Doctor Diff 8 3/4 Sure Grip

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512Stroker

512Stroker

We are all here because we are not all there.
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I am in need of a new Sure Grip section for my 489 case 8 3/4
Does anyone have experience with the Sure Grip replacement that the Doc is selling for $395 ?
Or has anybody used one his $185 ring and pinion sets?
Thanks in advance
 
I just received my gears from Doctor Diff this week, I am not sure what the difference is between Motive/Richmond Gear is, but the box is full on Richmond with their part number on it. If you look at a comparable Motive/Richmond on Summit, Cass at Doctor Diff is less money too.

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Can't speak to the sure grip as I get his spool but the ring and pinion hold up no issues running 10's anyways. Just put together his complete set up including new super duty case.

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scampy said:
Can't speak to the sure grip as I get his spool but the ring and pinion hold up no issues running 10's anyways. Just put together his complete set up including new super duty case.

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Thanks for the come back.
I will be running a set of the Doc's 3:55 gears on the street. Do they run pretty quiet?
 
512Stroker said:
Thanks for the come back.
I will be running a set of the Doc's 3:55 gears on the street. Do they run pretty quiet?
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Yes.
I have a set in my Dart Sport that I bought from Cass and have run them for 5 years now with no issues.
They are pretty quiet IMHO, and haven't changed one bit..........
 
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And Cass (Dr Diff) is a nice guy and always willing to help. He sells great quality products and has the personal service to back them up.
 
I bought a 8 3/4 housing and axles from Dr Diff. Been running those for years with a used 3.55 suregrip.

I ordered 3.73 gears, bearing/seal kit, and a sure grip clutch rebuild kit last month to rebuild the tired howling 3.55 diff.
 
I just rebuilt a 8.75 with a 741 using the Powr-Lok. Looks like a well made unit and I got all my stuff from Cass. Yes nice guy and shipped quickly. I’ll know how it works in a few weeks.
 
I have nothing but good things to say about Cass (dr. diff). I've used 2 of his sure grips and highly recommend them. As for gears, I think I read Motive was bought out by Richmond (or vise-versa). I've used both in the past. Always had good luck setting up Richmond. The Motive set I did was the first new setup I did and had a little trouble but I was a newbie and didn't understand everything about setting them up. First drive they howled pretty bad. Took them back apart and re-tried and that time they barely made a noise. If I would have got it right the first time they would have probably been completely quiet
 
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512Stroker said:
I am in need of a new Sure Grip section for my 489 case 8 3/4
Does anyone have experience with the Sure Grip replacement that the Doc is selling for $395 ?
Or has anybody used one his $185 ring and pinion sets?
Thanks in advance
Click to expand...
Bought this one (Powr-lok, which is the one you’re referring to?) and a set of 4.10’s from him. He said the Motive Gear and Richmond gear sets are the same manufacturer. Only the box may be different, I’m using a 10 spline pinion and he mentioned 10 splines will be Richmond, although it may be in a Motive box, iirc. Basically makes no difference what the name on the box is. Pretty sure they’re made in Italy. Use the Ford additive and weight lube he recommends if you can find it, and good to go. Only very very rarely, (on first trip out somewhere) making a sharp turn I get a little clunk from the Powr-lok but again, very rarely and only once then there’s no noise. Spend the extra time to get as perfect patterns as you can when setting up the gears
 
Cass is great to deal with! Bought a Powr Lok from him, been running it behind my 410 for several years,beating on it constantly, and no issues!

 
About a month ago I read about a lot of grief people were having with Richmond and Motive gear quality. It is in this section. Also saw a video of the US Gear factory making the gears. Really complex machinery.
 
Nothing but only good things to say about him. Helped this rookie out to the point where I was being obnoxious. However don’t ask him for one of his decals. Now I know why.:poke:
 
I met Cass when I was down in Polson, Montana last summer on holidays.
He is as great of a guy and as helpful in person as he is on the phone.
He showed me around a bit and we talked for an hour or so.
I saw some really cool stuff he had in stock (kind of a tour), like a complete S60 rear end for an E-Body that someone ordered and a crate of BBP 8 3/4'' A Body axles that he bought and then sends them out to the customers when ordered.
Impressive to say the least.
He had a lot of gear sets, bearings, housing ends, etc. all ready and ready to ship and in stock on the shelves.
He has a lot of inventory, and he's right on it to ship it out.
He was busy taking several phone calls and orders while I was there chatting with him and exchanging ideas, and he was very personable at all times.

To me, It goes a long way to have time for customers and to talk Mopars etc. from such a busy guy who knows his stuff to a guy who just ''walked in'' to buy a few parts.

I doubt that I would deal with anyone else..........
 
Thanks to everyone that responded.
I ordered from Doc a new Sure Grip carrier, bearing and seal kit and new 3:55 ring and pinion.
Parts shipped same day that I ordered them.
Good, fast service
 
Well here it is ready to go in the housing.
New Motive Gear 3:55 ring and pinion, new Sure Grip carrier, all new bearings and crush sleeve eliminator. Gear pattern is the best I have seen in a very long time.

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I've done several diffs but, that looks little close to the heel (shallow). I'm kind of a perfectionist when it comes to gears, I want it the best I can get. I would maybe move the pinon gear in a little to the ring gear. What is the backlash at. Backlash might be a little tight. What is it set at? I'm sure one of the experts will chime in. My 2 cents Craig.
 
my5thmopar said:
I've done several diffs but, that looks little close to the heel (shallow). I'm kind of a perfectionist when it comes to gears, I want it the best I can get. I would maybe move the pinon gear in a little to the ring gear. What is the backlash at. Backlash might be a little tight. What is it set at? I'm sure one of the experts will chime in. My 2 cents Craig.
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I thought it looked good
Backlash is good
 
There are quite a few acceptable pattern locations based on all the examples in manuals and instruction sheets I’ve seen. Looks good to me. :thumbsup:
 
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