Moparts Tech Archive
Spraque or Over Running ClutchHow do I install a bolt in sprag?
I have just recieved a bolt in sprag from J.W Performance for my 727. There are no installation instructions with it, so before I call them I thought I'd ask you guys what the procedure is. What has me confused is the 4 brass rings ( they look like the olives from a compression fitting), they look as if they fit into the chamfered bolt holes on the rear of the sprag, is this correct? Do you then press the sprag into the case then carefully drill through the bolt holes? I have seen an installation tool mentioned, is that what I am missing here? Also, whilst checking through the topics, I noticed someone say they were going to use an aluminium front drum on the street, is this possible? I assumed this was a race only mod, as surely the band would gall the drum in no time? Thanks in advance, this is a great site with some very knowledgable people ! More power to ya!
After removing the original, check the alignment of the bolts in the cam to the holes in the case. Ream as necessary. The brass bushings center the bolts in the case. You can press or use the bolts to pull the cam into the case. As for the aluminum drum on the street, I say no, but others may have a different opinion.
Thanks for that leigh! I haven't pulled the 'box apart yet, so I'm just makeing sure I know what I'm doing before I start. I have heard some people have modified the venting of the box by plugging the stock one and drilling a new one towards the rear of the case, is this required, and for what reason? I have 2 727's to go through, 1 for myself and the other for a friends '73 charger, both of us are looking to run high 10's next year so any tips for better performance, or safety would be appreciated! At present both 'boxes are identical, have been rebuilt and modified with B&M Transkits, run Cheetah manual valve bodies and deep pans. Both will get the bolt in sprags, and I will fit a low gear set to the Charger to try and get that 3800lb brick moveing! I'm thinking lightened sunshells, is that something I could do myself? Thanks for listening !!
It sounds like the current build up is very useable. The bolt in cam is a plus. I've never installed a rear vent, but know it is a must on the pro tree type vented front clutch T/A style trans brake. Have you priced the low gear set? SPENDY. If $ isn't an issue, or you simply want it , I say go for it! Either way, good building, and let us know how they turn out at the race track.
We already have the low gear set, my mate picked it up when he was in the States a couple of weeks ago. I agree, you can certainly get rid of a lot of money on transmission parts, worse for us of course, there's that small problem of getting the stuff across that 3000 miles of pond... Weather won't be good enough now to race till about March or April, so we've a while to get things sorted. I'll keep you posted! Thanks for your help!
I installed a bolt in sprag from Rick at A&A transmissions. I just used the bolts to pull it into the case. Make sure you work it in even.
If you are looking for some trans mods. Go to my website. Click on the "Tech" page, then scroll down and click on the "Trans Mod Tips". I collected these from other people.
There are a couple of different configurations of the bolt in sprag, here's the instructions from one type. This was posted before by John Russo I believe.
Thanks for posting those instructions John, it all makes sense now, I was assumeing that new bolt holes had to be drilled , I didn't realise it used the exsisting rear support bolt holes!
Jobs done! that was easy! the rest of the box was in good order with only a little wear on the clutch packs. I was wondering how many runs could you expect to see before it needs freshening, it is in a 3900LB Charger making around 570 HP on the bottle.