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TT truck top speed

Posted: Thu Nov 07, 2019 10:49 pm
by Michael Paul
Hi I just picked up a TT truck that has the early style rear end with the raised bead. It needs total restoration. No motor...I assume it has the low gearing, just how slow are they?

I'm wondering if I should put effort into finding a high speed gear set. I'd like to know what to expect before I get to deep into fixing it up

Thanks Mike

Re: TT truck top speed

Posted: Fri Nov 08, 2019 12:55 am
by 1925TT
Bone stock we have been told some topped out at 25 mph.

We have two three speed auxiliary trans and a two speed rear end and by the math we should be able to do 40-45. We don't have all of the shift assemblies made yet.

The worm gears are available in two different tooth counts, one is higher speed than the other.

There is someone manufacturing brand new high speed sets.

If speed is a concern, some people change the rears out to a car rear. The model t gives you a lot of options especially when you get into the period accessories.

Re: TT truck top speed

Posted: Fri Nov 08, 2019 12:58 am
by 1925TT
The trucks are fun. Find a theme and build it out. We built a tow truck.

Re: TT truck top speed

Posted: Fri Nov 08, 2019 3:48 am
by Tom Hicks
How fast it can go and still stop safely?

My first TT was stock with 7:1 rear and had a top speed of 17 mph, just like it was designed to have. Driveshaft whip and vibration were bad over 17 mph. It now has a 5:1 rear, a carrier bushing in the torque tube and probably runs 35. It stops very well with the rear disc brake kit.

My second TT has a 5:1 rear and a Warford. It ran 45 mph on gps, but I don't drive it over 30 because it does not stop well enough to suit me above that sped. It has front disc brakes. If I put rear disc brakes on her too I would guess it could stop safely going 45 mph.

For most of my driving 30 mph is just fine.

In my opinion, TT's were not designed to run over 30 top speed and should not be driven faster than 30 for safety reasons.

Re: TT truck top speed

Posted: Fri Nov 08, 2019 8:48 am
by bud delong
A simple tire change could speed you up and much cheaper than many other fixes.Bud. :D

Re: TT truck top speed

Posted: Fri Nov 08, 2019 9:25 am
by HPetrino
There are many possibilities to make a TT go faster. I've seen them with high speed rear end gears and two auxiliary transmissions capable of 60+ MPH. I'm pretty much with Tom. Anything much over 30 MPH is too fast for a TT. Mine has low speed rear end gears and a 3 speed Muncie. High/high gets me up to 33 MPH, but I only did that once to see where top end was.

Whatever you do with your truck, if you use any type of auxiliary gears be SURE to have auxiliary brakes!! Any of the auxiliary gear sets (transmission or rear end) have the potential to get stuck between gears, and when that happens if you do not have auxiliary brakes you have no service brake at all.

Re: TT truck top speed

Posted: Fri Nov 08, 2019 10:10 am
by George House
....no brakes in a TT caught between aux. tranny gears ? .... just aim it at something cheap 🤪

Re: TT truck top speed

Posted: Fri Nov 08, 2019 10:43 am
by Burger in Spokane
Farm gears, 15-25, with the poor thing shaking itself apart over 20. With Express
gears, .... and this is with a serious effort to balance everything in the powertrain/
driveline, I max out at 48 on flat ground. The truck runs out of power, rather than
get the shakes, like before. It cruises smoothly and happily at 35.

I have a Lincoln 3-speed, but have yet to install it. The math says it should then
cruise at 50 and max up north of 60. But this is where braking and driving conditions
come into play. I live where I can find lots of roads where there is no other traffic,
no stunt drivers, no real need for panic stops. Adding good brakes creates its own
set of problems in the spoke strength at the hubs. Stop the spinning of those hubs
and bring all that weight and interia to bear on the wood spokes, one is likely to
have themselves a new TT "sled" ! :shock:

fairfield2.jpg

Re: TT truck top speed

Posted: Fri Nov 08, 2019 12:19 pm
by Dallas Landers
My wood cab TT with 32x4 1/2 tires out back, 9 ft wood bed and wood cab tops out about 40mph. Very stock rebuilt engine 5:1 gears in the rear and Chicago 3 speed. 20-25 is where I run it cause it
" feels right". Pretty heavy rig with all new wood and large bed. Dont use overdrive much as she whines and I dont need the speed unless running with those fast DB cars my buddy has.
20190727_073447.jpg
Done a few car games at OCF and decided it was too fast for the slow race and to slow for the fast race! :D

Re: TT truck top speed

Posted: Fri Nov 08, 2019 12:47 pm
by RajoRacer
Same here - high speed Ruckstell w/3speed Warford - cruise pretty easy at 35mph but I do have large external brakes also.

Re: TT truck top speed

Posted: Fri Nov 08, 2019 3:28 pm
by A Whiteman
Bone stock we have been told some topped out at 25 mph.
Noooo.
My first TT was stock with 7:1 rear and had a top speed of 17 mph, just like it was designed to have. Driveshaft whip and vibration were bad over 17 mph.
This is more like it, maybe a mile or two faster if your engine/trans/drive train are 'balanced'.
20-25 is where I run it cause it " feels right".
That is a good point, each truck will have a 'sweet spot' where both it and you 'feel right'. You will find that by driving. Its not just gearing and brakes that matter, but state of your steering (loose? slop?), tyres, springs (stiff? rusted?), shackles (worn? tight?) etc. These all add up to 'feel' and safety.

9 Dec 08 - Registered Today.jpg
My truck has a Model AA (A truck) underdrive unit (which is made by Ruckstell by the way) installed 180 degrees around so it works as an over drive. I can get 45 plus down hill with a tail wind BUT after that experience my hair went white......

Probably 30 to 35 is the optimal cruising speed for an auxiliary gearbox equipped TT with a high ratio diff set and 17 to 20 (ish) for a standard low ratio rear set and no aux-box.

Plan ahead when it comes to stopping!
If you have an aux-box installed BEWARE - you probably have a neutral with it which means NO BRAKES if you get stuck in neutral UNLESS you fit auxiliary external brakes like Rocky Mountains or a disc brake set. Not a bad idea in today's traffic anyway, but it does highlight the 'knock on' effect of one change requiring further upgrades for safety.

BUY A TRUCK DRIVE A TRUICK HAVE FUN! ;-)

Re: TT truck top speed

Posted: Fri Nov 08, 2019 8:22 pm
by It's Bill
Cool trucks! Has anyone in the club built a house car (camper)? Cheers, Bill

Re: TT truck top speed

Posted: Fri Nov 08, 2019 9:23 pm
by Michael Paul
Thanks for all the great Info,... My plan is to use it as a ranch truck with a few trips to town. Lots of back roads to use. I'd like to at least do 35 comfortably, 17 mph would be a problem.

Now that I've emptied all of the parts out of the cab I can see the auxiliary transmission. It has layers of grease and dust, that tells me rain water must have floated the oil up and out of the shift tower, that can't be good for the gears sitting in water for years.

I imagine it's an underdrive unit. I'll try and post some photos once I clean it up.

Thanks again for the info, Mike

Re: TT truck top speed

Posted: Sun Nov 10, 2019 12:49 am
by A Whiteman
Yep, my truck gets used around the land too :-)
DSC07368.JPG

Re: TT truck top speed

Posted: Sun Nov 10, 2019 11:22 pm
by Michael Paul
Wow perfect! That's what I want to do!