100hp from 435hp/350sbc to a 535hp/406SBC. I called up California motorsports who built my G50. It is upgraded with all the good parts available for a G50 to make it stronger, side plate, steel synchro, and better gears when I changed ratios. I asked Rodger how much power I could put through my GRBX and he looked at my build sheet and told me he was comfortable with 525 ft/lbs. The car weighs 2500ish, runs Hoosiers, and has a Quaife TBD in the GRBX I will tune my motor on the engine dyno to that number. The smaller diameter 7.5-inch R&P in the g50-01-03s is the limiting factor whereas the 9-inch G50-52 is quite a bit stronger.
So that is what I can tell you about a well-built G50 run as a track car GRBX. If I was doing your car with a Porsche I think I would be looking at a G50-52 or a 930 which also uses a 9-inch R&P.
What about the offroad Porsche-derived GRBX's like the Fortin, Albins etc,
FRS5L SEQUENTIAL | Fortin Racing
Then there are the $$$$$$ race stuff
Xtrac - P1529 TRANSVERSE GT CAR GEARBOX
This rear transverse transaxle gearbox is designed and manufactured for the latest GT car applications where the vehicle package requires the cluster to be behind the differential. This gearbox is...
Homepage - Hewland Transmissions
Hewland delivers extraordinary race-bred transmission products and racing gearboxes to our racing, specialist and OEM customers.www.hewland.com
Does the use of any transaxle other than the ZFQ or ZF/RBT disqualify the car for use in vintage car racing?
Sorry Strong enough!!! Spell check is stupid too.
Perhaps its time to stop all the cheating and make everyone use engine parts that produce 1966 power levels along with tire sizes and compound as used in the day. No, never work would it.... cant believe I just wrote this..
As Ive heard, David Hart uses the RBT for qualifying and the ZF for racing during historic racing.
As Ive heard. both are not up to the job as these days 289's produce way more then back in the days.
Ill assume the RBT is eligible for historic racing.RBT Transmissions said:
I’m leaning towards the Holinger MFT 6sp sequential. It’ll fit an SPF.
Jac,
Yes, it is "racing" but it sure ain't "Vintage"! GT350s running here with 8K RPM engines and brakes/suspension that didn't exist in the day. I rather like the Goodwood model with the Dunlop spec tires, less grip, more slip! Makes for very entertaining racing.
