Custom transaxle

[Keith]

Out of all the considerations for a transaxle/gearbox for the road, or track, I put put gear ratios and final drive to be the ultimate deal maker. A high performance/race car with the wrong ratios is a sorry assed lump of uselessness. I would even trade box strength for getting a silky close ratio setup.

Nothing quite like it....

Therefore, ease of swapping out ratios and final drives would be a must for me for a regular track car...

 

[Frank Clark]

We run a Sprint Car locally on Saturday nights. Nothing beats a quick change. 5 minutes when you are NOT in a hurry and gears are in the $70/set range.

I personally would LOVE to have the old 850QC type setup.

 

[Leon]

Thats cool John, a GT40 !!. Is it a complete car or are we going to see a new build log on the forum or a rebuild maybe. You know I would look after you if you got a box off me

. Lets see some photos mate.

Keith, One of the reasons I made my T/A rear loader is to make it easy to change gear stacks and if I build one with a Jerico gear set then different ratios would be avalible also the Toploader's have Wide/Close ratios avalible and they are strong as well, the diff carrier is a LSD 9" with 31 spline so I think I have the strength side of things covered, it's only the R&P that is in question. I'm using Range Rover !! Thats not a typo. The reason is it's 10 bolt so easy to adapt to the 9" carrier and has Zero offset so easy clearence, comes in a good range of ratio's and there are after market high strength units availible. I guess the first one will be the test and if it is a problem then I will look at other options, suck it and see so to speak. I want to prove the design first without spending a fortune and these parts are avalible to me at little or no cost.

Frank, the QC option is avalible in my design but I chose this 2 shaft version because it's lighter, shorter and easier for the first time build. Cheers Leon

 

[Howard Jones]

Just a thought on ratios. 1st gear is REALLY only used for getting on and off the trailer, slow and easy around the paddock, starts from a traffic light/sign, and slow traffic. I'm talking about a duel use car that is licensed for the road and gets taken to the track from time to time. 2nd at about 2.2 is pretty good for mid range traffic and really slow corners. After all we're not talking about little four bangers in big heavy cars, 400 ft/lbs and 2500 pounds will pull just about any ratios nicely but a 3.0 first then a 2.2 2nd and 1.7ish 3rd, 1.0 4th with a .8 fifth is about right.

None of us are talking real racing here (for money) so at most of the tracks I know of, 3rd and 4th will get you around quite briskly with out a lot of foolish stress on the $$$parts.

5th would be best used to address cruising speed. Most V8's feel good at about 1600-1900 revs and about 75-80 MPH.

Finals seam to work best for a duel use car at about 3.4 - 3.5.

Would I buy one like this? I did, a Porsche G50 with about $6K in added pieces. Right at $14000 including starter, clutch, CV adapters, flywheel and slave cylinder. I can see quite clearly why a custom built, very small production quantity TA could get to 20K quickly. If I was building a old CANAM car or something of a one off then it would fit right in with all the other one off pieces. The one issue would be replacement pieces should they be necessary. Using in production internals such as gears and diff goes most of the way, but in the event a casting was damaged I think this would give me reservations. If I did actually buy one I think I would pay for a set of cases and other one off pieces as spares just to cover that base.

If I was the maker, support would be the one thing I wouldn't really want to deal with unless it was VERY limited (just a few close friends).

Oh and a torque bias diff type LSD is required in IMHO. I have a Quaife in both my R21 and the above mentioned Porsche.

The custom GB threads are always my favorite. Really brave of you guys. Very interesting, keep up the good work. Praise to the few who embrace the do it yourself right stuff!

 

[Robert May Eng.]

Aside of the zf I think the sub 550 hp sbf brigade are quite well catered for with the the g50 and porsche 4 speed variants , there are plenty of options on the g50 through powerhause and the like if you want different gear ratio`s or final drive.Chuck money at them and they will hold 700hp+ . Below 400hp is the audi and uni transaxle territory , these are suited well to a 302 that is built to rev and although not all are ideal there are variants of both that are acceptable 1st gear on either seems a waste of time. None of the above will break the bank , the saving grace is the cars are light with quite limited traction which ultimately stops torque from mashing the transmission. Enter the big block and you now have weight over the driven wheels which changes everything. The ford engineers of the day were on the money with that Colotti, I dont understand why a top loader internals rip off version of this has not been made. If it was kept as a four speed with its direct top 4th gear and ran through some interchangable drop gears at the back of the trans to a salisbury lsd it would be indestructible, you would have relatively cheap internals and quick change final drive ratio`s at the rear of the box. Surely that that could be built for under $8k

Bob

 

[Jac Mac]

Me-thinks your getting the Collotti & T44 mixed up together there Bob.
however both could be re-incarnated with a rethink of housings and internals to improve both strength and cost factors, but all I have posted previously still applies and you still have two basic camps in terms of potential clients, those who must have a dead nuts bolt for bolt reproduction to match there genuine copy of a MKII or MKIV and the others that simply want a strong reasonably priced transaxle- then you get the snowflakes who's car has a zillion hp and will never race past the nearest McDonalds , but must have paddle shift, synchro that works better than a dog box or vice versa....you know the type.

 

[Keith]

The ford engineers of the day were on the money with that T44 I dont understand why a top loader internals rip off version of this has not been made. If it was kept as a four speed with its direct top 4th gear and ran through some interchangable drop gears at the back of the trans to a salisbury lsd it would be indestructible, you would have relatively cheap internals and quick change final drive ratio`s at the rear of the box. Surely that that could be built for under $8k

Bob

Fixed that for you . As for "under $8k" see Leon's note above. Even doing your own moulds and castings, I would say no, not possible, but it would be interesting to see you have a go at it!

 

[Robert May Eng.]

Fixed that for you . As for "under $8k" see Leon's note above. Even doing your own moulds and castings, I would say no, not possible, but it would be interesting to see you have a go at it!

Sorry Keith and Jac I was having a senior moment
Sorry Keith and Jac I was having a senior moment
Sorry Keith and Jac I was having a senior moment.

I reckon if the music in my head got me at it I could have a mold made and ready to cast inside of 12 months, from past experience there is app £500 of castings there, also from past experience there is app £1500 of machining . I think £1000 would cover the extended input shaft and pinion, a further £1000 for some hewland style sets of drop gears, App £1000 for a clutch flywheel and starter , a £1000 for top loader internal gears and £1000 for a salisbury lsd with axle stubs. Allow £1000 for misc bits and pieces and you wont be far away. All of the above costs could be reduced massively if you were batch building. I do have a set of drawings for the above that were done through the back door of a F1 drawing office many years ago . I will see if they can be converted to a pdf and get them posted up. It does end up quite bulky . It does end up a bit bulky

Bob

 

[Jac Mac]

Sorry Keith and Jac I was having a senior moment
Sorry Keith and Jac I was having a senior moment
Sorry Keith and Jac I was having a senior moment.

I reckon if the music in my head got me at it I could have a mold made and ready to cast inside of 12 months, from past experience there is app £500 of castings there, also from past experience there is app £1500 of machining . I think £1000 would cover the extended input shaft and pinion, a further £1000 for some hewland style sets of drop gears, App £1000 for a clutch flywheel and starter , a £1000 for top loader internal gears and £1000 for a salisbury lsd with axle stubs. Allow £1000 for misc bits and pieces and you wont be far away. All of the above costs could be reduced massively if you were batch building. I do have a set of drawings for the above that were done through the back door of a F1 drawing office many years ago . I will see if they can be converted to a pdf and get them posted up. It does end up quite bulky . It does end up a bit bulky

Bob

Are you talking GBP sterling there Bob, if so that comes out at~US$12500.00.

So just for the hell of it I just updated USA $$ pricing of all the reqd 'off the shelf' bits for my effort incl the 'special' steel parts I have to make.
US$5800.00 for street version - US$8600.00 for race version.

Remember I would still have to add the cost of castings , machining of them plus assembly to that, also that being in NZ I would have to factor in freight costs to me from USA.

One thing to remember in all this, Ford only built around 27 original cars ( MKII, MKIV, & J-Car ) that used T44 or the auto evolutions of these, there are possibly more SPF MKII's than that, most of whom have taken tha ZFQ or RBT ZF option, and your not likely to get into the MKIV continuation market since that group have already got their T44 in production.
So then you look at the wider replica market & one of the first comments Ive noticed over the years is the sheer physical size of a T44 type setup, then you get the 'must have' 5-6 speeds which in most cases appears to be for bragging rights.... all which brings it back to why I've decided to look after my own interests first.

 

[Robert May Eng.]

I was basing the costs on a guesstimate Jac but I dont think they are that far out of bed. Batching would have a dramatic effect on overall costs, the upside of this type of project is you are using tried and tested components that have stood the test of time that are also readily available. How far down the road is your project Jac ?

Bob

 

[Leon]

Without giving too much away, NZ$2000 castings, $500 9" carrier, $2100 Toploader internals, $1000 - 1500 for input shaft and adapt Pinion to out put shaft. My first box will have the Nissan gear stack and RR R&P which owes me $200, I have the rear and side castings and a firm price for the main case so the $2000 is fact, the 9" is fact. The cost for Toploader is without freight. I could buy a complete C/R Toploader for $3000 so that leaves stub axles and mis parts I'm guessing $1500. Call it $8-9K. Thats NO labour and we all know how much time has been spent on this and its not finished. If I had the money believe me I would just go buy a LG500, but I'm so rapped up in the fun of doing it I want to finish just to see if it works. Cheers Leon

 

[Keith]

Have a search Bob. You're bound to find the 'root' of Jac's masterpiece in short order..

 

[Leon]

When I started this I believed I could do it for $5K and my first box will be about there but that is using all used parts if you exchange those for same but new parts the price goes up by at least $4k. Cheers Leon

 

[Jac Mac]

I was basing the costs on a guesstimate Jac but I dont think they are that far out of bed. Batching would have a dramatic effect on overall costs, the upside of this type of project is you are using tried and tested components that have stood the test of time that are also readily available. How far down the road is your project Jac ?

Bob

12,123 miles down the road from you according to google Bob.

Ready to make my castings early next year if everything else I have on my plate stays on track. All of the shelf parts procured for #1 and drawings done for all 'one of' bits. As you mention all the bits are well proven in their original application & if nothing else building the independent 9" based rear end for the TVR gave me a better idea of how critical the axle shafts are.

 

[Leon]

Speaking of axle shafts, would you be prepared to share your thoughts Jac. I have a 9" with 31spline side gears and I have a plan for the stubs based on what I need outside of them ie Brakes, CVs etc but always open to ideas. I hope to have the main case done by end of Sept. cheers Leon.

 

[Jac Mac]

Speaking of axle shafts, would you be prepared to share your thoughts Jac. I have a 9" with 31spline side gears and I have a plan for the stubs based on what I need outside of them ie Brakes, CVs etc but always open to ideas. I hope to have the main case done by end of Sept. cheers Leon.

Your axles 'should' be OK @ 31 spline with CV's since the CV shafts tend to be able to twist & absorb shock loads. Don't be tempted to use Ford USA axles to make your axle shafts out of, they dont last. We ended up using some German stuff to make ours from and so far ( touch wood) they have given no further trouble. If your looking at axle shafts splined both ends then 300m bar would be suitable. If your planning on really tweaking that BBC with 15" wide sticky Hoosiers then seriously consider using a 35 spline diff unit, or at least make sure that your 31 spline carrier unit has the same bearing size etc to enable a straight swap if/when it does break.

 

[Leon]

Thanks Jack, just a quick one, CVs vs Uni joints. I have CVs at the upright end and plan on using the Nissan axle shafts (30mm 31 spline) I had an idea of using Uni joints on the G/B end. I have a pair from a Nissan that I can adapt a 31 Spline into. ???
cheers Leon.

 

[Jac Mac]

Stay away from U-Joints if you can, the rotational speed difference they induce (twice in each revolution )is a large part of the halfshaft failure mode in high power/wide tire scenario.

 

[Leon]

Is that because I'm mix n matching them or is it Uni joints full stop, the reason I ask is the orginal cars ran Uni joints. I'll look at the Commodore CVs such as the ones John used on the 5000, means I'll have to custom make the Axle shafts. Cheers Leon

 

[Jac Mac]

Is that because I'm mix n matching them or is it Uni joints full stop, the reason I ask is the orginal cars ran Uni joints. I'll look at the Commodore CVs such as the ones John used on the 5000, means I'll have to custom make the Axle shafts. Cheers Leon

Both, if you run 1cv & 1 UJ the UJ will induce the speed up/down when running at an angle while the CV being constant wont cancel it out so you might feel it in the driveline.
If you run two UJ's then they only cancel one another out when running at the same angles or straight/inline, that's fine but virtually impossible to obtain thru all suspension movement etc , the other factor is with 2UJ's & probably a sliding spline in the halfshaft you can get bind in the splines, plus the sheer physical size of the halfshaft means that it wont/cant be allowed to twist, so it wont give the torsion bar effect that the CV type half shafts have and probably helps other bits in the driveline live longer. Wanni/Gearfox gave a better description than I can and mentioned that a modern F1 car will twist the halfshafts something like ~two turns when they drop the clutch off the line- must be good steel!, think that discussion was either in the ZFQ or why are transaxles so expensive threads- ignore all the rubbish between Chris Wanni& others, he shouldn't have 'invaded' Chris ZFQ thread, but he was a really interesting read & had a lot of good info, like a lot of others who no longer frequent these pages.