M Chassis measurements

[Slow M]

I’ll be measuring much of my M chassis over the next few weeks.
My objective is to find a cheap or free suspension analysis software suite and input the data.
I’d be grateful if any of you have the info to share.
If I have to measure everything myself, I’ll post it here soon.
I think this is important data to have at our fingertips for accident repair, racing mods...

Started earlier but stopped when I thought my hand was starting to freeze to the upper A-arm.
B

[Voodoo13]

Try this guy he should be able to supply all the info you need.

http://tvr.m-fix.co.uk/

Best of luck with he software.

[Slow M]

Initial teaser.
It looks like I have a LOT to learn.
B.

[Voodoo13]

My god thats a complicated diagram.

I thought my eyesight had gone.

[Slow M]

Progress update:

[heightswitch]

Slow M said:

Progress update:

Bernard. would you not be better just getting the thing built?
N

[crackedfinger]

What cheap/ free software are you using?

[Slow M]

heightswitch said:

Bernard. would you not be better just getting the thing built? N

Neil,
there are three resons for doing this model.
1.) I think all who have an M may at some point need accurate chassis dimensions.
2.) I hope to add a rollcage to the drawing and get someone to do a finite element analysis on it and let me know if I'm likely to get the resulting structure to even approach a torsional stiffness of 12,000 Nm/deg.
3.) Last time I worked on the rear suspension, my hands frozen claws were burning with cold for a half hour after I stopped. One of the joys of living in the midwestern states! We had 10" of snow in 24 hours last Wednesday. Also, my dog tried to mince my hand. I'll wait for another three or four weeks.

crackedfinger said:

What cheap/ free software are you using?

I use AutoCAD 2005. It's actually Architectural Desktop 2005. In my previous life, I was in architecture.
B.

[tegwin]

Wow... that is going to be such a useful resource for you once its completed! How accurate are you aiming to get the CAD drawing? Could it be used to design new laser cut plates etc?

[Slow M]

tegwin said:

Wow... that is going to be such a useful resource for you once its completed! How accurate are you aiming to get the CAD drawing? Could it be used to design new laser cut plates etc?

tegwin, I sincerely hope it will be a valuable resource to others as well. The goal is for the frame members in the drawing to be accurate to 1/16". There is no reason for the plates not to be totally accurate. Yes, they will be items that can be emailed to various machine shops for bids and, subsequently, used for laser, water jet or EDM production.

My initial aim was just to use the suspension pick-up points and suspension member dimensional data to attempt some rudimentary suspension analysis (with my less than basic understanding) but the project has grown.

I'll be happy to send the CAD file(s) out to anyone who wants them either before or after they're completed.

I'm using a truly EXCELLENT drawing by Adrian Venn in conjunction with measurements taken from my own chassis (3428TM) as the basis for this CAD drawing.
Adrian, it really is a beautiful drawing and I'm very grateful to have it.

From what Adrian has mentioned in his emails, there is a difference in the width between the frame members in the engine bay area between earlier and later frames. I believe this difference is limited to the distance between the top tubes with the bottom ones remaining the same. Upper wishbones were, apparently, changed to suit.
I'll model 3428TM which is the wider version. It'd be nice to know at what point (chassis #) the chassis changed.

Regards,
B.

[Slow M]

[Electron]

Bernard (and probably Neil and Adrian ...),

I have a very early '73 3000M chassis. The V5 has it with an "FM" suffix. I assume this makes it a "late" and "wider" chassis ?

I'd happily measure it once the rain stops ....

[Slow M]

Electron said:

Bernard (and probably Neil and Adrian ...),

I have a very early '73 3000M chassis. The V5 has it with an "FM" suffix. I assume this makes it a "late" and "wider" chassis ?

I'd happily measure it once the rain stops ....

Chris,

Sounds great!
Not sure but I think '73 makes it a narrow engine bay. The drawings Adrian sent to me are from a '73 and show a narrower engine bay than my chassis which is a 74/75 (from right around or immediately after the time of the factory fire). FM denotes an M chassis and a Ford motor.

B

[Electron]

Bernard,

Happy to measure it and PM you the chassis number. I guess you need to know the distance across the top front rails where the front wishbones attach ?

Hmmmm .... maybe this is why my 302 doesn't fit as well as others ??

Do you know if the Canadian conversions had narrow chassis as well ??

Thanks

Chris

[Slow M]

Chris,

Yes, would you please measure the distance between the upper main tubes

My car was John Wadman's first demonstrator when he bought JAG automotive and became a TVR dealer in what I'm guessing was 1974 or 1975. Theoretically, if the chassis design only underwent one major revision and that revision was implemented prior to 3428TM, all of John's 5000Ms built from new cars with empty engine bays have the wider chassis. He did also "convert" some for customers later though.
- - - - - - - - - - - - - -
I just double checked Adrian's and my drawings; there is only a discrepancy of 1/2" across the upper main frame tubes (not the very top ones).

Best,
B.

[Electron]

Bernard,

This is very very useful.

I'm needing every last 1/8" so this is starting to make sense .. on the rear nearside the manifold is too tight. The head gets a localised hotspot and the first head cracked between the exhaust and waterjacket. Now I have alloy heads I had planned on moving the engine 1" further forward .....

I guess we need a new thread to avoid derailing your hard work :-)

Thanks again,

Chris

[pumpkin]

After smashing my 1978 5000M the year before last I had to buy a donor car to get a chassis and bonnet. The donor car was a 1973 2500M. There are a number of chassis changes between the two, some of which caught out John Wadman at TVRNA. The earlier chassis has more clearance over the gearbox which helps with the 302 installation. Nothing else had changed in the engine area that made any difference and the engine is fitted in the same place as it was. (51% of the weight on the front wheels and engine far enough back so that you do not need a remote oil filter). We were caught out by the later chassis having a round cross tube for the outrigger at the bottom of the foot well so my body would not sit on the square one of the earlier chassis and the rear upper cross member behind the seats is much wider on the later chassis. Apart from this the main difference is the bonnet. The 2500 bonnet does not have the deep mouth and has the useless bonnet vents. I much prefer the later M ans Taimar bonnets. I do not think any chassis after 1978 were different but there might have been some changes before my 1973 donor.
I was very impressed how well I was protected by the car during my smash. I spun at about 115 MPH and hit the barrier on the side of the course when still doing about 100 and I had just a cracked rib and the main body of my car survived quite well but with a lot of stress cracks over the doors and around the windscreen. I do recommend the head on approach even though I have not tried any others. (Although I hit the barrier head on my car was going significantly sideways. Do not expect to survive a 100 mph head on crash. I did hit hard enough to break several of the Armco barrier support posts though. Sorry for drifting off topic here)
You could find out a lot about this very quickly by phoning John Wadman at TVRNA. He likes to talk but does not like e-mail very much.

[Slow M]

Electron said:

...I'm needing every last 1/8" so this is starting to make sense .. on the rear nearside the manifold is too tight. The head gets a localised hotspot and the first head cracked between the exhaust and waterjacket. Now I have alloy heads I had planned on moving the engine 1" further forward .....

Is it a cast manifold or tubular header? I'm really tight for space here too.

Electron said:

I guess we need a new thread to avoid derailing your hard work :-)

You better not, this is how I relax! My hard work is intended to go into our restaurant!

pumpkin said:

After smashing my 1978 5000M the year before last I had to buy a donor car ... a 1973 2500M...

John,
Could you let me know the chassis # of the donor? I'm trying to determine around what chassis # the changes took place.

pumpkin said:

I was very impressed how well I was protected by the car during my smash.

I know what you mean, I hit a truck on HWY 401 in Toronto @ about 70 MPH years ago and lost control, smashing into a concrete barrier. The bonnet absorbed almost all of the impact. Just another reason why I love that car.
B

[Electron]

My headers are one off tubulars that point forwards then do a gentle 180 degree bend back under the car (ie long primaries).

I'll try and pul the cover off the car, pull it off the trailer and get some measurements & photos.

My other challenge is you cant torque down the rearmost head bolt on the nearside (UK RHD nearside while I rememeber !!)

My chassis also had several diagonal reinforcements added to the centre sections around the gearbox tunnel when it was built ...

Which reminds me my brother has the photo album for his 302 Taimar build !!!

[pumpkin]

Slow M, my donor car was 2971TM and the rebuilt engine, gearbox and diff are still available at a very reasonable price!
For information, my 5000M uses 2 X Sanderson LHS FF2 headers with the RHS engine mount moved about 3" forward. This makes it easier to get past the starter. Considerable modification was needed to "bend" the headers closer to the block and, for the rear cylinders to bring the downward bend closer to the head to miss the top chassis tube. Engine position is a compromise between getting it as far back as possible and still being able to get the exhaust down beside the block. Some people solve this by bringing the exhaust up and forward but this usually means getting rid of the inner fenders which is not good on a road car that is going to be driven a lot in all weathers.