Box4VIR

I have a racing/HPDE buddy who is looking for a differential for his 981. There doesn’t seem to be a lot of options, I see that Deman makes one. I don’t have any experience with them, any feedback on their diffs? Any alternatives you’d recommend?

cheers,

Rick DeMan

PDK or Manual trans?

We manufacture both, in stock and ready to ship. Installation available.

981/911

If you have a Deman diff it needs to be examined for a defect which can lead to a catastrophic failure. After purchasing Rick Deman's new limited slip differential my transmission case exploded after five twenty-five-minute sessions. The axles were able to float inward resulting in compression of the trans case by both hubs. A video of the mechanism of failure was sent to Rick, he would not respond to phone calls or emails. One month later, I identified another defective LSD and asked that customer send documentation to Rick. He agreed there was a machining omission of the output shaft snap rings landing area". He would "have replacement parts made". I shared my expenses with Rick before ordering my new trans and he offered his sincere apologies stating "DEMAN MOTORSPORTS would reimburse me for my loss in this situation. Our first batch of diffs were NOT made with that clip groove missing. The proper parts are being sent and I will recall them all. Hopefully there are no other damaged trans because of it, but we will make them all right". Said he was sending a spacer which also should have been installed.

Three weeks later he decided I should return the trans to Porsche, have my core charge refunded, break the new install agreement and let him install one cheaper. He would do a review and get back to me". Refunded the diff after the day he received a certified letter. Then again, no response to multiple phone calls and emails about transmission reimbursement. Gets a 0 out of 5 stars.

Rick DeMan

Facts of this situation.
There are ZERO issues with ANY of the LSD's that are installed and being used right now.
This was isolated to a NEW batch of LDS's that were missing a spacer that the manufacturer omitted, Sale #1 was Glenn Spiegler and # 2 was Tim Curl. Tim has stated on here that his product works as advertised and ZERO issues.

DeMan Motorsport requested the customer bring the car and or trans to us after failure for us to figure out the problem. He ignored and declined. We have the communication to show that
The customer spent the next 3 weeks sending pictures with his diagnostic follies of reasons why and NONE were accurate or applicable.

The original poster listed his DeMan Motorsport LSD for sale!! Why would he try and sell it if he thought it was a problem...??
Another purchaser of our diff Tim Curl reached out to Glenn to ask why he was selling it and in that conversation Tim was able to verify with his install what Glenn not able to find out.

After my conversation with Tim, we dug in and found the issue and resolved with in short order.

When I got back to Glenn about the issue and that we would get it resolved and I wanted to send my truck and trailer to Pick up his car and repair it, I was told that he already made arrangements for a PORSCHE dealer to install a Factory remanufactured unit in his car at RETAIL pricing close to $20K and he expected me to cover that and every expense he incurred including track time lost.
We refunded his purchase for the LSD.

I advised him I would not pay a retail Porsche shop to install his trans and I would come get it, he said "its too late, I've already paid for it'

The original poster has decided to go into public forums and be dishonest by making statements saying there are problems with our product.

All of this is really not an issue for public discussion and the opinions instantly calling DeMan Motorsport "dishonest" and "bad customer service" are rather uncalled for.

Once we figured out the issue we resolved it immediately for Tim Curl and we always make things right.

981/911

My transmission failed on 3/19, my first day running my new LSD. I sent two emails with initial thoughts to Rick which he replied to, then on 3/29 after finding the problem I sent a video demonstrating what I believed had happened. and asked for his opinion. He did not reply to emails and phone calls until 4/21 when I discovered another case, Tim. On 4/21 Tim sent documentation to Rick and Rick contacted me.stating HE had dissected the issues and HE "discovered a machining omission of the output shafts snap ring landing area: The inner half of the snap ring groove was machined away and therefore the output shaft is allowed to travel inward without a stopper. Replacement parts would be made.
Prior to 4/21, after no response to my video or phone calls, I was missing the racing season and I made arrangements. with a highly thought of Porsche only shop, not a dealer. I paid $13089 for the trans and a $6000 core charge, install fee pending, to the shop who placed the order. The diff was listed for sale with full disclosure about the transmission failure to Tim in the add and by direct communication. I sent him photos of the broken case and diff. I was not sure about the mechanism of failure at that point. He had his car on the lift and was able to confirm my ideas prior to being on track. In another 4/21 email you said "the axles were allowed to travel inward without a stopper." Then you said you would send a spacer and I declined. I was committed to the other shop and made that clear in emails.
On 4/21 you apologized saying "Deman would reimburse me for my loss in this situation. Our first batch of these diffs were NOT made with the clip groove missing. The proper parts are being sent and I will recall them all. 5 of the current batch of LSD's are installed and in use currently. Hopefully there are no other damaged trans because of it. But we will make them all right." I thanked you and stated I would compile an itemized list of expenses.
On 5/8 you sent an email "how is this coming along? I told you everything was in and install on 5/12. Then you emailed you wanted to send a truck to pick up my car and I should return the trans, get a core refund and cancel on the shop who cleared their sch to help me. I said I would have accepted at the beginning, but it is too late now., everything was paid. You then changed your mind saying you would "only reimburse me for what your costs would be."
5/24 I sent you an itemized bill which included the diff return and shipped the diff back. After more unanswered communications again on 6/7 you sent "I am reviewing the info and situation and will be in touch."
On 6/16 I asked if your review was complete?
On 6/23 I sent a certified letter asking for a decision, with still not one phone call returned.
On 6/27 you responded the diff was refunded. I have tried to ask about the trans reimbursement and until now you have not responded or fulfilled your offers.
You told me this was a "machining omission of the output shafts snap rings. The inner half of the snap ring groove was machined away." Replacement parts are being made. That is why I used the term "defective diff". What would you call it? If it was that the spacer was inadvertently left out and it was not over reamed as you stated, please let us know. Then it could be possible my transmission failed due to the spacer being left out. I have no idea if there will be "future Issues". Thought the workmanship looked good. I posted because you would not respond and I felt a responsibility. to the 5 customers. that YOU mentioned. You said it failed because I was a "home mechanic" and never an issue with 100 sold".
I am not being dishonest. I was the first to diagnose this problem, found Tim prior to further problems and alerted you to recall the 5 you said were out there. You should appreciate my catching it before you shipped more out. You initially shouldered the responsibility, and I thanked you by saying you "restored the faith" and " thank you for standing behind your product". Then when the figures came out you changed, from full reimbursement to only what it would cost you, to only a diff refund.. What would your expenses have been to do the transmission replacement? Make a reasonable offer and I will compromise. Here and now or email me.
I hope it does well in the future as PDK owner need it.


981/911 is offline Report Post

Rick DeMan

OK, so all of the people who are qualified to install a diff, watch the attached video provided by Glenn Speigler. If you are not qualified to install a diff, show this video to your mechanic and ask him if this diff was installed correctly.

For the diff to move back and forth in the housing as shown in the video has NOTHING to do with the diff itself, this was installed by the original poster and he did NOT check to see if it fit correctly. This is installer error and the cause of his housing to get destroyed. It is the installers responsibility to check and insure correct fitment.

Also, Glenn's timeline leaves out the TRUTH very conveniently, plug into the timeline that DeMan Motorsport on 3/24 Requested that if Glenn thought there was a problem with the diff please return it for inspection. That was ignored and the Diff was put up for sale!!

981/911

The video Rick posted was after the case fracture. The diff was put back in the broken case to see what the preload would look like. Upon insertion the preload was not like this post installation. I have a video which is too large to post I will have to try and edit it. It shows the axles sinking into the diff because of the missing spacer. This fractured the case and may have damaged the bearings which I was trying to determine, but the case it was sitting in was also fractured. This had nothing to do with preload or installation which was confirmed by Tim Curl‘s post on Rennlist and confirmed by Rick in the above post by me. Do you think the differential perform properly with no spacer between the axles? Do you believe I drove five sessions at Vir with this amount of preload and didn’t blow up in the first 30 seconds?

Rick DeMan

This broken part has nothing to do with preload of the diff in ANY way...

981/911

This video demonstrates (without the spacer) the inward movement of the axles. The axle movement is not a duplicate of the original tolerances and compressed the case on both sides with the hubs, initiating a cascade of failure. Please note the condition of the ring gear and bearing- if it was driven for five sessions (200 miles) with the preload that was shown, the gear and bearings would’ve been significantly damaged and would not have performed normally. The preload was correct and the construct was sound until failure of the PDK housing neck, diff cover outer and inner case fragmentation when the stub axles were pushed in at 130mph. I expressed concerns regarding the case not being accepted as a core. It was the result of the inner axle movement (as demonstrated in the video) not the cause of it. Tim had the same inward movement of the axle hubs rubbing both sides of the case, please see his pictures. He clearly states that without the spacer, his hubs would have cracked his case as well. He had the same problem! Did he have preload issues also as the cause? Without the spacer, when on track the axle transverse load is not supported or transferred ,to the other axle as intended. The forces are transferred by the portion of the axle above the black line(video) making impact with the diff, loading the bearing eccentrically on the contralateral side, instead of transferring the force through the bushing to the contralateral axle centrally. It is an unrestricted inner movement of both axles until contact is made where it shouldn’t be. Argue when the preload failed all you want, but unrestricted inner axle inward movement would be a poor design, that is why a spacer was created in the first place. It seems that a spacer was left out of 5 diffs. Ownership of any portion of this scenario wouldn't have been a big deal and we would not be having this conversation publicly. If this diff is being driven without the spacer around town it is dangerous. It may survive briefly, but if put on track (in my experience) would last approximately 2.5 hours. I have never posted about a vendor problem online, actually have never had one and have only done so out of frustration about this business interaction. Should have done my homework better, did not check Yelp.
If you purchase a new motor that blew because they left out a connecting rod nut, most would object to being mailed the nut.

Surfndav

I'm looking forward to installing one of these in my 987.2 PDK car soon. I have an appointment to have the car caged, so that will take a few weeks first. I have a Porsche Indy shop with a Porsche-certified mechanic who says he has done this installation. When the time comes I will have him get with Deman and discuss any details. 981/991, I'm sorry you've had problems, but Deman has a very good reputation, he seems to be working in good faith. Let it go.

My profile pic is my wife's car, I get to drive it too, but my Cayman is going to be a race car....Soon.

Snowy999

my Deman LSD in a Cayman GT4 is excellent. Small increase in diff noise; much much better performance in hairpins. IN stalled by a leading specialist in the UK and the commented that they were impressed by the quality of the build and it fitted perfectly.. My OEM LSD failed when the cross shaft broke. On examination the ends of the shaft had developed small hairline cracks and one of the ends broke andthen they all did. I have read about this elsewhere on a high mileage GT4, so maybe as you all use and love your cars, there will be a big market for these great products.