Egomans GT40 esque project.

egoman · 04-07-08, 09:00 PM

When you say you are going to start from scratch do you really mean it?
Well I am starting with the build by designing my own transaxle loosely based on the McKee.I have allready acquired the quick change rear as well as the engine and trans.I understand that the Gt 40 transaxle measures 9 1/2 inches from the bellhousing to the axle centerline. A quick mockup with the stock bellhousing shows 14 inches.I can reduce this scenario to about 12. If I use a steel scattershield I can get to about 11.
My next option will be to use the bellhousing from a c4 auto which I could also get to about 11 or slightly less.I will never get to the other measurement because of the large ring gear in the quick change but these rears are proven in race trim to live with 800hp and beyond.
The car I plan to build will pay homage to the GT40 but will not be a faithful repro.I have included some pics to get this rolling and will be following this up as often as I have results.If you notice anything odd for Gods sake tell me .

GooseMeister · 04-15-08, 05:03 PM

Wedge,

If you go to the earlier (non-T-5) bellhousing, and perhaps a Tremec for a bigblock, couldn't you save the 1"-1 1/8" length difference of the two bellhousings? (Short bellhousing and short trans-input side)

You may need to run a 167T flywheel......vs the 154 version found on all the 5.0L's.....but the extra weight-momentum is always good?

I'm building a 331 based on a 92 5.0L block, using Eagle parts, so can stay with the 28oz imbalance rather than the 54oz used by the 5.0's. Keeps things simpler in the future should parts go south.... at least that's my story!

Steve

Jac Mac · 04-15-08, 05:20 PM

Trans input shaft is not really a problem since it has to be extended thru QC unit to reach Flywheel. 28 oz or capability for zero balance is a good idea should the competition /racing bug really bite.

I do have one concern in that the Tremec/T5 overdrive being in the tail housing is going to add a bit of length & complication to the 'now' rear of the T/Axle. Wont be a major hassle in a Mk IV body though.

Jac Mac

egoman · 04-15-08, 08:35 PM

Every where I go to you follow me J mac . I disassembled the T5 and found that I could significantly reduce the overall length. I also found the shifter assembly to be very condusive to linkage style shifting.I am also looking at the use of a scattershield reworked to make it as short as possible.I do see why in a racing app. like the Mckee they eliminated the reverse gear as it would help shorten everthing.The nice thing as you guys noted is that I can make shafts to go to any clutch that I want with a simple stub. Of course the idea is to get a working mockup and see if it will perform as wanted. After that then the idea would be to repackage it so it would be lighter and stronger than my original.I have done a lot of mental drawings and made a lot of changes as to how I will do things,but the same idea of using these components due to their availability low cost and ability to upgrade strength.Thanks for your interest for a while it looked like nobody cared.

Jac Mac · 04-15-08, 08:50 PM

Quote:

Originally Posted by egoman

Every where I go to you follow me J mac .

Thanks for your interest for a while it looked like nobody cared.

Have you ever considered the possibility that I might already have been down the road that you are cautiously navigating at the moment, along with several others that you have yet to consider

I dont mean that in a negative manner- nobody knows everything & as always there is a possibility that you may come up with something others have overlooked- meanwhile I along with I am sure many others will keep on watching.

Jac Mac

Scott Calabro · 04-15-08, 10:14 PM

Egoman,

Look at this link;

Scroll down to the transaxle pics.

Archibald Evans

Is that what you want to do?

Cheers,
S

egoman · 04-16-08, 08:21 PM

Allthough that is interesting it is not what I am trying to achieve at all.
The setup used there would be good only in a corvair.The trans then rear
layout that they have used is quite commonly used in drag racing but is excessively long for our use. This is what I want from the members though.Dont be afraid to interject as this project will be dynamic and you never know your ideas may become a part of this car.

Big-Foot · 04-16-08, 08:38 PM

I've sat on the sidelines through much of this but I find myself needing to ask - Why the T5?

It's really not a very good transmission in terms of strength and overall capacity.
It was originally designed for GM to go in the 4 cylinder S10 pickup truck (I spoke with the lead design engineer at Dana Spicer who was on this project).
The shaft centers are too close together which severely limits the torque capacity of the box due to gears being too small and shaft flex.
None of the American manufacturers installed this box in a car or small pickup truck with more than 5 liters and ~225 HP. My teammates and fellow competitors have destroyed many of these transmissions by using them in the SCCA's American Sedan class. Typically it's either 3rd gear or the input shaft that gets stripped of all it's teeth..

I think you would be very wise to reconsider this box. I would look into the Tremec TKO (3550 series) box which is based upon the design of the old Ford Top-Loader 4 speed. Wide shaft centers, massive gearing, well braced alloy housing.
Just my opinion and I wish you the very best in your endeavor...

Ian Anderson · 04-17-08, 03:46 AM

Hi you also mentioned a possibility of shortening if you did not have reverse gear.

Have you looked at an electric motor for reverse? It gets done on Lotus 7 replicas in the UK and they are accepted as street legal - I believe it must be strong enough to move the car over a 4 inch block of wood

Ian

Russ Noble · 04-17-08, 04:05 AM

Quote:

Originally Posted by egoman

using these components due to their availability low cost and ability to upgrade strength.Thanks for your interest for a while it looked like nobody cared.

I tend to agree with Randy about strength issues with the T5. Granted you can upgrade them, but that is not cheap, so you lose the low cost advantage that you were looking for....

Jac Mac · 04-17-08, 04:33 PM

In regard to your thoughts on the C4 bell housing. These are not designed to have the force of the clutch release etc & consequently lack the extra ribbing of manual bell housings. Also in a transaxle situation the engine/trans combo effectively becomes one big torque arm & therefore the point at which the T/Axle attachs to the bell housing should have fairly wide attachment points in a vertical sense. Your QC which has only the relatively small pcd point where the Torque tube used to attach & will require further braceing from the bolts the side plates attach to the bolts that attach bell housing to block to prevent this along with probable failure of the auto bell housing at this point.
I would recommend that you seriously consider fabricating your own custom steel bell housing with the necessary lugs etc to simplify this.

Dave Peterman · 04-17-08, 04:45 PM

Hi Egoman:

Wow you are biting off a huge chunk. I shortly thought about casting a Audi 5N Housing with a Ford bell housing. Best of luck Dave

egoman · 04-17-08, 09:24 PM

Jmac my leaning has allways been to use the steel scattershield. I know that I need to brace up the quickchange to combat the torque that would otherwise tear off the nose.I dont disagree with anyone about the strenght issues with the T5 because what I would really have liked to use would have been the old doug nash style trans. I believe these have been sold as G force trans lately. If my memory serves me well these were able to be mounted in allmost any orientation and could easily be adapted to cable shifting.Once again thanks for your input.

Jac Mac · 04-17-08, 09:51 PM

Doug Nash- Richmond 5 speed- whatever- In PAW Cat 2005 @ USD$ 2200.00 for synchro street version. Dont know what todays $$ or availibility is.

GooseMeister · 05-13-08, 06:34 PM

Egoman,

Ford had a realllllly short OD trans used in some trucks or Broncos I thought. It was a toploader, but had OD instead of 4th gear. Also used them in Granada/Monarch, but in longer form...... Wouldn't be a 5 speed....but would have OD. Who needs an extra gear anyway....I only use 4 most of the time!

Steve

egoman · 05-13-08, 08:03 PM

Goose my friend had a 81 ford half ton and I pulled the tranny out one time to do a clutch for him. I believe this is the tranny you are talking about. Do you have any further info on this? For anyone else who waswondering what was happening I have located a c4 bell and am still looking for a steel bellhousing. Jiminy you would think with all the 5 liter mustangs out there they would be everywhere but I am suffering trying to find one. I dont want to buy one initially that is new as I am going to cut away most of it.

Jac Mac · 05-13-08, 09:21 PM

Fairly sure that is the trans with OD top where 3rd used to be in top loader- new '3rd' was straight thru, not a strong trans due to very fine pitch of OD top gearset, available in alloy case , which could be modded to allow conventional Top Loader gearsets, but case was not up to the job.