th400 keep exploading the sprag

[muddytoy]

trying to figure out why these sprag wont hold up in th400 i have been usig the 34 elements too. its in mud racer 1250 hp + and i only use 2nd gear..car is 2800 lbs.

[Hutch]

They will not take the torque of pulling the motor down when the tires hook downtrack or during the pass. Its the same scenario that drag cars face when doing a burnout which is why I don't recommend leaving the burnout in any gear except high.
If your only using 2nd gear the fix is pretty simple, forget the sprag and use a solid drum.
Do you use a transbrake?
Do you need to backup ever?
How do you launch etc.
Need a little more info.

Take care ,Hutch

[muddytoy]

no trans brake yes i need it to back up i foot brake it to 4500 then mash it,i just pick up a dedenbear glide today shorty with all the good stuff for 2,000.00 looks like in glide guy know....

[Hutch]

NO problem , but it looks like you have a lot of work ahead of you if the 1.48 ratio worked for you before.
If you reconsider , let me know.

Take care ,Hutch

[muddytoy]

this is another reason for switching. w/1.48 gear it was only turning about 6300-6500 rpms.so by switching to a 1.76 should pick me up some rpm`s motor made peak hp/torq up around 7200 rpms..

[Hutch]

I thought you may have been geared for optimal rpm/wheel speed with the 1.48 and the switch would include axle ratios etc.
You will have a bunch more rpm now.

Take care ,Hutch

[muddytoy]

is there a way to figure out how much more rpm i will gain .

[Hutch]

The difference is 16 to 18% which would put you somewhere between 72-7500 rpm with the same wheel speed depending on converter slip.
Looks like you will be right where you want to be.

Take care ,Hutch