Gearbox choice ??

[UltimaAnimal]

I have noticed a worrying trend being set here, my chassis was ordered for ChevV8 and Porsche queerbox but i plan to throw about 600BHP and about 590 FtLb of grunt through it at 12PSI boost for road use and 18-20PSI for race, that should theoretically give about 670Bhp and 625 FtLb of tourqe (we think)...i know that is pushing the limits of the G50 Porker box, so has anyone any info on the Getrag 6 speed being sold from the factory, what is its true capabilities.

Any ideas ?

[bluesatin]

Try this

www.hewland-engineering.co.uk/svga/productrange/lsg.htm

Nice price but should take the torque

>> Edited by stig (moderator)to fix broken link on Tuesday 3rd December 13:01

>> Edited by stig (moderator) on Tuesday 3rd December 13:03

[UltimaAnimal]

Cheers BlueSatin....but im not gonna pay £27,000 for just a gearbox thats near the finished price for the car.
I would rather bust 10 Porker boxes than pay that...that is a hideous amount of cash, i know they are good but for road use and SC gears...hmmmm i think they are having a bit of a laugh.

Any ideas on the Getrag ?

[clubsport]

There is the G50 box put in the 911 from '87-'89.
however there is another G50 box (5 speed) that was put in the turbo from 1988....I think it is the G50/S
or something close,but the principal being it was built to take the 330bhp of the turbo rather than the 231 of the Carrera.It might be an idea to try to source one of these,in fact you could buy a great '89 Turbo for £27,000.....

[james]

I don't have any figures for the Getrag box, but you'll find that there is a single component that usually breaks on the G50. By the sound of it (from other postings) it's the input shaft. I run a Renault gearbox in my Sport, and it had the same problem. The input shaft is the weak point of the gearbox, and that's what limits the torque it can handle (mine was twisted like a bit of pasta when I took it out after the cars first outing with its new engine).

The solution (and a relatively cheap one too) was to get a new input shaft machined up out of a higher spec steel, and the problem went away. I have done quite a bit of racing with my car since, and the input shaft hasn't given me a moments trouble since. It cost me about £300 to have it made up, but that's pretty cheap in comparison to a series of new boxes, and the frustration of losing forward motion with a loud bang every time you extend your right toe towards the floor.

James

[pstockley]

Even the mega expensive hewland isn't foolproof. In one season of racing the guys racing a 630hp Ultima broke two boxes

[ultimapeter]

James are you running cable shift or rod linkage on that renault box, what ever do you have any pics or diagrams on your set up my old sport came with a cable set up but no connecting linkage to the box any info would be much appreciated

[ultimaandy]

I spoke to the factory today and asked the question.

I am told the Getrac 6 speed box is as strong as the G50 (I think thats the 5 speed), which is in turn slightly stronger than the porsche 6 speed.

Also I think the turbo box's are good for up to 600lft torque, those who exceed this shouldn't do loads of standing starts without upgrades.

I know you can get those Hewland box's for £12k and the quaife is around £9k.

[UltimaAnimal]

Well if the Getrag comes in at just over £3900 inc VAT and a second hand Porker G50 from a turbo comes in at £1300...then im gonna go for a Porker to get me in motion and then look at a more (serious) alternative..and im not talking Hewland :P

[james]

Peter,

I'm running it with a rod linkage. It's bad enough with that, so your cable mechanism must be abysmal

The linkage I have is the linkage that Ultima supplied with the kit at the time, so if you want to go that way, the factory are probably the people to talk to about it. There isn't much point in re-engineering something that is available off the shelf (unless you particularly want to of course)

If you want to have a look at it some time, if you happen to be in the Hampshire area, do feel free to drop me a line.

James

[ultiman]

UltimaAnimal said: Well if the Getrag comes in at just over £3900 inc VAT and a second hand Porker G50 from a turbo comes in at £1300...then im gonna go for a Porker to get me in motion and then look at a more (serious) alternative..and im not talking Hewland :P

Animal
Be aware that the G50/50 from the turbo is longer geared and therefor not the same as a G50. Having driven both there is a noticeable difference. You will lose a bit on accelleration of course but I find the different box makes an excellent excuse for being slower. I use the G50/50 for motorway cruising as the 1000s of miles I do in the car requires the longer gears than the G50 can offer.

[ultimapeter]

thanks james that really cheered me up the thing is the car has never been run in fact has never had an engine in it I bought it as an unstarted rather than un finished project and I`m in the process of sourcing any info I can, the factory did not want to know basically, so no info forthcoming from that direction it`s an old mk2 by the way, but thanks for the offer I may just take you up on that on the new year

[james]

Peter,

I'm surprised about that. They're usually pretty helpful when it comes to assisting cars in build. I'm not sure what the differences are between the Mk2 and Mk4 chassis, but I'm sure that the rod linkage will be possible with your car, even if you do have to modify a few components to get them to fit.

James