My TLT - Pics and.....issue!

[Shaggy39]

Finished my TLT which I am really pleased with. Bagged a few bargain hop ups from asia tees (cvds, linkage set, carbon chassis plates and alloy hex drives)

I just done a really simple paint job (only had enough black and silver!) as I waiting for a clear lexan baja bug (The TOyz, designed for Mini Revo),

I do have an issue however (nothing new there then) and that is with ride height. The drive shafts are at such an extreme angle in the drive cups that it stutters and low revs. When I turn car upside down and push suspension down and rev it, it's fine.

The cantilever suspension confuses me (Doesn't take much!). I tried shortening the little links on opposite end of shock cantilever arm but no real change.

I made sure when I built it that all the upgrade links were set to to stock length so I can only assume the geometery is correct. Also the cvd's are definitely for the tlt so they must be the correct length.

Any advice gratefully received

[alfagta]

hi, extend the upper links to ' clock' the axles round , (rotates the top of the front axle forward and the top of the rear axle backward , should be good to go

[spencertrax]

Looks great in that colour, and not a lot of decals.

[Percymon]

I had same issues with mine - i'd check the length of all your links eye to eye, rather than between the inner ends of the rod ends.

It can be a little tricky to get everything balanced - there's so mnay rods !

[Shaggy39]

Thanks guys, I'll give this a go and see how I get on.

[TWINSET]

The easiest way to check the 'clock' on the axles is the front bumper - make sure it's vertical before you start anything else

The other issue might be the length of the UJ bodies - if the hinge pin is further away from the gearbox or axle than the original, then the driveshaft will be at a steeper angle - don't forget the original driveshafts could slide in the drivecups, so any stuttering would've been minimized by the driveshaft sliding. If your driveshafts are too long, they won't slide so they will, in essence' be fixed-lenght as they're bottomed out at one end

First thing to do is get the numbers right - find out what the wheelbase of a TLT should be, take the wheels off yours and measure it - then got from there.

Because you've changed everything else, the original dimensions are your best reference point to start corrections from

[TWINSET]

The other thing to consider is that as you cycle (compress) the suspension you're moving the axles away from the gearbox on an arc - this will be why the stuttering stops as you're freeing up the entire drivetrain

Unless all the pivots are in line (suspension and UJs) then any cycling will have this affect

What this shows is the axles are too close to the gearbox for the driveshafts - the stuttering is probably pushing the axle down a bit to let the UJ work - again, with the original sliders this change in length was allowed for by having sliding components

If the axles were the exact length for correct running, then cycling the suspension would bind the gears inside the axle at full compression as they would be trying to pull the main gear thru the back of the axle - axle moves away, gear is attached to a solid shaft - two outcomes; shaft limits travel or gear comes out of axle

With the shaft too long at normal ride height the shaft pushes against the pivot in the UJ - either the UJ flexes to allow this or the axles rotate slightly when the UJ rotates (axles stutter)

If you look at the axles on the High-Lifts, even though they have relatively short suspension travel, both axles are still driven with sliding UJs to allow for changes in driveshaft length etc.

With travel like the TLT has, a solid shaft is probably a problem

Got bored and had a play with changes in UJ pivot position;

2mm at either end makes the overall shaft length (pivot to pivot) 3.2mm shorter - with a sliding driveshaft that's easily allowed for

[Shaggy39]

Hi twinset. Brilliant info and thanks for taking time to post. Before I saw this I had tried initially just to adjust the short links to cantilever but lengthening them this time but no change so I suspect as others have said I need to check all the links and geometry.

Before I do that however after reading your post twinset i will pop in stock drive shafts and see if that helps. If it does it may well mean I run these instead!

[TWINSET]

The geometry is totally the issue, but the driveshafts are what's making it evident - If you look at the pivots for the top and bottom links, they're all on different points and on different length shafts - without the UJ, the top and bottom links are effectively creating a triangle.

When the suspension cycles the axle also starts to rotate (or wants to) as the three shafts' (top links, bottom links and driveshafts) different arcs are all telling it different things - Any two would be ok, the third one is causing your problems.

If, however, the top and bottom links had their pivots in-line, and the UJ's pivots were exactly between them, then you'd have the near perfect setup (parallelogram) as the suspension would only bind when the UJ was at too sharp an angle to work any more.

In years of building crawlers, I've never once made one that didn't need to have sliding UJs (apart from Clods) - even if you look at touring cars which have pretty accurate suspension setups, I don't recall ever seeing one with four point pivoting and fixed-length driveshafts, especially once you start introducing camber into the mix - Even Traxxas Maxx trucks which are similar setups to massive touring cars have sliding driveshafts.

When you look at a SRB rear end, that's about as simple as it can get - all the pivots at one end, in-line and the driveshaft can slide a little in the bearings at the wheel end if it needs to

[Shaggy39]

Gotcha, thanks again. Just adjusted the links that 'roll' the axles round to get the bumpers vertical (they were way off before) and that has already made a huge difference.

I can see what you mean about sliding axles, there is a huge amount of potential movement expected from the fixed lengths

[alfagta]

not sure if they still do em short enough for the TLT but i can recommend RC4WD punisher shafts, once you get the cantilever geometry sorted , had mine for about 6 years on one of my ax10's and they are still solid as the day i got them ,

[TWINSET]

Either that or sliding UJs from the CC01/XC - you don't need very much movement and the strength of the shaft is irrelevant - the drive belt will snap first

Plus, Tamiya ones are prettier;

The slider is housed in the darker cover at the top end

If you take the bottom end off you can cut the shaft to whatever length you need.

[Shaggy39]

Good idea:-) yes I have heard (and am prepared) for the puny belt to go, plan to do the stampede transmission mod eventually